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+Project Gutenberg's Flying Machines, by W.J. Jackman and Thos. H. Russell
+
+This eBook is for the use of anyone anywhere at no cost and with
+almost no restrictions whatsoever.  You may copy it, give it away or
+re-use it under the terms of the Project Gutenberg License included
+with this eBook or online at www.gutenberg.org
+
+
+Title: Flying Machines
+       Construction and Operation
+
+Author: W.J. Jackman and Thos. H. Russell
+
+Posting Date: July 26, 2008 [EBook #907]
+Release Date: May, 1997
+
+Language: English
+
+Character set encoding: ASCII
+
+*** START OF THIS PROJECT GUTENBERG EBOOK FLYING MACHINES ***
+
+
+
+
+Produced by Charles Keller
+
+
+
+
+
+FLYING MACHINE: CONSTRUCTION AND OPERATION
+
+By W.J. Jackman and Thos. H. Russell
+
+
+A Practical Book Which Shows, in Illustrations, Working Plans and Text,
+How to Build and Navigate the Modern Airship.
+
+W.J. JACKMAN, M.E., Author of "A B C of the Motorcycle," "Facts for
+Motorists," etc. etc.
+
+and
+
+THOS. H. RUSSELL, A.M., M.E., Charter Member of the Aero Club of
+Illinois, Author of "History of the Automobile," "Motor Boats:
+Construction and Operation," etc. etc.
+
+With Introductory Chapter By Octave Chanute, C.E., President Aero Club
+of Illinois
+
+1912
+
+
+
+
+PREFACE.
+
+This book is written for the guidance of the novice in aviation--the
+man who seeks practical information as to the theory, construction and
+operation of the modern flying machine. With this object in view the
+wording is intentionally plain and non-technical. It contains some
+propositions which, so far as satisfying the experts is concerned, might
+doubtless be better stated in technical terms, but this would defeat the
+main purpose of its preparation. Consequently, while fully aware of its
+shortcomings in this respect, the authors have no apologies to make.
+
+In the stating of a technical proposition so it may be clearly
+understood by people not versed in technical matters it becomes
+absolutely necessary to use language much different from that which an
+expert would employ, and this has been done in this volume.
+
+No man of ordinary intelligence can read this book without obtaining
+a clear, comprehensive knowledge of flying machine construction and
+operation. He will learn, not only how to build, equip, and manipulate
+an aeroplane in actual flight, but will also gain a thorough
+understanding of the principle upon which the suspension in the air of
+an object much heavier than the air is made possible.
+
+This latter feature should make the book of interest even to those who
+have no intention of constructing or operating a flying machine. It will
+enable them to better understand and appreciate the performances of the
+daring men like the Wright brothers, Curtiss, Bleriot, Farman, Paulhan,
+Latham, and others, whose bold experiments have made aviation an
+actuality.
+
+For those who wish to engage in the fascinating pastime of construction
+and operation it is intended as a reliable, practical guide.
+
+It may be well to explain that the sub-headings in the articles by Mr.
+Chanute were inserted by the authors without his knowledge. The purpose
+of this was merely to preserve uniformity in the typography of the book.
+This explanation is made in justice to Mr. Chanute.
+
+THE AUTHORS.
+
+
+
+
+IN MEMORIAM.
+
+Octave Chanute, "the father of the modern flying machine," died at his
+home in Chicago on November 23, 1910, at the age of 72 years. His last
+work in the interest of aviation was to furnish the introductory chapter
+to the first edition of this volume, and to render valuable assistance
+in the handling of the various subjects. He even made the trip from his
+home to the office of the publishers one inclement day last spring,
+to look over the proofs of the book and, at his suggestion, several
+important changes were made. All this was "a labor of love" on Mr.
+Chanute's part. He gave of his time and talents freely because he was
+enthusiastic in the cause of aviation, and because he knew the authors
+of this book and desired to give them material aid in the preparation of
+the work--a favor that was most sincerely appreciated.
+
+
+The authors desire to make acknowledgment of many courtesies in the way
+of valuable advice, information, etc., extended by Mr. Octave Chanute,
+C. E., Mr. E. L. Jones, Editor of Aeronautics, and the publishers of,
+the New England Automobile Journal and Fly.
+
+
+
+
+CONTENTS
+
+Chapter
+
+   I.    Evolution of the Two-Surface Flying Machine
+             Introductory Chapter by Octave Chanute, C. E.
+   II.   Theory Development and Use
+             Origin of the Aeroplane--Developments by Chanute
+             and the Wrights--Practical Uses and Limits.
+   III.  Mechanical Bird Action
+             What the Motor Does--Puzzle in Bird Soaring.
+   IV.   Various Forms of Flying Machines
+             Helicopters, Ornithopters and Aeroplanes--
+             Monoplanes, Biplanes and Triplanes.
+   V.    Constructing a Gliding Machine
+             Plans and Materials Required--Estimate of Cost--
+             Sizes and Preparation of Various Parts--Putting the
+             Parts Together
+   VI.   Learning to Fly
+             How to Use the Glider--Effect of Body Movements
+             --Rules for Beginners--Safest Place to Glide.
+   VII.  Putting On the Rudder
+             Its Construction, Application and Use.
+   VIII. The Real Flying Machine
+             Surface Area Required--Proper Size of Frame and
+             Auxiliaries--Installation of Motor--Cost of
+             Constructing Machine.
+   IX.   Selection of the Motor
+             Essential Features--Multiplicity of Cylinders--Power
+             Required--Kind and Action of Propellers--Placing
+             of the Motor
+   X.    Proper Dimensions of Machines
+             Figuring Out the Details--How to Estimate Load
+             Capacity--Distribution of the Weight--Measurements
+             of Leading Machines.
+   XI.   Plane and Rudder Control
+             Various Methods in Use--Wheels and Hand and
+             Foot Levers
+   XII.  How to Use the Machine
+             Rules of Leading Aviators--Rising from the Ground
+             --Reasonable Altitude--Preserving Equilibrium--
+             Learning to Steer.
+   XIII. Peculiarities of Aeroplane Power
+             Pressure of the Wind--How to Determine Upon
+             Power--Why Speed Is Required--Bird find Flying
+             Machine Areas.
+   XIV.  About Wind Currents, Etc.
+             Uncertainty of Direct Force--Trouble With Gusty
+             Currents--Why Bird Action Is Imitated.
+   XV.   The Element of Danger
+             Risk Small Under Proper Conditions--Two Fields
+             of Safety--Lessons in Recent Accidents.
+   XVI.  Radical Changes Being Made
+             Results of Recent Experiments--New Dimensions
+             --Increased Speed--The One Governing Rule.
+   XVII. Some of the New Designs
+             Automatic Control of Plane Stability--Inventor
+             Herring's Devices--Novel Ideas of Students.
+   XVIII. Demand for Flying Machines
+             Wonderful Results in a Year--Factories Over-
+             crowded with Orders.
+   XIX.   Law of the Airship
+             Rights of Property Owners--Some Legal
+             Peculiarities--Danger of Trespass.
+   XX.     Soaring Flight
+   XXI.    Flying Machines vs. Balloons
+   XXII.   Problems of Aerial Flight
+   XXIII.  Amateurs May Use Wright Patents
+   XXIV.   Hints on Propeller Construction
+   XXV.    New Motors and Devices
+   XXVI.   Monoplanes, Triplanes, Multiplanes
+   XXVII.  Records of Various Kinds
+
+
+
+
+FLYING MACHINES: CONSTRUCTION and OPERATION
+
+
+
+
+CHAPTER I. EVOLUTION OF TWO-SURFACE FLYING MACHINE.
+
+By Octave Chanute.
+
+
+I am asked to set forth the development of the "two-surface" type of
+flying machine which is now used with modifications by Wright Brothers,
+Farman, [1] Delagrange, Herring and others.
+
+This type originated with Mr. F. H. Wenham, who patented it in
+England in 1866 (No. 1571), taking out provisional papers only. In the
+abridgment of British patent Aeronautical Specifications (1893) it is
+described as follows:
+
+"Two or more aeroplanes are arranged one above the other, and support a
+framework or car containing the motive power. The aeroplanes are made of
+silk or canvas stretched on a frame by wooden rods or steel ribs. When
+manual power is employed the body is placed horizontally, and oars or
+propellers are actuated by the arms or legs.
+
+"A start may be obtained by lowering the legs and running down hill or
+the machine may be started from a moving carriage. One or more screw
+propellers may be applied for propelling when steam power is employed."
+
+On June 27, 1866, Mr. Wenham read before the "Aeronautical Society of
+Great Britain," then recently organized, the ablest paper ever presented
+to that society, and thereby breathed into it a spirit which has
+continued to this day. In this paper he described his observations of
+birds, discussed the laws governing flight as to the surfaces and power
+required both with wings and screws, and he then gave an account of his
+own experiments with models and with aeroplanes of sufficient size to
+carry the weight of a man.
+
+Second Wenham Aeroplane.
+
+His second aeroplane was sixteen feet from tip to tip. A trussed spar at
+the bottom carried six superposed bands of thin holland fabric fifteen
+inches wide, connected with vertical webs of holland two feet apart,
+thus virtually giving a length of wing of ninety-six feet and one
+hundred and twenty square feet of supporting surface. The man was placed
+horizontally on a base board beneath the spar. This apparatus when tried
+in the wind was found to be unmanageable by reason of the fluttering
+motions of the fabric, which was insufficiently stiffened with crinoline
+steel, but Mr. Wenham pointed out that this in no way invalidated
+the principle of the apparatus, which was to obtain large supporting
+surfaces without increasing unduly the leverage and consequent weight of
+spar required, by simply superposing the surfaces.
+
+This principle is entirely sound and it is surprising that it is,
+to this day, not realized by those aviators who are hankering for
+monoplanes.
+
+Experiments by Stringfellow.
+
+The next man to test an apparatus with superposed surfaces was Mr.
+Stringfellow, who, becoming much impressed with Mr. Wenham's proposal,
+produced a largish model at the exhibition of the Aeronautical Society
+in 1868. It consisted of three superposed surfaces aggregating 28 square
+feet and a tail of 8 square feet more. The weight was under 12 pounds
+and it was driven by a central propeller actuated by a steam engine
+overestimated at one-third of a horsepower. It ran suspended to a wire
+on its trials but failed of free flight, in consequence of defective
+equilibrium. This apparatus has since been rebuilt and is now in the
+National Museum of the Smithsonian Institution at Washington. Linfield's
+Unsuccessful Efforts.
+
+In 1878 Mr. Linfield tested an apparatus in England consisting of a
+cigar-shaped car, to which was attached on each side frames five feet
+square, containing each twenty-five superposed planes of stretched and
+varnished linen eighteen inches wide, and only two inches apart, thus
+reminding one of a Spanish donkey with panniers. The whole weighed two
+hundred and forty pounds. This was tested by being mounted on a flat car
+behind a locomotive going 40 miles an hour. When towed by a line fifteen
+feet long the apparatus rose only a little from the car and exhibited
+such unstable equilibrium that the experiment was not renewed. The lift
+was only about one-third of what it would have been had the planes been
+properly spaced, say their full width apart, instead of one-ninth as
+erroneously devised.
+
+Renard's "Dirigible Parachute."
+
+In 1889 Commandant Renard, the eminent superintendent of the French
+Aeronautical Department, exhibited at the Paris Exposition of that year,
+an apparatus experimented with some years before, which he termed a
+"dirigible parachute." It consisted of an oviform body to which were
+pivoted two upright slats carrying above the body nine long superposed
+flat blades spaced about one-third of their width apart. When this
+apparatus was properly set at an angle to the longitudinal axis of the
+body and dropped from a balloon, it travelled back against the wind for
+a considerable distance before alighting. The course could be varied
+by a rudder. No practical application seems to have been made of this
+device by the French War Department, but Mr. J. P. Holland, the
+inventor of the submarine boat which bears his name, proposed in 1893
+an arrangement of pivoted framework attached to the body of a flying
+machine which combines the principle of Commandant Renard with the
+curved blades experimented with by Mr. Phillips, now to be noticed, with
+the addition of lifting screws inserted among the blades.
+
+Phillips Fails on Stability Problem.
+
+In 1893 Mr. Horatio Phillips, of England, after some very interesting
+experiments with various wing sections, from which he deduced
+conclusions as to the shape of maximum lift, tested an apparatus
+resembling a Venetian blind which consisted of fifty wooden slats of
+peculiar shape, 22 feet long, one and a half inches wide, and two inches
+apart, set in ten vertical upright boards. All this was carried upon a
+body provided with three wheels. It weighed 420 pounds and was driven
+at 40 miles an hour on a wooden sidewalk by a steam engine of nine
+horsepower which actuated a two-bladed screw. The lift was satisfactory,
+being perhaps 70 pounds per horsepower, but the equilibrium was quite
+bad and the experiments were discontinued. They were taken up again in
+1904 with a similar apparatus large enough to carry a passenger, but the
+longitudinal equilibrium was found to be defective. Then in 1907 a new
+machine was tested, in which four sets of frames, carrying similar
+sets of slat "sustainers" were inserted, and with this arrangement the
+longitudinal stability was found to be very satisfactory. The whole
+apparatus, with the operator, weighed 650 pounds. It flew about 200
+yards when driven by a motor of 20 to 22 h.p. at 30 miles an hour,
+thus exhibiting a lift of about 32 pounds per h.p., while it will be
+remembered that the aeroplane of Wright Brothers exhibits a lifting
+capacity of 50 pounds to the h.p.
+
+Hargrave's Kite Experiments.
+
+After experimenting with very many models and building no less than
+eighteen monoplane flying model machines, actuated by rubber, by
+compressed air and by steam, Mr. Lawrence Hargrave, of Sydney, New South
+Wales, invented the cellular kite which bears his name and made it known
+in a paper contributed to the Chicago Conference on Aerial Navigation
+in 1893, describing several varieties. The modern construction is well
+known, and consists of two cells, each of superposed surfaces with
+vertical side fins, placed one behind the other and connected by a
+rod or frame. This flies with great steadiness without a tail. Mr.
+Hargrave's idea was to use a team of these kites, below which he
+proposed to suspend a motor and propeller from which a line would be
+carried to an anchor in the ground. Then by actuating the propeller the
+whole apparatus would move forward, pick up the anchor and fly away. He
+said: "The next step is clear enough, namely, that a flying machine with
+acres of surface can be safely got under way or anchored and hauled to
+the ground by means of the string of kites."
+
+The first tentative experiments did not result well and emphasized the
+necessity for a light motor, so that Mr. Hargrave has since been engaged
+in developing one, not having convenient access to those which have been
+produced by the automobile designers and builders.
+
+Experiments With Glider Model.
+
+And here a curious reminiscence may be indulged in. In 1888 the present
+writer experimented with a two-cell gliding model, precisely similar to
+a Hargrave kite, as will be confirmed by Mr. Herring. It was frequently
+tested by launching from the top of a three-story house and glided
+downward very steadily in all sorts of breezes, but the angle of descent
+was much steeper than that of birds, and the weight sustained per square
+foot was less than with single cells, in consequence of the lesser
+support afforded by the rear cell, which operated upon air already set
+in motion downward by the front cell, so nothing more was done with
+it, for it never occurred to the writer to try it as a kite and he thus
+missed the distinction which attaches to Hargrave's name.
+
+Sir Hiram Maxim also introduced fore and aft superposed surfaces in his
+wondrous flying machine of 1893, but he relied chiefly for the lift upon
+his main large surface and this necessitated so many guys, to prevent
+distortion, as greatly to increase the head resistance and this,
+together with the unstable equilibrium, made it evident that the design
+of the machine would have to be changed.
+
+How Lilienthal Was Killed.
+
+In 1895, Otto Lilienthal, the father of modern aviation, the man to
+whose method of experimenting almost all present successes are due,
+after making something like two thousand glides with monoplanes, added
+a superposed surface to his apparatus and found the control of it much
+improved. The two surfaces were kept apart by two struts or vertical
+posts with a few guy wires, but the connecting joints were weak and
+there was nothing like trussing. This eventually cost his most useful
+life. Two weeks before that distressing loss to science, Herr Wilhelm
+Kress, the distinguished and veteran aviator of Vienna, witnessed a
+number of glides by Lilienthal with his double-decked apparatus. He
+noticed that it was much wracked and wobbly and wrote to me after the
+accident: "The connection of the wings and the steering arrangement were
+very bad and unreliable. I warned Herr Lilienthal very seriously. He
+promised me that he would soon put it in order, but I fear that he did
+not attend to it immediately."
+
+In point of fact, Lilienthal had built a new machine, upon a different
+principle, from which he expected great results, and intended to make
+but very few more flights with the old apparatus. He unwisely made one
+too many and, like Pilcher, was the victim of a distorted apparatus.
+Probably one of the joints of the struts gave way, the upper surface
+blew back and Lilienthal, who was well forward on the lower surface, was
+pitched headlong to destruction.
+
+Experiments by the Writer.
+
+In 1896, assisted by Mr. Herring and Mr. Avery, I experimented with
+several full sized gliding machines, carrying a man. The first was a
+Lilienthal monoplane which was deemed so cranky that it was discarded
+after making about one hundred glides, six weeks before Lilienthal's
+accident. The second was known as the multiple winged machine and
+finally developed into five pairs of pivoted wings, trussed together at
+the front and one pair in the rear. It glided at angles of descent of 10
+or 11 degrees or of one in five, and this was deemed too steep. Then
+Mr. Herring and myself made computations to analyze the resistances. We
+attributed much of them to the five front spars of the wings and on
+a sheet of cross-barred paper I at once drew the design for a new
+three-decked machine to be built by Mr. Herring.
+
+Being a builder of bridges, I trussed these surfaces together, in order
+to obtain strength and stiffness. When tested in gliding flight the
+lower surface was found too near the ground. It was taken off and the
+remaining apparatus now consisted of two surfaces connected together
+by a girder composed of vertical posts and diagonal ties, specifically
+known as a "Pratt truss." Then Mr. Herring and Mr. Avery together
+devised and put on an elastic attachment to the tail. This machine
+proved a success, it being safe and manageable. Over 700 glides were
+made with it at angles of descent of 8 to 10 degrees, or one in six to
+one in seven.
+
+First Proposed by Wenham.
+
+The elastic tail attachment and the trussing of the connecting frame of
+the superposed wings were the only novelties in this machine, for the
+superposing of the surfaces had first been proposed by Wenham, but in
+accordance with the popular perception, which bestows all the credit
+upon the man who adds the last touch making for success to the labors
+of his predecessors, the machine has since been known by many persons as
+the "Chanute type" of gliders, much to my personal gratification.
+
+It has since been improved in many ways. Wright Brothers, disregarding
+the fashion which prevails among birds, have placed the tail in front
+of their apparatus and called it a front rudder, besides placing the
+operator in horizontal position instead of upright, as I did; and also
+providing a method of warping the wings to preserve equilibrium. Farman
+and Delagrange, under the very able guidance and constructive work of
+Voisin brothers, then substituted many details, including a box tail for
+the dart-like tail which I used. This may have increased the resistance,
+but it adds to the steadiness. Now the tendency in France seems to be to
+go back to the monoplane.
+
+Monoplane Idea Wrong.
+
+The advocates of the single supporting surface are probably mistaken. It
+is true that a single surface shows a greater lift per square foot than
+superposed surfaces for a given speed, but the increased weight due to
+leverage more than counterbalances this advantage by requiring heavy
+spars and some guys. I believe that the future aeroplane dynamic flier
+will consist of superposed surfaces, and, now that it has been found
+that by imbedding suitably shaped spars in the cloth the head resistance
+may be much diminished, I see few objections to superposing three, four
+or even five surfaces properly trussed, and thus obtaining a compact,
+handy, manageable and comparatively light apparatus. [2]
+
+
+
+CHAPTER II. THEORY, DEVELOPMENT, AND USE.
+
+
+While every craft that navigates the air is an airship, all airships are
+not flying machines. The balloon, for instance, is an airship, but it is
+not what is known among aviators as a flying machine. This latter term
+is properly used only in referring to heavier-than-air machines which
+have no gas-bag lifting devices, and are made to really fly by the
+application of engine propulsion.
+
+Mechanical Birds.
+
+All successful flying machines--and there are a number of them--are
+based on bird action. The various designers have studied bird flight
+and soaring, mastered its technique as devised by Nature, and the modern
+flying machine is the result. On an exaggerated, enlarged scale the
+machines which are now navigating the air are nothing more nor less than
+mechanical birds.
+
+Origin of the Aeroplane.
+
+Octave Chanute, of Chicago, may well be called "the developer of the
+flying machine." Leaving balloons and various forms of gas-bags out
+of consideration, other experimenters, notably Langley and Lilienthal,
+antedated him in attempting the navigation of the air on aeroplanes,
+or flying machines, but none of them were wholly successful, and it
+remained for Chanute to demonstrate the practicability of what was then
+called the gliding machine. This term was adopted because the apparatus
+was, as the name implies, simply a gliding machine, being without motor
+propulsion, and intended solely to solve the problem of the best form of
+construction. The biplane, used by Chanute in 1896, is still the basis
+of most successful flying machines, the only radical difference being
+that motors, rudders, etc., have been added.
+
+Character of Chanute's Experiments.
+
+It was the privilege of the author of this book to be Mr. Chanute's
+guest at Millers, Indiana, in 1896, when, in collaboration with Messrs.
+Herring and Avery, he was conducting the series of experiments which
+have since made possible the construction of the modern flying machine
+which such successful aviators as the Wright brothers and others are
+now using. It was a wild country, much frequented by eagles, hawks, and
+similar birds. The enthusiastic trio, Chanute, Herring and Avery, would
+watch for hours the evolutions of some big bird in the air, agreeing
+in the end on the verdict, "When we master the principle of that bird's
+soaring without wing action, we will have come close to solving the
+problem of the flying machine."
+
+Aeroplanes of various forms were constructed by Mr. Chanute with the
+assistance of Messrs. Herring and Avery until, at the time of the
+writer's visit, they had settled upon the biplane, or two-surface
+machine. Mr. Herring later equipped this with a rudder, and made other
+additions, but the general idea is still the basis of the Wright,
+Curtiss, and other machines in which, by the aid of gasolene motors,
+long flights have been made.
+
+Developments by the Wrights.
+
+In 1900 the Wright brothers, William and Orville, who were then in
+the bicycle business in Dayton, Ohio, became interested in Chanute's
+experiments and communicated with him. The result was that the Wrights
+took up Chanute's ideas and developed them further, making many
+additions of their own, one of which was the placing of a rudder in
+front, and the location of the operator horizontally on the machine,
+thus diminishing by four-fifths the wind resistance of the man's
+body. For three years the Wrights experimented with the glider before
+venturing to add a motor, which was not done until they had thoroughly
+mastered the control of their movements in the air.
+
+Limits of the Flying Machine.
+
+In the opinion of competent experts it is idle to look for a commercial
+future for the flying machine. There is, and always will be, a limit to
+its carrying capacity which will prohibit its employment for passenger
+or freight purposes in a wholesale or general way. There are some, of
+course, who will argue that because a machine will carry two people
+another may be constructed that will carry a dozen, but those who make
+this contention do not understand the theory of weight sustentation in
+the air; or that the greater the load the greater must be the lifting
+power (motors and plane surface), and that there is a limit to these--as
+will be explained later on--beyond which the aviator cannot go.
+
+Some Practical Uses.
+
+At the same time there are fields in which the flying machine may be
+used to great advantage. These are:
+
+Sports--Flying machine races or flights will always be popular by reason
+of the element of danger. It is a strange, but nevertheless a true
+proposition, that it is this element which adds zest to all sporting
+events.
+
+Scientific--For exploration of otherwise inaccessible regions such as
+deserts, mountain tops, etc.
+
+Reconnoitering--In time of war flying machines may be used to advantage
+to spy out an enemy's encampment, ascertain its defenses, etc.
+
+
+
+CHAPTER III. MECHANICAL BIRD ACTION
+
+In order to understand the theory of the modern flying machine one must
+also understand bird action and wind action. In this connection the
+following simple experiment will be of interest:
+
+Take a circular-shaped bit of cardboard, like the lid of a hat box, and
+remove the bent-over portion so as to have a perfectly flat surface with
+a clean, sharp edge. Holding the cardboard at arm's length, withdraw
+your hand, leaving the cardboard without support. What is the result?
+The cardboard, being heavier than air, and having nothing to sustain
+it, will fall to the ground. Pick it up and throw it, with considerable
+force, against the wind edgewise. What happens? Instead of falling to
+the ground, the cardboard sails along on the wind, remaining afloat so
+long as it is in motion. It seeks the ground, by gravity, only as the
+motion ceases, and then by easy stages, instead of dropping abruptly as
+in the first instance.
+
+Here we have a homely, but accurate illustration of the action of the
+flying machine. The motor does for the latter what the force of your arm
+does for the cardboard--imparts a motion which keeps it afloat. The only
+real difference is that the motion given by the motor is continuous and
+much more powerful than that given by your arm. The action of the latter
+is limited and the end of its propulsive force is reached within a
+second or two after it is exerted, while the action of the motor is
+prolonged.
+
+Another Simple Illustration.
+
+Another simple means of illustrating the principle of flying machine
+operation, so far as sustentation and the elevation and depression of
+the planes is concerned, is explained in the accompanying diagram.
+
+A is a piece of cardboard about 2 by 3 inches in size. B is a piece of
+paper of the same size pasted to one edge of A. If you bend the paper
+to a curve, with convex side up and blow across it as shown in Figure
+C, the paper will rise instead of being depressed. The dotted lines show
+that the air is passing over the top of the curved paper and yet, no
+matter how hard you may blow, the effect will be to elevate the paper,
+despite the fact that the air is passing over, instead of under the
+curved surface.
+
+In Figure D we have an opposite effect. Here the paper is in a curve
+exactly the reverse of that shown in Figure C, bringing the concave side
+up. Now if you will again blow across the surface of the card the action
+of the paper will be downward--it will be impossible to make it rise.
+The harder you blow the greater will be the downward movement.
+
+Principle In General Use.
+
+This principle is taken advantage of in the construction of all
+successful flying machines. Makers of monoplanes and biplanes alike
+adhere to curved bodies, with the concave surface facing downward.
+Straight planes were tried for a time, but found greatly lacking in the
+power of sustentation. By curving the planes, and placing the concave
+surface downward, a sort of inverted bowl is formed in which the air
+gathers and exerts a buoyant effect. Just what the ratio of the curve
+should be is a matter of contention. In some instances one inch to the
+foot is found to be satisfactory; in others this is doubled, and there
+are a few cases in which a curve of as much as 3 inches to the foot has
+been used.
+
+Right here it might be well to explain that the word "plane" applied to
+flying machines of modern construction is in reality a misnomer. Plane
+indicates a flat, level surface. As most successful flying machines have
+curved supporting surfaces it is clearly wrong to speak of "planes," or
+"aeroplanes." Usage, however, has made the terms convenient and, as they
+are generally accepted and understood by the public, they are used in
+like manner in this volume.
+
+Getting Under Headway.
+
+A bird, on first rising from the ground, or beginning its flight from
+a tree, will flap its wings to get under headway. Here again we have
+another illustration of the manner in which a flying machine gets under
+headway--the motor imparts the force necessary to put the machine into
+the air, but right here the similarity ceases. If the machine is to be
+kept afloat the motor must be kept moving. A flying machine will not
+sustain itself; it will not remain suspended in the air unless it is
+under headway. This is because it is heavier than air, and gravity draws
+it to the ground.
+
+Puzzle in Bird Soaring.
+
+But a bird, which is also heavier than air, will remain suspended, in a
+calm, will even soar and move in a circle, without apparent movement
+of its wings. This is explained on the theory that there are generally
+vertical columns of air in circulation strong enough to sustain a bird,
+but much too weak to exert any lifting power on a flying machine, It is
+easy to understand how a bird can remain suspended when the wind is
+in action, but its suspension in a seeming dead calm was a puzzle
+to scientists until Mr. Chanute advanced the proposition of vertical
+columns of air.
+
+Modeled Closely After Birds.
+
+So far as possible, builders of flying machines have taken what may
+be called "the architecture" of birds as a model. This is readily
+noticeable in the form of construction. When a bird is in motion its
+wings (except when flapping) are extended in a straight line at right
+angles to its body. This brings a sharp, thin edge against the air,
+offering the least possible surface for resistance, while at the same
+time a broad surface for support is afforded by the flat, under side of
+the wings. Identically the same thing is done in the construction of the
+flying machine.
+
+Note, for instance, the marked similarity in form as shown in the
+illustration in Chapter II. Here A is the bird, and B the general
+outline of the machine. The thin edge of the plane in the latter is
+almost a duplicate of that formed by the outstretched wings of the bird,
+while the rudder plane in the rear serves the same purpose as the bird's
+tail.
+
+
+
+CHAPTER IV. VARIOUS FORMS OF FLYING MACHINES.
+
+There are three distinct and radically different forms of flying
+machines. These are:
+
+Aeroplanes, helicopters and ornithopers.
+
+Of these the aeroplane takes precedence and is used almost exclusively
+by successful aviators, the helicopters and ornithopers having been
+tried and found lacking in some vital features, while at the same
+time in some respects the helicopter has advantages not found in the
+aeroplane.
+
+What the Helicopter Is.
+
+The helicopter gets its name from being fitted with vertical propellers
+or helices (see illustration) by the action of which the machine is
+raised directly from the ground into the air. This does away with the
+necessity for getting the machine under a gliding headway before
+it floats, as is the case with the aeroplane, and consequently the
+helicopter can be handled in a much smaller space than is required for
+an aeroplane. This, in many instances, is an important advantage, but it
+is the only one the helicopter possesses, and is more than overcome
+by its drawbacks. The most serious of these is that the helicopter is
+deficient in sustaining capacity, and requires too much motive power.
+
+Form of the Ornithopter.
+
+The ornithopter has hinged planes which work like the wings of a bird.
+At first thought this would seem to be the correct principle, and most
+of the early experimenters conducted their operations on this line. It
+is now generally understood, however, that the bird in soaring is in
+reality an aeroplane, its extended wings serving to sustain, as well as
+propel, the body. At any rate the ornithoper has not been successful in
+aviation, and has been interesting mainly as an ingenious toy. Attempts
+to construct it on a scale that would permit of its use by man in actual
+aerial flights have been far from encouraging.
+
+Three Kinds of Aeroplanes.
+
+There are three forms of aeroplanes, with all of which more or less
+success has been attained. These are:
+
+The monoplane, a one-surfaced plane, like that used by Bleriot.
+
+The biplane, a two-surfaced plane, now used by the Wrights, Curtiss,
+Farman, and others.
+
+The triplane, a three-surfaced plane This form is but little used,
+its only prominent advocate at present being Elle Lavimer, a Danish
+experimenter, who has not thus far accomplished much.
+
+Whatever of real success has been accomplished in aviation may be
+credited to the monoplane and biplane, with the balance in favor of
+the latter. The monoplane is the more simple in construction and, where
+weight-sustaining capacity is not a prime requisite, may probably be
+found the most convenient. This opinion is based on the fact that the
+smaller the surface of the plane the less will be the resistance offered
+to the air, and the greater will be the speed at which the machine
+may be moved. On the other hand, the biplane has a much greater plane
+surface (double that of a monoplane of the same size) and consequently
+much greater weight-carrying capacity.
+
+Differences in Biplanes.
+
+While all biplanes are of the same general construction so far as the
+main planes are concerned, each aviator has his own ideas as to the
+"rigging."
+
+Wright, for instance, places a double horizontal rudder in front, with
+a vertical rudder in the rear. There are no partitions between the
+main planes, and the bicycle wheels used on other forms are replaced by
+skids.
+
+Voisin, on the contrary, divides the main planes with vertical
+partitions to increase stability in turning; uses a single-plane
+horizontal rudder in front, and a big box-tail with vertical rudder at
+the rear; also the bicycle wheels.
+
+Curtiss attaches horizontal stabilizing surfaces to the upper plane;
+has a double horizontal rudder in front, with a vertical rudder
+and horizontal stabilizing surfaces in rear. Also the bicycle wheel
+alighting gear.
+
+
+
+CHAPTER V. CONSTRUCTING A GLIDING MACHINE.
+
+First decide upon the kind of a machine you want--monoplane, biplane,
+or triplane. For a novice the biplane will, as a rule, be found the
+most satisfactory as it is more compact and therefore the more easily
+handled. This will be easily understood when we realize that the surface
+of a flying machine should be laid out in proportion to the amount of
+weight it will have to sustain. The generally accepted rule is that 152
+square feet of surface will sustain the weight of an average-sized man,
+say 170 pounds. Now it follows that if these 152 square feet of surface
+are used in one plane, as in the monoplane, the length and width of this
+plane must be greater than if the same amount of surface is secured by
+using two planes--the biplane. This results in the biplane being more
+compact and therefore more readily manipulated than the monoplane, which
+is an important item for a novice.
+
+Glider the Basis of Success.
+
+Flying machines without motors are called gliders. In making a flying
+machine you first construct the glider. If you use it in this form it
+remains a glider. If you install a motor it becomes a flying machine.
+You must have a good glider as the basis of a successful flying machine.
+
+It will be well for the novice, the man who has never had any experience
+as an aviator, to begin with a glider and master its construction and
+operation before he essays the more pretentious task of handling a
+fully-equipped flying machine. In fact, it is essential that he should
+do so.
+
+Plans for Handy Glider.
+
+A glider with a spread (advancing edge) of 20 feet, and a breadth or
+depth of 4 feet, will be about right to begin with. Two planes of this
+size will give the 152 square yards of surface necessary to sustain a
+man's weight. Remember that in referring to flying machine measurements
+"spread" takes the place of what would ordinarily be called "length,"
+and invariably applies to the long or advancing edge of the machine
+which cuts into the air. Thus, a glider is spoken of as being 20 feet
+spread, and 4 feet in depth. So far as mastering the control of the
+machine is concerned, learning to balance one's self in the air, guiding
+the machine in any desired direction by changing the position of the
+body, etc., all this may be learned just as readily, and perhaps more
+so, with a 20-foot glider than with a larger apparatus.
+
+Kind of Material Required.
+
+There are three all-important features in flying machine construction,
+viz.: lightness, strength and extreme rigidity. Spruce is the wood
+generally used for glider frames. Oak, ash and hickory are all stronger,
+but they are also considerably heavier, and where the saving of weight
+is essential, the difference is largely in favor of spruce. This will be
+seen in the following table:
+
+                   Weight       Tensile          Compressive
+                per cubic ft.   Strength           Strength
+      Wood         in lbs.    lbs. per sq. in.   lbs. per sq in.
+   Hickory           53           12,000          8,500
+   Oak               50           12,000          9,000
+   Ash               38           12,000          6,000
+   Walnut            38            8,000          6,000
+   Spruce            25            8,000          5,000
+   Pine              25            5,000          4,500
+
+
+Considering the marked saving in weight spruce has a greater percentage
+of tensile strength than any of the other woods. It is also easier to
+find in long, straight-grained pieces free from knots, and it is this
+kind only that should be used in flying machine construction.
+
+You will next need some spools or hanks of No. 6 linen shoe
+thread, metal sockets, a supply of strong piano wire, a quantity of
+closely-woven silk or cotton cloth, glue, turnbuckles, varnish, etc.
+
+Names of the Various Parts.
+
+The long strips, four in number, which form the front and rear edges of
+the upper and lower frames, are called the horizontal beams. These are
+each 20 feet in length. These horizontal beams are connected by upright
+strips, 4 feet long, called stanchions. There are usually 12 of these,
+six on the front edge, and six on the rear. They serve to hold the upper
+plane away from the lower one. Next comes the ribs. These are 4 feet in
+length (projecting for a foot over the rear beam), and while intended
+principally as a support to the cloth covering of the planes, also
+tend to hold the frame together in a horizontal position just as the
+stanchions do in the vertical. There are forty-one of these ribs,
+twenty-one on the upper and twenty on the lower plane. Then come the
+struts, the main pieces which join the horizontal beams. All of these
+parts are shown in the illustrations, reference to which will make the
+meaning of the various names clear.
+
+Quantity and Cost of Material.
+
+For the horizontal beams four pieces of spruce, 20 feet long, 1 1/2
+inches wide and 3/4 inch thick are necessary. These pieces must be
+straight-grain, and absolutely free from knots. If it is impossible to
+obtain clear pieces of this length, shorter ones may be spliced, but
+this is not advised as it adds materially to the weight. The twelve
+stanchions should be 4 feet long and 7/8 inch in diameter and rounded
+in form so as to offer as little resistance as possible to the wind. The
+struts, there are twelve of them, are 3 feet long by 11/4 x 1/2 inch.
+For a 20-foot biplane about 20 yards of stout silk or unbleached muslin,
+of standard one yard width, will be needed. The forty-one ribs are
+each 4 feet long, and 1/2 inch square. A roll of No. 12 piano wire,
+twenty-four sockets, a package of small copper tacks, a pot of glue, and
+similar accessories will be required. The entire cost of this material
+should not exceed $20. The wood and cloth will be the two largest
+items, and these should not cost more than $10. This leaves $10 for the
+varnish, wire, tacks, glue, and other incidentals. This estimate is
+made for cost of materials only, it being taken for granted that the
+experimenter will construct his own glider. Should the services of a
+carpenter be required the total cost will probably approximate $60 or
+$70.
+
+Application of the Rudders.
+
+The figures given also include the expense of rudders, but the details
+of these have not been included as the glider is really complete without
+them. Some of the best flights the writer ever saw were made by Mr. A.
+M. Herring in a glider without a rudder, and yet there can be no doubt
+that a rudder, properly proportioned and placed, especially a rear
+rudder, is of great value to the aviator as it keeps the machine with
+its head to the wind, which is the only safe position for a novice. For
+initial educational purposes, however, a rudder is not essential as the
+glides will, or should, be made on level ground, in moderate, steady
+wind currents, and at a modest elevation. The addition of a rudder,
+therefore, may well be left until the aviator has become reasonably
+expert in the management of his machine.
+
+Putting the Machine Together.
+
+Having obtained the necessary material, the first move is to have the
+rib pieces steamed and curved. This curve may be slight, about 2 inches
+for the 4 feet. While this is being done the other parts should be
+carefully rounded so the square edges will be taken off. This may be
+done with sand paper. Next apply a coat of shellac, and when dry rub
+it down thoroughly with fine sand paper. When the ribs are curved treat
+them in the same way.
+
+Lay two of the long horizontal frame pieces on the floor 3 feet apart.
+Between these place six of the strut pieces. Put one at each end, and
+each 4 1/2 feet put another, leaving a 2-foot space in the center. This
+will give you four struts 4 1/2 feet apart, and two in the center 2 feet
+apart, as shown in the illustration. This makes five rectangles. Be sure
+that the points of contact are perfect, and that the struts are exactly
+at right angles with the horizontal frames. This is a most important
+feature because if your frame "skews" or twists you cannot keep it
+straight in the air. Now glue the ends of the struts to the frame
+pieces, using plenty of glue, and nail on strips that will hold the
+frame in place while the glue is drying. The next day lash the joints
+together firmly with the shoe thread, winding it as you would to mend a
+broken gun stock, and over each layer put a coating of glue. This done,
+the other frame pieces and struts may be treated in the same way, and
+you will thus get the foundations for the two planes.
+
+Another Way of Placing Struts.
+
+In the machines built for professional use a stronger and more certain
+form of construction is desired. This is secured by the placing the
+struts for the lower plane under the frame piece, and those for the
+upper plane over it, allowing them in each instance to come out flush
+with the outer edges of the frame pieces. They are then securely
+fastened with a tie plate or clamp which passes over the end of the
+strut and is bound firmly against the surface of the frame piece by the
+eye bolts of the stanchion sockets.
+
+Placing the Rib Pieces.
+
+Take one of the frames and place on it the ribs, with the arched side
+up, letting one end of the ribs come flush with the front edge of the
+forward frame, and the other end projecting about a foot beyond the rear
+frame. The manner of fastening the ribs to the frame pieces is optional.
+In some cases they are lashed with shoe thread, and in others clamped
+with a metal clamp fastened with 1/2-inch wood screws. Where clamps and
+screws are used care should be taken to make slight holes in the wood
+with an awl before starting the screws so as to lessen any tendency to
+split the wood. On the top frame, twenty-one ribs placed one foot apart
+will be required. On the lower frame, because of the opening left for
+the operator's body, you will need only twenty.
+
+Joining the Two Frames.
+
+The two frames must now be joined together. For this you will need
+twenty-four aluminum or iron sockets which may be purchased at a
+foundry or hardware shop. These sockets, as the name implies, provide
+a receptacle in which the end of a stanchion is firmly held, and have
+flanges with holes for eye-bolts which hold them firmly to the frame
+pieces, and also serve to hold the guy wires. In addition to these
+eye-bolt holes there are two others through which screws are fastened
+into the frame pieces. On the front frame piece of the bottom plane
+place six sockets, beginning at the end of the frame, and locating them
+exactly opposite the struts. Screw the sockets into position with wood
+screws, and then put the eye-bolts in place. Repeat the operation on the
+rear frame. Next put the sockets for the upper plane frame in place.
+
+You are now ready to bring the two planes together. Begin by inserting
+the stanchions in the sockets in the lower plane. The ends may need a
+little rubbing with sandpaper to get them into the sockets, but care
+must be taken to have them fit snugly. When all the stanchions are in
+place on the lower plane, lift the upper plane into position, and fit
+the sockets over the upper ends of the stanchions.
+
+Trussing with Guy Wires.
+
+The next move is to "tie" the frame together rigidly by the aid of guy
+wires. This is where the No. 12 piano wire comes in. Each rectangle
+formed by the struts and stanchions with the exception of the small
+center one, is to be wired separately as shown in the illustration. At
+each of the eight corners forming the rectangle the ring of one of the
+eye-bolts will be found. There are two ways of doing this "tieing," or
+trussing. One is to run the wires diagonally from eye-bolt to eye-bolt,
+depending upon main strength to pull them taut enough, and then twist
+the ends so as to hold. The other is to first make a loop of wire
+at each eye-bolt, and connect these loops to the main wires with
+turn-buckles. This latter method is the best, as it admits of the
+tension being regulated by simply turning the buckle so as to draw the
+ends of the wire closer together. A glance at the illustration will make
+this plain, and also show how the wires are to be placed. The proper
+degree of tension may be determined in the following manner:
+
+After the frame is wired place each end on a saw-horse so as to lift the
+entire frame clear of the work-shop floor. Get under it, in the center
+rectangle and, grasping the center struts, one in each hand, put your
+entire weight on the structure. If it is properly put together it will
+remain rigid and unyielding. Should it sag ever so slightly the tension
+of the wires must be increased until any tendency to sag, no matter how
+slight it may be, is overcome.
+
+Putting on the Cloth.
+
+We are now ready to put on the cloth covering which holds the air and
+makes the machine buoyant. The kind of material employed is of small
+account so long as it is light, strong, and wind-proof, or nearly so.
+Some aviators use what is called rubberized silk, others prefer balloon
+cloth. Ordinary muslin of good quality, treated with a coat of light
+varnish after it is in place, will answer all the purposes of the
+amateur.
+
+Cut the cloth into strips a little over 4 feet in length. As you have
+20 feet in width to cover, and the cloth is one yard wide, you will need
+seven strips for each plane, so as to allow for laps, etc. This will
+give you fourteen strips. Glue the end of each strip around the front
+horizontal beams of the planes, and draw each strip back, over the ribs,
+tacking the edges to the ribs as you go along, with small copper or
+brass tacks. In doing this keep the cloth smooth and stretched tight.
+Tacks should also be used in addition to the glue, to hold the cloth to
+the horizontal beams.
+
+Next, give the cloth a coat of varnish on the clear, or upper side, and
+when this is dry your glider will be ready for use.
+
+Reinforcing the Cloth.
+
+While not absolutely necessary for amateur purposes, reinforcement
+of the cloth, so as to avoid any tendency to split or tear out from
+wind-pressure, is desirable. One way of doing this is to tack narrow
+strips of some heavier material, like felt, over the cloth where it laps
+on the ribs. Another is to sew slips or pockets in the cloth itself and
+let the ribs run through them. Still another method is to sew 2-inch
+strips (of the same material as the cover) on the cloth, placing them
+about one yard apart, but having them come in the center of each piece
+of covering, and not on the laps where the various pieces are joined.
+
+Use of Armpieces.
+
+Should armpieces be desired, aside from those afforded by the center
+struts, take two pieces of spruce, 3 feet long, by 1 x 1 3/4 inches, and
+bolt them to the front and rear beams of the lower plane about 14 inches
+apart. These will be more comfortable than using the struts, as the
+operator will not have to spread his arms so much. In using the struts
+the operator, as a rule, takes hold of them with his hands, while with
+the armpieces, as the name implies, he places his arms over them, one of
+the strips coming under each armpit.
+
+Frequently somebody asks why the ribs should be curved. The answer is
+easy. The curvature tends to direct the air downward toward the rear
+and, as the air is thus forced downward, there is more or less of an
+impact which assists in propelling the aeroplane upwards.
+
+
+
+CHAPTER VI. LEARNING TO FLY.
+
+Don't be too ambitious at the start. Go slow, and avoid unnecessary
+risks. At its best there is an element of danger in aviation which
+cannot be entirely eliminated, but it may be greatly reduced and
+minimized by the use of common sense.
+
+Theoretically, the proper way to begin a glide is from the top of an
+incline, facing against the wind, so that the machine will soar until
+the attraction of gravitation draws it gradually to the ground. This is
+the manner in which experienced aviators operate, but it must be kept in
+mind that these men are experts. They understand air currents, know how
+to control the action and direction of their machines by shifting the
+position of their bodies, and by so doing avoid accidents which would be
+unavoidable by a novice.
+
+Begin on Level Ground.
+
+Make your first flights on level ground, having a couple of men to
+assist you in getting the apparatus under headway. Take your position in
+the center rectangle, back far enough to give the forward edges of the
+glider an inclination to tilt upward very slightly. Now start and run
+forward at a moderately rapid gait, one man at each end of the glider
+assisting you. As the glider cuts into the air the wind will catch under
+the uplifted edges of the curved planes, and buoy it up so that it will
+rise in the air and take you with it. This rise will not be great, just
+enough to keep you well clear of the ground. Now project your legs a
+little to the front so as to shift the center of gravity a trifle and
+bring the edges of the glider on an exact level with the atmosphere.
+This, with the momentum acquired in the start, will keep the machine
+moving forward for some distance.
+
+Effect of Body Movements.
+
+When the weight of the body is slightly back of the center of gravity
+the edges of the advancing planes are tilted slightly upward. The glider
+in this position acts as a scoop, taking in the air which, in turn,
+lifts it off the ground. When a certain altitude is reached--this varies
+with the force of the wind--the tendency to a forward movement is
+lost and the glider comes to the ground. It is to prolong the forward
+movement as much as possible that the operator shifts the center of
+gravity slightly, bringing the apparatus on an even keel as it were by
+lowering the advancing edges. This done, so long as there is momentum
+enough to keep the glider moving, it will remain afloat.
+
+If you shift your body well forward it will bring the front edges of
+the glider down, and elevate the rear ones. In this way the air will be
+"spilled" out at the rear, and, having lost the air support or buoyancy,
+the glider comes down to the ground. A few flights will make any
+ordinary man proficient in the control of his apparatus by his body
+movements, not only as concerns the elevating and depressing of the
+advancing edges, but also actual steering. You will quickly learn,
+for instance, that, as the shifting of the bodily weight backwards
+and forwards affects the upward and downward trend of the planes, so a
+movement sideways--to the left or the right--affects the direction in
+which the glider travels.
+
+Ascends at an Angle.
+
+In ascending, the glider and flying machine, like the bird, makes an
+angular, not a vertical flight. Just what this angle of ascension may be
+is difficult to determine. It is probable and in fact altogether likely,
+that it varies with the force of the wind, weight of the rising body,
+power of propulsion, etc. This, in the language of physicists, is the
+angle of inclination, and, as a general thing, under normal conditions
+(still air) should be put down as about one in ten, or 5 3/4 degrees.
+This would be an ideal condition, but it has not, as vet been reached.
+The force of the wind affects the angle considerably, as does also the
+weight and velocity of the apparatus. In general practice the angle
+varies from 23 to 45 degrees. At more than 45 degrees the supporting
+effort is overcome by the resistance to forward motion.
+
+Increasing the speed or propulsive force, tends to lessen the angle at
+which the machine may be successfully operated because it reduces the
+wind pressure. Most of the modern flying machines are operated at an
+angle of 23 degrees, or less.
+
+Maintaining an Equilibrium.
+
+Stable equilibrium is one of the main essentials to successful flight,
+and this cannot be preserved in an uncertain, gusty wind, especially by
+an amateur. The novice should not attempt a glide unless the conditions
+are just right. These conditions are: A clear, level space, without
+obstructions, such as trees, etc., and a steady wind of not exceeding
+twelve miles an hour. Always fly against the wind.
+
+When a reasonable amount of proficiency in the handling of the machine
+on level ground has been acquired the field of practice may be changed
+to some gentle slope. In starting from a slope it will be found easier
+to keep the machine afloat, but the experience at first is likely to be
+very disconcerting to a man of less than iron nerve. As the glider sails
+away from the top of the slope the distance between him and the ground
+increases rapidly until the aviator thinks he is up a hundred miles
+in the air. If he will keep cool, manipulate his apparatus so as to
+preserve its equilibrium, and "let nature take its course," he will come
+down gradually and safely to the ground at a considerable distance
+from the starting place. This is one advantage of starting from an
+elevation--your machine will go further.
+
+But, if the aviator becomes "rattled"; if he loses control of his
+machine, serious results, including a bad fall with risk of death,
+are almost certain. And yet this practice is just as necessary as the
+initial lessons on level ground. When judgment is used, and "haste made
+slowly," there is very little real danger. While experimenting with
+gliders the Wrights made flights innumerable under all sorts of
+conditions and never had an accident of any kind.
+
+Effects of Wind Currents.
+
+The larger the machine the more difficult it will be to control its
+movements in the air, and yet enlargement is absolutely necessary as
+weight, in the form of motor, rudder, etc., is added.
+
+Air currents near the surface of the ground are diverted by every
+obstruction unless the wind is blowing hard enough to remove the
+obstruction entirely. Take, for instance, the case of a tree or shrub,
+in a moderate wind of from ten to twelve miles an hour. As the wind
+strikes the tree it divides, part going to one side and part going to
+the other, while still another part is directed upward and goes over
+the top of the obstruction. This makes the handling of a glider on
+an obstructed field difficult and uncertain. To handle a glider
+successfully the place of operation should be clear and the wind
+moderate and steady. If it is gusty postpone your flight. In this
+connection it will be well to understand the velocity of the wind, and
+what it means as shown in the following table:
+
+     Miles per hour Feet per second     Pressure per sq. foot
+          10                14.7                .492
+          25                36.7                3.075
+          50                73.3               12.300
+          100              146.6               49.200
+
+Pressure of wind increases in proportion to the square of the velocity.
+Thus wind at 10 miles an hour has four times the pressure of wind at
+5 miles an hour. The greater this pressure the large and heavier the
+object which can be raised. Any boy who has had experience in flying
+kites can testify to this, High winds, however, are almost invariably
+gusty and uncertain as to direction, and this makes them dangerous for
+aviators. It is also a self-evident fact that, beyond a certain stage,
+the harder the wind blows the more difficult it is to make headway
+against it.
+
+Launching Device for Gliders.
+
+On page 195 will be found a diagram of the various parts of a launcher
+for gliders, designed and patented by Mr. Octave Chanute. In describing
+this invention in Aeronautics, Mr. Chanute says:
+
+"In practicing, the track, preferably portable, is generally laid in
+the direction of the existing wind and the car, preferably a
+light platform-car, is placed on the track. The truck carrying
+the winding-drum and its motor is placed to windward a suitable
+distance--say from two hundred to one thousand feet--and is firmly
+blocked or anchored in line with the portable track, which is preferably
+80 or 100 feet in length. The flying or gliding machine to be launched
+with its operator is placed on the platform-car at the leeward end of
+the portable track. The line, which is preferably a flexible combination
+wire-and-cord cable, is stretched between the winding-drum on the track
+and detachably secured to the flying or gliding machine, preferably by
+means of a trip-hoop, or else held in the hand of the operator, so that
+the operator may readily detach the same from the flying-machine when
+the desired height is attained."
+
+How Glider Is Started.
+
+"Then upon a signal given by the operator the engineer at the motor
+puts it into operation, gradually increasing the speed until the line
+is wound upon the drum at a maximum speed of, say, thirty miles an
+hour. The operator of the flying-machine, whether he stands upright and
+carries it on his shoulders, or whether he sits or lies down prone upon
+it, adjusts the aeroplane or carrying surfaces so that the wind shall
+strike them on the top and press downward instead of upward until the
+platform-car under action of the winding-drum and line attains the
+required speed.
+
+"When the operator judges that his speed is sufficient, and this depends
+upon the velocity of the wind as well as that of the car moving against
+the wind, he quickly causes the front of the flying-machine to tip
+upward, so that the relative wind striking on the under side of the
+planes or carrying surfaces shall lift the flying machine into the air.
+It then ascends like a kite to such height as may be desired by the
+operator, who then trips the hook and releases the line from the
+machine."
+
+What the Operator Does.
+
+"The operator being now free in the air has a certain initial velocity
+imparted by the winding-drum and line and also a potential energy
+corresponding to his height above the ground. If the flying or gliding
+machine is provided with a motor, he can utilize that in his further
+flight, and if it is a simple gliding machine without motor he can make
+a descending flight through the air to such distance as corresponds to
+the velocity acquired and the height gained, steering meanwhile by the
+devices provided for that purpose.
+
+"The simplest operation or maneuver is to continue the flight straight
+ahead against the wind; but it is possible to vary this course to the
+right or left, or even to return in downward flight with the wind to
+the vicinity of the starting-point. Upon nearing the ground the operator
+tips upward his carrying-surfaces and stops his headway upon the
+cushion of increased air resistance so caused. The operator is in no way
+permanently fastened to his machine, and the machine and the operator
+simply rest upon the light platform-car, so that the operator is free
+to rise with the machine from the car whenever the required initial
+velocity is attained.
+
+Motor For the Launcher.
+
+"The motor may be of any suitable kind or construction, but is
+preferably an electric or gasolene motor. The winding-drum is furnished
+with any suitable or customary reversing-guide to cause the line to
+wind smoothly and evenly upon the drum. The line is preferably a cable
+composed of flexible wire and having a cotton or other cord core to
+increase its flexibility. The line extends from the drum to the flying
+or gliding machine. Its free end may, if desired, be grasped and held
+by the operator until the flying-machine ascends to the desired height,
+when by simply letting go of the line the operator may continue his
+flight free. The line, however, is preferably connected to the flying
+or gliding machine directly by a trip-hook having a handle or trip lever
+within reach of the operator, so that when he ascends to the required
+height he may readily detach the line from the flying or gliding
+machine."
+
+
+
+CHAPTER VII. PUTTING ON THE RUDDER.
+
+Gliders as a rule have only one rudder, and this is in the rear. It
+tends to keep the apparatus with its head to the wind. Unlike the rudder
+on a boat it is fixed and immovable. The real motor-propelled flying
+machine, generally has both front and rear rudders manipulated by wire
+cables at the will of the operator.
+
+Allowing that the amateur has become reasonably expert in the
+manipulation of the glider he should, before constructing an actual
+flying machine, equip his glider with a rudder.
+
+Cross Pieces for Rudder Beam.
+
+To do this he should begin by putting in a cross piece, 2 feet long by
+1/4 x 3/4 inches between the center struts, in the lower plane. This may
+be fastened to the struts with bolts or braces. The former method is
+preferable. On this cross piece, and on the rear frame of the plane
+itself, the rudder beam is clamped and bolted. This rudder beam is 8
+feet 11 inches long. Having put these in place duplicate them in exactly
+the same manner and dimensions from the upper frame The cross pieces on
+which the ends of the rudder beams are clamped should be placed about
+one foot in advance of the rear frame beam.
+
+The Rudder Itself.
+
+The next step is to construct the rudder itself. This consists of two
+sections, one horizontal, the other vertical. The latter keeps
+the aeroplane headed into the wind, while the former keeps it
+steady--preserves the equilibrium.
+
+The rudder beams form the top and bottom frames of the vertical rudder.
+To these are bolted and clamped two upright pieces, 3 feet, 10 inches
+in length, and 3/4 inch in cross section. These latter pieces are placed
+about two feet apart. This completes the framework of the vertical
+rudder. See next page (59).
+
+For the horizontal rudder you will require two strips 6 feet long, and
+four 2 feet long. Find the exact center of the upright pieces on the
+vertical rudder, and at this spot fasten with bolts the long pieces of
+the horizontal, placing them on the outside of the vertical strips. Next
+join the ends of the horizontal strips with the 2-foot pieces, using
+small screws and corner braces. This done you will have two of the
+2-foot pieces left. These go in the center of the horizontal frame,
+"straddling" the vertical strips, as shown in the illustration.
+
+The framework is to be covered with cloth in the same manner as the
+planes. For this about ten yards will be needed.
+
+Strengthening the Rudder.
+
+To ensure rigidity the rudder must be stayed with guy wires. For this
+purpose the No. 12 piano wire is the best. Begin by running two of these
+wires from the top eye-bolts of stanchions 3 and 4, page 37, to rudder
+beam where it joins the rudder planes, fastening them at the bottom.
+Then run two wires from the top of the rudder beam at the same point,
+to the bottom eye-bolts of the same stanchions. This will give you
+four diagonal wires reaching from the rudder beam to the top and bottom
+planes of the glider. Now, from the outer ends of the rudder frame run
+four similar diagonal wires to the end of the rudder beam where it rests
+on the cross piece. You will then have eight truss wires strengthening
+the connection of the rudder to the main body of the glider.
+
+The framework of the rudder planes is then to be braced in the same way,
+which will take eight more wires, four for each rudder plane. All the
+wires are to be connected at one end with turn-buckles so the tension
+may be regulated as desired.
+
+In forming the rudder frame it will be well to mortise the corners, tack
+them together with small nails, and then put in a corner brace in the
+inside of each joint. In doing this bear in mind that the material to be
+thus fastened is light, and consequently the lightest of nails, screws,
+bolts and corner pieces, etc., is necessary.
+
+
+
+CHAPTER VIII. THE REAL FLYING MACHINE.
+
+We will now assume that you have become proficient enough to warrant an
+attempt at the construction of a real flying machine--one that will not
+only remain suspended in the air at the will of the operator, but make
+respectable progress in whatever direction he may desire to go. The
+glider, it must be remembered, is not steerable, except to a limited
+extent, and moves only in one direction--against the wind. Besides this
+its power of flotation--suspension in the air--is circumscribed.
+
+Larger Surface Area Required.
+
+The real flying machine is the glider enlarged, and equipped with
+motor and propeller. The first thing to do is to decide upon the size
+required. While a glider of 20 foot spread is large enough to sustain a
+man it could not under any possible conditions, be made to rise with the
+weight of the motor, propeller and similar equipment added. As the load
+is increased so must the surface area of the planes be increased.
+Just what this increase in surface area should be is problematical as
+experienced aviators disagree, but as a general proposition it may be
+placed at from three to four times the area of a 20-foot glider. [3]
+
+Some Practical Examples.
+
+The Wrights used a biplane 41 feet in spread, and 6 1/2 ft. deep. This,
+for the two planes, gives a total surface area of 538 square feet,
+inclusive of auxiliary planes. This sustains the engine equipment,
+operator, etc., a total weight officially announced at 1,070 pounds. It
+shows a lifting capacity of about two pounds to the square foot of plane
+surface, as against a lifting capacity of about 1/2 pound per square
+foot of plane surface for the 20-foot glider. This same Wright machine
+is also reported to have made a successful flight, carrying a total load
+of 1,100 pounds, which would be over two pounds for each square foot of
+surface area, which, with auxiliary planes, is 538 square feet.
+
+To attain the same results in a monoplane, the single surface would
+have to be 60 feet in spread and 9 feet deep. But, while this is the
+mathematical rule, Bleriot has demonstrated that it does not always hold
+good. On his record-breaking trip across the English channel, July 25th,
+1909, the Frenchman was carried in a monoplane 24 1/2 feet in spread,
+and with a total sustaining surface of 150 1/2 square feet. The total
+weight of the outfit, including machine, operator and fuel sufficient
+for a three-hour run, was only 660 pounds. With an engine of (nominally)
+25 horsepower the distance of 21 miles was covered in 37 minutes.
+
+Which is the Best?
+
+Right here an established mathematical quantity is involved. A small
+plane surface offers less resistance to the air than a large one and
+consequently can attain a higher rate of speed. As explained further
+on in this chapter speed is an important factor in the matter of
+weight-sustaining capacity. A machine that travels one-third faster
+than another can get along with one-half the surface area of the latter
+without affecting the load. See the closing paragraph of this chapter on
+this point. In theory the construction is also the simplest, but this is
+not always found to be so in practice. The designing and carrying
+into execution of plans for an extensive area like that of a monoplane
+involves great skill and cleverness in getting a framework that will be
+strong enough to furnish the requisite support without an undue excess
+of weight. This proposition is greatly simplified in the biplane and,
+while the speed attained by the latter may not be quite so great as that
+of the monoplane, it has much larger weight-carrying capacity.
+
+Proper Sizes For Frame.
+
+Allowing that the biplane form is selected the construction may be
+practically identical with that of the 20-foot glider described in
+Chapter V., except as to size and elimination of the armpieces. In
+size the surface planes should be about twice as large as those of
+the 20-foot glider, viz: 40 feet spread instead of 20, and 6 feet deep
+instead of 3. The horizontal beams, struts, stanchions, ribs, etc.,
+should also be increased in size proportionately.
+
+While care in the selection of clear, straight-grained timber is
+important in the glider, it is still more important in the construction
+of a motor-equipped flying machine as the strain on the various parts
+will be much greater.
+
+How to Splice Timbers.
+
+It is practically certain that you will have to resort to splicing the
+horizontal beams as it will be difficult, if not impossible, to find
+40-foot pieces of timber totally free from knots and worm holes, and of
+straight grain.
+
+If splicing is necessary select two good 20-foot pieces, 3 inches wide
+and 1 1/2 inches thick, and one 10-foot long, of the same thickness and
+width. Plane off the bottom sides of the 10-foot strip, beginning about
+two feet back from each end, and taper them so the strip will be about
+3/4 inch thick at the extreme ends. Lay the two 20-foot beams end to
+end, and under the joint thus made place the 10-foot strip, with the
+planed-off ends downward. The joint of the 20-foot pieces should be
+directly in the center of the 10-foot piece. Bore ten holes (with a
+1/4-inch augur) equi-distant apart through the 20-foot strips and the
+10-foot strip under them. Through these holes run 1/4-inch stove bolts
+with round, beveled heads. In placing these bolts use washers top and
+bottom, one between the head and the top beam, and the other between the
+bottom beam and the screw nut which holds the bolt. Screw the nuts down
+hard so as to bring the two beams tightly together, and you will have a
+rigid 40-foot beam.
+
+Splicing with Metal Sleeves.
+
+An even better way of making a splice is by tonguing and grooving the
+ends of the frame pieces and enclosing them in a metal sleeve, but
+it requires more mechanical skill than the method first named. The
+operation of tonguing and grooving is especially delicate and calls for
+extreme nicety of touch in the handling of tools, but if this dexterity
+is possessed the job will be much more satisfactory than one done with a
+third timber.
+
+As the frame pieces are generally about 1 1/2 inch in diameter, the
+tongue and the groove into which the tongue fits must be correspondingly
+small. Begin by sawing into one side of one of the frame pieces about
+4 inches back from the end. Make the cut about 1/2 inch deep. Then turn
+the piece over and duplicate the cut. Next saw down from the end
+to these cuts. When the sawed-out parts are removed you will have a
+"tongue" in the end of the frame timber 4 inches long and 1/2 inch
+thick. The next move is to saw out a 5/8-inch groove in the end of the
+frame piece which is to be joined. You will have to use a small chisel
+to remove the 5/8-inch bit. This will leave a groove into which the
+tongue will fit easily.
+
+Joining the Two Pieces.
+
+Take a thin metal sleeve--this is merely a hollow tube of aluminum
+or brass open at each end--8 inches long, and slip it over either the
+tongued or grooved end of one of the frame timbers. It is well to have
+the sleeve fit snugly, and this may necessitate a sand-papering of the
+frame pieces so the sleeve will slip on.
+
+Push the sleeve well back out of the way. Cover the tongue thoroughly
+with glue, and also put some on the inside of the groove. Use plenty
+of glue. Now press the tongue into the groove, and keep the ends firmly
+together until the glue is thoroughly dried. Rub off the joint lightly
+with sand-paper to remove any of the glue which may have oozed out, and
+slip the sleeve into place over the joint. Tack the sleeve in position
+with small copper tacks, and you will have an ideal splice.
+
+The same operation is to be repeated on each of the four frame pieces.
+Two 20-foot pieces joined in this way will give a substantial frame, but
+when suitable timber of this kind can not be had, three pieces, each 6
+feet 11 inches long, may be used. This would give 20 feet 9 inches, of
+which 8 inches will be taken up in the two joints, leaving the frame 20
+feet 1 inch long.
+
+Installation of Motor.
+
+Next comes the installation of the motor. The kinds and efficiency of
+the various types are described in the following chapter (IX). All we
+are interested in at this point is the manner of installation. This
+varies according to the personal ideas of the aviator. Thus one man puts
+his motor in the front of his machine, another places it in the center,
+and still another finds the rear of the frame the best. All get
+good results, the comparative advantages of which it is difficult
+to estimate. Where one man, as already explained, flies faster than
+another, the one beaten from the speed standpoint has an advantage in
+the matter of carrying weight, etc.
+
+The ideas of various well-known aviators as to the correct placing of
+motors may be had from the following:
+
+Wrights--In rear of machine and to one side.
+
+Curtiss--Well to rear, about midway between upper and lower planes.
+
+Raich--In rear, above the center.
+
+Brauner-Smith--In exact center of machine.
+
+Van Anden--In center.
+
+Herring-Burgess--Directly behind operator.
+
+Voisin--In rear, and on lower plane.
+
+Bleriot--In front.
+
+R. E. P.--In front.
+
+The One Chief Object.
+
+An even distribution of the load so as to assist in maintaining the
+equilibrium of the machine, should be the one chief object in deciding
+upon the location of the motor. It matters little what particular spot
+is selected so long as the weight does not tend to overbalance the
+machine, or to "throw it off an even keel." It is just like loading
+a vessel, an operation in which the expert seeks to so distribute
+the weight of the cargo as to keep the vessel in a perfectly upright
+position, and prevent a "list" or leaning to one side. The more evenly
+the cargo is distributed the more perfect will be the equilibrium of the
+vessel and the better it can be handled. Sometimes, when not properly
+stowed, the cargo shifts, and this at once affects the position of the
+craft. When a ship "lists" to starboard or port a preponderating weight
+of the cargo has shifted sideways; if bow or stern is unduly depressed
+it is a sure indication that the cargo has shifted accordingly. In
+either event the handling of the craft becomes not only difficult, but
+extremely hazardous. Exactly the same conditions prevail in the handling
+of a flying machine.
+
+Shape of Machine a Factor.
+
+In placing the motor you must be governed largely by the shape and
+construction of the flying machine frame. If the bulk of the weight
+of the machine and auxiliaries is toward the rear, then the natural
+location for the motor will be well to the front so as to counterbalance
+the excess in rear weight. In the same way if the preponderance of the
+weight is forward, then the motor should be placed back of the center.
+
+As the propeller blade is really an integral part of the motor, the
+latter being useless without it, its placing naturally depends upon the
+location selected for the motor.
+
+Rudders and Auxiliary Planes.
+
+Here again there is great diversity of opinion among aviators as to
+size, location and form. The striking difference of ideas in this
+respect is well illustrated in the choice made by prominent makers as
+follows:
+
+Voisin--horizontal rudder, with two wing-like planes, in front; box-like
+longitudinal stability plane in rear, inside of which is a vertical
+rudder.
+
+Wright--large biplane horizontal rudder in front at considerable
+distance--about 10 feet--from the main planes; vertical biplane rudder
+in rear; ends of upper and lower main planes made flexible so they may
+be moved.
+
+Curtiss--horizontal biplane rudder, with vertical damping plane between
+the rudder planes about 10 feet in front of main planes; vertical rudder
+in rear; stabilizing planes at each end of upper main plane.
+
+Bleriot--V-shaped stabilizing fin, projecting from rear of plane, with
+broad end outward; to the broad end of this fin is hinged a vertical
+rudder; horizontal biplane rudder, also in rear, under the fin.
+
+These instances show forcefully the wide diversity of opinion existing
+among experienced aviators as to the best manner of placing the rudders
+and stabilizing, or auxiliary planes, and make manifest how hopeless
+would be the task of attempting to select any one form and advise its
+exclusive use.
+
+Rudder and Auxiliary Construction.
+
+The material used in the construction of the rudders and auxiliary
+planes is the same as that used in the main planes--spruce for the
+framework and some kind of rubberized or varnished cloth for the
+covering. The frames are joined and wired in exactly the same manner
+as the frames of the main planes, the purpose being to secure the same
+strength and rigidity. Dimensions of the various parts depend upon the
+plan adopted and the size of the main plane.
+
+No details as to exact dimensions of these rudders and auxiliary planes
+are obtainable. The various builders, while willing enough to supply
+data as to the general measurements, weight, power, etc., of their
+machines, appear to have overlooked the details of the auxiliary parts,
+thinking, perhaps, that these were of no particular import to the
+general public. In the Wright machine, the rear horizontal and front
+vertical rudders may be set down as being about one-quarter (probably a
+little less) the size of the main supporting planes.
+
+Arrangement of Alighting Gear.
+
+Most modern machines are equipped with an alighting gear, which not
+only serves to protect the machine and aviator from shock or injury in
+touching the ground, but also aids in getting under headway. All the
+leading makes, with the exception of the Wright, are furnished with a
+frame carrying from two to five pneumatic rubber-tired bicycle wheels.
+In the Curtiss and Voisin machines one wheel is placed in front and two
+in the rear. In the Bleriot and other prominent machines the reverse is
+the rule--two wheels in front and one in the rear. Farman makes use of
+five wheels, one in the extreme rear, and four, arranged in pairs, a
+little to the front of the center of the main lower plane.
+
+In place of wheels the Wright machine is equipped with a skid-like
+device consisting of two long beams attached to the lower plane by
+stanchions and curving up far in front, so as to act as supports to the
+horizontal rudder.
+
+Why Wood Is Favored.
+
+A frequently asked question is: "Why is not aluminum, or some similar
+metal, substituted for wood." Wood, particularly spruce, is preferred
+because, weight considered, it is much stronger than aluminum, and this
+is the lightest of all metals. In this connection the following table
+will be of interest:
+
+                                                      Compressive
+                   Weight      Tensile Strength         Strength
+               per cubic foot    per sq. inch         per sq. inch
+  Material        in lbs.           in lbs.              in lbs.
+  Spruce....    25               8,000                5,000
+  Aluminum         162              16,000              ......
+  Brass (sheet)    510              23,000               12,000
+  Steel (tool)     490             100,000               40,000
+  Copper (sheet)   548              30,000               40,000
+
+As extreme lightness, combined with strength, especially tensile
+strength, is the great essential in flying-machine construction, it can
+be readily seen that the use of metal, even aluminum, for the framework,
+is prohibited by its weight. While aluminum has double the strength
+of spruce wood it is vastly heavier, and thus the advantage it has in
+strength is overbalanced many times by its weight. The specific gravity
+of aluminum is 2.50; that of spruce is only 0.403.
+
+Things to Be Considered.
+
+In laying out plans for a flying machine there are five important points
+which should be settled upon before the actual work of construction is
+started. These are:
+
+First--Approximate weight of the machine when finished and equipped.
+
+Second--Area of the supporting surface required.
+
+Third--Amount of power that will be necessary to secure the desired
+speed and lifting capacity.
+
+Fourth--Exact dimensions of the main framework and of the auxiliary
+parts.
+
+Fifth--Size, speed and character of the propeller.
+
+In deciding upon these it will be well to take into consideration
+the experience of expert aviators regarding these features as given
+elsewhere. (See Chapter X.)
+
+Estimating the Weights Involved.
+
+In fixing upon the probable approximate weight in advance of
+construction much, of course, must be assumed. This means that it will
+be a matter of advance estimating. If a two-passenger machine is to be
+built we will start by assuming the maximum combined weight of the two
+people to be 350 pounds. Most of the professional aviators are lighter
+than this. Taking the medium between the weights of the Curtiss and
+Wright machines we have a net average of 850 pounds for the framework,
+motor, propeller, etc. This, with the two passengers, amounts to 1,190
+pounds. As the machines quoted are in successful operation it will be
+reasonable to assume that this will be a safe basis to operate on.
+
+What the Novice Must Avoid.
+
+This does not mean, however, that it will be safe to follow these
+weights exactly in construction, but that they will serve merely as
+a basis to start from. Because an expert can turn out a machine,
+thoroughly equipped, of 850 pounds weight, it does not follow that a
+novice can do the same thing. The expert's work is the result of years
+of experience, and he has learned how to construct frames and motor
+plants of the utmost lightness and strength.
+
+It will be safer for the novice to assume that he can not duplicate the
+work of such men as Wright and Curtiss without adding materially to the
+gross weight of the framework and equipment minus passengers.
+
+How to Distribute the Weight.
+
+Let us take 1,030 pounds as the net weight of the machine as against the
+same average in the Wright and Curtiss machines. Now comes the question
+of distributing this weight between the framework, motor, and other
+equipment. As a general proposition the framework should weigh about
+twice as much as the complete power plant (this is for amateur work).
+
+The word "framework" indicates not only the wooden frames of the main
+planes, auxiliary planes, rudders, etc., but the cloth coverings as
+well--everything in fact except the engine and propeller.
+
+On the basis named the framework would weigh 686 pounds, and the power
+plant 344. These figures are liberal, and the results desired may be
+obtained well within them as the novice will learn as he makes progress
+in the work.
+
+Figuring on Surface Area.
+
+It was Prof. Langley who first brought into prominence in connection
+with flying machine construction the mathematical principle that the
+larger the object the smaller may be the relative area of support. As
+explained in Chapter XIII, there are mechanical limits as to size which
+it is not practical to exceed, but the main principle remains in effect.
+
+Take two aeroplanes of marked difference in area of surface. The larger
+will, as a rule, sustain a greater weight in relative proportion to
+its area than the smaller one, and do the work with less relative
+horsepower. As a general thing well-constructed machines will average
+a supporting capacity of one pound for every one-half square foot of
+surface area. Accepting this as a working rule we find that to sustain
+a weight of 1,200 pounds--machine and two passengers--we should have 600
+square feet of surface.
+
+Distributing the Surface Area.
+
+The largest surfaces now in use are those of the Wright, Voisin and
+Antoinette machines--538 square feet in each. The actual sustaining
+power of these machines, so far as known, has never been tested to the
+limit; it is probable that the maximum is considerably in excess of what
+they have been called upon to show. In actual practice the average is a
+little over one pound for each one-half square foot of surface area.
+
+Allowing that 600 square feet of surface will be used, the next question
+is how to distribute it to the best advantage. This is another important
+matter in which individual preference must rule. We have seen how the
+professionals disagree on this point, some using auxiliary planes
+of large size, and others depending upon smaller auxiliaries with an
+increase in number so as to secure on a different plan virtually the
+same amount of surface.
+
+In deciding upon this feature the best thing to do is to follow the
+plans of some successful aviator, increasing the area of the auxiliaries
+in proportion to the increase in the area of the main planes. Thus, if
+you use 600 square feet of surface where the man whose plans you
+are following uses 500, it is simply a matter of making your planes
+one-fifth larger all around.
+
+The Cost of Production.
+
+Cost of production will be of interest to the amateur who essays to
+construct a flying machine. Assuming that the size decided upon is
+double that of the glider the material for the framework, timber, cloth,
+wire, etc., will cost a little more than double. This is because it must
+be heavier in proportion to the increased size of the framework, and
+heavy material brings a larger price than the lighter goods. If we allow
+$20 as the cost of the glider material it will be safe to put down
+the cost of that required for a real flying machine framework at $60,
+provided the owner builds it himself.
+
+As regards the cost of motor and similar equipment it can only be said
+that this depends upon the selection made. There are some reliable
+aviation motors which may be had as low as $500, and there are others
+which cost as much as $2,000.
+
+Services of Expert Necessary.
+
+No matter what kind of a motor may be selected the services of an expert
+will be necessary in its proper installation unless the amateur has
+considerable genius in this line himself. As a general thing $25 should
+be a liberal allowance for this work. No matter how carefully the engine
+may be placed and connected it will be largely a matter of luck if it is
+installed in exactly the proper manner at the first attempt. The chances
+are that several alterations, prompted by the results of trials, will
+have to be made. If this is the case the expert's bill may readily run
+up to $50. If the amateur is competent to do this part of the work the
+entire item of $50 may, of course, be cut out.
+
+As a general proposition a fairly satisfactory flying machine, one that
+will actually fly and carry the operator with it, may be constructed for
+$750, but it will lack the better qualities which mark the higher priced
+machines. This computation is made on the basis of $60 for material, $50
+for services of expert, $600 for motor, etc., and an allowance of $40
+for extras.
+
+No man who has the flying machine germ in his system will be long
+satisfied with his first moderate price machine, no matter how well it
+may work. It's the old story of the automobile "bug" over again. The man
+who starts in with a modest $1,000 automobile invariably progresses by
+easy stages to the $4,000 or $5,000 class. The natural tendency is to
+want the biggest and best attainable within the financial reach of the
+owner.
+
+It's exactly the same way with the flying machine convert. The more
+proficient he becomes in the manipulation of his car, the stronger
+becomes the desire to fly further and stay in the air longer than the
+rest of his brethren. This necessitates larger, more powerful, and more
+expensive machines as the work of the germ progresses.
+
+Speed Affects Weight Capacity.
+
+Don't overlook the fact that the greater speed you can attain the
+smaller will be the surface area you can get along with. If a machine
+with 500 square feet of sustaining surface, traveling at a speed of
+40 miles an hour, will carry a weight of 1,200 pounds, we can cut the
+sustaining surface in half and get along with 250 square feet, provided
+a speed of 60 miles an hour can be obtained. At 100 miles an hour only
+80 square feet of surface area would be required. In both instances the
+weight sustaining capacity will remain the same as with the 500 square
+feet of surface area--1,200 pounds.
+
+One of these days some mathematical genius will figure out this problem
+with exactitude and we will have a dependable table giving the maximum
+carrying capacity of various surface areas at various stated speeds,
+based on the dimensions of the advancing edges. At present it is largely
+a matter of guesswork so far as making accurate computation goes.
+Much depends upon the shape of the machine, and the amount of surface
+offering resistance to the wind, etc.
+
+
+
+CHAPTER IX. SELECTION OF THE MOTOR.
+
+Motors for flying machines must be light in weight, of great strength,
+productive of extreme speed, and positively dependable in action.
+It matters little as to the particular form, or whether air or water
+cooled, so long as the four features named are secured. There are at
+least a dozen such motors or engines now in use. All are of the gasolene
+type, and all possess in greater or lesser degree the desired qualities.
+Some of these motors are:
+
+Renault--8-cylinder, air-cooled; 50 horse power; weight 374 pounds.
+
+Fiat--8-cylinder, air-cooled; 50 horse power; weight 150 pounds.
+
+Farcot--8-cylinder, air-cooled; from 30 to 100 horse power, according to
+bore of cylinders; weight of smallest, 84 pounds.
+
+R. E. P.--10-cylinder, air-cooled; 150 horse power; weight 215 pounds.
+
+Gnome--7 and 14 cylinders, revolving type, air-cooled; 50 and 100 horse
+power; weight 150 and 300 pounds.
+
+Darracq--2 to 14 cylinders, water cooled; 30 to 200 horse power; weight
+of smallest 100 pounds.
+
+Wright--4-cylinder, water-cooled; 25 horse power; weight 200 pounds.
+
+Antoinette--8 and 16-cylinder, water-cooled; 50 and 100 horse power;
+weight 250 and 500 pounds.
+
+E. N. V.--8-cylinder, water-cooled; from 30 to 80 horse power, according
+to bore of cylinder; weight 150 to 400 pounds.
+
+Curtiss--8-cylinder, water-cooled; 60 horse power; weight 300 pounds.
+
+Average Weight Per Horse Power.
+
+It will be noticed that the Gnome motor is unusually light, being about
+three pounds to the horse power produced, as opposed to an average of 4
+1/2 pounds per horse power in other makes. This result is secured by
+the elimination of the fly-wheel, the engine itself revolving, thus
+obtaining the same effect that would be produced by a fly-wheel. The
+Farcot is even lighter, being considerably less than three pounds per
+horse power, which is the nearest approach to the long-sought engine
+equipment that will make possible a complete flying machine the total
+weight of which will not exceed one pound per square foot of area.
+
+How Lightness Is Secured.
+
+Thus far foreign manufacturers are ahead of Americans in the production
+of light-weight aerial motors, as is evidenced by the Gnome and Farcot
+engines, both of which are of French make. Extreme lightness is made
+possible by the use of fine, specially prepared steel for the cylinders,
+thus permitting them to be much thinner than if ordinary forms of steel
+were used. Another big saving in weight is made by substituting what are
+known as "auto lubricating" alloys for bearings. These alloys are made
+of a combination of aluminum and magnesium.
+
+Still further gains are made in the use of alloy steel tubing instead of
+solid rods, and also by the paring away of material wherever it can be
+done without sacrificing strength. This plan, with the exclusive use of
+the best grades of steel, regardless of cost, makes possible a marked
+reduction in weight.
+
+Multiplicity of Cylinders.
+
+Strange as it may seem, multiplicity of cylinders does not always add
+proportionate weight. Because a 4-cylinder motor weighs say 100 pounds,
+it does not necessarily follow that an 8-cylinder equipment will weigh
+200 pounds. The reason of this will be plain when it is understood
+that many of the parts essential to a 4-cylinder motor will fill the
+requirements of an 8-cylinder motor without enlargement or addition.
+
+Neither does multiplying the cylinders always increase the horsepower
+proportionately. If a 4-cylinder motor is rated at 25 horsepower it is
+not safe to take it for granted that double the number of cylinders
+will give 50 horsepower. Generally speaking, eight cylinders, the bore,
+stroke and speed being the same, will give double the power that can be
+obtained from four, but this does not always hold good. Just why this
+exception should occur is not explainable by any accepted rule.
+
+Horse Power and Speed.
+
+Speed is an important requisite in a flying-machine motor, as the
+velocity of the aeroplane is a vital factor in flotation. At
+first thought, the propeller and similar adjuncts being equal, the
+inexperienced mind would naturally argue that a 50-horsepower engine
+should produce just double the speed of one of 25-horsepower. That
+this is a fallacy is shown by actual performances. The Wrights, using a
+25-horsepower motor, have made 44 miles an hour, while Bleriot, with a
+50-horsepower motor, has a record of a short-distance flight at the rate
+of 52 miles an hour. The fact is that, so far as speed is concerned,
+much depends upon the velocity of the wind, the size and shape of the
+aeroplane itself, and the size, shape and gearing of the propeller. The
+stronger the wind is blowing the easier it will be for the aeroplane
+to ascend, but at the same time the more difficult it will be to make
+headway against the wind in a horizontal direction. With a strong head
+wind, and proper engine force, your machine will progress to a certain
+extent, but it will be at an angle. If the aviator desired to keep
+on going upward this would be all right, but there is a limit to the
+altitude which it is desirable to reach--from 100 to 500 feet for
+experts--and after that it becomes a question of going straight ahead.
+
+Great Waste of Power.
+
+One thing is certain--even in the most efficient of modern aerial motors
+there is a great loss of power between the two points of production and
+effect. The Wright outfit, which is admittedly one of the most effective
+in use, takes one horsepower of force for the raising and propulsion of
+each 50 pounds of weight. This, for a 25-horsepower engine, would give
+a maximum lifting capacity of 1250 pounds. It is doubtful if any of
+the higher rated motors have greater efficiency. As an 8-cylinder motor
+requires more fuel to operate than a 4-cylinder, it naturally follows
+that it is more expensive to run than the smaller motor, and a normal
+increase in capacity, taking actual performances as a criterion, is
+lacking. In other words, what is the sense of using an 8-cylinder motor
+when one of 4 cylinders is sufficient?
+
+What the Propeller Does.
+
+Much of the efficiency of the motor is due to the form and gearing of
+the propeller. Here again, as in other vital parts of flying-machine
+mechanism, we have a wide divergence of opinion as to the best form. A
+fish makes progress through the water by using its fins and tail; a
+bird makes its way through the air in a similar manner by the use of its
+wings and tail. In both instances the motive power comes from the body
+of the fish or bird.
+
+In place of fins or wings the flying machine is equipped with a
+propeller, the action of which is furnished by the engine. Fins and
+wings have been tried, but they don't work.
+
+While operating on the same general principle, aerial propellers are
+much larger than those used on boats. This is because the boat
+propeller has a denser, more substantial medium to work in (water), and
+consequently can get a better "hold," and produce more propulsive force
+than one of the same size revolving in the air. This necessitates the
+aerial propellers being much larger than those employed for marine
+purposes. Up to this point all aviators agree, but as to the best form
+most of them differ.
+
+Kinds of Propellers Used.
+
+One of the most simple is that used by Curtiss. It consists of two
+pear-shaped blades of laminated wood, each blade being 5 inches wide
+at its extreme point, tapering slightly to the shaft connection. These
+blades are joined at the engine shaft, in a direct line. The propeller
+has a pitch of 5 feet, and weighs, complete, less than 10 pounds. The
+length from end to end of the two blades is 6 1/2 feet.
+
+Wright uses two wooden propellers, in the rear of his biplane, revolving
+in opposite directions. Each propeller is two-bladed.
+
+Bleriot also uses a two-blade wooden propeller, but it is placed in
+front of his machine. The blades are each about 3 1/2 feet long and have
+an acute "twist."
+
+Santos-Dumont uses a two-blade wooden propeller, strikingly similar to
+the Bleriot.
+
+On the Antoinette monoplane, with which good records have been made, the
+propeller consists of two spoon-shaped pieces of metal, joined at the
+engine shaft in front, and with the concave surfaces facing the machine.
+
+The propeller on the Voisin biplane is also of metal, consisting of two
+aluminum blades connected by a forged steel arm.
+
+Maximum thrust, or stress--exercise of the greatest air-displacing
+force--is the object sought. This, according to experts, is best
+obtained with a large propeller diameter and reasonably low speed. The
+diameter is the distance from end to end of the blades, which on the
+largest propellers ranges from 6 to 8 feet. The larger the blade surface
+the greater will be the volume of air displaced, and, following this,
+the greater will be the impulse which forces the aeroplane ahead. In all
+centrifugal motion there is more or less tendency to disintegration in
+the form of "flying off" from the center, and the larger the revolving
+object is the stronger is this tendency. This is illustrated in the many
+instances in which big grindstones and fly-wheels have burst from being
+revolved too fast. To have a propeller break apart in the air would
+jeopardize the life of the aviator, and to guard against this it has
+been found best to make its revolving action comparatively slow.
+Besides this the slow motion (it is only comparatively slow) gives the
+atmosphere a chance to refill the area disturbed by one propeller blade,
+and thus have a new surface for the next blade to act upon.
+
+Placing of the Motor.
+
+As on other points, aviators differ widely in their ideas as to the
+proper position for the motor. Wright locates his on the lower plane,
+midway between the front and rear edges, but considerably to one side of
+the exact center. He then counter-balances the engine weight by placing
+his seat far enough away in the opposite direction to preserve the
+center of gravity. This leaves a space in the center between the motor
+and the operator in which a passenger may be carried without disturbing
+the equilibrium.
+
+Bleriot, on the contrary, has his motor directly in front and preserves
+the center of gravity by taking his seat well back, this, with the
+weight of the aeroplane, acting as a counter-balance.
+
+On the Curtiss machine the motor is in the rear, the forward seat of the
+operator, and weight of the horizontal rudder and damping plane in front
+equalizing the engine weight.
+
+No Perfect Motor as Yet.
+
+Engine makers in the United States, England, France and Germany are all
+seeking to produce an ideal motor for aviation purposes. Many of the
+productions are highly creditable, but it may be truthfully said that
+none of them quite fill the bill as regards a combination of the minimum
+of weight with the maximum of reliable maintained power. They are all,
+in some respects, improvements upon those previously in use, but the
+great end sought for has not been fully attained.
+
+One of the motors thus produced was made by the French firm of Darracq
+at the suggestion of Santos Dumont, and on lines laid down by him.
+Santos Dumont wanted a 2-cylinder horizontal motor capable of developing
+30 horsepower, and not exceeding 4 1/2 pounds per horsepower in weight.
+
+There can be no question as to the ability and skill of the Darracq
+people, or of their desire to produce a motor that would bring new
+credit and prominence to the firm. Neither could anything radically
+wrong be detected in the plans. But the motor, in at least one important
+requirement, fell short of expectations.
+
+It could not be depended upon to deliver an energy of 30 horsepower
+continuously for any length of time. Its maximum power could be secured
+only in "spurts."
+
+This tends to show how hard it is to produce an ideal motor for aviation
+purposes. Santos Dumont, of undoubted skill and experience as an
+aviator, outlined definitely what he wanted; one of the greatest
+designers in the business drew the plans, and the famous house of
+Darracq bent its best energies to the production. But the desired end
+was not fully attained.
+
+Features of Darracq Motor.
+
+Horizontal motors were practically abandoned some time ago in favor of
+the vertical type, but Santos Dumont had a logical reason for reverting
+to them. He wanted to secure a lower center of gravity than would be
+possible with a vertical engine. Theoretically his idea was correct as
+the horizontal motor lies flat, and therefore offers less resistance to
+the wind, but it did not work out as desired.
+
+At the same time it must be admitted that this Darracq motor is a marvel
+of ingenuity and exquisite workmanship. The two cylinders, having a bore
+of 5 1-10 inches and a stroke of 4 7-10 inches, are machined out of a
+solid bar of steel until their weight is only 8 4-5 pounds complete.
+The head is separate, carrying the seatings for the inlet and exhaust
+valves, is screwed onto the cylinder, and then welded in position. A
+copper water-jacket is fitted, and it is in this condition that the
+weight of 8 4-5 pounds is obtained.
+
+On long trips, especially in regions where gasolene is hard to get,
+the weight of the fuel supply is an important feature in aviation. As a
+natural consequence flying machine operators favor the motor of greatest
+economy in gasolene consumption, provided it gives the necessary power.
+
+An American inventor, Ramsey by name, is working on a motor which
+is said to possess great possibilities in this line. Its distinctive
+features include a connecting rod much shorter than usual, and a crank
+shaft located the length of the crank from the central axis of the
+cylinder. This has the effect of increasing the piston stroke, and also
+of increasing the proportion of the crank circle during which effective
+pressure is applied to the crank.
+
+Making the connecting rod shorter and leaving the crank mechanism the
+same would introduce excessive cylinder friction. This Ramsey overcomes
+by the location of his crank shaft. The effect of the long piston stroke
+thus secured, is to increase the expansion of the gases, which in turn
+increases the power of the engine without increasing the amount of fuel
+used.
+
+Propeller Thrust Important.
+
+There is one great principle in flying machine propulsion which must
+not be overlooked. No matter how powerful the engine may be unless the
+propeller thrust more than overcomes the wind pressure there can be no
+progress forward. Should the force of this propeller thrust and that of
+the wind pressure be equal the result is obvious. The machine is at a
+stand-still so far as forward progress is concerned and is deprived of
+the essential advancing movement.
+
+Speed not only furnishes sustentation for the airship, but adds to the
+stability of the machine. An aeroplane which may be jerky and uncertain
+in its movements, so far as equilibrium is concerned, when moving at
+a slow gait, will readily maintain an even keel when the speed is
+increased.
+
+Designs for Propeller Blades.
+
+It is the object of all men who design propellers to obtain the maximum
+of thrust with the minimum expenditure of engine energy. With this
+purpose in view many peculiar forms of propeller blades have been
+evolved. In theory it would seem that the best effects could be secured
+with blades so shaped as to present a thin (or cutting) edge when they
+come out of the wind, and then at the climax of displacement afford a
+maximum of surface so as to displace as much air as possible. While
+this is the form most generally favored there are others in successful
+operation.
+
+There is also wide difference in opinion as to the equipment of the
+propeller shaft with two or more blades. Some aviators use two and some
+four. All have more or less success. As a mathematical proposition it
+would seem that four blades should give more propulsive force than two,
+but here again comes in one of the puzzles of aviation, as this result
+is not always obtained.
+
+Difference in Propeller Efficiency.
+
+That there is a great difference in propeller efficiency is made readily
+apparent by the comparison of effects produced in two leading makes of
+machines--the Wright and the Voisin.
+
+In the former a weight of from 1,100 to 1,200 pounds is sustained and
+advance progress made at the rate of 40 miles an hour and more, with
+half the engine speed of a 25 horse-power motor. This would be a
+sustaining capacity of 48 pounds per horsepower. But the actual capacity
+of the Wright machine, as already stated, is 50 pounds per horsepower.
+
+The Voisin machine, with aviator, weighs about 1,370 pounds, and is
+operated with a so-horsepower motor. Allowing it the same speed as the
+Wright we find that, with double the engine energy, the lifting capacity
+is only 27 1/2 pounds per horsepower. To what shall we charge this
+remarkable difference? The surface of the planes is exactly the same in
+both machines so there is no advantage in the matter of supporting area.
+
+Comparison of Two Designs.
+
+On the Wright machine two wooden propellers of two blades each (each
+blade having a decided "twist") are used. As one 25 horsepower motor
+drives both propellers the engine energy amounts to just one-half of
+this for each, or 12 1/2 horsepower. And this energy is utilized at
+one-half the normal engine speed.
+
+On the Voisin a radically different system is employed. Here we have
+one metal two-bladed propeller with a very slight "twist" to the blade
+surfaces. The full energy of a 50-horsepower motor is utilized.
+
+Experts Fail to Agree.
+
+Why should there be such a marked difference in the results obtained?
+Who knows? Some experts maintain that it is because there are two
+propellers on the Wright machine and only one on the Voisin, and
+consequently double the propulsive power is exerted. But this is not a
+fair deduction, unless both propellers are of the same size. Propulsive
+power depends upon the amount of air displaced, and the energy put into
+the thrust which displaces the air.
+
+Other experts argue that the difference in results may be traced to the
+difference in blade design, especially in the matter of "twist."
+
+The fact is that propeller results depend largely upon the nature of
+the aeroplanes on which they are used. A propeller, for instance,
+which gives excellent results on one type of aeroplane, will not work
+satisfactorily on another.
+
+There are some features, however, which may be safely adopted in
+propeller selection. These are: As extensive a diameter as possible;
+blade area 10 to 15 per cent of the area swept; pitch four-fifths of
+the diameter; rotation slow. The maximum of thrust effort will be thus
+obtained.
+
+
+
+CHAPTER X. PROPER DIMENSIONS OF MACHINES.
+
+In laying out plans for a flying machine the first thing to decide upon
+is the size of the plane surfaces. The proportions of these must be
+based upon the load to be carried. This includes the total weight of
+the machine and equipment, and also the operator. This will be a rather
+difficult problem to figure out exactly, but practical approximate
+figures may be reached.
+
+It is easy to get at the weight of the operator, motor and propeller,
+but the matter of determining, before they are constructed, what the
+planes, rudders, auxiliaries, etc., will weigh when completed is an
+intricate proposition. The best way is to take the dimensions of some
+successful machine and use them, making such alterations in a minor way
+as you may desire.
+
+Dimensions of Leading Machines.
+
+In the following tables will be found the details as to surface area,
+weight, power, etc., of the nine principal types of flying machines
+which are now prominently before the public:
+
+                             MONOPLANES.
+                              Surface area    Spread in     Depth in
+   Make          Passengers     sq. feet      linear feet  linear
+   feet
+   Santos-Dumont.. 1           110             16.0         26.0
+   Bleriot..... 1           150.6           24.6         22.0
+   R. E. P..... 1           215             34.1         28.9
+   Bleriot..... 2           236             32.9         23.0
+   Antoinette.... 2           538             41.2         37.9
+                  No. of                  Weight Without
+   Propeller
+   Make         Cylinders   Horse Power       Operator
+   Diameter
+   Santos-Dumont.. 2          30                250            5.0
+   Bleriot..... 3          25                680            6.9
+   R. E. P..... 7          35                900            6.6
+   Bleriot..... 7          50              1,240            8.1
+   Antoinette... 8          50              1,040            7.2
+
+                               BIPLANES.
+                            Surface Area       Spread in      Depth
+   in
+   Make      Passengers       sq. feet        linear feet    linear
+   feet
+   Curtiss... 2               258             29.0
+   28.7
+   Wright.... 2               538             41.0
+   30.7
+   Farman.... 2               430             32.9
+   39.6
+   Voisin.... 2               538             37.9
+   39.6
+
+                No. of                     Weight Without
+   Propeller
+   Make       Cylinders      Horse Power      Operator
+   Diameter
+   Curtiss... 8               50               600          6.0
+   Wright.... 4               25             1,100          8.1
+   Farman.... 7               50             1,200          8.9
+   Voisin.... 8               50             1,200          6.6
+
+In giving the depth dimensions the length over all--from the extreme
+edge of the front auxiliary plane to the extreme tip of the rear is
+stated. Thus while the dimensions of the main planes of the Wright
+machine are 41 feet spread by 6 1/2 feet in depth, the depth over all is
+30.7.
+
+Figuring Out the Details.
+
+With this data as a guide it should be comparatively easy to decide
+upon the dimensions of the machine required. In arriving at the maximum
+lifting capacity the weight of the operator must be added. Assuming this
+to average 170 pounds the method of procedure would be as follows:
+
+Add the weight of the operator to the weight of the complete machine.
+The new Wright machine complete weighs 900 pounds. This, plus 170, the
+weight of the operator, gives a total of 1,070 pounds. There are 538
+square feet of supporting surface, or practically one square foot of
+surface area to each two pounds of load.
+
+There are some machines, notably the Bleriot, in which the supporting
+power is much greater. In this latter instance we find a surface area of
+150 1/2 square feet carrying a load of 680 plus 170, or an aggregate of
+850 pounds. This is the equivalent of five pounds to the square foot.
+This ratio is phenomenally large, and should not be taken as a guide by
+amateurs.
+
+The Matter of Passengers.
+
+These deductions are based on each machine carrying one passenger, which
+is admittedly the limit at present of the monoplanes like those operated
+for record-making purposes by Santos-Dumont and Bleriot. The biplanes,
+however, have a two-passenger capacity, and this adds materially to the
+proportion of their weight-sustaining power as compared with the surface
+area. In the following statement all the machines are figured on the
+one-passenger basis. Curtiss and Wright have carried two passengers on
+numerous occasions, and an extra 170 pounds should therefore be added to
+the total weight carried, which would materially increase the capacity.
+Even with the two-passenger load the limit is by no means reached,
+but as experiments have gone no further it is impossible to make more
+accurate figures.
+
+Average Proportions of Load.
+
+It will be interesting, before proceeding to lay out the dimension
+details, to make a comparison of the proportion of load effect with
+the supporting surfaces of various well-known machines. Here are the
+figures:
+
+Santos-Dumont--A trifle under four pounds per square foot.
+
+Bleriot--Five pounds.
+
+R. E. P.--Five pounds.
+
+Antoinette--About two and one-quarter pounds.
+
+Curtiss--About two and one-half pounds.
+
+Wright--Two and one-quarter pounds.
+
+Farman--A trifle over three pounds.
+
+Voisin--A little under two and one-half pounds.
+
+Importance of Engine Power.
+
+While these figures are authentic, they are in a way misleading, as the
+important factor of engine power is not taken into consideration. Let us
+recall the fact that it is the engine power which keeps the machine in
+motion, and that it is only while in motion that the machine will remain
+suspended in the air. Hence, to attribute the support solely to the
+surface area is erroneous. True, that once under headway the planes
+contribute largely to the sustaining effect, and are absolutely
+essential in aerial navigation--the motor could not rise without
+them--still, when it comes to a question of weight-sustaining power, we
+must also figure on the engine capacity.
+
+In the Wright machine, in which there is a lifting capacity of
+approximately 2 1/4 pounds to the square foot of surface area, an engine
+of only 25 horsepower is used. In the Curtiss, which has a lifting
+capacity of 2 1/2 pounds per square foot, the engine is of 50
+horsepower. This is another of the peculiarities of aerial construction
+and navigation. Here we have a gain of 1/4 pound in weight-lifting
+capacity with an expenditure of double the horsepower. It is this
+feature which enables Curtiss to get along with a smaller surface area
+of supporting planes at the expense of a big increase in engine power.
+Proper Weight of Machine.
+
+As a general proposition the most satisfactory machine for amateur
+purposes will be found to be one with a total weight-sustaining power of
+about 1,200 pounds. Deducting 170 pounds as the weight of the operator,
+this will leave 1,030 pounds for the complete motor-equipped machine,
+and it should be easy to construct one within this limit. This implies,
+of course, that due care will be taken to eliminate all superfluous
+weight by using the lightest material compatible with strength and
+safety.
+
+This plan will admit of 686 pounds weight in the frame work, coverings,
+etc., and 344 for the motor, propeller, etc., which will be ample. Just
+how to distribute the weight of the planes is a matter which must be
+left to the ingenuity of the builder.
+
+Comparison of Bird Power.
+
+There is an interesting study in the accompanying illustration. Note
+that the surface area of the albatross is much smaller than that of the
+vulture, although the wing spread is about the same. Despite this the
+albatross accomplishes fully as much in the way of flight and soaring as
+the vulture. Why? Because the albaboss is quicker and more powerful in
+action. It is the application of this same principle in flying machines
+which enables those of great speed and power to get along with less
+supporting surface than those of slower movement.
+
+Measurements of Curtiss Machine.
+
+Some idea of framework proportion may be had from the following
+description of the Curtiss machine. The main planes have a spread
+(width) of 29 feet, and are 4 1/2 feet deep. The front double surface
+horizontal rudder is 6x2 feet, with an area of 24 square feet. To the
+rear of the main planes is a single surface horizontal plane 6x2 feet,
+with an area of 12 square feet. In connection with this is a vertical
+rudder 2 1/2 feet square. Two movable ailerons, or balancing planes, are
+placed at the extreme ends of the upper planes. These are 6x2 feet,
+and have a combined area of 24 square feet. There is also a triangular
+shaped vertical steadying surface in connection with the front rudder.
+
+Thus we have a total of 195 square feet, but as the official figures are
+258, and the size of the triangular-shaped steadying surface is unknown,
+we must take it for granted that this makes up the difference. In
+the matter of proportion the horizontal double-plane rudder is about
+one-tenth the size of the main plane, counting the surface area of
+only one plane, the vertical rudder one-fortieth, and the ailerons
+one-twentieth.
+
+
+
+CHAPTER XI. PLANE AND RUDDER CONTROL.
+
+Having constructed and equipped your machine, the next thing is to
+decide upon the method of controlling the various rudders and auxiliary
+planes by which the direction and equilibrium and ascending and
+descending of the machine are governed.
+
+The operator must be in position to shift instantaneously the position
+of rudders and planes, and also to control the action of the motor. This
+latter is supposed to work automatically and as a general thing does
+so with entire satisfaction, but there are times when the supply of
+gasolene must be regulated, and similar things done. Airship navigation
+calls for quick action, and for this reason the matter of control is an
+important one--it is more than important; it is vital.
+
+Several Methods of Control.
+
+Some aviators use a steering wheel somewhat after the style of that used
+in automobiles, and by this not only manipulate the rudder planes, but
+also the flow of gasolene. Others employ foot levers, and still others,
+like the Wrights, depend upon hand levers.
+
+Curtiss steers his aeroplane by means of a wheel, but secures the
+desired stabilizing effect with an ingenious jointed chair-back. This is
+so arranged that by leaning toward the high point of his wing planes the
+aeroplane is restored to an even keel. The steering post of the wheel is
+movable backward and forward, and by this motion elevation is obtained.
+
+The Wrights for some time used two hand levers, one to steer by and warp
+the flexible tips of the planes, the other to secure elevation. They
+have now consolidated all the functions in one lever. Bleriot also uses
+the single lever control.
+
+Farman employs a lever to actuate the rudders, but manipulates the
+balancing planes by foot levers.
+
+Santos-Dumont uses two hand levers with which to steer and elevate,
+but manipulates the planes by means of an attachment to the back of his
+outer coat.
+
+Connection With the Levers.
+
+No matter which particular method is employed, the connection between
+the levers and the object to be manipulated is almost invariably by
+wire. For instance, from the steering levers (or lever) two wires
+connect with opposite sides of the rudder. As a lever is moved so as to
+draw in the right-hand wire the rudder is drawn to the right and vice
+versa. The operation is exactly the same as in steering a boat. It
+is the same way in changing the position of the balancing planes. A
+movement of the hands or feet and the machine has changed its course,
+or, if the equilibrium is threatened, is back on an even keel.
+
+Simple as this seems it calls for a cool head, quick eye, and steady
+hand. The least hesitation or a false movement, and both aviator and
+craft are in danger.
+
+Which Method is Best?
+
+It would be a bold man who would attempt to pick out any one of these
+methods of control and say it was better than the others. As in other
+sections of aeroplane mechanism each method has its advocates who dwell
+learnedly upon its advantages, but the fact remains that all the various
+plans work well and give satisfaction.
+
+What the novice is interested in knowing is how the control is effected,
+and whether he has become proficient enough in his manipulation of it to
+be absolutely dependable in time of emergency. No amateur should attempt
+a flight alone, until he has thoroughly mastered the steering and plane
+control. If the services and advice of an experienced aviator are not to
+be had the novice should mount his machine on some suitable supports so
+it will be well clear of the ground, and, getting into the operator's
+seat, proceed to make himself well acquainted with the operation of the
+steering wheel and levers.
+
+Some Things to Be Learned.
+
+He will soon learn that certain movements of the steering gear produce
+certain effects on the rudders. If, for instance, his machine is
+equipped with a steering wheel, he will find that turning the wheel to
+the right turns the aeroplane in the same direction, because the tiller
+is brought around to the left. In the same way he will learn that a
+given movement of the lever throws the forward edge of the main plane
+upward, and that the machine, getting the impetus of the wind under the
+concave surfaces of the planes, will ascend. In the same way it will
+quickly become apparent to him that an opposite movement of the lever
+will produce an opposite effect--the forward edges of the planes will be
+lowered, the air will be "spilled" out to the rear, and the machine will
+descend.
+
+The time expended in these preliminary lessons will be well spent. It
+would be an act of folly to attempt to actually sail the craft without
+them.
+
+
+
+CHAPTER XII. HOW TO USE THE MACHINE.
+
+It is a mistaken idea that flying machines must be operated at extreme
+altitudes. True, under the impetus of handsome prizes, and the incentive
+to advance scientific knowledge, professional aviators have ascended to
+considerable heights, flights at from 500 to 1,500 feet being now
+common with such experts as Farman, Bleriot, Latham, Paulhan, Wright and
+Curtiss. The altitude record at this time is about 4,165 feet, held by
+Paulhan.
+
+One of the instructions given by experienced aviators to pupils, and for
+which they insist upon implicit obeyance, is: "If your machine gets more
+than 30 feet high, or comes closer to the ground than 6 feet, descend at
+once." Such men as Wright and Curtiss will not tolerate a violation of
+this rule. If their instructions are not strictly complied with they
+decline to give the offender further lessons.
+
+Why This Rule Prevails.
+
+There is good reason for this precaution. The higher the altitude the
+more rarefied (thinner) becomes the air, and the less sustaining power
+it has. Consequently the more difficult it becomes to keep in suspension
+a given weight. When sailing within 30 feet of the ground sustentation
+is comparatively easy and, should a fall occur, the results are not
+likely to be serious. On the other hand, sailing too near the ground
+is almost as objectionable in many ways as getting up too high. If the
+craft is navigated too close to the ground trees, shrubs, fences and
+other obstructions are liable to be encountered. There is also the
+handicap of contrary air currents diverted by the obstructions referred
+to, and which will be explained more fully further on.
+
+How to Make a Start.
+
+Taking it for granted that the beginner has familiarized himself with
+the manipulation of the machine, and especially the control mechanism,
+the next thing in order is an actual flight. It is probable that his
+machine will be equipped with a wheeled alighting gear, as the skids
+used by the Wrights necessitate the use of a special starting track.
+In this respect the wheeled machine is much easier to handle so far as
+novices are concerned as it may be easily rolled to the trial grounds.
+This, as in the case of the initial experiments, should be a clear,
+reasonably level place, free from trees, fences, rocks and similar
+obstructions with which there may be danger of colliding.
+
+The beginner will need the assistance of three men. One of these should
+take his position in the rear of the machine, and one at each end. On
+reaching the trial ground the aviator takes his seat in the machine and,
+while the men at the ends hold it steady the one in the rear assists in
+retaining it until the operator is ready. In the meantime the aviator
+has started his motor. Like the glider the flying machine, in order to
+accomplish the desired results, should be headed into the wind.
+
+When the Machine Rises.
+
+Under the impulse of the pushing movement, and assisted by the motor
+action, the machine will gradually rise from the ground--provided it
+has been properly proportioned and put together, and everything is in
+working order. This is the time when the aviator requires a cool head,
+At a modest distance from the ground use the control lever to bring the
+machine on a horizontal level and overcome the tendency to rise. The
+exact manipulation of this lever depends upon the method of control
+adopted, and with this the aviator is supposed to have thoroughly
+familiarized himself as previously advised in Chapter XI.
+
+It is at this juncture that the operator must act promptly, but with the
+perfect composure begotten of confidence. One of the great drawbacks in
+aviation by novices is the tendency to become rattled, and this is much
+more prevalent than one might suppose, even among men who, under other
+conditions, are cool and confident in their actions.
+
+There is something in the sensation of being suddenly lifted from the
+ground, and suspended in the air that is disconcerting at the start,
+but this will soon wear off if the experimenter will keep cool. A few
+successful flights no matter how short they may be, will put a lot of
+confidence into him.
+
+Make Your Flights Short.
+
+Be modest in your initial flights. Don't attempt to match the records
+of experienced men who have devoted years to mastering the details of
+aviation. Paulhan, Farman, Bleriot, Wright, Curtiss, and all the rest of
+them began, and practiced for years, in the manner here described, being
+content to make just a little advancement at each attempt. A flight of
+150 feet, cleanly and safely made, is better as a beginning than one of
+400 yards full of bungling mishaps.
+
+And yet these latter have their uses, provided the operator is of a
+discerning mind and can take advantage of them as object lessons. But,
+it is not well to invite them. They will occur frequently enough under
+the most favorable conditions, and it is best to have them come later
+when the feeling of trepidation and uncertainty as to what to do has
+worn off.
+
+Above all, don't attempt to fly too high. Keep within a reasonable
+distance from the ground--about 25 or 30 feet. This advice is not given
+solely to lessen the risk of serious accident in case of collapse, but
+mainly because it will assist to instill confidence in the operator.
+
+It is comparatively easy to learn to swim in shallow water, but the
+knowledge that one is tempting death in deep water begets timidity.
+
+Preserving the Equilibrium.
+
+After learning how to start and stop, to ascend and descend, the next
+thing to master is the art of preserving equilibrium, the knack of
+keeping the machine perfectly level in the air--on an "even keel," as
+a sailor would say. This simile is particularly appropriate as all
+aviators are in reality sailors, and much more daring ones than those
+who course the seas. The latter are in craft which are kept afloat by
+the buoyancy of the water, whether in motion or otherwise and, so long
+as normal conditions prevail, will not sink. Aviators sail the air in
+craft in which constant motion must be maintained in order to ensure
+flotation.
+
+The man who has ridden a bicycle or motorcycle around curves at anything
+like high speed, will have a very good idea as to the principle of
+maintaining equilibrium in an airship. He knows that in rounding curves
+rapidly there is a marked tendency to change the direction of the motion
+which will result in an upset unless he overcomes it by an inclination
+of his body in an opposite direction. This is why we see racers lean
+well over when taking the curves. It simply must be done to preserve the
+equilibrium and avoid a spill.
+
+How It Works In the Air.
+
+If the equilibrium of an airship is disturbed to an extent which
+completely overcomes the center of gravity it falls according to the
+location of the displacement. If this displacement, for instance, is at
+either end the apparatus falls endways; if it is to the front or rear,
+the fall is in the corresponding direction.
+
+Owing to uncertain air currents--the air is continually shifting and
+eddying, especially within a hundred feet or so of the earth--the
+equilibrium of an airship is almost constantly being disturbed to some
+extent. Even if this disturbance is not serious enough to bring on
+a fall it interferes with the progress of the machine, and should
+be overcome at once. This is one of the things connected with aerial
+navigation which calls for prompt, intelligent action.
+
+Frequently, when the displacement is very slight, it may be overcome,
+and the craft immediately righted by a mere shifting of the operator's
+body. Take, for illustration, a case in which the extreme right end
+of the machine becomes lowered a trifle from the normal level. It is
+possible to bring it back into proper position by leaning over to the
+left far enough to shift the weight to the counter-balancing point. The
+same holds good as to minor front or rear displacements.
+
+When Planes Must Be Used.
+
+There are other displacements, however, and these are the most frequent,
+which can be only overcome by manipulation of the stabilizing planes.
+The method of procedure depends upon the form of machine in use. The
+Wright machine, as previously explained, is equipped with plane ends
+which are so contrived as to admit of their being warped (position
+changed) by means of the lever control. These flexible tip planes move
+simultaneously, but in opposite directions. As those on one end rise,
+those on the other end fall below the level of the main plane. By this
+means air is displaced at one point, and an increased amount secured in
+another.
+
+This may seem like a complicated system, but its workings are simple
+when once understood. It is by the manipulation or warping of these
+flexible tips that transverse stability is maintained, and any tendency
+to displacement endways is overcome. Longitudinal stability is governed
+by means of the front rudder.
+
+Stabilizing planes of some form are a feature, and a necessary feature,
+on all flying machines, but the methods of application and manipulation
+vary according to the individual ideas of the inventors. They all tend,
+however, toward the same end--the keeping of the machine perfectly level
+when being navigated in the air.
+
+When to Make a Flight.
+
+A beginner should never attempt to make a flight when a strong wind is
+blowing. The fiercer the wind, the more likely it is to be gusty and
+uncertain, and the more difficult it will be to control the machine.
+Even the most experienced and daring of aviators find there is a limit
+to wind speed against which they dare not compete. This is not because
+they lack courage, but have the sense to realize that it would be silly
+and useless.
+
+The novice will find a comparatively still day, or one when the wind is
+blowing at not to exceed 15 miles an hour, the best for his experiments.
+The machine will be more easily controlled, the trip will be safer, and
+also cheaper as the consumption of fuel increases with the speed of the
+wind against which the aeroplane is forced.
+
+
+
+CHAPTER XIII. PECULIARITIES OF AIRSHIP POWER.
+
+As a general proposition it takes much more power to propel an airship
+a given number of miles in a certain time than it does an automobile
+carrying a far heavier load. Automobiles with a gross load of 4,000
+pounds, and equipped with engines of 30 horsepower, have travelled
+considerable distances at the rate of 50 miles an hour. This is an
+equivalent of about 134 pounds per horsepower. For an average modern
+flying machine, with a total load, machine and passengers, of 1,200
+pounds, and equipped with a 50-horsepower engine, 50 miles an hour
+is the maximum. Here we have the equivalent of exactly 24 pounds per
+horsepower. Why this great difference?
+
+No less an authority than Mr. Octave Chanute answers the question in a
+plain, easily understood manner. He says:
+
+"In the case of an automobile the ground furnishes a stable support;
+in the case of a flying machine the engine must furnish the support and
+also velocity by which the apparatus is sustained in the air."
+
+Pressure of the Wind.
+
+Air pressure is a big factor in the matter of aeroplane horsepower.
+Allowing that a dead calm exists, a body moving in the atmosphere
+creates more or less resistance. The faster it moves, the greater is
+this resistance. Moving at the rate of 60 miles an hour the resistance,
+or wind pressure, is approximately 50 pounds to the square foot of
+surface presented. If the moving object is advancing at a right angle
+to the wind the following table will give the horsepower effect of the
+resistance per square foot of surface at various speeds.
+
+                            Horse Power
+          Miles per Hour    per sq. foot
+          10             0.013
+          15             0 044
+          20             0.105
+          25             0.205
+          30             0.354
+          40             0.84
+          50             1.64
+          60             2.83
+          80             6.72
+          100            13.12
+
+While the pressure per square foot at 60 miles an hour, is only 1.64
+horsepower, at 100 miles, less than double the speed, it has increased
+to 13.12 horsepower, or exactly eight times as much. In other words the
+pressure of the wind increases with the square of the velocity. Wind at
+10 miles an hour has four times more pressure than wind at 5 miles an
+hour.
+
+How to Determine Upon Power.
+
+This element of air resistance must be taken into consideration in
+determining the engine horsepower required. When the machine is under
+headway sufficient to raise it from the ground (about 20 miles an hour),
+each square foot of surface resistance, will require nearly nine-tenths
+of a horsepower to overcome the wind pressure, and propel the machine
+through the air. As shown in the table the ratio of power required
+increases rapidly as the speed increases until at 60 miles an hour
+approximately 3 horsepower is needed.
+
+In a machine like the Curtiss the area of wind-exposed surface is about
+15 square feet. On the basis of this resistance moving the machine at 40
+miles an hour would require 12 horsepower. This computation covers only
+the machine's power to overcome resistance. It does not cover the power
+exerted in propelling the machine forward after the air pressure is
+overcome. To meet this important requirement Mr. Curtiss finds it
+necessary to use a 50-horsepower engine. Of this power, as has been
+already stated, 12 horsepower is consumed in meeting the wind pressure,
+leaving 38 horsepower for the purpose of making progress.
+
+The flying machine must move faster than the air to which it is opposed.
+Unless it does this there can be no direct progress. If the two forces
+are equal there is no straight-ahead advancement. Take, for sake of
+illustration, a case in which an aeroplane, which has developed a speed
+of 30 miles an hour, meets a wind velocity of equal force moving in an
+opposite direction. What is the result? There can be no advance because
+it is a contest between two evenly matched forces. The aeroplane stands
+still. The only way to get out of the difficulty is for the operator to
+wait for more favorable conditions, or bring his machine to the ground
+in the usual manner by manipulation of the control system.
+
+Take another case. An aeroplane, capable of making 50 miles an hour in a
+calm, is met by a head wind of 25 miles an hour. How much progress does
+the aeroplane make? Obviously it is 25 miles an hour over the ground.
+
+Put the proposition in still another way. If the wind is blowing harder
+than it is possible for the engine power to overcome, the machine will
+be forced backward.
+
+Wind Pressure a Necessity.
+
+While all this is true, the fact remains that wind pressure, up to
+a certain stage, is an absolute necessity in aerial navigation. The
+atmosphere itself has very little real supporting power, especially if
+inactive. If a body heavier than air is to remain afloat it must move
+rapidly while in suspension.
+
+One of the best illustrations of this is to be found in skating over
+thin ice. Every school boy knows that if he moves with speed he may
+skate or glide in safety across a thin sheet of ice that would not
+begin to bear his weight if he were standing still. Exactly the same
+proposition obtains in the case of the flying machine.
+
+The non-technical reason why the support of the machine becomes easier
+as the speed increases is that the sustaining power of the atmosphere
+increases with the resistance, and the speed with which the object is
+moving increases this resistance. With a velocity of 12 miles an hour
+the weight of the machine is practically reduced by 230 pounds. Thus, if
+under a condition of absolute calm it were possible to sustain a weight
+of 770 pounds, the same atmosphere would sustain a weight of 1,000
+pounds moving at a speed of 12 miles an hour. This sustaining power
+increases rapidly as the speed increases. While at 12 miles the
+sustaining power is figured at 230 pounds, at 24 miles it is four times
+as great, or 920 pounds.
+
+Supporting Area of Birds.
+
+One of the things which all producing aviators seek to copy is the
+motive power of birds, particularly in their relation to the area of
+support. Close investigation has established the fact that the larger
+the bird the less is the relative area of support required to secure a
+given result. This is shown in the following table:
+
+                                                   Supporting
+                  Weight       Surface       Horse      area
+     Bird         in lbs.     in sq. feet   power     per lb.
+     Pigeon         1.00      0.7           0.012     0.7
+     Wild Goose     9.00      2.65          0.026     0.2833
+     Buzzard        5.00      5.03          0.015     1.06
+     Condor        17.00      9.85          0.043     0.57
+
+So far as known the condor is the largest of modern birds. It has a wing
+stretch of 10 feet from tip to tip, a supporting area of about 10 square
+feet, and weighs 17 pounds. It. is capable of exerting perhaps 1-30
+horsepower. (These figures are, of course, approximate.) Comparing the
+condor with the buzzard with a wing stretch of 6 feet, supporting area
+of 5 square feet, and a little over 1-100 horsepower, it may be seen
+that, broadly speaking, the larger the bird the less surface area
+(relatively) is needed for its support in the air.
+
+Comparison With Aeroplanes.
+
+If we compare the bird figures with those made possible by the
+development of the aeroplane it will be readily seen that man has made a
+wonderful advance in imitating the results produced by nature. Here are
+the figures:
+
+                                                       Supporting
+                     Weight      Surface       Horse      area
+     Machine         in lbs.    in sq. feet    power     per lb.
+     Santos-Dumont..  350      110.00        30        0.314
+     Bleriot.....     700      150.00        25        0.214
+     Antoinette.... 1,200      538.00        50        0.448
+     Curtiss.....     700      258.00        60        0.368
+     Wright.....[4] 1,100      538.00        25        0.489
+     Farman......   1,200      430.00        50        0.358
+     Voisin......   1,200      538.00        50        0.448
+
+While the average supporting surface is in favor of the aeroplane, this
+is more than overbalanced by the greater amount of horsepower required
+for the weight lifted. The average supporting surface in birds is about
+three-quarters of a square foot per pound. In the average aeroplane it
+is about one-half square foot per pound. On the other hand the average
+aeroplane has a lifting capacity of 24 pounds per horsepower, while the
+buzzard, for instance, lifts 5 pounds with 15-100 of a horsepower.
+If the Wright machine--which has a lifting power of 50 pounds per
+horsepower--should be alone considered the showing would be much more
+favorable to the aeroplane, but it would not be a fair comparison.
+
+More Surface, Less Power.
+
+Broadly speaking, the larger the supporting area the less will be the
+power required. Wright, by the use of 538 square feet of supporting
+surface, gets along with an engine of 25 horsepower. Curtiss, who uses
+only 258 square feet of surface, finds an engine of 50 horsepower is
+needed. Other things, such as frame, etc., being equal, it stands
+to reason that a reduction in the area of supporting surface will
+correspondingly reduce the weight of the machine. Thus we have the
+Curtiss machine with its 258 square feet of surface, weighing only 600
+pounds (without operator), but requiring double the horsepower of
+the Wright machine with 538 square feet of surface and weighing 1,100
+pounds. This demonstrates in a forceful way the proposition that the
+larger the surface the less power will be needed.
+
+But there is a limit, on account of its bulk and awkwardness in
+handling, beyond which the surface area cannot be enlarged. Otherwise
+it might be possible to equip and operate aeroplanes satisfactorily with
+engines of 15 horsepower, or even less.
+
+The Fuel Consumption Problem.
+
+Fuel consumption is a prime factor in the production of engine power.
+The veriest mechanical tyro knows in a general way that the more power
+is secured the more fuel must be consumed, allowing that there is no
+difference in the power-producing qualities of the material used. But
+few of us understand just what the ratio of increase is, or how it is
+caused. This proposition is one of keen interest in connection with
+aviation.
+
+Let us cite a problem which will illustrate the point quoted: Allowing
+that it takes a given amount of gasolene to propel a flying machine a
+given distance, half the way with the wind, and half against it, the
+wind blowing at one-half the speed of the machine, what will be the
+increase in fuel consumption?
+
+Increase of Thirty Per Cent.
+
+On the face of it there would seem to be no call for an increase as the
+resistance met when going against the wind is apparently offset by the
+propulsive force of the wind when the machine is travelling with
+it. This, however, is called faulty reasoning. The increase in fuel
+consumption, as figured by Mr. F. W. Lanchester, of the Royal Society of
+Arts, will be fully 30 per cent over the amount required for a similar
+operation of the machine in still air. If the journey should be made at
+right angles to the wind under the same conditions the increase would be
+15 per cent.
+
+In other words Mr. Lanchester maintains that the work done by the motor
+in making headway against the wind for a certain distance calls for more
+engine energy, and consequently more fuel by 30 per cent, than is saved
+by the helping force of the wind on the return journey.
+
+
+
+CHAPTER XIV. ABOUT WIND CURRENTS, ETC.
+
+One of the first difficulties which the novice will encounter is the
+uncertainty of the wind currents. With a low velocity the wind, some
+distance away from the ground, is ordinarily steady. As the velocity
+increases, however, the wind generally becomes gusty and fitful in its
+action. This, it should be remembered, does not refer to the velocity of
+the machine, but to that of the air itself.
+
+In this connection Mr. Arthur T. Atherholt, president of the Aero
+Club of Pennsylvania, in addressing the Boston Society of Scientific
+Research, said:
+
+"Probably the whirlpools of Niagara contain no more erratic currents
+than the strata of air which is now immediately above us, a fact hard to
+realize on account of its invisibility."
+
+Changes In Wind Currents.
+
+While Mr. Atherholt's experience has been mainly with balloons it is all
+the more valuable on this account, as the balloons were at the mercy of
+the wind and their varying directions afforded an indisputable guide as
+to the changing course of the air currents. In speaking of this he said:
+
+"In the many trips taken, varying in distance traversed from twenty-five
+to 900 miles, it was never possible except in one instance to maintain
+a straight course. These uncertain currents were most noticeable in
+the Gordon-Bennett race from St. Louis in 1907. Of the nine aerostats
+competing in that event, eight covered a more or less direct course
+due east and southeast, whereas the writer, with Major Henry B. Hersey,
+first started northwest, then north, northeast, east, east by south,
+and when over the center of Lake Erie were again blown northwest
+notwithstanding that more favorable winds were sought for at altitudes
+varying from 100 to 3,000 meters, necessitating a finish in Canada
+nearly northeast of the starting point.
+
+"These nine balloons, making landings extending from Lake Ontario,
+Canada, to Virginia, all started from one point within the same hour.
+
+"The single exception to these roving currents occurred on October 21st,
+of last year (1909) when, starting from Philadelphia, the wind shifted
+more than eight degrees, the greatest variation being at the lowest
+altitudes, yet at no time was a height of over a mile reached.
+
+"Throughout the entire day the sky was overcast, with a thermometer
+varying from fifty-seven degrees at 300 feet to forty-four degrees,
+Fahrenheit at 5,000 feet, at which altitude the wind had a velocity of
+43 miles an hour, in clouds of a cirro-cumulus nature, a landing finally
+being made near Tannersville, New York, in the Catskill mountains, after
+a voyage of five and one-half hours.
+
+"I have no knowledge of a recorded trip of this distance and duration,
+maintained in practically a straight line from start to finish."
+
+This wind disturbance is more noticeable and more difficult to contend
+with in a balloon than in a flying machine, owing to the bulk and
+unwieldy character of the former. At the same time it is not conducive
+to pleasant, safe or satisfactory sky-sailing in an aeroplane. This is
+not stated with the purpose of discouraging aviation, but merely that
+the operator may know what to expect and be prepared to meet it.
+
+Not only does the wind change its horizontal course abruptly and without
+notice, but it also shifts in a vertical direction, one second blowing
+up, and another down. No man has as yet fathomed the why and wherefore
+of this erratic action; it is only known that it exists.
+
+The most stable currents will be found from 50 to 100 feet from the
+earth, provided the wind is not diverted by such objects as trees,
+rocks, etc. That there are equally stable currents higher up is true,
+but they are generally to be found at excessive altitudes.
+
+How a Bird Meets Currents.
+
+Observe a bird in action on a windy day and you will find it continually
+changing the position of its wings. This is done to meet the varying
+gusts and eddies of the air so that sustentation may be maintained and
+headway made. One second the bird is bending its wings, altering the
+angle of incidence; the next it is lifting or depressing one wing at a
+time. Still again it will extend one wing tip in advance of the other,
+or be spreading or folding, lowering or raising its tail.
+
+All these motions have a meaning, a purpose. They assist the bird in
+preserving its equilibrium. Without them the bird would be just as
+helpless in the air as a human being and could not remain afloat.
+
+When the wind is still, or comparatively so, a bird, having secured the
+desired altitude by flight at an angle, may sail or soar with no wing
+action beyond an occasional stroke when it desires to advance. But, in a
+gusty, uncertain wind it must use its wings or alight somewhere.
+
+Trying to Imitate the Bird.
+
+Writing in _Fly_, Mr. William E. White says:
+
+"The bird's flight suggests a number of ways in which the equilibrium
+of a mechanical bird may be controlled. Each of these methods of control
+may be effected by several different forms of mechanism.
+
+"Placing the two wings of an aeroplane at an angle of three to five
+degrees to each other is perhaps the oldest way of securing lateral
+balance. This way readily occurs to anyone who watches a sea gull
+soaring. The theory of the dihedral angle is that when one wing is
+lifted by a gust of wind, the air is spilled from under it; while
+the other wing, being correspondingly depressed, presents a greater
+resistance to the gust and is lifted restoring the balance. A fixed
+angle of three to five degrees, however, will only be sufficient for
+very light puffs of wind and to mount the wings so that the whole
+wing may be moved to change the dihedral angle presents mechanical
+difficulties which would be better avoided.
+
+"The objection of mechanical impracticability applies to any plan
+to preserve the balance by shifting weight or ballast. The center of
+gravity should be lower than the center of the supporting surfaces,
+but cannot be made much lower. It is a common mistake to assume that
+complete stability will be secured by hanging the center of gravity very
+low on the principle of the parachute. An aeroplane depends upon rapid
+horizontal motion for its support, and if the center of gravity be far
+below the center of support, every change of speed or wind pressure will
+cause the machine to turn about its center of gravity, pitching forward
+and backward dangerously.
+
+Preserving Longitudinal Balance.
+
+"The birds maintain longitudinal, or fore and aft balance, by elevating
+or depressing their tails. Whether this action is secured in an
+aeroplane by means of a horizontal rudder placed in the rear, or by
+deflecting planes placed in front of the main planes, the principle is
+evidently the same. A horizontal rudder placed well to the rear as in
+the Antoinette, Bleriot or Santos-Dumont monoplanes, will be very much
+safer and steadier than the deflecting planes in front, as in the Wright
+or Curtiss biplanes, but not so sensitive or prompt in action.
+
+"The natural fore and aft stability is very much strengthened by placing
+the load well forward. The center of gravity near the front and a
+tail or rudder streaming to the rear secures stability as an arrow is
+balanced by the head and feathering. The adoption of this principle
+makes it almost impossible for the aeroplane to turn over.
+
+The Matter of Lateral Balance.
+
+"All successful aeroplanes thus far have maintained lateral balance by
+the principle of changing the angle of incidence of the wings.
+
+"Other ways of maintaining the lateral balance, suggested by observation
+of the flight of birds are--extending the wing tips and spilling the air
+through the pinions; or, what is the same thing, varying the area of the
+wings at their extremities.
+
+"Extending the wing tips seems to be a simple and effective solution of
+the problem. The tips may be made to swing outward upon a vertical axis
+placed at the front edge of the main planes; or they may be hinged to
+the ends of the main plane so as to be elevated or depressed through
+suitable connections by the aviator; or they may be supported from a
+horizontal axis parallel with the ends of the main planes so that they
+may swing outward, the aviator controlling both tips through one lever
+so that as one tip is extended the other is retracted.
+
+"The elastic wing pinions of a bird bend easily before the wind,
+permitting the gusts to glance off, but presenting always an even and
+efficient curvature to the steady currents of the air."
+
+High Winds Threaten Stability.
+
+To ensure perfect stability, without control, either human or automatic,
+it is asserted that the aeroplane must move faster than the wind is
+blowing. So long as the wind is blowing at the rate of 30 miles an hour,
+and the machine is traveling 40 or more, there will be little trouble as
+regards equilibrium so far as wind disturbance goes, provided the wind
+blows evenly and does not come in gusts or eddying currents. But when
+conditions are reversed--when the machine travels only 30 miles an hour
+and the wind blows at the rate of 50, look out for loss of equilibrium.
+
+One of the main reasons for this is that high winds are rarely steady;
+they seldom blow for any length of time at the same speed. They are
+usually "gusty," the gusts being a momentary movement at a higher speed.
+Tornadic gusts are also formed by the meeting of two opposing currents,
+causing a whirling motion, which makes stability uncertain. Besides, it
+is not unusual for wind of high speed to suddenly change its direction
+without warning.
+
+Trouble With Vertical Columns.
+
+Vertical currents--columns of ascending air--are frequently encountered
+in unexpected places and have more or less tendency, according to their
+strength, to make it difficult to keep the machine within a reasonable
+distance from the ground.
+
+These vertical currents are most generally noticeable in the vicinity
+of steep cliffs, or deep ravines. In such instances they are usually of
+considerable strength, being caused by the deflection of strong winds
+blowing against the face of the cliffs. This deflection exerts a back
+pressure which is felt quite a distance away from the point of origin,
+so that the vertical current exerts an influence in forcing the machine
+upward long before the cliff is reached.
+
+
+
+CHAPTER XV. THE ELEMENT OF DANGER.
+
+That there is an element of danger in aviation is undeniable, but it is
+nowhere so great as the public imagines. Men are killed and injured in
+the operation of flying machines just as they are killed and injured
+in the operation of railways. Considering the character of aviation the
+percentage of casualties is surprisingly small.
+
+This is because the results following a collapse in the air are very
+much different from what might be imagined. Instead of dropping to the
+ground like a bullet an aeroplane, under ordinary conditions will, when
+anything goes wrong, sail gently downward like a parachute, particularly
+if the operator is cool-headed and nervy enough to so manipulate the
+apparatus as to preserve its equilibrium and keep the machine on an even
+keel.
+
+Two Fields of Safety.
+
+At least one prominent aviator has declared that there are two fields
+of safety--one close to the ground, and the other well up in the air. In
+the first-named the fall will be a slight one with little chance of the
+operator being seriously hurt. From the field of high altitude the the
+descent will be gradual, as a rule, the planes of the machine serving to
+break the force of the fall. With a cool-headed operator in control the
+aeroplane may be even guided at an angle (about 1 to 8) in its descent
+so as to touch the ground with a gliding motion and with a minimum of
+impact.
+
+Such an experience, of course, is far from pleasant, but it is by no
+means so dangerous as might appear. There is more real danger in falling
+from an elevation of 75 or 100 feet than there is from 1,000 feet, as
+in the former case there is no chance for the machine to serve as a
+parachute--its contact with the ground comes too quickly.
+
+Lesson in Recent Accidents.
+
+Among the more recent fatalities in aviation are the deaths of Antonio
+Fernandez and Leon Delagrange. The former was thrown to the ground by a
+sudden stoppage of his motor, the entire machine seeming to collapse. It
+is evident there were radical defects, not only in the motor, but in the
+aeroplane framework as well. At the time of the stoppage it is
+estimated that Fernandez was up about 1,500 feet, but the machine got
+no opportunity to exert a parachute effect, as it broke up immediately.
+This would indicate a fatal weakness in the structure which, under
+proper testing, could probably have been detected before it was used in
+flight.
+
+It is hard to say it, but Delagrange appears to have been culpable to
+great degree in overloading his machine with a motor equipment much
+heavier than it was designed to sustain. He was 65 feet up in the air
+when the collapse occurred, resulting in his death. As in the case of
+Fernandez common-sense precaution would doubtless have prevented the
+fatality.
+
+Aviation Not Extra Hazardous.
+
+All told there have been, up to the time of this writing (April, 1910),
+just five fatalities in the history of power-driven aviation. This is
+surprisingly low when the nature of the experiments, and the fact that
+most of the operators were far from having extended experience, is taken
+into consideration. Men like the Wrights, Curtiss, Bleriot, Farman,
+Paulhan and others, are now experts, but there was a time, and it was
+not long ago, when they were unskilled. That they, with numerous
+others less widely known, should have come safely through their many
+experiments would seem to disprove the prevailing idea that aviation is
+an extra hazardous pursuit.
+
+In the hands of careful, quick-witted, nervy men the sailing of an
+airship should be no more hazardous than the sailing of a yacht. A
+vessel captain with common sense will not go to sea in a storm, or
+navigate a weak, unseaworthy craft. Neither should an aviator attempt to
+sail when the wind is high and gusty, nor with a machine which has not
+been thoroughly tested and found to be strong and safe.
+
+Safer Than Railroading.
+
+Statistics show that some 12,000 people are killed and 72,000 injured
+every year on the railroads of the United States. Come to think it over
+it is small wonder that the list of fatalities is so large. Trains
+are run at high speeds, dashing over crossings at which collisions are
+liable to occur, and over bridges which often collapse or are swept away
+by floods. Still, while the number of casualties is large, the actual
+percentage is small considering the immense number of people involved.
+
+It is so in aviation. The number of casualties is remarkably small in
+comparison with the number of flights made. In the hands of competent
+men the sailing of an airship should be, and is, freer from risk of
+accident than the running of a railway train. There are no rails
+to spread or break, no bridges to collapse, no crossings at which
+collisions may occur, no chance for some sleepy or overworked employee
+to misunderstand the dispatcher's orders and cause a wreck.
+
+Two Main Causes of Trouble.
+
+The two main causes of trouble in an airship leading to disaster may
+be attributed to the stoppage of the motor, and the aviator becoming
+rattled so that he loses control of his machine. Modern ingenuity is
+fast developing motors that almost daily become more and more reliable,
+and experience is making aviators more and more self-confident in their
+ability to act wisely and promptly in cases of emergency. Besides this
+a satisfactory system of automatic control is in a fair way of being
+perfected.
+
+Occasionally even the most experienced and competent of men in all
+callings become careless and by foolish action invite disaster. This
+is true of aviators the same as it is of railroaders, men who work in
+dynamite mills, etc. But in nearly every instance the responsibility
+rests with the individual; not with the system. There are some men
+unfitted by nature for aviation, just as there are others unfitted to be
+railway engineers.
+
+
+
+CHAPTER XVI. RADICAL CHANGES BEING MADE.
+
+Changes, many of them extremely radical in their nature, are continually
+being made by prominent aviators, and particularly those who have won
+the greatest amount of success. Wonderful as the results have been
+few of the aviators are really satisfied. Their successes have merely
+spurred them on to new endeavors, the ultimate end being the development
+of an absolutely perfect aircraft.
+
+Among the men who have been thus experimenting are the Wright Brothers,
+who last year (1909) brought out a craft totally different as regards
+proportions and weight from the one used the preceding year. One marked
+result was a gain of about 3 1/2 miles an hour in speed.
+
+Dimensions of 1908 Machine.
+
+The 1908 model aeroplane was 40 by 29 feet over all. The carrying
+surfaces, that is, the two aerocurves, were 40 by 6 feet, having a
+parabolical curve of one in twelve. With about 70 square feet of surface
+in the rudders, the total surface given was about 550 square feet.
+The engine, which is the invention of the Wright brothers, weighed,
+approximately, 200 pounds, and gave about 25 horsepower at 1,400
+revolutions per minute. The total weight of the aeroplane, exclusive of
+passenger, but inclusive of engine, was about 1,150 pounds. This result
+showed a lift of a fraction over 2 1/4 pounds to the square foot of
+carrying surface. The speed desired was 40 miles an hour, but the
+machine was found to make only a scant 39 miles an hour. The upright
+struts were about 7/8-inch thick, the skids, 2 1/2 by 1 1/4 inches
+thick.
+
+Dimensions of 1909 Machine.
+
+The 1909 aeroplane was built primarily for greater speed, and relatively
+heavier; to be less at the mercy of the wind. This result was obtained
+as follows: The aerocurves, or carrying surfaces, were reduced in
+dimensions from 40 by 6 feet to 36 by 5 1/2 feet, the curve remaining
+the same, one in twelve. The upright struts were cut from seven-eighths
+inch to five-eighths inch, and the skids from two and one-half by one
+and one-quarter to two and one-quarter by one and three-eighths inches.
+This result shows that there were some 81 square feet of carrying
+surface missing over that of last year's model. and some 25 pounds loss
+of weight. Relatively, though, the 1909 model aeroplane, while actually
+25 pounds lighter, is really some 150 pounds heavier in the air than the
+1908 model, owing to the lesser square feet of carrying surface.
+
+Some of the Results Obtained.
+
+Reducing the carrying surfaces from 6 to 5 1/2 feet gave two
+results--first, less carrying capacity; and, second, less head-on
+resistance, owing to the fact that the extent of the parabolic curve
+in the carrying surfaces was shortened. The "head-on" resistance is
+the retardance the aeroplane meets in passing through the air, and is
+counted in square feet. In the 1908 model the curve being one in twelve
+and 6 feet deep, gave 6 inches of head-on resistance. The plane being
+40 feet spread, gave 6 inches by 40 feet, or 20 square feet of head-on
+resistance. Increasing this figure by a like amount for each plane, and
+adding approximately 10 square feet for struts, skids and wiring, we
+have a total of approximately, 50 square feet of surface for "head-on"
+resistance.
+
+In the 1909 aeroplane, shortening the curve 6 inches at the parabolic
+end of the curve took off 1 inch of head-on resistance. Shortening the
+spread of the planes took off between 3 and 4 square feet of head-on
+resistance. Add to this the total of 7 square feet, less curve surface
+and about 1 square foot, less wire and woodwork resistance, and we
+have a grand total of, approximately, 12 square feet of less "head-on"
+resistance over the 1908 model.
+
+Changes in Engine Action.
+
+The engine used in 1909 was the same one used in 1908, though some minor
+changes were made as improvements; for instance, a make and break spark
+was used, and a nine-tooth, instead of a ten-tooth magneto gear-wheel
+was used. This increased the engine revolutions per minute from 1,200 to
+1,400, and the propeller revolutions per minute from 350 to 371, giving
+a propeller thrust of, approximately, 170 foot pounds instead of 153, as
+was had last year.
+
+More Speed and Same Capacity.
+
+One unsatisfactory feature of the 1909 model over that of 1908,
+apparently, was the lack of inherent lateral stability. This was caused
+by the lesser surface and lesser extent of curvatures at the portions
+of the aeroplane which were warped. This defect did not show so plainly
+after Mr. Orville Wright had become fully proficient in the handling of
+the new machine, and with skillful management, the 1909 model aeroplane
+will be just as safe and secure as the other though it will take a
+little more practice to get that same degree of skill.
+
+To sum up: The aeroplane used in 1909 was 25 pounds lighter, but really
+about 150 pounds heavier in the air, had less head-on resistance, and
+greater propeller thrust. The speed was increased from about 39 miles
+per hour to 42 1/2 miles per hour. The lifting capacity remained about
+the same, about 450 pounds capacity passenger-weight, with the 1908
+machine. In this respect, the loss of carrying surface was compensated
+for by the increased speed.
+
+During the first few flights it was plainly demonstrated that it would
+need the highest skill to properly handle the aeroplane, as first one
+end and then the other would dip and strike the ground, and either tear
+the canvas or slew the aeroplane around and break a skid.
+
+Wrights Adopt Wheeled Gears.
+
+In still another important respect the Wrights, so far as the output
+of one of their companies goes, have made a radical change. All the
+aeroplanes turned out by the Deutsch Wright Gesellschaft, according to
+the German publication, _Automobil-Welt_, will hereafter be equipped
+with wheeled running gears and tails. The plan of this new machine is
+shown in the illustration on page 145. The wheels are three in number,
+and are attached one to each of the two skids, just under the front edge
+of the planes, and one forward of these, attached to a cross-member. It
+is asserted that with these wheels the teaching of purchasers to operate
+the machines is much simplified, as the beginners can make short flights
+on their own account without using the starting derrick.
+
+This is a big concession for the Wrights to make, as they have hitherto
+adhered stoutly to the skid gear. While it is true they do not control
+the German company producing their aeroplanes, yet the nature of their
+connection with the enterprise is such that it may be taken for granted
+no radical changes in construction would be made without their approval
+and consent.
+
+Only Three Dangerous Rivals.
+
+Official trials with the 1909 model smashed many records and leave the
+Wright brothers with only three dangerous rivals in the field, and with
+basic patents which cover the curve, warp and wing-tip devices found on
+all the other makes of aeroplanes. These three rivals are the Curtiss
+and Voisin biplane type and the Bleriot monoplane pattern.
+
+The Bleriot monoplane is probably the most dangerous rival, as this make
+of machine has a record of 54 miles per hour, has crossed the English
+channel, and has lifted two passengers besides the operator. The
+latest type of this machine only weighs 771.61 pounds complete, without
+passengers, and will lift a total passenger weight of 462.97 pounds,
+which is a lift of 5.21 pounds to the square foot. This is a better
+result than those published by the Wright brothers, the best noted being
+4.25 pounds per square foot.
+
+Other Aviators at Work.
+
+The Wrights, however, are not alone in their efforts to promote the
+efficiency of the flying machine. Other competent inventive aviators,
+notably Curtiss, Voisin, Bleriot and Farman, are close after them. The
+Wrights, as stated, have a marked advantage in the possession of
+patents covering surface plane devices which have thus far been found
+indispensable in flying machine construction. Numerous law suits growing
+out of alleged infringements of these patents have been started, and
+others are threatened. What effect these actions will have in deterring
+aviators in general from proceeding with their experiments remains to be
+seen.
+
+In the meantime the four men named--Curtiss, Voisin, Bleriot and
+Farman--are going ahead regardless of consequences, and the inventive
+genius of each is so strong that it is reasonable to expect some
+remarkable developments in the near future.
+
+Smallest of Flying Machines.
+
+To Santos Dumont must be given the credit of producing the smallest
+practical flying machine yet constructed. True, he has done nothing
+remarkable with it in the line of speed, but he has demonstrated the
+fact that a large supporting surface is not an essential feature.
+
+This machine is named "La Demoiselle." It is a monoplane of the dihedral
+type, with a main plane on each side of the center. These main
+planes are of 18 foot spread, and nearly 6 1/2 feet in depth, giving
+approximately 115 feet of surface area. The total weight is 242
+pounds, which is 358 pounds less than any other machine which has been
+successfully used. The total depth from front to rear is 26 feet.
+
+The framework is of bamboo, strengthened and held taut with wire guys.
+
+Have One Rule in Mind.
+
+In this struggle for mastery in flying machine efficiency all the
+contestants keep one rule in mind, and this is:
+
+"The carrying capacity of an aeroplane is governed by the peripheral
+curve of its carrying surfaces, plus the speed; and the speed
+is governed by the thrust of the propellers, less the 'head-on'
+resistance."
+
+Their ideas as to the proper means of approaching the proposition
+may, and undoubtedly are, at variance, but the one rule in solving the
+problem of obtaining the greatest carrying capacity combined with the
+greatest speed, obtains in all instances.
+
+
+
+CHAPTER XVII. SOME OF THE NEW DESIGNS.
+
+Spurred on by the success attained by the more experienced and better
+known aviators numerous inventors of lesser fame are almost daily
+producing practical flying machines varying radically in construction
+from those now in general use.
+
+One of these comparatively new designs is the Van Anden biplane, made
+by Frank Van Anden of Islip, Long Island, a member of the New York
+Aeronautic Society. While his machine is wholly experimental, many
+successful short flights were made with it last fall (1909). One flight,
+made October 19th, 1909, is of particular interest as showing the
+practicability of an automatic stabilizing device installed by the
+inventor. The machine was caught in a sudden severe gust of wind and
+keeled over, but almost immediately righted itself, thus demonstrating
+in a most satisfactory manner the value of one new attachment.
+
+Features of Van Anden Model.
+
+In size the surfaces of the main biplane are 26 feet in spread, and 4
+feet in depth from front to rear. The upper and lower planes are 4 feet
+apart. Silkolene coated with varnish is used for the coverings. Ribs
+(spruce) are curved one inch to the foot, the deepest part of the curve
+(4 inches) being one foot back from the front edge of the horizontal
+beam. Struts (also of spruce, as is all the framework) are elliptical in
+shape. The main beams are in three sections, nearly half round in form,
+and joined by metal sleeves.
+
+There is a two-surface horizontal rudder, 2x2x4 feet, in front. This
+is pivoted at its lateral center 8 feet from the front edge of the main
+planes. In the rear is another two-surface horizontal rudder 2x2x2 1/2
+feet, pivoted in the same manner as the front one, 15 feet from the rear
+edges of the main planes.
+
+Hinged to the rear central strut of the rear rudder is a vertical rudder
+2 feet high by 3 feet in length.
+
+The Method of Control.
+
+In the operation of these rudders--both front and rear--and the
+elevation and depression of the main planes, the Curtiss system is
+employed. Pushing the steering-wheel post outward depresses the front
+edges of the planes, and brings the machine downward; pulling the
+steering-wheel post inward elevates the front edges of the planes and
+causes the machine to ascend.
+
+Turning the steering wheel itself to the right swings the tail rudder to
+the left, and the machine, obeying this like a boat, turns in the same
+direction as the wheel is turned. By like cause turning the wheel to the
+left turns the machine to the left.
+
+Automatic Control of Wings.
+
+There are two wing tips, each of 6 feet spread (length) and 2 feet from
+front to rear. These are hinged half way between the main surfaces to
+the two outermost rear struts. Cables run from these to an automatic
+device working with power from the engine, which automatically operates
+the tips with the tilting of the machine. Normally the wing tips are
+held horizontal by stiff springs introduced in the cables outside of the
+device.
+
+It was the successful working of this device which righted the Van
+Anden craft when it was overturned in the squall of October 19th, 1909.
+Previous to that occurrence Mr. Van Anden had looked upon the device as
+purely experimental, and had admitted that he had grave uncertainty as
+to how it would operate in time of emergency. He is now quoted as being
+thoroughly satisfied with its practicability. It is this automatic
+device which gives the Van Anden machine at least one distinctively new
+feature.
+
+While on this subject it will not be amiss to add that Mr. Curtiss does
+not look kindly on automatic control. "I would rather trust to my own
+action than that of a machine," he says. This is undoubtedly good
+logic so far as Mr. Curtiss is concerned, but all aviators are not so
+cool-headed and resourceful.
+
+Motive Power of Van Anden.
+
+A 50-horsepower "H-F" water cooled motor drives a laminated wood
+propeller 6 feet in diameter, with a 17 degree pitch at the extremities,
+increasing toward the hub. The rear end of the motor is about 6 inches
+back from the rear transverse beam and the engine shaft is in a direct
+line with the axes of the two horizontal rudders. An R. I. V. ball
+bearing carries the shaft at this point. Flying, the motor turns at
+about 800 revolutions per minute, delivering 180 pounds pull. A test of
+the motor running at 1,200 showed a pull of 250 pounds on the scales.
+
+Still Another New Aeroplane.
+
+Another new aeroplane is that produced by A. M. Herring (an old-timer)
+and W. S. Burgess, under the name of the Herring-Burgess. This is also
+equipped with an automatic stability device for maintaining the balance
+transversely. The curvature of the planes is also laid out on new
+lines. That this new plan is effective is evidenced by the fact that the
+machine has been elevated to an altitude of 40 feet by using one-half
+the power of the 30-horsepower motor.
+
+The system of rudder and elevation control is very simple. The aviator
+sits in front of the lower plane, and extending his arms, grasps two
+supports which extend down diagonally in front. On the under side of
+these supports just beneath his fingers are the controls which operate
+the vertical rudder, in the rear. Thus, if he wishes to turn to the
+right, he presses the control under the fingers of his right hand; if to
+the left, that under the fingers of his left hand. The elevating rudder
+is operated by the aviator's right foot, the control being placed on a
+foot-rest.
+
+Motor Is Extremely Light.
+
+Not the least notable feature of the craft is its motor. Although
+developing, under load, 30-horsepower, or that of an ordinary
+automobile, it weighs, complete, hardly 100 pounds. Having occasion to
+move it a little distance for inspection, Mr. Burgess picked it up and
+walked off with it--cylinders, pistons, crankcase and all, even the
+magneto, being attached. There are not many 30-horsepower engines which
+can be so handled. Everything about it is reduced to its lowest terms
+of simplicity, and hence, of weight. A single camshaft operates not
+only all of the inlet and exhaust valves, but the magneto and gear water
+pump, as well. The motor is placed directly behind the operator, and the
+propeller is directly mounted on the crankshaft.
+
+This weight of less than 100 pounds, it must be remembered, is not for
+the motor alone; it includes the entire power plant equipment.
+
+The "thrust" of the propeller is also extraordinary, being between 250
+and 260 pounds. The force of the wind displacement is strong enough to
+knock down a good-sized boy as one youngster ascertained when he got
+behind the propeller as it was being tested. He was not only knocked
+down but driven for some distance away from the machine. The propeller
+has four blades which are but little wider than a lath.
+
+Machine Built by Students.
+
+Students at the University of Pennsylvania, headed by Laurence J. Lesh,
+a protege of Octave Chanute, have constructed a practical aeroplane of
+ordinary maximum size, in which is incorporated many new ideas. The most
+unique of these is to be found in the steering gear, and the provision
+made for the accommodation of a pupil while taking lessons under an
+experienced aviator.
+
+Immediately back of the aviator is an extra seat and an extra steering
+wheel which works in tandem style with the front wheel. By this
+arrangement a beginner may be easily and quickly taught to have
+perfect control of the machine. These tandem wheels are also handy for
+passengers who may wish to operate the car independently of one another,
+it being understood, of course, that there will be no conflict of
+action.
+
+Frame Size and Engine Power.
+
+The frame has 36 feet spread and measures 35 feet from the front edge to
+the end of the tail in the rear. It is equipped with two rear propellers
+operated by a Ramsey 8-cylinder motor of 50 horsepower, placed
+horizontally across the lower plane, with the crank shaft running clear
+through the engine.
+
+The "Pennsylvania I" is the first two-propeller biplane chainless
+car, this scheme having been adopted in order to avoid the crossing of
+chains. The lateral control is by a new invention by Octave Chanute
+and Laurence J. Lesh, for which Lesh is now applying for a patent. The
+device was worked out before the Wright brothers' suit was begun, and is
+said to be superior to the Wright warping or the Curtiss ailerons. The
+landing device is also new in design. This aeroplane will weigh about
+1,500 pounds, and will carry fuel for a flight of 150 miles, and it is
+expected to attain a speed of at least 45 miles an hour.
+
+There are others, lots of them, too numerous in fact to admit of mention
+in a book of this size.
+
+
+
+CHAPTER XVIII. DEMAND FOR FLYING MACHINES.
+
+As a commercial proposition the manufacture and sale of motor-equipped
+aeroplanes is making much more rapid advance than at first obtained in
+the similar handling of the automobile. Great, and even phenomenal,
+as was the commercial development of the motor car, that of the flying
+machine is even greater. This is a startling statement, but it is fully
+warranted by the facts.
+
+It is barely more than a year ago (1909) that attention was seriously
+attracted to the motor-equipped aeroplane as a vehicle possible of
+manipulation by others than professional aviators. Up to that time
+such actual flights as were made were almost exclusively with the sole
+purpose of demonstrating the practicability of the machine, and the
+merits of the ideas as to shape, engine power, etc., of the various
+producers.
+
+Results of Bleriot's Daring.
+
+It was not until Bleriot flew across the straits of Dover on July 25th,
+1909, that the general public awoke to a full realization of the fact
+that it was possible for others than professional aviators to indulge
+in aviation. Bleriot's feat was accepted as proof that at last
+an absolutely new means of sport, pleasure and research, had been
+practically developed, and was within the reach of all who had the
+inclination, nerve and financial means to adopt it.
+
+From this event may be dated the birth of the modern flying machine into
+the world of business. The automobile was taken up by the general public
+from the very start because it was a proposition comparatively easy of
+demonstration. There was nothing mysterious or uncanny in the fact that
+a wheeled vehicle could be propelled on solid, substantial roads by
+means of engine power. And yet it took (comparatively speaking) a long
+time to really popularize the motor car.
+
+Wonderful Results in a Year.
+
+Men of large financial means engaged in the manufacture of automobiles,
+and expended fortunes in attracting public attention to them through the
+medium of advertisements, speed and road contests, etc. By these means
+a mammoth business has been built up, but bringing this business to its
+present proportions required years of patient industry and indomitable
+pluck.
+
+At this writing, less than a year from the day when Bleriot crossed the
+channel, the actual sales of flying machines outnumber the actual sales
+of automobiles in the first year of their commercial development. This
+may appear incredible, but it is a fact as statistics will show.
+
+In this connection we should take into consideration the fact that up to
+a year ago there was no serious intention of putting flying machines
+on the market; no preparations had been made to produce them on a
+commercial scale; no money had been expended in advertisements with a
+view to selling them.
+
+Some of the Actual Results.
+
+Today flying machines are being produced on a commercial basis, and
+there is a big demand for them. The people making them are overcrowded
+with orders. Some of the producers are already making arrangements to
+enlarge their plants and advertise their product for sale the same as
+is being done with automobiles, while a number of flying machine motor
+makers are already promoting the sale of their wares in this way.
+
+Here are a few actual figures of flying machine sales made by the more
+prominent producers since July 25th, 1909.
+
+Santos Dumont, 90 machines; Bleriot, 200; Farman, 130;
+Clemenceau-Wright, 80; Voisin, 100; Antoinette, 100. Many of these
+orders have been filled by delivery of the machines, and in others the
+construction work is under way.
+
+The foregoing are all of foreign make. In this country Curtiss and the
+Wrights are engaged in similar work, but no actual figures of their
+output are obtainable.
+
+Larger Plants Are Necessary.
+
+And this situation exists despite the fact that none of the producers
+are really equipped with adequate plants for turning out their
+machines on a modern, business-like basis. The demand was so sudden and
+unexpected that it found them poorly prepared to meet it. This, however,
+is now being remedied by the erection of special plants, the enlargement
+of others, and the introduction of new machinery and other labor-saving
+conveniences.
+
+Companies, with large capitalization, to engage in the exclusive
+production of airships are being organized in many parts of the world.
+One notable instance of this nature is worth quoting as illustrative
+of the manner in which the production of flying machines is being
+commercialized. This is the formation at Frankfort, Germany, of the
+Flugmaschine Wright, G. m. b. H., with a capital of $119,000, the
+Krupps, of Essen, being interested.
+
+Prices at Which Machines Sell.
+
+This wonderful demand from the public has come notwithstanding the fact
+that the machines, owing to lack of facilities for wholesale production,
+are far from being cheap. Such definite quotations as are made are on
+the following basis:
+
+Santos Dumont--List price $1,000, but owing to the rush of orders agents
+are readily getting from $1,300 to $1,500. This is the smallest machine
+made.
+
+Bleriot--List price $2,500. This is for the cross-channel type, with
+Anzani motor.
+
+Antoinette--List price from $4,000 to $5,000, according to size.
+
+Wright--List price $5,600.
+
+Curtiss--List price $5,000.
+
+There is, however, no stability in prices as purchasers are almost
+invariably ready to pay a considerable premium to facilitate delivery.
+
+The motor is the most expensive part of the flying machine. Motor
+prices range from $500 to $2,000, this latter amount being asked for the
+Curtiss engine.
+
+Systematic Instruction of Amateurs.
+
+In addition to the production of flying machines many of the experienced
+aviators are making a business of the instruction of amateurs. Curtiss
+and the Wrights in this country have a number of pupils, as have also
+the prominent foreigners. Schools of instruction are being opened in
+various parts of the world, not alone as private money-making ventures,
+but in connection with public educational institutions. One of these
+latter is to be found at the University of Barcelona, Spain.
+
+The flying machine agent, the man who handles the machines on a
+commission, has also become a known quantity, and will soon be as
+numerous as his brother of the automobile. The sign "John Bird, agent
+for Skimmer's Flying Machine," is no longer a curiosity.
+
+Yes, the Airship Is Here.
+
+From all of which we may well infer that the flying machine in practical
+form has arrived, and that it is here to stay. It is no exaggeration to
+say that the time is close at hand when people will keep flying machines
+just as they now keep automobiles, and that pleasure jaunts will be
+fully as numerous and popular. With the important item of practicability
+fully demonstrated, "Come, take a trip in my airship," will have more
+real significance than now attaches to the vapid warblings of the
+vaudeville vocalist.
+
+As a further evidence that the airship is really here, and that its
+presence is recognized in a business way, the action of life and
+accident insurance companies is interesting. Some of them are
+reconstructing their policies so as to include a special waiver of
+insurance by aviators. Anything which compels these great corporations
+to modify their policies cannot be looked upon as a mere curiosity or
+toy.
+
+It is some consolation to know that the movement in this direction is
+not thus far widespread. Moreover it is more than probable that the
+competition for business will eventually induce the companies to act
+more liberally toward aviators, especially as the art of aviation
+advances.
+
+
+
+CHAPTER XIX. LAW OF THE AIRSHIP.
+
+Successful aviation has evoked some peculiar things in the way of legal
+action and interpretation of the law.
+
+It is well understood that a man's property cannot be used without his
+consent. This is an old established principle in common law which holds
+good today.
+
+The limits of a man's property lines, however, have not been so well
+understood by laymen. According to eminent legal authorities such as
+Blackstone, Littleton and Coke, the "fathers of the law," the owner of
+realty also holds title above and below the surface, and this theory is
+generally accepted without question by the courts.
+
+Rights of Property Owners.
+
+In other words the owner of realty also owns the sky above it without
+limit as to distance. He can dig as deep into his land, or go as high
+into the air as he desires, provided he does not trespass upon or injure
+similar rights of others.
+
+The owner of realty may resist by force, all other means having failed,
+any trespass upon, or invasion of his property. Other people, for
+instance, may not enter upon it, or over or under it, without his
+express permission and consent. There is only one exception, and this is
+in the case of public utility corporations such as railways which,
+under the law of eminent domain, may condemn a right of way across the
+property of an obstinate owner who declines to accept a fair price for
+the privilege.
+
+Privilege Sharply Confined.
+
+The law of eminent domain may be taken advantage of only by corporations
+which are engaged in serving the public. It is based upon the principle
+that the advancement and improvement of a community is of more
+importance and carries with it more rights than the interests of the
+individual owner. But even in cases where the right of eminent domain is
+exercised there can be no confiscation of the individual's property.
+
+Exercising the right of eminent domain is merely obtaining by public
+purchase what is held to be essential to the public good, and which
+cannot be secured by private purchase. When eminent domain proceedings
+are resorted to the court appoints appraisers who determine upon the
+value of the property wanted, and this value (in money) is paid to the
+owner.
+
+How It Affects Aviation.
+
+It should be kept in mind that this privilege of the "right of eminent
+domain" is accorded only to corporations which are engaged in serving
+the public. Individuals cannot take advantage of it. Thus far all
+aviation has been conducted by individuals; there are no flying machine
+or airship corporations regularly engaged in the transportation of
+passengers, mails or freight.
+
+This leads up to the question "What would happen if realty owners
+generally, or in any considerable numbers, should prohibit the
+navigation of the air above their holdings?" It is idle to say such
+a possibility is ridiculous--it is already an actuality in a few
+individual instances.
+
+One property owner in New Jersey, a justice of the peace, maintains a
+large sign on the roof of his house warning aviators that they must not
+trespass upon his domain. That he is acting well within his rights in
+doing this is conceded by legal authorities.
+
+Hard to Catch Offenders.
+
+But, suppose the alleged trespass is committed, what is the property
+owner going to do about it? He must first catch the trespasser and this
+would be a pretty hard job. He certainly could not overtake him, unless
+he kept a racing aeroplane for this special purpose. It would be
+equally difficult to identify the offender after the offense had been
+committed, even if he were located, as aeroplanes carry no license
+numbers.
+
+Allowing that the offender should be caught the only recourse of the
+realty owner is an action for damages. He may prevent the commission of
+the offense by force if necessary, but after it is committed he can only
+sue for damages. And in doing this he would have a lot of trouble.
+
+Points to Be Proven.
+
+One of the first things the plaintiff would be called upon to prove
+would be the elevation of the machine. If it were reasonably close to
+the ground there would, of course, be grave risk of damage to fences,
+shrubbery, and other property, and the court would be justified in
+holding it to be a nuisance that should be suppressed.
+
+If, on the other hand; the machine was well up in the air, but going
+slowly, or hovering over the plaintiff's property, the court might be
+inclined to rule that it could not possibly be a nuisance, but right
+here the court would be in serious embarrassment. By deciding that it
+was not a nuisance he would virtually override the law against invasion
+of a man's property without his consent regardless of the nature of the
+invasion. By the same decision he would also say in effect that, if one
+flying machine could do this a dozen or more would have equal right to
+do the same thing. While one machine hovering over a certain piece of
+property may be no actual nuisance a dozen or more in the same position
+could hardly be excused.
+
+Difficult to Fix Damages.
+
+Such a condition would tend to greatly increase the risk of accident,
+either through collision, or by the carelessness of the aviators in
+dropping articles which might cause damages to the people or property
+below. In such a case it would undoubtedly be a nuisance, and in
+addition to a fine, the offender would also be liable for the damages.
+
+Taking it for granted that no actual damage is done, and the owner
+merely sues on account of the invasion of his property, how is the
+amount of compensation to be fixed upon? The owner has lost nothing; no
+part of his possessions has been taken away; nothing has been injured
+or destroyed; everything is left in exactly the same condition as before
+the invasion. And yet, if the law is strictly interpreted, the offender
+is liable.
+
+Right of Way for Airships.
+
+Somebody has suggested the organization of flying-machine corporations
+as common carriers, which would give them the right of eminent domain
+with power to condemn a right of way. But what would they condemn? There
+is nothing tangible in the air. Railways in condemning a right of way
+specify tangible property (realty) within certain limits. How would an
+aviator designate any particular right of way through the air a certain
+number of feet in width, and a certain distance from the ground?
+
+And yet, should the higher courts hold to the letter of the law and
+decide that aviators have no right to navigate their craft over private
+property, something will have to be done to get them out of the dilemma,
+as aviation is too far advanced to be discarded. Fortunately there is
+little prospect of any widespread antagonism among property owners so
+long as aviators refrain from making nuisances of themselves.
+
+Possible Solution Offered.
+
+One possible solution is offered and that is to confine the path of
+airships to the public highways so that nobody's property rights would
+be invaded. In addition, as a matter of promoting safety for both
+operators and those who may happen to be beneath the airships as they
+pass over a course, adoption of the French rules are suggested. These
+are as follows:
+
+Aeroplanes, when passing, must keep to the right, and pass at a distance
+of at least 150 feet. They are free from this rule when flying at
+altitudes of more than 100 feet. Every machine when flying at night or
+during foggy weather must carry a green light on the right, and a red
+light on the left, and a white headlight on the front.
+
+These are sensible rules, but may be improved upon by the addition of a
+signal system of some kind, either horn, whistle or bell.
+
+Responsibility of Aviators.
+
+Mr. Jay Carver Bossard, in recent numbers of _Fly_, brings out some
+curious and interesting legal points in connection with aviation, among
+which are the following:
+
+"Private parties who possess aerial craft, and desire to operate the
+same in aerial territory other than their own, must obtain from land
+owners special permission to do so, such permission to be granted only
+by agreement, founded upon a valid consideration. Otherwise, passing
+over another's land will in each instance amount to a trespass.
+
+"Leaving this highly technical side of the question, let us turn to
+another view: the criminal and tort liability of owners and operators to
+airship passengers. If A invites B to make an ascension with him in his
+machine, and B, knowing that A is merely an enthusiastic amateur and
+far from being an expert, accepts and is through A's innocent negligence
+injured, he has no grounds for recovery. But if A contracts with B, to
+transport him from one place to another, for a consideration, and B is
+injured by the poor piloting of A, A would be liable to B for damages
+which would result. Now in order to safeguard such people as B, curious
+to the point of recklessness, the law will have to require all airship
+operators to have a license, and to secure this license airship pilots
+will have to meet certain requirements. Here again is a question. Who
+is going to say whether an applicant is competent to pilot a balloon or
+airship?
+
+Fine for an Aeronaut.
+
+"An aeroplane while maneuvering is suddenly caught by a treacherous gale
+and swept to the ground. A crowd of people hasten over to see if the
+aeronaut is injured, and in doing so trample over Tax-payer Smith's
+garden, much to the detriment of his growing vegetables and flowers. Who
+is liable for the damages? Queer as it may seem, a case very similar to
+this was decided in 1823, in the New York supreme court, and it was held
+that the aeronaut was liable upon the following grounds: 'To render one
+man liable in trespass for the acts of others, it must appear either
+that they acted in concert, or that the act of the one, ordinarily and
+naturally produced the acts of the others, Ascending in a balloon is not
+an unlawful act, but it is certain that the aeronaut has no control
+over its motion horizontally, but is at the sport of the wind, and is
+to descend when and how he can. His reaching the earth is a matter of
+hazard. If his descent would according to the circumstances draw a crowd
+of people around him, either out of curiosity, or for the purpose
+of rescuing him from a perilous situation, all this he ought to have
+foreseen, and must be responsible for.'
+
+Air Not Really Free.
+
+"The general belief among people is, that the air is free. Not only free
+to breathe and enjoy, but free to travel in, and that no one has any
+definite jurisdiction over, or in any part of it. Now suppose this were
+made a legal doctrine. Would a murder perpetrated above the clouds have
+to go unpunished? Undoubtedly. For felonies committed upon the high seas
+ample provision is made for their punishment, but new provisions will
+have to be made for crimes committed in the air.
+
+Relations of Owner and Employee.
+
+"It is a general rule of law that a master is bound to provide
+reasonably safe tools, appliances and machines for his servant. How this
+rule is going to be applied in cases of aeroplanes, remains to be seen.
+The aeroplane owner who hires a professional aeronaut, that is, one who
+has qualified as an expert, owes him very little legal duty to supply
+him with a perfect aeroplane. The expert is supposed to know as much
+regarding the machine as the owner, if not more, and his acceptance of
+his position relieves the owner from liability. When the owner hires an
+amateur aeronaut to run the aeroplane, and teaches him how to manipulate
+it, even though the prescribed manner of manipulation will make flight
+safe, nevertheless if the machine is visibly defective, or known to be
+so, any injury which results to the aeronaut the owner is liable for.
+
+As to Aeroplane Contracts.
+
+"At the present time there are many orders being placed with aeroplane
+manufacturing companies. There are some unique questions to be raised
+here under the law of contract. It is an elementary principle of law
+that no one can be compelled to complete a contract which in itself is
+impossible to perform. For instance, a contract to row a boat across
+the Atlantic in two weeks, for a consideration, could never be enforced
+because it is within judicial knowledge that such an undertaking is
+beyond human power. Again, contracts formed for the doing of acts
+contrary to nature are never enforcible, and here is where our
+difficulty comes in. Is it possible to build a machine or species of
+craft which will transport a person or goods through the air? The courts
+know that balloons are practical; that is, they know that a bag
+filled with gas has a lifting power and can move through the air at an
+appreciable height. Therefore, a contract to transport a person in such
+manner is a good contract, and the conditions being favorable could
+undoubtedly be enforced. But the passengers' right of action for injury
+would be very limited.
+
+No Redress for Purchasers.
+
+"In the case of giving warranties on aeroplanes, we have yet to see just
+what a court is going to say. It is easy enough for a manufacturer to
+guarantee to build a machine of certain dimensions and according to
+certain specifications, but when he inserts a clause in the contract to
+the effect that the machine will raise itself from the surface of the
+earth, defy the laws of gravity, and soar in the heavens at the will of
+the aviator, he is to say the least contracting to perform a miracle.
+
+"Until aeroplanes have been made and accepted as practical, no court
+will force a manufacturer to turn out a machine guaranteed to fly. So
+purchasers can well remember that if their machines refuse to fly they
+have no redress against the maker, for he can always say, 'The industry
+is still in its experimental stage.' In contracting for an engine no
+builder will guarantee that the particular engine will successfully
+operate the aeroplane. In fact he could never be forced to live up to
+such an agreement, should he agree to a stipulation of that sort. The
+best any engine maker will guarantee is to build an engine according to
+specifications."
+
+
+
+CHAPTER XX. SOARING FLIGHT.
+
+By Octave Chanute.
+
+[5] There is a wonderful performance daily exhibited in southern climes
+and occasionally seen in northerly latitudes in summer, which has
+never been thoroughly explained. It is the soaring or sailing flight
+of certain varieties of large birds who transport themselves on rigid,
+unflapping wings in any desired direction; who in winds of 6 to 20
+miles per hour, circle, rise, advance, return and remain aloft for hours
+without a beat of wing, save for getting under way or convenience in
+various maneuvers. They appear to obtain from the wind alone all the
+necessary energy, even to advancing dead against that wind. This feat is
+so much opposed to our general ideas of physics that those who have
+not seen it sometimes deny its actuality, and those who have only
+occasionally witnessed it subsequently doubt the evidence of their own
+eyes. Others, who have seen the exceptional performances, speculate on
+various explanations, but the majority give it up as a sort of "negative
+gravity."
+
+Soaring Power of Birds.
+
+The writer of this paper published in the "Aeronautical Annual" for 1896
+and 1897 an article upon the sailing flight of birds, in which he gave
+a list of the authors who had described such flight or had advanced
+theories for its explanation, and he passed these in review. He also
+described his own observations and submitted some computations to
+account for the observed facts. These computations were correct as
+far as they went, but they were scanty. It was, for instance, shown
+convincingly by analysis that a gull weighing 2.188 pounds, with a total
+supporting surface of 2.015 square feet, a maximum body cross-section
+of 0.126 square feet and a maximum cross-section of wing edges of 0.098
+square feet, patrolling on rigid wings (soaring) on the weather side of
+a steamer and maintaining an upward angle or attitude of 5 degrees to 7
+degrees above the horizon, in a wind blowing 12.78 miles an hour, which
+was deflected upward 10 degrees to 20 degrees by the side of the steamer
+(these all being carefully observed facts), was perfectly sustained at
+its own "relative speed" of 17.88 miles per hour and extracted from
+the upward trend of the wind sufficient energy to overcome all the
+resistances, this energy amounting to 6.44 foot-pounds per second.
+
+Great Power of Gulls.
+
+It was shown that the same bird in flapping flight in calm air, with an
+attitude or incidence of 3 degrees to 5 degrees above the horizon and
+a speed of 20.4 miles an hour was well sustained and expended 5.88
+foot-pounds per second, this being at the rate of 204 pounds sustained
+per horsepower. It was stated also that a gull in its observed
+maneuvers, rising up from a pile head on unflapping wings, then plunging
+forward against the wind and subsequently rising higher than his
+starting point, must either time his ascents and descents exactly with
+the variations in wind velocities, or must meet a wind billow rotating
+on a horizontal axis and come to a poise on its crest, thus availing of
+an ascending trend.
+
+But the observations failed to demonstrate that the variations of the
+wind gusts and the movements of the bird were absolutely synchronous,
+and it was conjectured that the peculiar shape of the soaring wing of
+certain birds, as differentiated from the flapping wing, might, when
+experimented upon, hereafter account for the performance.
+
+Mystery to be Explained.
+
+These computations, however satisfactory they were for the speed of
+winds observed, failed to account for the observed spiral soaring of
+buzzards in very light winds and the writer was compelled to confess:
+"Now, this spiral soaring in steady breezes of 5 to 10 miles per hour
+which are apparently horizontal, and through which the bird maintains an
+average speed of about 20 miles an hour, is the mystery to be explained.
+It is not accounted for, quantitatively, by any of the theories which
+have been advanced, and it is the one performance which has led some
+observers to claim that it was done through 'aspiration.' i, e., that
+a bird acted upon by a current, actually drew forward into that current
+against its exact direction of motion."
+
+Buzzards Soar in Dead Calm.
+
+A still greater mystery was propounded by the few observers who asserted
+that they had seen buzzards soaring in a dead calm, maintaining their
+elevation and their speed. Among these observers was Mr. E. C. Huffaker,
+at one time assistant experimenter for Professor Langley. The writer
+believed and said then that he must in some way have been mistaken, yet,
+to satisfy himself, he paid several visits to Mr. Huffaker, in Eastern
+Tennessee and took along his anemometer. He saw quite a number of
+buzzards sailing at a height of 75 to 100 feet in breezes measuring 5
+or 6 miles an hour at the surface of the ground, and once he saw one
+buzzard soaring apparently in a dead calm.
+
+The writer was fairly baffled. The bird was not simply gliding,
+utilizing gravity or acquired momentum, he was actually circling
+horizontally in defiance of physics and mathematics. It took two years
+and a whole series of further observations to bring those two sciences
+into accord with the facts.
+
+Results of Close Observations.
+
+Curiously enough the key to the performance of circling in a light wind
+or a dead calm was not found through the usual way of gathering human
+knowledge, i. e., through observations and experiment. These had failed
+because I did not know what to look for. The mystery was, in fact,
+solved by an eclectic process of conjecture and computation, but once
+these computations indicated what observations should be made, the
+results gave at once the reasons for the circling of the birds, for
+their then observed attitude, and for the necessity of an independent
+initial sustaining speed before soaring began. Both Mr. Huffaker and
+myself verified the data many times and I made the computations.
+
+These observations disclosed several facts:
+
+1st.--That winds blowing five to seventeen miles per hour frequently had
+rising trends of 10 degrees to 15 degrees, and that upon occasions when
+there seemed to be absolutely no wind, there was often nevertheless a
+local rising of the air estimated at a rate of four to eight miles or
+more per hour. This was ascertained by watching thistledown, and rising
+fogs alongside of trees or hills of known height. Everyone will readily
+realize that when walking at the rate of four to eight miles an hour in
+a dead calm the "relative wind" is quite inappreciable to the senses and
+that such a rising air would not be noticed.
+
+2nd.--That the buzzard, sailing in an apparently dead horizontal calm,
+progressed at speeds of fifteen to eighteen miles per hour, as measured
+by his shadow on the ground. It was thought that the air was then
+possibly rising 8.8 feet per second, or six miles per hour.
+
+3rd.--That when soaring in very light winds the angle of incidence of
+the buzzards was negative to the horizon--i. e., that when seen coming
+toward the eye, the afternoon light shone on the back instead of on the
+breast, as would have been the case had the angle been inclined above
+the horizon.
+
+4th.--That the sailing performance only occurred after the bird had
+acquired an initial velocity of at least fifteen or eighteen miles per
+hour, either by industrious flapping or by descending from a perch.
+
+An Interesting Experiment.
+
+5th.--That the whole resistance of a stuffed buzzard, at a negative
+angle of 3 degrees in a current of air of 15.52 miles per hour, was 0.27
+pounds. This test was kindly made for the writer by Professor A. F. Zahm
+in the "wind tunnel" of the Catholic University at Washington, D. C.,
+who, moreover, stated that the resistance of a live bird might be less,
+as the dried plumage could not be made to lie smooth.
+
+This particular buzzard weighed in life 4.25 pounds, the area of his
+wings and body was 4.57 square feet, the maximum cross-section of
+his body was 0.110 square feet, and that of his wing edges when fully
+extended was 0.244 square feet.
+
+With these data, it became surprisingly easy to compute the performance
+with the coefficients of Lilienthal for various angles of incidence
+and to demonstrate how this buzzard could soar horizontally in a dead
+horizontal calm, provided that it was not a vertical calm, and that the
+air was rising at the rate of four or six miles per hour, the lowest
+observed, and quite inappreciable without actual measuring.
+
+Some Data on Bird Power.
+
+The most difficult case is purposely selected. For if we assume that the
+bird has previously acquired an initial minimum speed of seventeen miles
+an hour (24.93 feet per second, nearly the lowest measured), and that
+the air was rising vertically six miles an hour (8.80 feet per second),
+then we have as the trend of the "relative wind" encountered:
+
+      6
+      -- = 0.353, or the tangent of 19 degrees 26'.
+      17
+
+which brings the case into the category of rising wind effects. But the
+bird was observed to have a negative angle to the horizon of about 3
+degrees, as near as could be guessed, so that his angle of incidence to
+the "relative wind" was reduced to 16 degrees 26'.
+
+The relative speed of his soaring was therefore:
+
+Velocity = square root of (17 squared + 6 squared) = 18.03 miles per
+hour.
+
+At this speed, using the Langley co-efficient recently practically
+confirmed by the accurate experiments of Mr. Eiffel, the air pressure
+would be:
+
+18.03 squared X 0.00327 = 1.063 pounds per square foot.
+
+If we apply Lilienthal's co-efficients for an angle of 6 degrees 26', we
+have for the force in action:
+
+   Normal: 4.57 X 1.063 X 0.912 = 4.42 pounds.
+
+   Tangential: 4.57 X 1.063 X 0.074 = - 0.359 pounds,
+   which latter, being negative, is a propelling force.
+
+Results Astonish Scientists.
+
+Thus we have a bird weighing 4.25 pounds not only thoroughly supported,
+but impelled forward by a force of 0.359 pounds, at seventeen miles
+per hour, while the experiments of Professor A. F. Zahm showed that the
+resistance at 15.52 miles per hour was only 0.27 pounds,
+
+              17 squared
+   or 0.27 X ------- = 0.324 pounds, at seventeen miles an
+             15.52 squared
+   hour.
+
+These are astonishing results from the data obtained, and they lead to
+the inquiry whether the energy of the rising air is sufficient to make
+up the losses which occur by reason of the resistance and friction of
+the bird's body and wings, which, being rounded, do not encounter air
+pressures in proportion to their maximum cross-section.
+
+We have no accurate data upon the co-efficients to apply and estimates
+made by myself proved to be much smaller than the 0.27 pounds resistance
+measured by Professor Zahm, so that we will figure with the latter as
+modified. As the speed is seventeen miles per hour, or 24.93 feet per
+second, we have for the work:
+
+Work done, 0.324 X 24.93 = 8.07 foot pounds per second.
+
+Endorsed by Prof. Marvin.
+
+Corresponding energy of rising air is not sufficient at four miles per
+hour. This amounts to but 2.10 foot pounds per second, but if we assume
+that the air was rising at the rate of seven miles per hour (10.26 feet
+per second), at which the pressure with the Langley coefficient would be
+0.16 pounds per square foot, we have on 4.57 square feet for energy of
+rising air: 4.57 X 0.16 X 10.26 = 7.50 foot pounds per second, which
+is seen to be still a little too small, but well within the limits of
+error, in view of the hollow shape of the bird's wings, which receive
+greater pressure than the flat planes experimented upon by Langley.
+
+These computations were chiefly made in January, 1899, and were
+communicated to a few friends, who found no fallacy in them, but thought
+that few aviators would understand them if published. They were then
+submitted to Professor C. F. Marvin of the Weather Bureau, who is well
+known as a skillful physicist and mathematician. He wrote that they
+were, theoretically, entirely sound and quantitatively, probably, as
+accurate as the present state of the measurements of wind pressures
+permitted. The writer determined, however, to withhold publication until
+the feat of soaring flight had been performed by man, partly because he
+believed that, to ensure safety, it would be necessary that the machine
+should be equipped with a motor in order to supplement any deficiency in
+wind force.
+
+Conditions Unfavorable for Wrights.
+
+The feat would have been attempted in 1902 by Wright brothers if the
+local circumstances had been more favorable. They were experimenting on
+"Kill Devil Hill," near Kitty Hawk, N. C. This sand hill, about 100
+feet high, is bordered by a smooth beach on the side whence come the
+sea breezes, but has marshy ground at the back. Wright brothers were
+apprehensive that if they rose on the ascending current of air at the
+front and began to circle like the birds, they might be carried by the
+descending current past the back of the hill and land in the marsh.
+Their gliding machine offered no greater head resistance in proportion
+than the buzzard, and their gliding angles of descent are practically as
+favorable, but the birds performed higher up in the air than they.
+
+Langley's Idea of Aviation.
+
+Professor Langley said in concluding his paper upon "The Internal Work
+of the Wind":
+
+"The final application of these principles to the art of aerodromics
+seems, then, to be, that while it is not likely that the perfected
+aerodrome will ever be able to dispense altogether with the ability
+to rely at intervals on some internal source of power, it will not be
+indispensable that this aerodrome of the future shall, in order to go
+any distance--even to circumnavigate the globe without alighting--need
+to carry a weight of fuel which would enable it to perform this journey
+under conditions analogous to those of a steamship, but that the fuel
+and weight need only be such as to enable it to take care of itself in
+exceptional moments of calm."
+
+Now that dynamic flying machines have been evolved and are being brought
+under control, it seems to be worth while to make these computations and
+the succeeding explanations known, so that some bold man will attempt
+the feat of soaring like a bird. The theory underlying the performance
+in a rising wind is not new, it has been suggested by Penaud and others,
+but it has attracted little attention because the exact data and
+the maneuvers required were not known and the feat had not yet been
+performed by a man. The puzzle has always been to account for the
+observed act in very light winds, and it is hoped that by the present
+selection of the most difficult case to explain--i. e., the soaring in a
+dead horizontal calm--somebody will attempt the exploit.
+
+Requisites for Soaring Flights.
+
+The following are deemed to be the requisites and maneuvers to master
+the secrets of soaring flight:
+
+1st--Develop a dynamic flying machine weighing about one pound per
+square foot of area, with stable equilibrium and under perfect control,
+capable of gliding by gravity at angles of one in ten (5 3/4 degrees) in
+still air.
+
+2nd.--Select locations where soaring birds abound and occasions where
+rising trends of gentle winds are frequent and to be relied on.
+
+3rd.--Obtain an initial velocity of at least 25 feet per second before
+attempting to soar.
+
+4th.--So locate the center of gravity that the apparatus shall assume a
+negative angle, fore and aft, of about 3 degrees.
+
+Calculations show, however, that sufficient propelling force may still
+exist at 0 degrees, but disappears entirely at +4 degrees.
+
+5th.--Circle like the bird. Simultaneously with the steering, incline
+the apparatus to the side toward which it is desired to turn, so that
+the centrifugal force shall be balanced by the centripetal force. The
+amount of the required inclination depends upon the speed and on the
+radius of the circle swept over.
+
+6th.--Rise spirally like the bird. Steer with the horizontal rudder, so
+as to descend slightly when going with the wind and to ascend when going
+against the wind. The bird circles over one spot because the rising
+trends of wind are generally confined to small areas or local chimneys,
+as pointed out by Sir H. Maxim and others.
+
+7th.--Once altitude is gained, progress may be made in any direction by
+gliding downward by gravity.
+
+The bird's flying apparatus and skill are as yet infinitely superior
+to those of man, but there are indications that within a few years the
+latter may evolve more accurately proportioned apparatus and obtain
+absolute control over it.
+
+It is hoped, therefore, that if there be found no radical error in the
+above computations, they will carry the conviction that soaring flight
+is not inaccessible to man, as it promises great economies of motive
+power in favorable localities of rising winds.
+
+The writer will be grateful to experts who may point out any mistake
+committed in data or calculations, and will furnish additional
+information to any aviator who may wish to attempt the feat of soaring.
+
+
+
+CHAPTER XXI. FLYING MACHINES VS. BALLOONS.
+
+While wonderful success has attended the development of the dirigible
+(steerable) balloon the most ardent advocates of this form of aerial
+navigation admit that it has serious drawbacks. Some of these may be
+described as follows:
+
+Expense and Other Items.
+
+Great Initial Expense.--The modern dirigible balloon costs a fortune.
+The Zeppelin, for instance, costs more than $100,000 (these are official
+figures).
+
+Expense of Inflation.--Gas evaporates rapidly, and a balloon must
+be re-inflated, or partially re-inflated, every time it is used. The
+Zeppelin holds 460,000 cubic feet of gas which, even at $1 per thousand,
+would cost $460.
+
+Difficulty of Obtaining Gas.--If a balloon suddenly becomes deflated, by
+accident or atmospheric conditions, far from a source of gas supply, it
+is practically worthless. Gas must be piped to it, or the balloon carted
+to the gas house--an expensive proceeding in either event.
+
+Lack of Speed and Control.
+
+Lack of Speed.--Under the most favorable conditions the maximum speed
+of a balloon is 30 miles an hour. Its great bulk makes the high speed
+attained by flying machines impossible.
+
+Difficulty of Control.--While the modern dirigible balloon is readily
+handled in calm or light winds, its bulk makes it difficult to control
+in heavy winds.
+
+The Element of Danger.--Numerous balloons have been destroyed by
+lightning and similar causes. One of the largest of the Zeppelins was
+thus lost at Stuttgart in 1908.
+
+Some Balloon Performances.
+
+It is only a matter of fairness to state that, under favorable
+conditions, some very creditable records have been made with modern
+balloons, viz:
+
+November 23d, 1907, the French dirigible Patrie, travelled 187 miles in
+6 hours and 45 minutes against a light wind. This was a little over 28
+miles an hour.
+
+The Clement-Bayard, another French machine, sold to the Russian
+government, made a trip of 125 miles at a rate of 27 miles an hour.
+
+Zeppelin No. 3, carrying eight passengers, and having a total lifting
+capacity of 5,500 pounds of ballast in addition to passengers, weight
+of equipment, etc., was tested in October, 1906, and made 67 miles in 2
+hours and 17 minutes, about 30 miles an hour.
+
+These are the best balloon trips on record, and show forcefully the
+limitations of speed, the greatest being not over 30 miles an hour.
+
+Speed of Flying Machines.
+
+Opposed to the balloon performances we have flying machine trips (of
+authentic records) as follows:
+
+Bleriot--monoplane--in 1908--52 miles an hour.
+
+Delagrange--June 22, 1908--10 1/2 miles in 16 minutes, approximately 42
+miles an hour.
+
+Wrights--October, 1905--the machine was then in its infancy--24 miles
+in 38 minutes, approximately 44 miles an hour. On December 31, 1908, the
+Wrights made 77 miles in 2 hours and 20 minutes.
+
+Lambert, a pupil of the Wrights, and using a Wright biplane, on October
+18, 1909, covered 29.82 miles in 49 minutes and 39 seconds, being at
+the rate of 36 miles an hour. This flight was made at a height of 1,312
+feet.
+
+Latham--October 21, 1909--made a short flight, about 11 minutes, in
+the teeth of a 40 mile gale, at Blackpool, Eng. He used an Antoniette
+monoplane, and the official report says: "This exhibition of nerve,
+daring and ability is unparalled in the history of aviation."
+
+Farman--October 20, 1909--was in the air for 1 hour, 32 min., 16
+seconds, travelling 47 miles, 1,184 yards, a duration record for
+England.
+
+Paulhan--January 18, 1901--47 1/2 miles at the rate of 45 miles an hour,
+maintaining an altitude of from 1,000 to 2,000 feet.
+
+Expense of Producing Gas.
+
+Gas is indispensable in the operation of dirigible balloons, and gas
+is expensive. Besides this it is not always possible to obtain it in
+sufficient quantities even in large cities, as the supply on hand is
+generally needed for regular customers. Such as can be had is either
+water or coal gas, neither of which is as efficient in lifting power as
+hydrogen.
+
+Hydrogen is the lightest and consequently the most buoyant of all known
+gases. It is secured commercially by treating zinc or iron with dilute
+sulphuric or hydrochloric acid. The average cost may be safely placed
+at $10 per 1,000 feet so that, to inflate a balloon of the size of the
+Zeppelin, holding 460,000 cubic feet, would cost $4,600.
+
+Proportions of Materials Required.
+
+In making hydrogen gas it is customary to allow 20 per cent for loss
+between the generation and the introduction of the gas into the balloon.
+Thus, while the formula calls for iron 28 times heavier than the weight
+of the hydrogen required, and acid 49 times heavier, the real quantities
+are 20 per cent greater. Hydrogen weighs about 0.09 ounce to the cubic
+foot. Consequently if we need say 450,000 cubic feet of gas we must have
+2,531.25 pounds in weight. To produce this, allowing for the 20 percent
+loss, we must have 35 times its weight in iron, or over 44 tons. Of acid
+it would take 60 times the weight of the gas, or nearly 76 tons.
+
+In Time of Emergency.
+
+These figures are appalling, and under ordinary conditions would be
+prohibitive, but there are times when the balloon operator, unable to
+obtain water or coal gas, must foot the bills. In military maneuvers,
+where the field of operation is fixed, it is possible to furnish
+supplies of hydrogen gas in portable cylinders, but on long trips
+where sudden leakage or other cause makes descent in an unexpected spot
+unavoidable, it becomes a question of making your own hydrogen gas or
+deserting the balloon. And when this occurs the balloonist is up against
+another serious proposition--can he find the necessary zinc or iron? Can
+he get the acid?
+
+Balloons for Commercial Use.
+
+Despite all this the balloon has its uses. If there is to be such a
+thing as aerial navigation in a commercial way--the carrying of freight
+and passengers--it will come through the employment of such monster
+balloons as Count Zeppelin is building. But even then the carrying
+capacity must of necessity be limited. The latest Zeppelin creation,
+a monster in size, is 450 feet long, and 42 1/2 feet in diameter. The
+dimensions are such as to make all other balloons look like pigmies;
+even many ocean-going steamers are much smaller, and yet its passenger
+capacity is very small. On its 36-hour flight in May, 1909, the
+Zeppelin, carried only eight passengers. The speed, however, was quite
+respectable, 850 miles being covered in the 36 hours, a trifle over 23
+miles an hour. The reserve buoyancy, that is the total lifting capacity
+aside from the weight of the airship and its equipment, is estimated at
+three tons.
+
+
+
+CHAPTER XXII. PROBLEMS OF AERIAL FLIGHT.
+
+In a lecture before the Royal Society of Arts, reported in Engineering,
+F. W. Lanchester took the position that practical flight was not the
+abstract question which some apparently considered it to be, but a
+problem in locomotive engineering. The flying machine was a locomotive
+appliance, designed not merely to lift a weight, but to transport it
+elsewhere, a fact which should be sufficiently obvious. Nevertheless one
+of the leading scientific men of the day advocated a type in which
+this, the main function of the flying machine, was overlooked. When
+the machine was considered as a method of transport, the vertical screw
+type, or helicopter, became at once ridiculous. It had, nevertheless,
+many advocates who had some vague and ill-defined notion of subsequent
+motion through the air after the weight was raised.
+
+Helicopter Type Useless.
+
+When efficiency of transport was demanded, the helicopter type was
+entirely out of court. Almost all of its advocates neglected the effect
+of the motion of the machine through the air on the efficiency of the
+vertical screws. They either assumed that the motion was so slow as not
+to matter, or that a patch of still air accompanied the machine in its
+flight. Only one form of this type had any possibility of success. In
+this there were two screws running on inclined axles--one on each
+side of the weight to be lifted. The action of such inclined screw was
+curious, and in a previous lecture he had pointed out that it was almost
+exactly the same as that of a bird's wing. In high-speed racing craft
+such inclined screws were of necessity often used, but it was at
+a sacrifice of their efficiency. In any case the efficiency of the
+inclined-screw helicopter could not compare with that of an aeroplane,
+and that type might be dismissed from consideration so soon as
+efficiency became the ruling factor of the design.
+
+Must Compete With Locomotive.
+
+To justify itself the aeroplane must compete, in some regard or other,
+with other locomotive appliances, performing one or more of the purposes
+of locomotion more efficiently than existing systems. It would be no use
+unless able to stem air currents, so that its velocity must be greater
+than that of the worst winds liable to be encountered. To illustrate the
+limitations imposed on the motion of an aeroplane by wind velocity, Mr.
+Lanchester gave the diagrams shown in Figs. 1 to 4. The circle in each
+case was, he said, described with a radius equal to the speed of the
+aeroplane in still air, from a center placed "down-wind" from the
+aeroplane by an amount equal to the velocity of the wind.
+
+Fig. 1 therefore represented the case in which the air was still, and
+in this case the aeroplane represented by _A_ had perfect liberty of
+movement in any direction
+
+In Fig. 2 the velocity of the wind was half that of the aeroplane, and
+the latter could still navigate in any direction, but its speed against
+the wind was only one-third of its speed with the wind.
+
+In Fig. 3 the velocity of the wind was equal to that of the aeroplane,
+and then motion against the wind was impossible; but it could move to
+any point of the circle, but not to any point lying to the left of the
+tangent _A_ _B_. Finally, when the wind had a greater speed than the
+aeroplane, as in Fig. 4, the machine could move only in directions
+limited by the tangents _A_ _C_ and _A_ _D_.
+
+Matter of Fuel Consumption.
+
+Taking the case in which the wind had a speed equal to half that of the
+aeroplane, Mr. Lanchester said that for a given journey out and home,
+down wind and back, the aeroplane would require 30 per cent more fuel
+than if the trip were made in still air; while if the journey was made
+at right angles to the direction of the wind the fuel needed would be 15
+per cent more than in a calm. This 30 per cent extra was quite a heavy
+enough addition to the fuel; and to secure even this figure it was
+necessary that the aeroplane should have a speed of twice that of the
+maximum wind in which it was desired to operate the machine. Again, as
+stated in the last lecture, to insure the automatic stability of the
+machine it was necessary that the aeroplane speed should be largely in
+excess of that of the gusts of wind liable to be encountered.
+
+Eccentricities of the Wind.
+
+There was, Mr. Lanchester said, a loose connection between the average
+velocity of the wind and the maximum speed of the gusts. When the
+average speed of the wind was 40 miles per hour, that of the gusts might
+be equal or more. At one moment there might be a calm or the direction
+of the wind even reversed, followed, the next moment, by a violent gust.
+About the same minimum speed was desirable for security against gusts as
+was demanded by other considerations. Sixty miles an hour was the least
+figure desirable in an aeroplane, and this should be exceeded as much as
+possible. Actually, the Wright machine had a speed of 38 miles per hour,
+while Farman's Voisin machine flew at 45 miles per hour.
+
+Both machines were extremely sensitive to high winds, and the speaker,
+in spite of newspaper reports to the contrary, had never seen either
+flown in more than a gentle breeze. The damping out of the oscillations
+of the flight path, discussed in the last lecture, increased with the
+fourth power of the natural velocity of flight, and rapid damping
+formed the easiest, and sometimes the only, defense against dangerous
+oscillations. A machine just stable at 35 miles per hour would have
+reasonably rapid damping if its speed were increased to 60 miles per
+hour.
+
+Thinks Use Is Limited.
+
+It was, the lecturer proceeded, inconceivable that any very extended use
+should be made of the aeroplane unless the speed was much greater than
+that of the motor car. It might in special cases be of service,
+apart from this increase of speed, as in the exploration of countries
+destitute of roads, but it would have no general utility. With an
+automobile averaging 25 to 35 miles per hour, almost any part of Europe,
+Russia excepted, was attainable in a day's journey. A flying machine
+of but equal speed would have no advantages, but if the speed could be
+raised to 90 or 100 miles per hour, the whole continent of Europe
+would become a playground, every part being within a daylight flight of
+Berlin. Further, some marine craft now had speeds of 40 miles per hour,
+and efficiently to follow up and report movements of such vessels an
+aeroplane should travel at 60 miles per hour at least. Hence from
+all points of view appeared the imperative desirability of very high
+velocities of flight. The difficulties of achievement were, however,
+great.
+
+Weight of Lightest Motors.
+
+As shown in the first lecture of his course, the resistance to motion
+was nearly independent of the velocity, so that the total work done in
+transporting a given weight was nearly constant. Hence the question of
+fuel economy was not a bar to high velocities of flight, though should
+these become excessive, the body resistance might constitute a large
+proportion of the total. The horsepower required varied as the
+velocity, so the factor governing the maximum velocity of flight was
+the horsepower that could be developed on a given weight. At present the
+weight per horsepower of feather-weight motors appeared to range from
+2 1/4 pounds up to 7 pounds per brake horsepower, some actual figures
+being as follows:
+
+         Antoinette........ 5 lbs.
+         Fiat.............. 3 lbs.
+         Gnome....... Under 3 lbs.
+         Metallurgic....... 8 lbs.
+         Renault........... 7 lbs.
+         Wright.............6 lbs.
+
+Automobile engines, on the other hand, commonly weighed 12 pounds to 13
+pounds per brake horsepower.
+
+For short flights fuel economy was of less importance than a saving
+in the weight of the engine. For long flights, however, the case
+was different. Thus, if the gasolene consumption was 1/2 pound per
+horsepower hour, and the engine weighed 3 pounds per brake horsepower,
+the fuel needed for a six-hour flight would weigh as much as the engine,
+but for half an hour's flight its weight would be unimportant.
+
+Best Means of Propulsion.
+
+The best method of propulsion was by the screw, which acting in air
+was subject to much the same conditions as obtained in marine work.
+Its efficiency depended on its diameter and pitch and on its position,
+whether in front of or behind the body propelled. From this theory
+of dynamic support, Mr. Lanchester proceeded, the efficiency of each
+element of a screw propeller could be represented by curves such as were
+given in his first lecture before the society, and from these curves the
+over-all efficiency of any proposed propeller could be computed, by mere
+inspection, with a fair degree of accuracy. These curves showed that the
+tips of long-bladed propellers were inefficient, as was also the portion
+of the blade near the root. In actual marine practice the blade from
+boss to tip was commonly of such a length that the over-all efficiency
+was 95 per cent of that of the most efficient element of it.
+
+Advocates Propellers in Rear.
+
+From these curves the diameter and appropriate pitch of a screw could
+be calculated, and the number of revolutions was then fixed. Thus, for a
+speed of 80 feet per second the pitch might come out as 8 feet, in which
+case the revolutions would be 600 per minute, which might, however, be
+too low for the motor. It was then necessary either to gear down the
+propeller, as was done in the Wright machine, or, if it was decided to
+drive it direct, to sacrifice some of the efficiency of the propeller.
+An analogous case arose in the application of the steam turbine to the
+propulsion of cargo boats, a problem as yet unsolved. The propeller
+should always be aft, so that it could abstract energy from the wake
+current, and also so that its wash was clear of the body propelled. The
+best possible efficiency was about 70 per cent, and it was safe to rely
+upon 66 per cent.
+
+Benefits of Soaring Flight.
+
+There was, Mr. Lanchester proceeded, some possibility of the aeronaut
+reducing the power needed for transport by his adopting the principle of
+soaring flight, as exemplified by some birds. There were, he continued,
+two different modes of soaring flight. In the one the bird made use of
+the upward current of air often to be found in the neighborhood of steep
+vertical cliffs. These cliffs deflected the air upward long before it
+actually reached the cliff, a whole region below being thus the seat of
+an upward current. Darwin has noted that the condor was only to be found
+in the neighborhood of such cliffs. Along the south coast also the gulls
+made frequent use of the up currents due to the nearly perpendicular
+chalk cliffs along the shore.
+
+In the tropics up currents were also caused by temperature differences.
+Cumulus clouds, moreover, were nearly always the terminations of such
+up currents of heated air, which, on cooling by expansion in the upper
+regions, deposited their moisture as fog. These clouds might, perhaps,
+prove useful in the future in showing the aeronaut where up currents
+were to be found. Another mode of soaring flight was that adopted by
+the albatross, which took advantage of the fact that the air moved
+in pulsations, into which the bird fitted itself, being thus able to
+extract energy from the wind. Whether it would be possible for the
+aeronaut to employ a similar method must be left to the future to
+decide.
+
+Main Difficulties in Aviation.
+
+In practical flight difficulties arose in starting and in alighting.
+There was a lower limit to the speed at which the machine was stable,
+and it was inadvisable to leave the ground till this limit was attained.
+Similarly, in alighting it was inexpedient to reduce the speed below the
+limit of stability. This fact constituted a difficulty in the adoption
+of high speeds, since the length of run needed increased in proportion
+to the square of the velocity. This drawback could, however, be
+surmounted by forming starting and alighting grounds of ample size.
+He thought it quite likely in the future that such grounds would be
+considered as essential to the flying machine as a seaport was to an
+ocean-going steamer or as a road was to the automobile.
+
+Requisites of Flying Machine.
+
+Flying machines were commonly divided into monoplanes and biplanes,
+according as they had one or two supporting surfaces. The distinction
+was not, however, fundamental. To get the requisite strength some
+form of girder framework was necessary, and it was a mere question of
+convenience whether the supporting surface was arranged along both
+the top and the bottom of this girder, or along the bottom only. The
+framework adopted universally was of wood braced by ties of pianoforte
+wire, an arrangement giving the stiffness desired with the least
+possible weight. Some kind of chassis was also necessary.
+
+
+
+CHAPTER XXIII. AMATEURS MAY USE WRIGHT PATENTS.
+
+Owing to the fact that the Wright brothers have enjoined a number of
+professional aviators from using their system of control, amateurs have
+been slow to adopt it. They recognize its merits, and would like to use
+the system, but have been apprehensive that it might involve them in
+litigation. There is no danger of this, as will be seen by the following
+statement made by the Wrights:
+
+What Wright Brothers Say.
+
+"Any amateur, any professional who is not exhibiting for money, is at
+liberty to use our patented devices. We shall be glad to have them do
+so, and there will be no interference on our part, by legal action, or
+otherwise. The only men we proceed against are those who, without our
+permission, without even asking our consent, coolly appropriate the
+results of our labors and use them for the purpose of making money.
+Curtiss, Delagrange, Voisin, and all the rest of them who have used our
+devices have done so in money-making exhibitions. So long as there
+is any money to be made by the use of the products of our brains, we
+propose to have it ourselves. It is the only way in which we can get
+any return for the years of patient work we have given to the problem of
+aviation. On the other hand, any man who wants to use these devices for
+the purpose of pleasure, or the advancement of science, is welcome to do
+so, without money and without price. This is fair enough, is it not?"
+
+Basis of the Wright Patents.
+
+In a flying machine a normally flat aeroplane having lateral marginal
+portions capable of movement to different positions above or below the
+normal plane of the body of the aeroplane, such movement being about
+an axis transverse to the line of flight, whereby said lateral marginal
+portions may be moved to different angles relatively to the normal
+plane of the body of the aeroplane, so as to present to the atmosphere
+different angles of incidence, and means for so moving said lateral
+marginal portions, substantially as described.
+
+Application of vertical struts near the ends having flexible joints.
+
+Means for simultaneously imparting such movement to said lateral
+portions to different angles relatively to each other.
+
+Refers to the movement of the lateral portions on the same side to the
+same angle.
+
+Means for simultaneously moving vertical rudder so as to present to
+the wind that side thereof nearest the side of the aeroplane having the
+smallest angle of incidence.
+
+Lateral stability is obtained by warping the end wings by moving the
+lever at the right hand of the operator, connection being made by wires
+from the lever to the wing tips. The rudder may also be curved or warped
+in similar manner by lever action.
+
+Wrights Obtain an Injunction.
+
+In January, 1910, Judge Hazel, of the United States Circuit Court,
+granted a preliminary injunction restraining the Herring-Curtiss
+Co., and Glenn H. Curtiss, from manufacturing, selling, or using for
+exhibition purposes the machine known as the Curtiss aeroplane. The
+injunction was obtained on the ground that the Curtiss machine is an
+infringement upon the Wright patents in the matter of wing warping and
+rudder control.
+
+It is not the purpose of the authors to discuss the subject pro or con.
+Such discussion would have no proper place in a volume of this kind. It
+is enough to say that Curtiss stoutly insists that his machine is not
+an infringement of the Wright patents, although Judge Hazel evidently
+thinks differently.
+
+What the Judge Said.
+
+In granting the preliminary injunction the judge said:
+
+"Defendants claim generally that the difference in construction of their
+apparatus causes the equilibrium or lateral balance to be maintained and
+its aerial movement secured upon an entirely different principle from
+that of complainant; the defendants' aeroplanes are curved, firmly
+attached to the stanchions and hence are incapable of twisting or
+turning in any direction; that the supplementary planes or so-called
+rudders are secured to the forward stanchion at the extreme lateral ends
+of the planes and are adjusted midway between the upper and lower
+planes with the margins extending beyond the edges; that in moving the
+supplementary planes equal and uniform angles of incidence are presented
+as distinguished from fluctuating angles of incidence. Such claimed
+functional effects, however, are strongly contradicted by the expert
+witness for complainant.
+
+Similar to Plan of Wrights.
+
+"Upon this contention it is sufficient to say that the affidavits for
+the complainant so clearly define the principle of operation of the
+flying machines in question that I am reasonably satisfied that there
+is a variableness of the angle of incidence in the machine of defendants
+which is produced when a supplementary plane on one side is tilted
+or raised and the other stimultaneously tilted or lowered. I am also
+satisfied that the rear rudder is turned by the operator to the side
+having the least angle of incidence and that such turning is done at the
+time the supplementary planes are raised or depressed to prevent tilting
+or upsetting the machine. On the papers presented I incline to the view,
+as already indicated, that the claims of the patent in suit should be
+broadly construed; and when given such construction, the elements of
+the Wright machine are found in defendants' machine performing the
+same functional result. There are dissimilarities in the defendants'
+structure--changes of form and strengthening of parts--which may be
+improvements, but such dissimilarities seem to me to have no bearing
+upon the means adopted to preserve the equilibrium, which means are the
+equivalent of the claims in suit and attain an identical result.
+
+Variance From Patent Immaterial.
+
+"Defendants further contend that the curved or arched surfaces of the
+Wright aeroplanes in commercial use are departures from the patent,
+which describes 'substantially flat surfaces,' and that such a
+construction would be wholly impracticable. The drawing, Fig. 3,
+however, attached to the specification, shows a curved line inward of
+the aeroplane with straight lateral edges, and considering such drawing
+with the terminology of the specification, the slight arching of the
+surface is not thought a material departure; at any rate, the patent in
+issue does not belong to the class of patents which requires narrowing
+to the details of construction."
+
+"June Bug" First Infringement.
+
+Referring to the matter of priority, the judge said:
+
+"Indeed, no one interfered with the rights of the patentees by
+constructing machines similar to theirs until in July, 1908, when
+Curtiss exhibited a flying machine which he called the 'June Bug.' He
+was immediately notified by the patentees that such machine with its
+movable surfaces at the tips of wings infringed the patent in suit, and
+he replied that he did not intend to publicly exhibit the machine for
+profit, but merely was engaged in exhibiting it for scientific purposes
+as a member of the Aerial Experiment Association. To this the patentees
+did not object. Subsequently, however, the machine, with supplementary
+planes placed midway between the upper and lower aeroplanes, was
+publicly exhibited by the defendant corporation and used by Curtiss in
+aerial flights for prizes and emoluments. It further appears that the
+defendants now threaten to continue such use for gain and profit, and to
+engage in the manufacture and sale of such infringing machines, thereby
+becoming an active rival of complainant in the business of constructing
+flying machines embodying the claims in suit, but such use of the
+infringing machines it is the duty of this court, on the papers
+presented, to enjoin.
+
+"The requirements in patent causes for the issuance of an injunction
+pendente lite--the validity of the patent, general acquiescence by the
+public and infringement by the defendants--are so reasonably clear that
+I believe if not probable the complainant may succeed at final hearing,
+and therefore, status quo should be preserved and a preliminary
+injunction granted.
+
+"So ordered."
+
+Points Claimed By Curtiss.
+
+That the Herring-Curtiss Co. will appeal is a certainty. Mr. Emerson R.
+Newell, counsel for the company, states its case as follows:
+
+"The Curtiss machine has two main supporting surfaces, both of which are
+curved * * * and are absolutely rigid at all times and cannot be moved,
+warped or distorted in any manner. The front horizontal rudder is used
+for the steering up or down, and the rear vertical rudder is used only
+for steering to the right or left, in the same manner as a boat is
+steered by its rudder. The machine is provided at the rear with a fixed
+horizontal surface, which is not present in the machine of the patent,
+and which has a distinct advantage in the operation of defendants'
+machine, as will be hereafter discussed.
+
+Does Not Warp Main Surface.
+
+"Defendants' machine does not use the warping of the main supporting
+surfaces in restoring the lateral equilibrium, but has two comparatively
+small pivoted balancing surfaces or rudders. When one end of the machine
+is tipped up or down from the normal, these planes may be thrown in
+opposite directions by the operator, and so steer each end of the
+machine up or down to its normal level, at which time tension upon them
+is released and they are moved back by the pressure of the wind to their
+normal position.
+
+Rudder Used Only For Steering.
+
+"When defendants' balancing surfaces are moved they present equal angles
+of incidence to the normal rush of air and equal resistances, at each
+side of the machine, and there is therefore no tendency to turn around a
+vertical axis as is the case of the machine of the patent, consequently
+no reason or necessity for turning the vertical rear rudder in
+defendants' machine to counteract any such turning tendency. At any
+rate, whatever may be the theories in regard to this matter, the fact is
+that the operator of defendants' machine does not at any time turn his
+vertical rudder to counteract any turning tendency clue to the side
+balancing surfaces, but only uses it to steer the machine the same as a
+boat is steered."
+
+Aero Club Recognizes Wrights.
+
+The Aero Club of America has officially recognized the Wright patents.
+This course was taken following a conference held April 9th, 1910,
+participated in by William Wright and Andrew Freedman, representing the
+Wright Co., and the Aero Club's committee, of Philip T. Dodge, W. W.
+Miller, L. L. Gillespie, Wm. H. Page and Cortlandt F. Bishop.
+
+At this meeting arrangements were made by which the Aero Club recognizes
+the Wright patents and will not give its section to any open meet
+where the promoters thereof have not secured a license from the Wright
+Company.
+
+The substance of the agreement was that the Aero Club of America
+recognizes the rights of the owners of the Wright patents under
+the decisions of the Federal courts and refuses to countenance the
+infringement of those patents as long as these decisions remain in
+force.
+
+In the meantime, in order to encourage aviation, both at home and
+abroad, and in order to permit foreign aviators to take part in aviation
+contests in this country it was agreed that the Aero Club of America, as
+the American representative of the International Aeronautic Federation,
+should approve only such public contests as may be licensed by the
+Wright Company and that the Wright Company, on the other hand, should
+encourage the holding of open meets or contests where ever approved as
+aforesaid by the Aero Club of America by granting licenses to promoters
+who make satisfactory arrangements with the company for its compensation
+for the use of its patents. At such licensed meet any machine of any
+make may participate freely without securing any further license or
+permit. The details and terms of all meets will be arranged by the
+committee having in charge the interests of both organizations.
+
+
+
+CHAPTER XXIV. HINTS ON PROPELLER CONSTRUCTION.
+
+Every professional aviator has his own ideas as to the design of
+the propeller, one of the most important features of flying-machine
+construction. While in many instances the propeller, at a casual glance,
+may appear to be identical, close inspection will develop the fact
+that in nearly every case some individual idea of the designer has been
+incorporated. Thus, two propellers of the two-bladed variety, while of
+the same general size as to length and width of blade, will vary greatly
+as to pitch and "twist" or curvature.
+
+What the Designers Seek.
+
+Every designer is seeking for the same result--the securing of the
+greatest possible thrust, or air displacement, with the least possible
+energy.
+
+The angles of any screw propeller blade having a uniform or true pitch
+change gradually for every increased diameter. In order to give a
+reasonably clear explanation, it will be well to review in a primary way
+some of the definitions or terms used in connection with and applied to
+screw propellers.
+
+Terms in General Use.
+
+Pitch.--The term "pitch," as applied to a screw propeller, is the
+theoretical distance through which it would travel without slip in one
+revolution, and as applied to a propeller blade it is the angle at
+which the blades are set so as to enable them to travel in a spiral path
+through a fixed distance theoretically without slip in one revolution.
+
+Pitch speed.--The term "pitch speed" of a screw propeller is the speed
+in feet multiplied by the number of revolutions it is caused to make
+in one minute of time. If a screw propeller is revolved 600 times
+per minute, and if its pitch is 7 ft., then the pitch speed of such a
+propeller would be 7x600 revolutions, or 4200 ft. per minute.
+
+Uniform pitch.--A true pitch screw propeller is one having its blades
+formed in such a manner as to enable all of its useful portions, from
+the portion nearest the hub to its outer portion, to travel at a uniform
+pitch speed. Or, in other words, the pitch is uniform when the projected
+area of the blade is parallel along its full length and at the same time
+representing a true sector of a circle.
+
+All screw propellers having a pitch equal to their diameters have the
+same angle for their blades at their largest diameter.
+
+When Pitch Is Not Uniform.
+
+A screw propeller not having a uniform pitch, but having the same angle
+for all portions of its blades, or some arbitrary angle not a true
+pitch, is distinguished from one having a true pitch in the variation of
+the pitch speeds that the various portions of its blades are forced to
+travel through while traveling at its maximum pitch speed.
+
+On this subject Mr. R. W. Jamieson says in Aeronautics:
+
+"Take for example an 8-foot screw propeller having an 8-foot pitch at
+its largest diameter. If the angle is the same throughout its entire
+blade length, then all the porions of its blades approaching the hub
+from its outer portion would have a gradually decreasing pitch. The
+2-foot portion would have a 2-foot pitch; the 3-foot portion a 3-foot
+pitch, and so on to the 8-foot portion which would have an 8-foot pitch.
+When this form of propeller is caused to revolve, say 500 r.p.m., the
+8-foot portion would have a calculated pitch speed of 8 feet by 500
+revolutions, or 4,000 feet per min.; while the 2-foot portion would have
+a calculated pitch speed of 500 revolutions by 2 feet, or 1,000 feet per
+minute.
+
+Effect of Non-Uniformity.
+
+"Now, as all of the portions of this type of screw propeller must travel
+at some pitch speed, which must have for its maximum a pitch speed
+in feet below the calculated pitch speed of the largest diameter, it
+follows that some portions of its blades would perform useful work
+while the action of the other portions would be negative--resisting
+the forward motion of the portions having a greater pitch speed. The
+portions having a pitch speed below that at which the screw is traveling
+cease to perform useful work after their pitch speed has been exceeded
+by the portions having a larger diameter and a greater pitch speed.
+
+"We might compare the larger and smaller diameter portions of this form
+of screw propeller, to two power-driven vessels connected with a line,
+one capable of traveling 20 miles per hour, the other 10 miles per hour.
+It can be readily understood that the boat capable of traveling 10 miles
+per hour would have no useful effect to help the one traveling 20 miles
+per hour, as its action would be such as to impose a dead load upon the
+latter's progress."
+
+The term "slip," as applied to a screw propeller, is the distance
+between its calculated pitch speed and the actual distance it travels
+through under load, depending upon the efficiency and proportion of its
+blades and the amount of load it has to carry.
+
+The action of a screw propeller while performing useful work might be
+compared to a nut traveling on a threaded bolt; little resistance is
+offered to its forward motion while it spins freely without load, but
+give it a load to carry; then it will take more power to keep up its
+speed; if too great a load is applied the thread will strip, and so
+it is with a screw propeller gliding spirally on the air. A propeller
+traveling without load on to new air might be compared to the nut
+traveling freely on the bolt. It would consume but little power and it
+would travel at nearly its calculated pitch speed, but give it work to
+do and then it will take power to drive it.
+
+There is a reaction caused from the propeller projecting air backward
+when it slips, which, together with the supporting effect of the blades,
+combine to produce useful work or pull on the object to be carried.
+
+A screw propeller working under load approaches more closely to its
+maximum efficiency as it carries its load with a minimum amount of slip,
+or nearing its calculated pitch speed.
+
+Why Blades Are Curved.
+
+It has been pointed out by experiment that certain forms of curved
+surfaces as applied to aeroplanes will lift more per horse power, per
+unit of square foot, while on the other hand it has been shown that a
+flat surface will lift more per horse power, but requires more area of
+surface to do it.
+
+As a true pitch screw propeller is virtually a rotating aeroplane, a
+curved surface may be advantageously employed when the limit of size
+prevents using large plane surfaces for the blades.
+
+Care should be exercised in keeping the chord of any curve to be used
+for the blades at the proper pitch angle, and in all cases propeller
+blades should be made rigid so as to preserve the true angle and not be
+distorted by centrifugal force or from any other cause, as flexibility
+will seriously affect their pitch speed and otherwise affect their
+efficiency.
+
+How to Determine Angle.
+
+To find the angle for the proper pitch at any point in the diameter of
+a propeller, determine the circumference by multiplying the diameter by
+3.1416, which represent by drawing a line to scale in feet. At the end
+of this line draw another line to represent the desired pitch in feet.
+Then draw a line from the point representing the desired pitch in feet
+to the beginning of the circumference line. For example:
+
+If the propeller to be laid out is 7 feet in diameter, and is to have
+a 7-foot pitch, the circumference will be 21.99 feet. Draw a diagram
+representing the circumference line and pitch in feet. If this diagram
+is wrapped around a cylinder the angle line will represent a true thread
+7 feet in diameter and 7 feet long, and the angle of the thread will be
+17 3/4 degrees.
+
+Relation of Diameter to Circumference.
+
+Since the areas of circles decrease as the diameter lessens, it follows
+that if a propeller is to travel at a uniform pitch speed, the volume of
+its blade displacement should decrease as its diameter becomes less, so
+as to occupy a corresponding relation to the circumferences of larger
+diameters, and at the same time the projected area of the blade must be
+parallel along its full length and should represent a true sector of a
+circle.
+
+Let us suppose a 7-foot circle to be divided into 20 sectors, one of
+which represents a propeller blade. If the pitch is to be 7 feet, then
+the greatest depth of the angle would be 1/20 part of the pitch, or 4
+2/10 inch. If the line representing the greatest depth of the angle is
+kept the same width as it approaches the hub, the pitch will be uniform.
+If the blade is set at an angle so its projected area is 1/20 part of
+the pitch, and if it is moved through 20 divisions for one revolution,
+it would have a travel of 7 feet.
+
+
+
+CHAPTER XXV. NEW MOTORS AND DEVICES.
+
+Since the first edition of this book was printed, early in 1910, there
+has been a remarkable advance in the construction of aeroplane motors,
+which has resulted in a wonderful decrease in the amount of surface area
+from that formerly required. Marked gain in lightness and speed of
+the motor has enabled aviators to get along, in some instances, with
+one-quarter of the plane supporting area previously used. The first
+Wright biplane, propelled by a motor of 25 h.p., productive of a fair
+average speed of 30 miles an hour, had a plane surface of 538 square
+feet. Now, by using a specially designed motor of 65 h. p., capable
+of developing a speed of from 70 to 80 miles an hour, the Wrights are
+enabled to successfully navigate a machine the plane area of which is
+about 130 square feet. This apparatus is intended to carry only one
+person (the operator). At Belmont Park, N. Y., the Wrights demonstrated
+that the small-surfaced biplane is much faster, easier to manage in the
+hands of a skilled manipulator, and a better altitude climber than the
+large and cumbersome machines with 538 square feet of surface heretofore
+used by them.
+
+In this may be found a practical illustration of the principle that
+increased speed permits of a reduction in plane area in mathematical
+ratio to the gain in speed. The faster any object can be made to move
+through the air, the less will be the supporting surface required to
+sustain a given weight. But, there is a limit beyond which the plane
+surface cannot be reduced with safety. Regard must always be had to
+the securing of an ample sustaining surface so that in case of motor
+stoppage there will be sufficient buoyancy to enable the operator to
+descend safely.
+
+The baby Wright used at the Belmont Park (N. Y.) aviation meet in the
+fall of 1910, had a plane length of 19 feet 6 inches, and an extreme
+breadth of 21 feet 6 inches, with a total surface area of 146 square
+feet. It was equipped with a new Wright 8-cylinder motor of 60 h. p.,
+and two Wright propellers of 8 feet 6 inches diameter and 500 r. p. m.
+It was easily the fastest machine at the meet. After the tests, Wilbur
+Wright said:
+
+"It is our intention to put together a machine with specially designed
+propellers, specially designed gears and a motor which will give us 65
+horsepower at least. We will then be able, after some experimental work
+we are doing now, to send forth a machine that will make a new speed
+record."
+
+In the new Wright machines the front elevating planes for up-and-down
+control have been eliminated, and the movements of the apparatus are now
+regulated solely by the rear, or "tail" control.
+
+A Powerful Light Motor.
+
+Another successful American aviation motor is the aeromotor,
+manufactured by the Detroit Aeronautic Construction. Aeromotors are made
+in four models as follows:
+
+Model 1.--4-cylinder, 30-40 h. p., weight 200 pounds.
+
+Model 2.--4-cylinder, (larger stroke and bore) 40-50 h. p., weight 225
+pounds.
+
+Model 3.--6-cylinder. 50-60 h. p., weight 210 pounds.
+
+Model 4.--6-cylinder, 60-75 h. p., weight 275 pounds.
+
+This motor is of the 4-cycle, vertical, water-cooled type. Roberts
+Aviation Motor.
+
+One of the successful aviation motors of American make, is that produced
+by the Roberts Motor Co., of Sandusky, Ohio. It is designed by E. W.
+Roberts, M. E., who was formerly chief assistant and designer for Sir
+Hiram Maxim, when the latter was making his celebrated aeronautical
+experiments in England in 1894-95. This motor is made in both the
+4- and 6-cylinder forms. The 4-cylinder motor weighs complete with Bosch
+magneto and carbureter 165 pounds, and will develop 40 actual brake
+h. p. at 1,000 r. p. m., 46 h. p. at 1,200 and 52 h. p. at 1,400. The
+6-cylinder weighs 220 pounds and will develop 60 actual brake h. p. at
+1,000 r. p. m., 69 h. p. at 1,200 and 78 h. p. at 1,500.
+
+Extreme lightness has been secured by doing away with all superfluous
+parts, rather than by a shaving down of materials to a dangerous
+thinness. For example, there is neither an intake or exhaust manifold on
+the motor. The distributing valve forms a part of the crankcase as
+does the water intake, and the gear pump. Magnalium takes the place of
+aluminum in the crankcase, because it is not only lighter but stronger
+and can be cast very thin. The crankshaft is 2 1/2-inch diameter with a
+2 1/4-inch hole, and while it would be strong enough in ordinary 40
+per cent carbon steel it is made of steel twice the strength of that
+customarily employed. Similar care has been exercised on other parts and
+the result is a motor weighing 4 pounds per h. p.
+
+The Rinek Motor.
+
+The Rinek aviation motor, constructed by the Rinek Aero Mfg. Co., of
+Easton, Pa., is another that is meeting with favor among aviators. Type
+B-8 is an 8-cylinder motor, the cylinders being set at right angles,
+on a V-shaped crank case. It is water cooled, develops 50-60 h. p., the
+minimum at 1,220 r. p. m., and weighs 280 pounds with all accessories.
+Type B-4, a 4-cylinder motor, develops 30 h. p. at 1,800 r. p. m., and
+weighs 130 pounds complete. The cylinders in both motors are made of
+cast iron with copper water jackets.
+
+The Overhead Camshaft Boulevard.
+
+The overhead camshaft Boulevard is still another form of aviation motor
+which has been favorably received. This is the product of the Boulevard
+Engine Co., of St. Louis. It is made with 4 and 8 cylinders. The former
+develops 30-35 h. p. at 1,200 r. p. m., and weighs 130 pounds. The
+8-cylinder motor gives 60-70 h. p. at 1,200 r. p. m., and weighs 200
+pounds. Simplicity of construction is the main feature of this motor,
+especially in the manipulation of the valves.
+
+
+
+CHAPTER XXVI. MONOPLANES, TRIPLANES, MULTIPLANES.
+
+Until recently, American aviators had not given serious attention to
+any form of flying machines aside from biplanes. Of the twenty-one
+monoplanes competing at the International meet at Belmont Park, N. Y.,
+in November, 1910, only three makes were handled by Americans. Moissant
+and Drexel navigated Bleriot machines, Harkness an Antoinette, and Glenn
+Curtiss a single decker of his own construction. On the other hand the
+various foreign aviators who took part in the meet unhesitatingly gave
+preference to monoplanes.
+
+Whatever may have been the cause of this seeming prejudice against
+the monoplane on the part of American air sailors, it is slowly being
+overcome. When a man like Curtiss, who has attained great success with
+biplanes, gives serious attention to the monoplane form of construction
+and goes so far as to build and successfully operate a single surface
+machine, it may be taken for granted that the monoplane is a fixture in
+this country.
+
+Dimensions of Monoplanes.
+
+The makes, dimensions and equipment of the various monoplanes used at
+Belmont Park are as follows:
+
+Bleriot--(Moissant, operator)--plane length 23 feet, extreme breadth 28
+feet, surface area 160 square feet, 7-cylinder, 50 h. p. Gnome engine,
+Chauviere propeller, 7 feet 6 inches diameter, 1,200 r. p. m.
+
+Bleriot--(Drexel, operator)--exactly the same as Moissant's machine.
+
+Antoinette--(Harkness, operator)--plane length 42 feet, extreme breadth
+46 feet, surface area 377 square feet, Emerson 6-cylinder, 50 h. p.
+motor, Antoinette propeller, 7 feet 6 inches diameter, 1,200 r. p. m.
+
+Curtiss--(Glenn H. Curtiss, operator)--plane length 25 feet, extreme
+breadth 26 feet, surface area 130 square feet, Curtiss 8-cylinder, 60 h.
+p. motor, Paragon propeller, 7 feet in diameter, 1,200 r. p. m.
+
+With one exception Curtiss had the smallest machine of any of those
+entering into competition. The smallest was La Demoiselle, made by
+Santos-Dumont, the proportions of which were: plane length 20 feet,
+extreme breadth 18 feet, surface area 100 square feet, Clement-Bayard
+2-cylinder, 30 h. p. motor, Chauviere propeller, 6 feet 6 inches in
+diameter, 1,100 r. p. m.
+
+Winnings Made with Monoplanes.
+
+Operators of monoplanes won a fair share of the cash prizes. They won
+$30,283 out of a total of $63,250, to say nothing about Grahame-White's
+winnings. The latter won $13,600, but part of his winning flights were
+made in a Bleriot monoplane, and part in a Farman machine. Aside from
+Grahame-White the winnings were divided as follows: Moissant (Bleriot)
+$13,350; Latham (Antoinette) $8,183; Aubrun (Bleriot) $2,400; De Lesseps
+(Bleriot) $2,300; Drexel (Bleriot) $1,700; Radley (Bleriot) $1,300;
+Simon (Bleriot) $750; Andemars (Clement-Bayard) $100; Barrier (Bleriot)
+$100.
+
+Out of a total of $30,283, operators of Bleriot machines won $21,900,
+again omitting Grahame-White's share. If the winnings with monoplane and
+biplane could be divided so as to show the amount won with each type
+of machine the credit side of the Bleriot account would be materially
+enlarged.
+
+The Most Popular Monoplanes.
+
+While the number of successful monoplanes is increasing rapidly, and
+there is some feature of advantage in nearly all the new makes, interest
+centers chiefly in the Santos-Dumont, Antoinette and Bleriot machines.
+This is because more has been accomplished with them than with any of
+the others, possibly because they have had greater opportunities.
+
+For the guidance of those who may wish to build a machine of the
+monoplane type after the Santos-Dumont or Bleriot models, the following
+details will be found useful.
+
+Santos-Dumont--The latest production of this maker is called the "No. 20
+Baby." It is of 18 feet spread, and 20 feet over all in depth. It stands
+4 feet 2 inches in height, not counting the propeller. When this latter
+is in a vertical position the extreme height of the machine is 7 feet
+5 inches. It is strictly a one-man apparatus. The total surface area
+is 115 square feet. The total weight of the monoplane with engine and
+propeller is 352 pounds. Santos-Dumont weighs 110 pounds, so the entire
+weight carried while in flight is 462 pounds, or about 3.6 pounds per
+square foot of surface.
+
+Bamboo is used in the construction of the body frame, and also for the
+frame of the tail. The body frame consists of three bamboo poles about
+2 inches in diameter at the forward end and tapering to about 1 inch at
+the rear. These poles are jointed with brass sockets near the rear of
+the main plane so they may be taken apart easily for convenience in
+housing or transportation. The main plane is built upon four transverse
+spars of ash, set at a slight dihedral angle, two being placed on each
+side of the central bamboo. These spars are about 2 inches wide by 1
+1/8-inch deep for a few feet each side of the center of the machine, and
+from there taper down to an inch in depth at the center bamboo, and at
+their outer ends, but the width remains the same throughout their entire
+length. The planes are double surfaced with silk and laced above and
+below the bamboo ribs which run fore and aft under the main spars and
+terminate in a forked clip through which a wire is strung for lacing on
+the silk. The tail consists of a horizontal and vertical surface placed
+on a universal joint about 10 feet back of the rear edge of the main
+plane. Both of these surfaces are flat and consist of a silk covering
+stretched upon bamboo ribs. The horizontal surface is 6 feet 5 inches
+across, and 4 feet 9 inches from front to back. The vertical surface
+is of the same width (6 feet 5 inches) but is only 3 feet 7 inches
+from front to back. All the details of construction are shown in the
+accompanying illustration.
+
+Power is furnished by a very light (110 pounds) Darracq motor, of the
+double-opposed-cylinder type. It has a bore of 4.118 inches, and stroke
+of 4.724 inches, runs at 1,800 r. p. m., and with a 6 1/2-foot propeller
+develops a thrust of 242 1/2 pounds when the monoplane is held steady.
+
+Bleriot--No. XI, the latest of the Bleriot productions, and the greatest
+record maker of the lot, is 28 feet in spread of main plane, and depth
+of 6 feet in largest part. This would give a main surface of 168 square
+feet, but as the ends of the plane are sharply tapered from the rear,
+the actual surface is reduced to 150 square feet. Projecting from
+the main frame is an elongated tail (shown in the illustration) which
+carries the horizontal and vertical rudders. The former is made in three
+sections. The center piece is 6 feet 1 inch in spread, and 2 feet 10
+inches in depth, containing 17 square feet of surface. The end sections,
+which are made movable for warping purposes, are each 2 feet 10 inches
+square, the combined surface area in the entire horizontal rudder
+being 33 square feet. The vertical rudder contains 4 1/2 square feet of
+surface, making the entire supporting area 187 1/2 square feet.
+
+From the outer end of the propeller shaft in front to the extreme rear
+edge of the vertical rudder, the machine is 25 feet deep. Deducting
+the 6-foot depth of the main plane leaves 19 feet as the length of the
+rudder beam and rudders. The motor equipment consists of a 3-cylinder,
+air-cooled engine of about 30 h. p. placed at the front end of the body
+frame, and carrying on its crankshaft a two-bladed propeller 6 feet 8
+inches in diameter. The engine speed is about 1,250 r. p. m. at which
+the propeller develops a thrust of over 200 pounds.
+
+The Bleriot XI complete weighs 484 pounds, and with operator and fuel
+supply ready for a 25- or 30-mile flight, 715 pounds. One peculiarity of
+the Bleriot construction is that, while the ribs of the main plane are
+curved, there is no preliminary bending of the pieces as in other forms
+of construction. Bleriot has his rib pieces cut a little longer than
+required and, by springing them into place, secures the necessary
+curvature. A good view of the Bleriot plane framework is given on page
+63.
+
+Combined Triplane and Biplane.
+
+At Norwich, Conn., the Stebbins-Geynet Co., after several years of
+experiment, has begun the manufacture of a combination triplane and
+biplane machine. The center plane, which is located about midway
+between the upper and lower surfaces, is made removable. The change
+from triplane to biplane, or vice versa, may be readily made in a few
+minutes. The constructors claim for this type of air craft a large
+supporting surface area with the minimum of dimensions in planes.
+Although this machine has only 24-foot spread and is only 26 feet over
+all, its total amount of supporting area is 400 square feet; weight, 600
+pounds in flying order, and lifting capacity approximately 700 pounds
+more.
+
+The frame is made entirely of a selected grade of Oregon spruce,
+finished down to a smooth surface and varnished. All struts are
+fish-shaped and set in aluminum sockets, which are bolted to top and
+lower beams with special strong bolts of small diameter. The middle
+plane is set inside the six uprights and held in place by aluminum
+castings. A flexible twisted seven-strand wire cable and Stebbins-Geynet
+turnbuckles are used for trussing.
+
+The top plane is in three sections, laced together. It has a 24-foot
+spread and is 7 feet in depth. The middle plane is in two sections each
+of 7 1/2 feet spread and 6 feet in depth. The center ends of the middle
+plane sections do not come within 5 feet of joining, this open space
+being left for the engine. The bottom plane is of 16 feet spread and 5
+feet in depth. It will thus be seen that the planes overhang one another
+in depth, the bottom one being the smallest in this respect. The planes
+are set at an angle of 9 degrees, and there is a clear space of 3 1/2
+feet between each, making the total distance from the bottom to the top
+plane a trifle over 7 feet. The total supporting surface in the main
+planes is 350 square feet. By arranging the three plane surfaces at
+an angle as described and varying their size, the greatest amount of
+lifting area is secured above the center of gravity, and the greatest
+weight carried below.
+
+The ribs are made of laminated spruce, finished down to 1/2x3/4-inch
+cross section dimensions, with a curvature of about 1 in 20, and
+fastened to the beams with special aluminum castings. Number 2 Naiad
+aeroplane cloth is used in covering the planes, with pockets sewn in for
+the ribs.
+
+Two combination elevating rudders are set up well in front, each having
+18 square feet of supporting area. These rudders are arranged to work
+in unison, independently, or in opposite directions. In the Model B
+machine, there are also two small rear elevating rudders, which work in
+unison with the front rudders. One vertical rudder of 10 square feet is
+suspended in the rear of a small stationary horizontal plane in Model A,
+while the vertical rudder on Model B is only 6 square feet in size. The
+elevating rudders are arranged so as to act as stabilizing planes when
+the machine is in flight. The wing tips are held in place with a special
+two-piece casting which forms a hinge, and makes a quick detachable
+joint. Wing tips are also used in balancing.
+
+Model A is equipped with a Cameron 25-30 h. p., 4-cylinder, air-cooled
+motor. On Model B a Holmes rotary 7-cylinder motor of 4x4-inch bore and
+stroke is used.
+
+Positive control is secured by use of the Stebbins-Geynet "auto-control"
+system. A pull or push movement operates the elevating rudders, while
+the balancing is done by means of side movements or slight turns. The
+rear vertical rudder is manipulated by means of a foot lever.
+
+New Cody Biplane.
+
+Among the comparatively new biplanes is one constructed by Willard F.
+Cody, of London, Eng., the principal distinctive feature of which is an
+automatic control which works independently of the hand levers. For the
+other control a long lever carrying a steering wheel furnishes all the
+necessary control movements, there being no footwork at all. The lever
+is universally jointed and when moved fore and aft operates the two
+ailerons as if they were one; when the shaft is rotated it moves the
+tail as a whole. The horizontal tail component is immovable. When the
+lever is moved from side to side it works not only the ailerons and
+the independent elevators, but also through a peculiar arrangement, the
+vertical rear rudder as well.
+
+The spread of the planes is 46 feet 6 inches and the width 6 feet 6
+inches. The ailerons jut out 1 foot 6 inches on each side of the machine
+and are 13 feet 6 inches long. The cross-shaped tail is supported by an
+outrigger composed of two long bamboos and of this the vertical plane
+is 9 feet by 4 feet, while the horizontal plane is 8 feet by 4 feet. The
+over-all length of the machine is 36 feet. The lifting surface is 857
+square feet. It will weigh, with a pilot, 1,450 pounds. The distance
+between the main planes is 8 feet 6 inches, which is a rather notable
+feature in this flyer.
+
+The propeller has a diameter of 11 feet and 2 inches with a 13-foot
+6-inch pitch; it is driven at 560 revolutions by a chain, and the gear
+reduction between the chain and propeller shaft is two to one.
+
+The machine from elevator to tail plane bristles in original points. The
+hump in the ribs has been cut away entirely, so that although the plane
+is double surfaced, the surfaces are closest together at a point which
+approximates the center of pressure. The plane is practically of two
+stream-line forms, of which one is the continuation of the other.
+This construction, claims the inventor, will give increased lift, and
+decreased head resistance. The trials substantiate this, as the angle of
+incidence in flying is only about one in twenty-six.
+
+The ribs in the main planes are made of strips of silver spruce one-half
+by one-half inch, while those in the ailerons are solid and one-fourth
+inch thick. In the main planes the fabric is held down with thin wooden
+fillets. Cody's planes are noted for their neatness, rigidity and
+smoothness. Pegamoid fabric is used throughout.
+
+Pressey Automatic Control.
+
+Another ingenious system of automatic control has been perfected by Dr.
+J. B. Pressey, of Newport News, Va. The aeroplane is equipped with a
+manually operated, vertical rudder, (3), at the stern, and a horizontal,
+manually operated, front control, (4), in front. At the ends of the main
+plane, and about midway between the upper and lower sections thereof,
+there are supplemental planes, (5).
+
+In connection with these supplemental planes (5), there is employed a
+gravity influenced weight, the aviator in his seat, for holding them in
+a horizontal, or substantially horizontal, position when the main plane
+is traveling on an even keel; and for causing them to tip when the main
+plane dips laterally, to port or starboard, the planes (5) having
+a lifting effect upon the depressed end of the main plane, and a
+depressing effect upon the lifted end of the main plane, so as to
+correct such lateral dip of the main plane, and restore it to an even
+keel. To the forward, upper edge of planes (5) connection is made by
+means of rod (13) to one arm of a bellcrank lever, (14) the latter being
+pivotally mounted upon a fore and aft pin (15), supported from the main
+plane; and the other arms of the port and starboard bellcrank levers
+(16), are connected by rod (17), which has an eye (18), for receiving
+the segmental rod (19), secured to and projecting from cross bar on seat
+supporting yoke (7). When, therefore, the main plane tips downwardly on
+the starboard side, the rod (17) will be moved bodily to starboard, and
+the starboard balancing plane (5) will be inclined so as to raise its
+forward edge and depress its rear edge, while, at the same time, the
+port balancing plane (5), will be inclined so as to depress its forward
+edge, and raise its rear edge, thereby causing the starboard balancing
+plane to exert a lifting effect, and the port balancing plane to exert a
+depressing effect upon the main plane, with the result of restoring the
+main plane to an even keel, at which time the balancing planes (5), will
+have resumed their normal, horizontal position.
+
+When the main plane dips downwardly on the port side, a reverse action
+takes place, with the like result of restoring the main plane to an even
+keel. In order to correct forward and aft dip of the main plane, fore
+and aft balancing planes (20) and (23) are provided. These planes are
+carried by transverse rock shafts, which may be pivotally mounted in
+any suitable way, upon structures carried by main plane. In the present
+instance, the forward balancing plane is pivotally mounted in extensions
+(21) of the frame (22) which carries the forward, manually operated,
+horizontal ascending and descending plane
+
+It is absolutely necessary, in making a turn with an aeroplane, if that
+turn is to be made in safety, that the main plane shall be inclined, or
+"banked," to a degree proportional to the radius of the curve and to the
+speed of the aeroplane. Each different curve, at the same speed, demands
+a different inclination, as is also demanded by each variation in speed
+in rounding like curves. This invention gives the desired result with
+absolute certainty.
+
+The Sellers' Multiplane.
+
+Another innovation is a multiplane, or four-surfaced machine, built and
+operated by M. B. Sellers, formerly of Grahn, Ky., but now located at
+Norwood, Ga. Aside from the use of four sustaining surfaces, the novelty
+in the Sellers machine lies in the fact that it is operated successfully
+with an 8 h. p. motor, which is the smallest yet used in actual flight.
+In describing his work, Mr. Sellers says his purpose has been to develop
+the efficiency of the surfaces to a point where flight may be obtained
+with the minimum of power and, judging by the results accomplished,
+he has succeeded. In a letter written to the authors of this book, Mr.
+Sellers says:
+
+"I dislike having my machine called a quadruplane, because the number of
+planes is immaterial; the distinctive feature being the arrangement
+of the planes in steps; a better name would be step aeroplane, or step
+plane.
+
+"The machine as patented, comprises two or more planes arranged in step
+form, the highest being in front. The machine I am now using has four
+planes 3 ft. x 18 ft.; total about 200 square feet; camber (arch) 1 in
+16.
+
+"The vertical keel is for lateral stability; the rudder for direction.
+This is the first machine (so far as I know) to have a combination
+of wheels and runners or skids (Oct. 1908). The wheels rise up
+automatically when the machine leaves the ground, so that it may alight
+on the runners.
+
+"A Duthirt & Chalmers 2-cylinder opposed, 3 1/8-inch engine was used
+first, and several hundred short flights were made. The engine gave
+four brake h. p., which was barely sufficient for continued flight. The
+aeroplane complete with this engine weighed 78 pounds. The engine now
+used is a Bates 3 5/8-inch, 2-cylinder opposed, showing 8 h. p., and
+apparently giving plenty of power. The weight of aeroplane with this
+engine is now 110 pounds. Owing to poor grounds only short flights have
+been made, the longest to date (Dec. 31, 1910) being about 1,000 feet.
+
+"In building the present machine, my object was to produce a safe, slow,
+light, and small h. p. aeroplane, a purpose which I have accomplished."
+
+
+
+CHAPTER XXVII. 1911 AEROPLANE RECORDS.
+
+THE WORLD AT LARGE.
+
+Greatest Speed Per Hour, Whatever Length of Flight, Aviator Alone--E.
+Nieuport, Mourmelon, France, June 21, Nieuport Machine, 82.72 miles;
+with one passenger, E. Nieuport, Moumlelon, France, June 12, Nieuport
+Machine, 67.11 miles; with two passengers, E. Nieuport, Mourmelon,
+France, March 9, Nieuport Machine, 63.91 miles; with three passengers,
+G. Busson, Rheims, France, March 10, Deperdussin Machine, 59.84 miles;
+with four passengers, G. Busson, Rheims, France, March 10, Deperdussin
+Machine, 54.21 miles.
+
+Greatest Distance Aviator Alone--G. Fourny, no stops, Buc, France,
+September 2, M. Farman Machine, 447.01 miles; E. Helen, three stops,
+Etampes, France, September 8, Nieuport Machine, 778.45 miles; with
+one passenger, Lieut. Bier, Austria, October 2, Etrich Machine, 155.34
+miles; with two passengers, Lieut. Bier, Austria, October 4, Etrich
+Machine, 69.59 miles; with three passengers, G. Busson, Rheims, France,
+March 10, Deperdussin Machine, 31.06 miles; with four passengers, G.
+Busson, Rheims, France, March 10, Deperdussin Machine, 15.99 miles.
+
+Greatest Duration Aviator Alone--G. Fourny, no stops, Buc, France,
+September 2, M. Farman Machine, 11 hours, 1 minute, 29 seconds, E.
+Helen, three stops, Etampes, France, September 8, Nieuport Machine, 14
+hours, 7 minutes, 50 seconds, 13 hours, 17 minutes net time; with one
+passenger, Suvelack, Johannisthal, Germany, December 8, 4 hours, 23
+minutes; with two passengers, T. de W. Milling, Nassau Boulevard, New
+York, September 26, Burgess-Wright Machine, 1 hour, 54 minutes, 42 3-5
+seconds; with three passengers, Warchalowski, Wiener-Neustadt, Aust.,
+October 30, 45 minutes, 46 seconds; with four passengers, G. Busson,
+Rheims, France, March 10, Deperdussin Machine, 17 minutes, 28 1-5
+seconds.
+
+Greatest Altitude Aviator Alone--Garros, St. Malo, France, September
+4, Bleriot Machine, 13,362 feet; with one passenger, Prevost, Courcy,
+France, December 2, 9,840 feet; with two passengers, Lieut. Bier,
+Austria, Etrich Machine, 4,010 feet.
+
+AMERICAN RECORDS.
+
+Greatest Speed Per Hour, Whatever Length of Flight, Aviator Alone--A.
+Leblanc, Belmont Park, N. Y., October 29, Bleriot Machine, 67.87 miles;
+with one passenger, C. Grahame-White, Squantum, Mass., September 4,
+Nieuport Machine, 63.23 miles; with two passengers, T. O. M. Sopwith,
+Chicago, Ill., August 15, Wright Machine, 34.96 miles.
+
+Greatest Distance Aviator Alone--St. Croix Johnstone, Mineola, N. Y.,
+July 27, Moisant (Bleriot Type) Machine, 176.23 miles.
+
+Greatest Duration Aviator Alone--Howard W. Gill, Kinloch, Mo., October
+19, Wright Machine, 4 hours, 16 minutes, 35 seconds; with one passenger,
+G. W. Beatty, Chicago, Ill., August 19, Wright Machine, 3 hours, 42
+minutes, 22 1-5 seconds; with two passengers, T. de W. Milling, Nassau
+Boulevard, N. Y., September 26, Burgess-Wright Machine, 1 hour, 54
+minutes, 42 3-5 seconds.
+
+Greatest Altitude Aviator Alone--L. Beachy, Chicago, Ill., August 20,
+Curtiss Machine, 11,642 feet; with one passenger, C. Grahame-White,
+Nassau Boulevard, N. Y., September 30, Nieuport Machine, 3,347 feet.
+
+Weight Carrying--P. O. Parmelee, Chicago, III., August 19, Wright
+Machine, 458 lbs.
+
+AVIATION DEVELOPMENT.
+
+The wonderful progress made in the science of aviation during the
+year 1911 far surpasses any twelve months' advancement recorded. The
+advancement has not been confined to any country or continent, since
+every part of the world is taking its part in aviation history making.
+
+The rapidly increasing interest in aviation has brought forth schools
+for the instruction of flying in both the old and new world, and
+licensed air pilots before they receive their sanctions from the
+governing aero clubs of their country are required to pass an extremely
+trying examination in actual flights. Exhibition flights and races
+were common in all parts of the world during 1911, and touring aviators
+visited India, China, Japan, South Africa, Australia and South America,
+giving exhibitions and instruction.
+
+Europe was the scene of a number of cross-country races in which entries
+ranging from ten to twenty aviators flew from city to city around a
+given circuit, which in some instances exceeded 1,000 miles in distance.
+Cross-country flights with and without passengers became so common that
+those of less than two hours' duration attracted little attention.
+There were fewer attempts at high altitude soaring, although the world's
+record in this department of aviation was bettered several times. In
+place of these high flights, the aviators devoted more attention to
+speed, duration and spectacular manoeuvres, which appeared to satisfy
+the spectators. The prize money won during 1911 exceeded $1,000,000, but
+owing to the increased number of aviators the individual winnings were
+not as large as in 1910.
+
+It is estimated that within the past twelve months more than 300,000
+miles have been covered in aeroplane flights and more than seven
+thousand persons, classed either as aviators or passengers, taken up
+into the air. The aeroplane of today ranges through monoplane, biplane,
+triplane and even quadraplane, and more than two hundred types of these
+machines are in use.
+
+Aeroplanes are becoming a factor of international commerce. The records
+of the Bureau of Statistics show that more than $50,000 worth of
+aeroplanes were imported into, and exported from, the United States in
+the months of July, August and September, 1911. The Bureau of Statistics
+only began the maintenance of a separate record of this comparatively
+new article of commerce with the opening of the fiscal year 1911-12.
+
+Two of the prominent developments of 1911 were the introduction of
+the hydro-aeroplane and the motorless glider experiments of the
+Wright brothers at Killdevil Hills, N. C., where during the two weeks'
+experiments numerous flights with and against the wind were made,
+culminating in the establishing of a record by Orville Wright on October
+25, 1911, when in a 52-mile per hour blow he reached an elevation of 225
+feet and remained in the air 10 minutes and 34 seconds. The search
+for the secret of automatic stability still continues, and though some
+remarkable progress has been made the solution has not yet been reached.
+
+NOTABLE CROSS-COUNTRY FLIGHTS OF 1911.
+
+One of the important features of 1911 in aviation was the rapid increase
+in the number and distance of cross-country flights made either for the
+purpose of exhibition, testing, instruction or pleasure. Flights between
+cities in almost every country of the world became common occurrences.
+So great was the number that only those of more than ordinary importance
+because of speed, distance or duration are recorded. The flights of
+Harry N. Atwood from Boston to Washington and from St. Louis to New
+York, and C. P. Rodgers from New York to Los Angeles were the most
+important events of the kind in this country. The St Louis to New York
+flight was a distance by air route, 1,266 miles. Duration of flight, 12
+days. Net flying time, 28 hours 53 minutes. Average daily flight, 105.5
+miles. Average speed, 43.9 miles per hour.
+
+Transcontinental Flight of Calbraith P. Rodgers.--All world records
+for cross-country flying were broken during the New York to Los Angeles
+flight of Calbraith P. Rodgers, who left Sheepshead Bay, N. Y., on
+Sunday, September 17, 1911, and completed his flight to the Pacific
+Coast on Sunday, November 5, at Pasadena, Cal. Rodgers flew a Wright
+biplane, and during his long trip the machine was repeatedly repaired,
+so great was the strain of the long journey in the air. Rodgers is
+estimated to have covered 4,231 miles, although the actual route as
+mapped out was but 4,017 miles. Elapsed time to Pasadena, Cal., 49 days;
+actual time in the air, 4,924 minutes, equivalent to 3 days 10 hours 4
+minutes; average speed approximating 51 miles per hour. Rodgers' longest
+flight in one day was from Sanderson to Sierra Blanca, Texas, on October
+28, when he covered 231 miles. On November 12, Rodgers fell at Compton,
+Cal., and was badly injured, causing a delay of 28 days.
+
+European Circuit Race.--Started from Paris on June 18, 1911. Distance,
+1,073 miles, via Paris to Liege; Liege to Spa to Liege; Liege to
+Utrecht, Holland; Utrecht to Brussels, Belgium; Brussels to Roubaix;
+Roubaix to Calais; Calais to London; London to Calais and Calais to
+Paris. Three aeronauts were killed either at the start or shortly after
+the race was in progress. They were Capt. Princetau, M. Le Martin and
+M. Lendron. Three others were injured by falls. Seven hundred thousand
+spectators witnessed the start from the aviation field at Vincennes,
+near Paris. There were more than forty starters, of which eight
+finished. The winner, Lieut. Jean Conneau, who flies under the name of
+"Andre Beaumont," completed the circuit on July 7; his actual net flying
+time for the distance being 58h. 38m. 4-5s.
+
+Circuit of England Race--1,010 Miles in Five Sections.--
+
+Start, July 22. Finish, July 26. Prize, $50,000. Twenty-eight entries
+and eighteen starters. Seventeen finished the first section from
+Brooklands to Hendon, a distance of twenty miles. Five reached
+Edinburgh, the second section, a distance of 343 miles, and four
+completed the entire circuit.
+
+Paris to Madrid Race.--This race was started at the Paris aviation
+held at Issy-les-Moulineaux on Sunday, May 21. There were twenty-one
+entrants, and fully 300,000 spectators gathered to witness the initial
+flight of the aerial races. The race was divided into three stages as
+follows: Paris to Angouleme, 248 miles; Angouleme to St. Sebastian, 208
+miles, and from St. Sebastian to Madrid, 386 miles, a total distance
+of 842 miles. After three of the entrants had safely left the field,
+Aviator Train lost control of his plane, and in falling struck and
+killed M. Berteaux, the French Minister of War, and seriously injured
+Premier Monis. The accident caused the withdrawal of all but six of the
+original entrants, and of these but one finished. The race called for
+a flight over the Pyrenees Mountains, and Vedrines, the winner, had to
+rise to a height of more than 7,000 feet to pass the mountain barrier
+near Somosierra Pass. Both Vedrines and Gibert, another competitor, were
+attacked by eagles during the latter stages of the flight. Vedrines,
+who started from Paris on Monday, May 22, finished the long and perilous
+race at 8:06 a. m. Friday, May 26. Vedrines net flying time, all
+controls and enforced stops subtracted, was 14h. 55m. 18s. The various
+prizes to the winner aggregated $30,000.
+
+The Paris-Rome-Turin Race.--The conditions of this race called for a
+flight between the cities of Paris, Rome and Turin, covering a distance
+of 1,300 miles. The aviators were permitted by the rules to alight
+whenever and wherever they desired and the time limit was set from
+May 28 to June 15. A prize of $100,000 was offered the winner, but the
+contest was never finished, as one after another the aviators dropped
+out until Frey fell near Roncigilione, France, breaking both arms and
+legs and unofficially ending the contest. There were twenty-one entries
+and twelve actual starters.
+
+International Speed Cup Race.--The third annual international James
+Gordon Bennett speed cup race was held at Eastchurch, England, on July
+1, 1911, and for the second time was won by an American aviator, C. T.
+Weymann, in a French racing aeroplane. The distance was 150 kilometres
+equivalent to 94 miles, and the winner's time of 1h. 11m. 36s. showed an
+average speed of 78.77 miles per hour. The first race was held in 1909
+and was won by Glenn Curtiss, who flew the twenty kilometres (12.4
+miles) in 15 minutes 50 2-5 seconds at an average speed of 47 miles per
+hour. In 1910 the winner was Grahame-White, who covered 100 kilometres
+(62 miles) at Belmont Park, L. I., in 60 minutes 47 3-5 seconds, an
+average speed of 61.3 miles per hour. In the 1911 race there were six
+starters: three from France, two from Great Britain and one from the
+United States.
+
+Milan to Turin to Milan Race.--This race which was started from Milan,
+Italy, on October 29, was restricted to Italian aviators and had six
+starters. The distance was approximately 177 miles and won by Manissero
+in a Bleriot machine in 3h. 16m. 2 4-5s.
+
+New York to Philadelphia Race.--The first intercity aeroplane race ever
+held in the United States was started from New York City on August
+5, and finished in Philadelphia the same day. The prize of $5,000 was
+offered by a commercial concern with stores in the two cities: Three
+entrants competed from the Curtiss Exhibition Company. The distance was
+approximately 83 miles and won by L. Beachey in a Curtiss machine in 1h.
+50m. at an average speed of 45 miles per hour.
+
+Tri-State Race.--The tri-state race was the feature event of the Harvard
+Aviation Society meet held at Squantum, Mass., August 26 to September
+6. It was held Labor Day, September 4, over a course of 174 miles, from
+Boston to Nashua to Worcester to Providence to Boston. Four competitors
+started, of which two finished, the winner, E. Ovington, in a Bleriot
+machine. Ovington's net flying time, 3h. 6m. 22 1-5s. Winner's prize,
+$10,000.
+
+AEROPLANES AND DIRIGIBLE BALLOONS IN WARFARE.
+
+Wonderful progress has been made in the development of the aeroplane in
+this country and in Europe since 1903, and within the last two or three
+years the leading powers of the world have entered upon extensive tests
+and experiments to determine its availability and usefulness in land and
+naval warfare.
+
+At the present time all the great powers are building or purchasing
+aeroplanes on an extensive scale. They have established government
+schools for the instruction of their army and navy officers and for
+experimental work. So-called "Airship Fleets" have been constructed and
+placed in commission as auxiliaries to the armies and navies. The fleets
+of France and Germany are about equal and are larger by far than those
+of any of the other powers. The length of the dirigibles composing these
+fleets runs from 150 to 500 feet; they are equipped with engines of from
+50 to 500 horse-power, with a rate of speed ranging from 20 to 30 miles
+per hour. Their approximate range is from 200 to 900 miles; the longest
+actual run (made by the Zeppelin II, Germany) is 800 miles.
+
+A British naval airship, one of the largest yet built, was completed
+last summer. It has cost over $200,000, and it was in course of
+designing and construction two years. It is 510 feet long; can carry 22
+persons, and has a lift of 21 tons.
+
+The relative value of the dirigible balloon and the aeroplane in actual
+war is yet to be determined. The dirigible is considered to be the
+safer, yet several large balloons of this class in Germany and France
+have met with disaster, involving loss of lives. The capacity of the
+dirigible for longer flights and its superior facilities for carrying
+apparatus and operators for wireless telegraphy are distinct advantages.
+
+There has not yet been much opportunity to test the airship in actual
+warfare. The aeroplane has been used by the Italians in Tripoli for
+scouting and reconnoitering and is said to have justified expectations.
+On several occasions the Italian military aviators followed the
+movements of the enemy, in one instance as far as forty miles inland. At
+the time of the attack by the Turks a skillful aeroplane reconnaissance
+revealed the approach of a large Turkish force, believed to be at the
+time sixty miles away in the mountains.
+
+Aeroplanes and airships, as they exist today, would doubtless render
+very valuable service in a time of war, both over land and water, in
+scouting, reconnoitering, carrying dispatches, and as some experts
+believe, in locating submarines and mines placed by the enemy in
+channels of exits from ports. A "coast aeroplane" could fly out 30 or 40
+miles from land, and rising to a great height, descry any hostile ships
+on the distant horizon, observe their number, strength, formation and
+direction, and return within two hours with a report to obtain which
+would require several swift torpedo-boat destroyers and a much greater
+time. The question as to whether it would be practicable to bombard an
+enemy on land or sea with explosive bombs dropped or discharged from
+flying machines or airships, is one which is much discussed but hardly
+yet determined.
+
+Aeroplanes have been constructed with floats in the place of runners and
+several attempts have been made, in some cases successfully, to light
+with them on and to rise from the water. Mr. Curtiss did this at San
+Francisco, in January, 1911. Attempts have also been made with the
+aeroplane to alight on and to take flight from the deck of a warship.
+Toward the end of 1910 Aviator Ely flew to land from the cruiser
+Birmingham, and in January, 1911, he flew from land and alighted on the
+cruiser Pennsylvania. But in these cases special arrangements were made
+which would be hardly practicable in a time of actual war.
+
+In November, 1911, a test was made at Newport, R. I., by Lieut. Rodgers,
+of the navy, of a "hydro-areoplane" as an auxiliary to a battleship. The
+idea of the test was to alight alongside of the ship, hoist the machine
+aboard, put out to sea and launch the machine again with the use of a
+crane. Lieut. Rodgers came down smoothly alongside the Ohio, his machine
+was easily drawn aboard with a crane, and the Ohio steamed down to
+the open sea, where it was blowing half a gale. But, owing to the
+misjudgment of the ship's headway, one of the wings of the machine when
+it struck the water after being released from the crane, went under the
+water and was snapped off. Lieut. Rodgers was convinced that this method
+was too risky and that some other must be devised.
+
+
+
+CHAPTER XXVIII. GLOSSARY OF AERONAUTICAL TERMS.
+
+Aerodrome.--Literally a machine that runs in the air. Aerofoil.--The
+advancing transverse section of an aeroplane.
+
+Aeroplane.--A flying machine of the glider pattern, used in
+contra-distinction to a dirigible balloon.
+
+Aeronaut.--A person who travels in the air.
+
+Aerostat.--A machine sustaining weight in the air. A balloon is an
+aerostat.
+
+Aerostatic.--Pertaining to suspension in the air; the art of aerial
+navigation.
+
+Ailerons.--Small stabilizing planes attached to the main planes to
+assist in preserving equilibrium.
+
+Angle of Incidence.--Angle formed by making comparison with a
+perpendicular line or body.
+
+Angle of Inclination.--Angle at which a flying machine rises. This
+angle, like that of incidence, is obtained by comparison with an
+upright, or perpendicular line.
+
+Auxiliary Planes.--Minor plane surfaces, used in conjunction with the
+main planes for stabilizing purposes.
+
+Biplane.--A flying-machine of the glider type with two surface planes.
+
+Blade Twist.--The angle of twist or curvature on a propeller blade.
+
+Cambered.--Curve or arch in plane, or wing from port to starboard.
+
+Chassis.--The under framework of a flying machine; the framework of the
+lower plane.
+
+Control.--System by which the rudders and stabilizing planes are
+manipulated.
+
+Dihedral.--Having two sides and set at an angle, like dihedral planes,
+or dihedral propeller blades.
+
+Dirigible.--Obedient to a rudder; something that may be steered or
+directed.
+
+Helicopter.--Flying machine the lifting power of which is furnished by
+vertical propellers.
+
+Lateral Curvature.--Parabolic form in a transverse direction.
+
+Lateral Equilibrium or Stability.--Maintenance of the machine on an even
+keel transversely. If the lateral equilibrium is perfect the extreme
+ends of the machine will be on a dead level.
+
+Longitudinal Equilibrium or Stability.--Maintenance of the machine on an
+even keel from front to rear.
+
+Monoplane.--Flying machine with one supporting, or surface plane.
+
+Multiplane.--Flying machine with more than three surface planes.
+
+Ornithopter.--Flying machine with movable bird-like wings.
+
+Parabolic Curves.--Having the form of a parabola--a conic section.
+
+Pitch of Propeller Blade.--See "Twist."
+
+Ribs.--The pieces over which the cloth covering is stretched.
+
+Spread.--The distance from end to end of the main surface; the
+transverse dimension.
+
+Stanchions.--Upright pieces connecting the upper and lower frames.
+
+Struts.--The pieces which hold together longitudinally the main frame
+beams.
+
+Superposed.--Placed one over another.
+
+Surface Area.--The amount of cloth-covered supporting surface which
+furnishes the sustaining quality.
+
+Sustentation.--Suspension in the air. Power of sustentation; the quality
+of sustaining a weight in the air.
+
+Triplane.--Flying machine with three surface planes.
+
+Thrust of Propeller.--Power with which the blades displace the air.
+
+Width.--The distance from the front to the rear edge of a flying
+machine.
+
+Wind Pressure.--The force exerted by the wind when a body is moving
+against it. There is always more or less wind pressure, even in a calm.
+
+Wing Tips.--The extreme ends of the main surface planes. Sometimes these
+are movable parts of the main planes, and sometimes separate auxiliary
+planes.
+
+
+
+
+Footnotes:
+
+[Footnote 1: Now dead.]
+
+[Footnote 2: Aeronautics.]
+
+[Footnote 3: See Chapter XXV.]
+
+[Footnote 4: The Wrights' new machine weighs only 900 pounds.]
+
+[Footnote 5: Aeronautics.]
+
+
+
+
+
+
+End of the Project Gutenberg EBook of Flying Machines, by 
+W.J. Jackman and Thos. H. Russell
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