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 The early history of the Airplaneo 
 
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 EARLY Ht/TORY 
 
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 AIRPLANE 
 
 OAYTON-WRIGHT AIRPLANE Oa 
 
 OAYTON*OHIO 
 
LIBRARY 
 
 UNIVERSITY OF CALIFORNIA 
 DAVIS 
 
Digitized by the Internet Archive 
 
 in 2007 with funding from 
 
 IVIicrosoft Corporation 
 
 http://www.archive.org/details/earlyhistoryofaiOOwrigrich 
 
The IDright Brothers' Aeroplane 
 
 By OrvilU and Wilbur Wright 
 
 ^ m I >HOUGH the subject of aerial 
 Y l"^ navigation is generally consid- 
 \^j J ered new, it has occupied the 
 ^^ minds of men more or less 
 from the earliest ages. Our personal in- 
 terest in it dates from our childhood 
 days. Late in the autumn of 1878 our 
 father came into the house one evening 
 with some object partly concealed in his 
 hands, and before we could see what it 
 was, he tossed it into the air. Instead of 
 falling to the floor, as we expected, it flew 
 across the room, till it struck the ceiling, 
 where it fluttered awhile, and finally 
 sank to the floor. It was a little toy, 
 known to scientists as a "helicoptere," 
 but which we, with sublime disregard for 
 science, at once dubbed a "bat." It was 
 a light frame of cork and bamboo, cov- 
 ered with paper, which formed two 
 screws, driven in opposite directions by 
 rubber bands under torsion. A toy so 
 delicate lasted only a short time in the 
 hands of small boys, but its memoiy was 
 abiding. 
 
 Several years later we began building 
 these helicop teres for ourselves, making 
 each one larger than that preceding. But, 
 to our astonishment, we found that the 
 larger the "bat" the less it flew. Wejlid 
 noMaixDw^tlial^^^nachir^^ only 
 
 twicejh e Imear dimensions of another 
 wouldrgguire^ightjt imes the power. We 
 finally became discouragedTandreturned 
 to kite-flying, a sport to which we had de- 
 voted so much attention that we were 
 regarded as experts. But as we became 
 older we had to give up this fascinating 
 sport as unbecoming to boys of our ages. 
 
 It was not till the news of the sad death 
 of Lilienthal reached America in the 
 
 summer of 1896 that we again gave more 
 than passing attention to the subject of 
 flying. We then studied with great in- 
 terest Chanute's "Progress in Flying Ma- 
 chines," Langley's "Experiments in 
 Aerodynamics," the "Aeronautical An- 
 nuals" of 1905, 1906, and 1907, and sev- 
 eral pamphlets published by the Smith- 
 sonian Institution, especially articles by 
 Lilienthal and extracts from Mouillard's 
 "Empire of the Air." The larger works 
 gave us a good understanding of the na- 
 ture of the flying problem, and the diffi- 
 culties in past attempts to solve it, while 
 Mouillard and Lilienthal, the great mis- 
 sionaries of the flying cause, infected us 
 with their own unquenchable enthusi- 
 asm, and transformed idle curiosity into 
 the active zeal of workers. 
 
 In the field of aviation there were two 
 schools. The first, represented by such 
 men as Professor Langley and Sir Hiram 
 Maxim, gave chief attention to power 
 flight; the second, represented by Lilien- 
 thal, Mouillard, and Chanute, to soaring 
 flight. Our sympathies were with the 
 latter school, partly from impatience at 
 the wasteful extravagance of mounting 
 delicate and costly machinery on wings 
 which no one knew how to manage, and 
 partly, no doubt, from the extraordinary 
 charm and enthusiasm with which the 
 apostles of soaring flight set forth the 
 beauties of sailing through the air on 
 fixed wdngs, deriving the motive power 
 from the wind itself. 
 
 The balancing of a flyer may seem, at 
 first thought, to be a very simple matter, 
 yet almost ever>' experimenter had found 
 in this one point which he could not sat- 
 isfactorily master. Many diflerent meth- 
 
 LIBRARV 
 
 UNIVERSITY OF CALIFORNIA 
 
 DAVIS 
 
THE 
 
 EARLY 
 
 HISTORY 
 
 O F 
 
 THE 
 
 AIRPLANE 
 
 ods were tried. Some experimenters 
 placed the center of gravity far below 
 the wings, in the belief that the weight 
 would naturally seek to remain at the 
 lowest point. It is true, that, like the 
 pendulum, it tended to seek the lowest 
 point; but also, like the pendulum, it 
 tended to oscillate in a manner destruc- 
 tive of all stability. A more satisfactory 
 system, especially for lateral balance, 
 was that of arranging the wings in the 
 shape of a broad V, to form a dihedral 
 angle, with the center low and the wing- 
 tips elevated. In theory this was an au- 
 tomatic system, but in practice it had two 
 serious defects: first, it tended to keep 
 the machine oscillating; and second, its 
 usefulness was restricted to calm air. 
 
 In a slightly modified form the same 
 system was applied to the fore-and-aft 
 balance. The main aeroplane was set at 
 a positive angle, and a horizontal tail at 
 a negative angle, while the center of 
 gravity was placed far forward. As in 
 the case of lateral control, there was a 
 tendency to constant undulation, and the 
 very forces which caused a restoration 
 of balance in calms caused a disturbance 
 of the balance in winds. Notwithstand- 
 ing the known limitations of this prin- 
 ciple, it had been embodied in almost 
 every prominent flying machine which 
 had been built. 
 
 After considering the practical effect 
 of the dihedral principle, we reached the 
 conclusion that a flyer founded upon it 
 might be of interest from a scientific 
 point of view, but could be of no value 
 in a practical way. We therefore re- 
 solved to try a fundamentally different 
 principle. We would arrange the ma- 
 chine so that it would not tend to right 
 itself. We would make it as inert as 
 possible to the effects of change of direc- 
 tion or speed, and thus reduce the effects 
 of wind-gusts to a minimum. We would 
 do this in the fore-and-aft stability by 
 
 giving the aeroplanes a peculiar shape; 
 and in the lateral balance by arching the 
 surfaces from tip to tip, just the reverse 
 of what our predecessors had done. Then 
 by some suitable contrivance, actuated 
 by the operator, forces should be brought 
 into play to regulate the balance. 
 
 Lilienthal and Chanute had guided and 
 balanced their machines, by shifting the 
 weight of the operator's body. But this 
 method seemed to us incapable of ex- 
 pansion to meet large conditions, be- 
 cause the weight to be moved and the 
 distance of possible motion were limited, 
 while the disturbing forces steadily in- 
 creased, both with wing area and with 
 wind velocity. In order to meet the 
 needs of large machines, we wished to 
 employ some system whereby the oper- 
 ator could vary at will the inclination of 
 different parts of the wings, and thus ob- 
 tain from the wind forces to restore the 
 balance which the wind itself had dis- 
 turbed. This could easily be done by 
 Using wings capable of being warped, and 
 by supplementary adjustable surfaces in 
 the shape of rudders. As the forces ob- 
 tainable for control would necessarily 
 increase in the same ratio as the disturb- 
 ing forces, the method seemed capable of 
 expansion to an almost unlimited extent. 
 A happy device was discovered whereby 
 the apparently rigid system of super- 
 posed surfaces, invented by Wenham, 
 and improved by Stringfellow and 
 Chanute, could be warped in a most un- 
 expected way, so that the aeroplanes 
 could be presented on the right and left 
 sides at different angles to the wind. 
 This, with an adjustable, horizontal front 
 rudder, formed the main feature of our 
 first glider. 
 
 The period from 1885 to 1900 was one 
 of unexampled activity in aeronautics, 
 and for a time there was high hope that 
 the age of flying was at hand. But Max- 
 im, after spending $100,000, abandoned 
 
THE 
 
 EARLY 
 
 HISTORY 
 
 O F 
 
 THE 
 
 AIRPLANE 
 
 the work; the Ader machine, built at the 
 expense of the French Government, was 
 a failure; Lilienthal and Pitcher were 
 killed in experiments; and Chanute and 
 many others, from one cause or another, 
 had relaxed their efforts, though it sub- 
 sequently became known that Professor 
 Langley was still secretly at work on a 
 machine for the United States Govern- 
 ment. The public, discouraged by the 
 failures and tragedies just witnessed, 
 considered flight bej'ond the reach of 
 man, and classed its adherents with the 
 inventors of perpetual motion. 
 
 We began our active experiments at 
 the close of this period, in October, 1900, 
 at Kitty Hawk, North Carolina. Our ma- 
 chine was designed to be flown as a kite, 
 with a man on board, in winds from 15 
 to 20 miles an hour. But, upon trial, it 
 was found that much stronger winds 
 were required to lift it. Suitable winds 
 not being plentiful, we found it neces- 
 sary, in order to test the new balancing 
 system, to fly the machine as a kite with- 
 out a man on board, operating the levers 
 through cords from the ground. This 
 did not give the practice anticipated, but 
 it inspired confidence in the new system 
 of balance. 
 
 In the summer of 1901 we became per- 
 sonally acquainted with Mr. Chanute. 
 When he learned that we were interested 
 in flying as a sport, and not with any ex- 
 pectation of recovering the money we 
 were expending on it, he gave us much 
 encouragement. At our invitation, he 
 spent several weeks with us at our camp 
 at Kill Devil Hill, four miles south of 
 Kitty Hawk, during our experiments of 
 that and the two succeeding years. He 
 also witnessed one flight of the power 
 machine near Dayton, Ohio, in October, 
 1904. 
 
 The machine of 1901 was built with 
 the shape of surface used by Lilienthal, 
 curved from front to rear like the seg- 
 
 ment of a parabola, with a curvature 
 1/12 the depth of its cord; but to make 
 doubly sure that it would have sufficient 
 lifting capacity when flown as a kite in 
 15 or 20-mile winds, we increased the 
 area from 165 square feet, used in 1900, 
 to 308 square feet — a size much larger 
 than Lilienthal, Pitcher, or Chanute had 
 deemed safe. Upon trial, however, the 
 lifting capacity again fell very far short 
 of calculation, so that the idea of secur- 
 ing practice while flying as a kite had to 
 be abandoned. Mr. Chanute, who wit- 
 nessed the experiments, told us that the 
 trouble was not due to poor construction 
 of the machine. We saw only one other 
 explanation — that the tables of air-pres- 
 sures in general use were incorrect. 
 
 We then turned to gliding — coasting 
 downhill on the air — ^as the only method 
 of getting the desired practice in balanc- 
 ing a machine. After a few minutes' 
 practice we were able to make glides of 
 over 300 feet, and in a few days were 
 safely operating in 27-mile winds. In 
 these experiments we met with several 
 unexpected phenomena. We found that, 
 contrary to the teachings of the books, 
 the center of pressure on a curved sur- 
 face traveled backward when the surface 
 was inclined, at small angles, more and 
 more edgewise to the wind. We also dis- 
 covered that in free flight, when the wing 
 on one side of the machine was presented 
 to the wind at a greater angle than the 
 one on the other side, the wing with the 
 greater angle descended, and the machine 
 turned in a direction just the reverse of 
 
THE 
 
 EARLY 
 
 HISTORY 
 
 O F 
 
 THE 
 
 AIRPLANE 
 
 what we were led to expect when flying 
 the machine as a kite. The larger angle 
 gave more resistance to forward motion, 
 and reduced the speed of the wing on 
 that side. The decrease in speed more 
 than counterbalanced the eflect of the 
 larger angle. The addition of a fixed 
 vertical vane in the rear increased the 
 trouble, and made the machine absolute- 
 ly dangerous. It was some time before 
 a remedy was discovered. This consisted 
 of movable rudders working in conjunc- 
 tion with the twisting of the wings. The 
 details of this arrangement are given in 
 specifications published several years 
 ago. 
 
 The experiments of 1901 were far 
 from encouraging. Although M r . 
 Chanute assured us that, both in control 
 and in weight carried per horse-power, 
 the results obtained were better than 
 those of any of our predecessors, yet we 
 saw that the calculations upon which all 
 flying machines had been based were un- 
 reliable, and that all were simply groping 
 in the dark. Having set out with abso- 
 lute faith in the existing scientific data, 
 we were driven to doubt one thing after 
 another, till finally, after two years of 
 experiment, we cast it all aside, and de- 
 cided to rely entirely upon our own in- 
 vestigations. Truth and error were 
 everywhere so intimately mixed as to be 
 undistinguishable. Nevertheless, the 
 time expended in preliminary study of 
 books was not misspent, for they gave us 
 J a good general understanding of the sub- 
 ject, and enabled us at the outset to avoid 
 effort in many directions in which re- 
 sults would have been hopeless. 
 
 The standard measurements of wind- 
 pressures is the force produced by a cur- 
 rent of air of one mile per hour velocity 
 striking square against a plane of one 
 square foot area. The practical difficul- 
 ties of obtaining an exact measurement 
 of this force have been great. The meas- 
 
 / 
 
 urements by different recognized author- / 
 ities vary 50 i^er cent. When this simp- 
 lest of measurements presents so great 
 difficulties, what shall be said of the 
 troubles encountered by those who at- 
 tempt to find the pressure at each angle 
 as the plane is inclined more and more 
 edgewise to the wind? In the eighteenth 
 centui*y the French Academy prepared 
 tables giving such information, and at a 
 later date the Aeronautical Society of 
 Great Britain made similar experiments. 
 Manj' persons likewise published meas- 
 urements and formulas; but the results 
 were so discordant that Professor Lang- 
 ley undertook a new series of measure- 
 ments, the results of which form the 
 basis of his celebrated work, "Experi- 
 ments in Aerodynamics." Yet a critical 
 examination of the data upon which he 
 based his conclusions as to the pressures 
 at small angles shows results so various 
 as to make many of his conclusions little 
 better than guesswork. 
 
 To work intelligently, one needs to 
 know the effects of a multitude of varia- 
 tions that could be incorporated in the 
 surfaces of flying machines. The pres- 
 sures on squares are different from 
 those on rectangles, circles, triangles, or 
 ellipses; arched surfaces differ from 
 planes, and vary among themselves ac- 
 cording to the depth of cur\'ature; true 
 arcs differ from parabolas, and the latter 
 differ among themselves; thick surfaces 
 differ from thin, and surfaces thicker in 
 one place than another vary in pressure 
 when the positions of maximum thick- 
 ness are difterent; some surfaces are 
 most efficient at one angle, others at other 
 angles. The shape of the edge also makes 
 a difference, so that thousands of com- 
 binations are possible in so simple a 
 thing as a wing. 
 
 We had taken up aeronautics merely 
 as a sport. We reluctantly entered upon 
 the scientific side of it. But we soon 
 
THE 
 
 EARLY 
 
 HISTORY 
 
 O F 
 
 THE 
 
 AIRPLANE 
 
 found the work so fascinating that we 
 were drawn into it deeper and deeper. 
 Two testing machines were built, which 
 we believed would avoid the errors to 
 which the measurements of others had 
 been subject. After making preliminary 
 measurements on a great number of dif- 
 ferent-shaped surfaces, to secure a gen- 
 eral understanding of the subject, we be- 
 gan systematic measurements of stan- 
 dard surfaces, so varied in design as to 
 bring out the underlying causes of dif- 
 ferences noted in their pressures. Meas- 
 urements were tabulated on nearly 50 of 
 these at all angles from zero to 45 de- 
 grees at intervals of 2i/2 degrees. Meas- 
 urements were also secured showing the 
 effects on each other when surfaces are 
 superposed, or when they follow one an- 
 other. 
 
 Some strange results were obtained. 
 One surface, with a heavy roll at the 
 front edge, showed the same lift for all 
 angles from 7I/2 to 45 degrees. A square 
 plane, contrary to the measurements of 
 all our predecessors, gave a greater pres- 
 sure at 30 degrees than at 45 degrees. 
 This seemed so anomalous that we were 
 almost ready to doubt our own measure- 
 ments, when a simple test was suggested. 
 A weather-vane, with two planes attached 
 to the pointer at an angle of 80 degrees 
 with each other, was made. According 
 to our tables, such a vane would be in 
 unstable equilibrium when pointing di- 
 rectly into the wind; for if by chance the 
 wind should happen to strike one plane 
 at 39 degrees and the other at 41 degrees, 
 the plane with the smaller angle would 
 have the greater pressure, and the pointer 
 would be turned still farther out of the 
 course of the wind until the two vanes 
 again secured equal pressures, which 
 would be at approximately 30 and 50 de- 
 grees. But the vane performed in this 
 very manner. Further corroboration of 
 the tables was obtained in experiments 
 
 with the new glider at Kill Devil Hill the 
 next season. 
 
 In September and October, 1902, near- 
 ly 1,000 gliding flights were made, sev- 
 eral of whicli covered distances of over 
 600 feet. Some, made against a wind of 
 36 miles an hour, gave proof of the ef-^ 
 fectiveness of the devices for control. 
 With this machine, in the autumn of 
 1903, we made a number of flights in 
 which we remained in the air for over a 
 minute, often soaring for a considerable 
 time in one spot, without any descent at 
 all. Little wonder that our unscientific 
 assistant should think the only thing 
 needed to keep it indefinitely in the air 
 would be a coat of feathers to make it 
 light! 
 
 With accurate data for making calcu- 
 lations, and a system of balance effective 
 in winds as well as in calms, we were 
 now in a position, we thought, to build a 
 successful power-flyer. The first designs 
 provided for a total weight of 600 lbs., in- 
 cluding the operator and an eight horse- 
 power motor. But, upon completion, the 
 motor gave more power than had been 
 estimated, and this allowed 150 lbs. to be 
 added for strengthening the wings and 
 other parts. , 
 
 Our tables made the designing of the 
 wings an easy matter, and as screw- 
 propellers are simply wings traveling in 
 a spiral course, we anticipated no trouble 
 from this source. W^e had thought of 
 getting the theory of the screw-propeller 
 from the marine engineers, and then, by 
 applying our tables of air-pressures to 
 their formulas, of designing air-propel-y 
 lers suitable for our purpose. But so far 
 as we could learn, the marine engineers 
 possessed only empirical formulas, and 
 the exact action of the screw-propeller, 
 after a century of use, was still very ob- 
 scure. As we were not in a position to 
 undertake a long series of practical ex- 
 periments to discover a propeller suitable 
 
THE 
 
 EARLY 
 
 HISTORY 
 
 O F 
 
 THE 
 
 AIRPLANE 
 
 for our machine, it seemed necessary to 
 obtain such a thorough understanding 
 of the theory of its reactions as would 
 enable us to design them from calcula- 
 tions alone. What at first seemed a prob- 
 lem became more complex the longer we 
 studied it. With the machine moving 
 forward, the air flying backward, the 
 propellers turning sidewise, and nothing 
 standing still, it seemed impossible to find 
 a starting-point from which to trace the 
 various simultaneous reactions. Con- 
 templation of it was confusing. After 
 long arguments we often found our- 
 selves in the ludicrous position of each 
 having been converted to the other's side, 
 with no more agreement than when the 
 discussion began. 
 
 It was not till several months had 
 passed, and every phase of the problem 
 had been thrashed over and over, that 
 the various reactions began to untangle 
 themselves. When once a clear under- 
 standing had been obtained there was no 
 difficulty in designing suitable propellers, 
 with proper diameter, pitch, and area of 
 blade, to meet the requirements of the 
 flyer. High eflQciency in a screw-propel- 
 ler is not dependent upon any particular 
 or peculiar shape; and there is no such 
 thing as a "best" screw. A propeller giv- 
 ing a high dynamic efficiency when used 
 upon one machine may be almost worth- 
 
 less when used upon another. The 
 propeller should in every case be 
 designed to meet the particular condi- 
 tions of the machine to which it is to be 
 applied. Our first propellers, built en- . 
 tirely from calculation, gave in useful ^ 
 work 66 per cent, of the power expended. 
 This was about one-third more than had 
 been secured by Maxim or Langley. 
 
 The first flights with the power ma- 
 chine were made on December 17, 1903. 
 Only five persons besides ourselves were 
 present. These were Messrs. John T. 
 Daniels, W. S. Dough, and A. D. Ether- 
 idge, of the Kill Devil Life-Saving Sta- 
 tion; Mr. W. C. Brinkley, of Manteo; and 
 Mr. John Ward, of Naghead. Although 
 a general invitation had been extended 
 to the people living within five or six 
 miles, not many were willing to face the 
 rigors of a cold December wind in order 
 to see, as they no doubt thought, another 
 flying machine not fly. The first flight 
 lasted only 12 seconds, a flight very mod- 
 est compared with that of birds, but it 
 was, nevertheless, the first in the history 
 of the world in which a machine carry- 
 ing a man had raised itself by its own 
 power into the air in free flight, had 
 saileed forward on a level course without 
 reduction of speed, and had finally land- 
 ed without being wrecked. The second 
 and third flights were a little longer, and 
 the fourth lasted 59 seconds, covering a 
 distance of 852 feet over the ground 
 against a 20-mile wind. 
 
 After the last flight the machine was 
 carried back to camp and set down in 
 what was thought to be a safe place. But 
 a few minutes later, while we were en- 
 gaged in conversation about the flights, a 
 sudden gust of wind struck the machine, 
 and started to turn it over. All made a 
 rush to stop it, but we were too late. 
 Mr. Daniels, a giant in stature and 
 strength, was lifted off his feet, and fall- 
 ing inside, between the surfaces, was 
 
THE 
 
 EARLY 
 
 HISTORY 
 
 O F 
 
 THE 
 
 AIRPLANE 
 
 shaken about like a rattle in a box as the 
 machine rolled over and over. He finally 
 fell out upon the sand with nothing worse 
 than painful bruises, but the damage to 
 the machine caused a discontinuance of 
 experiments. 
 
 In the spring of 1904, through the 
 kindness of Mr. Torrence Huffman, of 
 Daj'ton, Ohio, we were permitted to erect 
 a shed, and to continue experiments, on 
 what is known as the Huffman Prairie, 
 at Simms Station, eight miles east of Day- 
 ton. The new machine was heavier and 
 stronger, but similar to the one flown at 
 Kill Devil Hill. When it was ready for 
 its first trial every newspaper in Dayton 
 was notified, and about a dozen represen- 
 tatives of the Press were present. Our 
 only request was that no pictures be 
 taken, and that the reports be unsensa- 
 tional, so as not to attract crowds to our 
 experiment grounds. There were prob- 
 ably 50 persons altogether on the ground. 
 When preparations had been completed 
 a wind of only three or four miles was 
 blowing — insufficient for starting on so 
 short a track — but since many had come 
 a long way to see the machine in action, 
 an attempt was made. To add to the 
 other difficulty, the engine refused to 
 work properly. The machine, after run- 
 ning the length of the track, slid off the 
 end without rising into the air at all. 
 Several of the newspaper men returned 
 the next day, but were again disappoint- 
 ed. The engine performed badly, and 
 after a glide of only 60 feet, the machine 
 came to the ground. Further trial was 
 postponed till the motor could be put in 
 better running condition. The reporters 
 had now, no doubt, lost confidence in the 
 machine, though their reports, in kind- 
 ness, concealed it. Later, when they 
 heard that we were making flights of sev- 
 eral minutes' duration, knowing that 
 longer flights had been made with air- 
 
 ships, and not knowing any essential dif- 
 ference between airships and flying ma- 
 chines, they were but little interested. 
 
 We had not been flying long in 1904 
 before we found that the problem of 
 equilibrium had not as yet been entirely 
 solved. Sometimes, in making a circle, 
 the machine would turn over sidewise 
 despite anything the operator could do, 
 although, under the same conditions in 
 ordinary straight flight, it could have 
 been righted in an instant. In one flight, 
 in 1905, while circling around a honey 
 locust tree at a height of about 50 feet, 
 the machine suddenly began to turn up 
 on one wing, and took a course toward 
 the tree. The operator, not relishing the 
 idea of landing in a thorn-tree, attempted 
 to reach the ground. The left wing, 
 however, struck the tree at a height of 10 
 or 12 feet from the ground and carried 
 away several branches; but the flight, 
 which had already covered a distance of 
 six miles, was continued to the starting- 
 point. 
 
 The causes of these troubles — too tech- 
 nical for explanation here — ^were not en- 
 tirely overcome till the end of Septem- 
 ber, 1905. The flights then rapidly in- 
 creased in length, till experiments were 
 discontinued after October 5, on account 
 of the number of people attracted to the 
 field. Although made on a ground open 
 on every side, and bordered on two sides 
 by much-traveled thoroughfares, with 
 electric cars passing every hour, and seen 
 by aU the people living in the neighbor- 
 hood for miles around, and by several 
 hundred others, yet these flights have 
 been made by some newspapers the sub- 
 ject of a great "mystery." 
 
 A practical flyer having been finally 
 realized, we spent the years 1906 and 
 1907 in constructing new machines and 
 in business negotiations. It was not till 
 May of this year that experiments (dis- 
 continued in October, 1905) were re- 
 
THE 
 
 EARLY 
 
 HISTORY 
 
 O F 
 
 THE 
 
 AIRPLANE 
 
 sumed at Kill Devil Hill, North Carolina. 
 The recent flights were made to test the 
 ability of our machine to meet the re- 
 quirements of a contract with the United 
 States Government to furnish a flyer 
 capable of carrying two men and sutli- 
 cient fuel supplies for a flight of 125 
 miles, with a speed of 40 miles an hour. 
 The machine used in these tests was the 
 same one with which the flights were 
 made at Simms Station in 1905, though 
 several changes had been made to meet 
 present requirements. The operator as- 
 sumed a sitting position, instead of lying 
 prone, as in 1905, and a seat was added 
 for a passenger. A larger motor was in- 
 stalled, and radiators and gasoline reser- 
 voirs of larger capacity replaced those 
 previously used. No attempt was made 
 to make high or long flights. 
 
 In order to show the general reader the 
 way in which the machine operates, let 
 us fancy ourselves ready for the start. 
 The machine is placed upon a single-rail 
 track facing the wind, and is securely 
 fastened with a cable. The engine is put 
 in motion, and the propellers in the rear 
 whir. You take j^our seat at the center 
 of the machine beside the operator. He 
 slips the cable, and you shoot forward. 
 An assistant who has been holding the 
 machine in balance on the rail starts for- 
 ward with you, but before you have gone 
 50 feet the speed is too great for him, and 
 he lets go. Before reaching the end of 
 the track the operator moves the front 
 rudder, and the machine lifts from the 
 rail like a kite supported by the pressure 
 of the air underneath it. The ground 
 under you is at first a perfect blur, but as 
 you rise the objects become clearer. At 
 a height of 100 feet you feel hardly any 
 motion at all, except for the wind which 
 strikes your face. If you did not take 
 the precaution to fasten your hat before 
 
 starting, you have probably lost it by 
 this time. The operator moves a lever: 
 the right wing rises, and the machine 
 swings about to the left. You make a 
 very short turn, yet you do not feel the 
 sensation of being thrown from your 
 seat, so often experienced in automo- 
 bile and railway travel. You find your- 
 self facing toward the point from which 
 you started. The objects on the ground 
 now seem to be moving at much higher 
 speed, though you perceive no change in 
 the pressure of the wind on your face. 
 You know then that you are traveling 
 with the wind. When you near the start- 
 ing-point the operator stops the motor 
 while still high in the air. The machine 
 coasts down at an oblique angle to the 
 ground, and after sliding 50 or 100 feet, 
 comes to rest. Although the machine 
 often lands when traveling at a speed of 
 a mile a minute, you feel no shock what- 
 ever, and cannot, in fact, tell the exact 
 moment at which it first touched the 
 ground. The motor close beside you 
 kept up an almost deafening roar during 
 the whole flight, yet in your excitement 
 you did not notice it till it stopped! 
 
 Our experiments have been conducted 
 entirelj' at our own expense. In the be- 
 ginning we had no thought of recovering 
 what we were expending, which was not 
 great, and was limited to what we could 
 afford in recreation. Later, when a suc- 
 cessful flight had been made with a mo- 
 tor, we gave up the business in which we 
 were engaged, to devote our entire time 
 and capital to the development of a ma- 
 chine for practical uses. As soon as our 
 condition is such that constant attention 
 to business is not required, we expect to 
 prepare for publication the results of our 
 laboratory experiments, which alone 
 made an early solution of the flying 
 problem possible. 
 
liou? IPe Made the First Flight 
 
 By OrvilU Wright 
 
 .HE flights of the 1902 glider had 
 demonstrated the efficiency of 
 our system o f maintaining 
 equihbrium, and also the accu- 
 racy of the laboratory work upon which 
 the design of the glider was based. We 
 then felt that we were prepared to calcu- 
 late in advance the performance of ma- 
 chines with a degree of accuracy that had 
 never been possible with the data and 
 tables possessed by our predecessors. 
 Before leaving camp in 1902 we were al- 
 ready at work on the general design of a 
 new machine which we proposed to 
 propel with a motor. 
 
 Immediately upon our return to Day- 
 ton, we wrote to a number of automobile 
 and motor builders, stating the purpose 
 for which we desired a motor, and ask- 
 ing whether they could furnish one that 
 would develop eight brake-horsepower, 
 with a weight complete not exceeding 200 
 pounds. Most of the companies an- 
 swered that they were too busy with their 
 regular business to undertake the build- 
 ing of such a motor for us; but one com- 
 pany replied that they had motors rated 
 at 8 horse-power, according to the 
 French system of ratings, which weighed 
 only 135 pounds, and that if we thought 
 this motor would develop enough power 
 for our purpose they would be glad to 
 sell us one. After an examination of the 
 particulars of this motor, from which 
 we learned that it had but a single cylin- 
 der of 4-inch bore and 5-inch stroke, we 
 were afraid it was much over-rated. 
 Unless the motor would develop a full 8 
 brake-horsepower, it would be useless 
 for our purpose. 
 
 Finally we decided to undertake the 
 building of the motor ourselves. We es- 
 
 timated that we could make one of four 
 cylinders with 4-inch bore and 4-inch 
 stroke, weighing not over two hundred 
 pounds, including all accessories. Our 
 only experience up to that time in the 
 building of gasoline motors had been in 
 the construction of an air-cooled motor, 
 5-inch bore and 7-incli stroke, which was 
 used to run the machinery of our small 
 workshop. To be certain that four cylin- 
 ders of the size we had adopted (4" x 4") 
 would develop the necessary 8 horse- 
 power, we first fitted them in a tempor- 
 ary frame of simple and cheap construc- 
 tion. In just six weeks from the time the 
 design was started, we had the motor on 
 the block testing its power. The ability 
 to do this so quickly was largely due to 
 the enthusiastic and elTicient services of 
 Mr. C. E. Taylor, who did all the machine 
 work in our shop for the first as well as 
 the succeeding experimental machines. 
 There was no provision for lubricating 
 either cylinders or bearings while this 
 motor was running. For that reason it 
 was not possible to run it more than a 
 minute or two at a time. In these short 
 tests the motor developed about nine 
 horse-power. We were then satisfied 
 that, with proper lubrication and better 
 adjustments, a little more power could 
 
THE 
 
 EARLY 
 
 HISTORY 
 
 O P 
 
 THE 
 
 AIRPLANE 
 
 be expected. The completion of the mo- 
 tor according to drawing was, therefore, 
 proceeded with at once. 
 
 While Mr. Taylor was engaged with 
 this work, Wilbur and I were busy in 
 completing the design of the machine 
 itself. The preliminary tests of the mo- 
 tor having convinced us that more than 
 8 horse-power would be secured, we felt 
 free to add enough weight to build a 
 more substantial machine than we had 
 
 originally contemplated. 
 
 ****** 
 
 For two reasons we decided to use two 
 propellers. In the first place we could, 
 by the use of two propellers, secure a re- 
 action against a greater quantity of air, 
 and at the same time use a larger pitch 
 angle than was possible with one propel- 
 ler; and in the second place by having the 
 propellers turn in opposite direction, the 
 gyroscopic action of one would neutral- 
 ize that of the other. The method we 
 adopted of driving the propellers in op- 
 posite directions by means of chains is 
 now too well known to need description 
 here. We decided to place the motor to 
 one side of the man, so that in case of a 
 plunge headfirst, the motor could not fall 
 upon him. In our gliding experiments 
 w^e had had a numbei- of experiences in 
 which we had landed upon one wing, but 
 the crushing of the wing had absorbed 
 the shock, so that we were not uneasy 
 about the motor in case of a landing of 
 that kind. To provide against the ma- 
 chine rolling over forward in landing, we 
 designed skids like sled runners, extend- 
 ing out in front of the main surfaces. 
 Otherwise the general construction and 
 operation of the machine was to be simi- 
 lar to that of the 1902 glider. 
 
 When the motor was completed and 
 tested, we found that it would develop 16 
 horse-power for a few seconds, but that 
 the power rapidlj^ dropped till, at the end 
 of a minute, it was only 12 horse-power. 
 
 Ignorant of what a motor of this size 
 ought to develop, we were greatly pleased 
 with its performance. More experience 
 showed us that we did not get one-half 
 of the power we should have had. 
 
 With 12 horse-power at our command, 
 we considered that we could pennit the 
 weight of the machine with operator to 
 rise to 750 or 800 pounds, and still have 
 as much surplus power as we had orig- 
 inally allowed for in the first estimate of 
 550 pounds. 
 
 Before leaving for our camp at Kitty 
 Hawk we tested the chain drive for tlie 
 propellers in our shop at Dayton, and 
 found it satisfactory. We found, how- 
 ever, that our first propeller shafts, 
 which were constructed of heavy gauge 
 steel tubing, were not strong enough to 
 stand the shocks received from a gaso- 
 line motor with light fly wheel, although 
 they would have been able to ti'ansmit 
 three or four times the power uniformly 
 applied. We therefore built a new set of 
 shafts of heavier tubing, which we tested 
 and thought to be abundantly strong. 
 
 We left Dayton, September 23, and ar- 
 rived at our camp at Kill Devil Hill on 
 Friday, the 25th. We found there pro- 
 visions and tools, which had been ship- 
 ped by freight several weeks in advance. 
 The building, erected in 1901 and en- 
 larged in 1902, was found to have been 
 blown by a stonn from its foundation 
 posts a few months previously. While 
 we were awaiting the arrival of the ship- 
 ment of machinery and parts from Day- 
 ton, we were busy putting the old build- 
 ing in repair, and erecting a new build- 
 ing to serve as a workshop for assemb- 
 ling and housing the new machine. 
 
 Just as the building was being com- 
 pleted, the parts and material for the ma- 
 chines arrived simultaneously with one 
 of the worst storms that had visited Kitty 
 Hawk in years. The storm came on sud- 
 denly, blowing 30 to 40 miles an hour. 
 
 w 
 
THE 
 
 EARLY 
 
 HISTORY 
 
 O F 
 
 THE 
 
 AIRPLANE 
 
 It increased during the night, and the 
 next day was blowing over 75 miles an 
 hour. In order to save the tar-paper 
 roof, we decided it would be necessary 
 to get out in this wind and nail down 
 more securely certain parts that were 
 especially exposed. When I ascended 
 the ladder and reached the edge of the 
 roof, the wind caught under my large 
 coat, blew it up around my head and 
 bound my arms till I was perfectly help- 
 less. Wilbur came to mj' assistance and 
 held down my coat while I tried to drive 
 the nails. But the wind was so strong I 
 could not guide the hammer and succeed- 
 ed in striking my fingers as often as the 
 nails. 
 
 The next three weeks were spent in 
 setting the motor-machine together. On 
 days with more favorable winds we 
 gained additional experience in handling 
 a flyer bj^ gliding with the 1902 machine, 
 which we had found in pretty fair condi- 
 tion in the old building, where we had 
 left it the year before. 
 
 Mr. Chanute and Dr. Spratt, who had 
 been guests in our camp in 1901 and 
 1902, spent some time with us, but neith- 
 er one was able to remain to see the test 
 of the motor-machine, on account of the 
 delays caused by trouble which devel- 
 oped in the propeller shafts. 
 
 While Mr. Chanute was with us, a good 
 deal of time was spent in discussion of 
 the mathematical calculations upon 
 which we had based our machine. He 
 informed us that, in designing machin- 
 ery, about 20 per cent, was usually al- 
 lowed for the loss in the transmission of 
 powej*. As we had allowed only 5 per 
 cent., a figure we had arrived at by some 
 crude measurements of the friction of 
 one of tlie cliains when carrying only a 
 very light load, we were much alanned. 
 More than the whole surplus in power al- 
 lowed in our calculations would, accord- 
 ing to Mr. Ghanute's estimate, be con- 
 
 sumed in friction in the driving chains. 
 After Mr. Ghanute's departure, we sus- 
 pended one of the drive chains over a 
 sprocket, hanging bags of sand on either 
 side of the sprocket of a weight approx- 
 imately equal to the pull that would be 
 exerted on the chains when driving the 
 propellers. By measuring the extra 
 amount of weight needed on one side to 
 lift the weight on the other, we calcu- 
 lated the loss in transmission. This indi- 
 cated that the loss of power from this 
 source would be only 5 per cent., as we 
 originally estimated. But while we 
 could see no serious error in this method 
 of determining the loss, we were very 
 uneasy until we had a chance to run the 
 propellers with the motor to see whether 
 we could get the estimated number of 
 turns. 
 
 The first run of the motor on the ma- 
 chine developed a flaw in one of the 
 propeller shafts which had not been dis- 
 covered in the test at Dayton. The shafts 
 were sent at once to Daj'ton for repair, 
 and were not received again until No- 
 vember 20, having been gone two weeks. 
 We immediately put them in the machine 
 and made another test. A new trouble 
 developed. The sprockets which were 
 screwed on the shafts, and locked with 
 nuts of opposite thread, persisted in com- 
 ing loose. After many futile attempts to 
 get them fast, we had to give it up for 
 that day, and went to bed much discour- 
 aged. However, after a night's rest, we 
 got up the next morning in better spirits 
 and resolved to try again. 
 
 While in the bicycle business we had 
 become well acquainted with the use of 
 hard tire cement for fastening tires on 
 the rims. We had once used it success- 
 fully in repairing a stop watch after sev- 
 eral watchsmiths had told us it could not 
 be repaired. If tire cement was good for 
 fastening the hands on a stop watch, why- 
 should it not be good for fastening the 
 
 u 
 
THE 
 
 EARLY 
 
 HISTORY 
 
 O F 
 
 THE 
 
 AIRPLANE 
 
 sprockets on the propeller shaft of a fly- 
 ing machine? We decided to try it. We 
 heated the shafts and sprockets, melted 
 cement into the threads, and screwed 
 them together again. This trouble was 
 over. The sprockets stayed fast. 
 
 Just as the machine was ready for test 
 bad weather set in. It had been disagree- 
 ably cold for several weeks, so cold that 
 we could scarcely work on the machine 
 for some days. But now we began to 
 have rain and snow, and a wind of 25 to 
 30 miles blew for several days from the 
 north. While we were being delayed by 
 the weather we arranged a mechanism to 
 measure automatically the duration of a 
 flight from the time the machine started 
 to move forward to the time it stopped, 
 the distance traveled through the air in 
 that time, and the number of revolutions 
 made by the motor and propeller. A 
 stop watch took the time; an anemo- 
 meter measured the air traveled 
 through; and a counter took the number 
 of revolutions made by the propellers. 
 The watch anemometer and revolution 
 counter were all automatically started 
 and stopped simultaneously. From data 
 thus obtained we expected to prove or 
 disprove the accuracy of our propeller 
 calculations. 
 
 On November 28, while giving the mo- 
 tor a run indoors, we thought we again 
 saw something wrong with one of the 
 propeller shafts. On stopping the motor 
 we discovered that one of the tubular 
 shafts had cracked! 
 
 Immediate preparation was made for 
 returning to Dayton to build another set 
 of shafts. We decided to abandon the 
 
 use of tubes, as they did not afford 
 enough spring to take up the shocks of 
 premature or missed explosions of the 
 motor. Solid tool-steel shafts of smaller 
 diameter tJian the tubes previouslj' used 
 were decided upon. These would allow 
 a certain amount of spring. The tubular 
 shafts were many times stronger than 
 would have been necessary to transmit 
 the power of our motor if the strains up- 
 on them had been unifonn. But the 
 large hollow shafts had no spring in them 
 to absorb the unequal strains. 
 
 Wilbur remained in camp while I went 
 to get the new shafts. I did not get back 
 to camp again till Friday, the 11th of De- 
 cember. Saturday afternoon the ma- 
 chine was again ready for trial, but the 
 wind was so light a start could not have 
 been made from level ground with the 
 run of only sixty feet permitted by our 
 monorail track. Nor was there enough 
 time before dark to take the machine to 
 one of the hills, where, by placing the 
 track on a steep incline, sufficient speed 
 could be secured for starting in calm air. 
 
 Monday, December 14, was a beautiful 
 day, but there was not enough wind to 
 enable a start to be made from the level 
 ground about camp. We therefore de- 
 cided to attempt a flight from the side of 
 the big Kill Devil Hill. We had arranged 
 with the members of the Kill Devil Hill 
 Life Saving Station, which was located a 
 little over a mile from our camp, to in- 
 form them when we were ready to make 
 the first trial of the machine. We were 
 soon joined by J. T. Daniels, Robert 
 Westcott, Thomas Beachem, W. S. Dough 
 and Uncle Benny O'Neal, of the station, 
 who helped us get the machine to the hill, 
 a quarter mile away. We laid the track 
 150 feet up the side of the hill on a 9-de- 
 gree slope. With the slope of the track, 
 the thrust of the propellers and the ma- 
 chine starting directly into the wind, we 
 did not anticipate any ti'ouble in getting 
 
 i« 
 
THE 
 
 EARLY 
 
 HISTORY 
 
 O F 
 
 THE 
 
 AIRPLANE 
 
 up flying speed on the 60-foot monorail 
 track. But we did not feel certain the 
 operator could keep the machine bal- 
 anced on the track. 
 
 When the machine had been fastened 
 with a wire to the track, so that it could 
 not start until released by the operator, 
 and the motor had been run to make sure 
 that it was in condition, we tossed up a 
 coin to decide who should have the first 
 trial. Wilbur won. I took a position at 
 one of the wings, intending to help bal- 
 ance the machine as it ran down the 
 track. But when the restraining wire 
 was slipped, the machine started off so 
 quickly I could stay with it only a few 
 feet. After a 35 to 40-foot run it lifted 
 from the rail. But it was allowed to turn 
 up too much. It climbed a few feet, 
 stalled, ^nd then settled to the ground 
 near the foot of the hill, 105 feet below. 
 My stop watch showed that it had been 
 in the air just 3l^ seconds. In landing 
 the left wing touched first. The machine 
 swung around, dug the skids into the 
 sand and broke one of them. Several 
 other parts were also broken, but the 
 damage to the machine was not serious. 
 While the test had shown nothing as to 
 whether the power of the motor was suf- 
 ficient to keep the machine up, since the 
 landing was made many feet below the 
 starting point, the experiment had dem- 
 onstrated that the method adopted for 
 launching the machine was a safe and 
 practical one. On the whole, we were 
 much pleased. 
 
 Two days were consumed in making 
 repairs, and the machine was not ready 
 again till late in the afternoon of the 
 16th. While we had it out on the track 
 in front of the building, making the final 
 adjustments, a stranger came along. 
 After looking at the machine a few sec- 
 onds he inquired what it was. When we 
 told him it was a flying machine he asked 
 whether we intended to fly it. We said 
 
 we did, as soon as we had a suitable wind. 
 He looked at it several minutes longer 
 and then, wishing to be courteous, re- 
 marked that it looked as if it would fly, 
 if it had a "suitable wind." We were 
 much amused, for, no doubt, he had in 
 mind the recent 75-mile gale when he re- 
 peated our words, "a suitable wind!" 
 
 During the night of December 16, 
 1903, a strong cold wind blew from the 
 north. When we arose on the morning 
 of the 17th, the puddles of water, which 
 had been standing about camp since the 
 recent rains, were covered with ice. The 
 wind had a velocity of 10 to 12 meters per 
 second (22 to 27 miles an hour). We 
 thought it would die down before long, 
 and so remained indoors the early part 
 of the morning. But when ten o'clock 
 arrived, and the wind was as brisk as 
 ever, we decided that we had better get 
 the machine out and attempt a flight. 
 We hung out the signal for the men of 
 the life saving station. We thought that 
 by facing the tlyer into a strong wind, 
 there ought to be no trouble in launch- 
 ing it from the level ground about camp. 
 We realized the difficulties of flying in 
 so high a wind, but estimated that the 
 added dangers in flight would be partly 
 compensated for by the slower speed in 
 landing. 
 
 We laid the track on a smooth stretch 
 of ground about one hundred feet north 
 of the new building. The biting cold 
 wind made work difficult, and we had to 
 warm up frequently in our living room, 
 where we had a good fire in an impro- 
 vised stove made of a large carbide can. 
 By the time afl was ready, J. T. Daniels, 
 W. S. Dough and A. D. Etheridge, mem- 
 bers of the Kill Devil Life Saving Station; 
 W. C. Brinkley, of Manleo, and Johnny 
 Moore, a boy from Nag's Head, had ar- 
 rived. 
 
 We had a "Richards" hand anemo- 
 meter with which we measured the ve- 
 
 » 
 
THE 
 
 EARLY 
 
 HISTORY 
 
 O F 
 
 THE 
 
 AIRPLANE 
 
 locity of the wind. , Measurements made 
 just before starting the first flight showed 
 velocities of 11 to 12 meters per second, 
 or 24 to 27 miles per hour. Measure- 
 ments made just before the last flight 
 gave between 9 and 10 meters per sec- 
 ond. One made just after showed a little 
 over 8 meters. The records of the Gov- 
 ernment Weather Bureau at Kitty Hawk 
 gave the velocity of the wind between the 
 hours of 10:30 and 12 o'clock, the time 
 during which the four flights were made, 
 as averaging 27 miles at the time of the 
 first flight and 24 miles at the time of the 
 last. 
 
 ***** -0 
 
 Wilbur, having used his turn in the 
 unsuccessful attempt on the 14th, the 
 right to the first trial now belonged to 
 me. After running the motor a few min- 
 utes to heat it up, I released the wire that 
 held the machine to the track, and the 
 machine started forward into the wind. 
 Wilbur ran at the side of the machine, 
 holding the wing to balance it on the 
 track. Unlike the start on the 14th, made 
 in a calm, the machine, facing a 27-mile 
 wind, started verj' slowly. Wilbur was 
 able to stay with it till it lifted from the 
 track after a forty-foot run. One of the 
 life saving men snapped the camera for 
 us, taking a picture just as the machine 
 had reached the end of the track and had 
 risen to a height of about two feet. The 
 slow forward speed of the machine over 
 the ground is clearly shown in the pic- 
 lure by Wilbur's attitude. He stayed 
 along beside the machine witliout any 
 effort. 
 
 The course of the flight up and down 
 was exceedingly erratic, partly due to the 
 irregularity of the air, and partly to lack 
 of experience in handUng this machine. 
 The control of the front rudder was difQ- 
 cult on account of its being balanced too 
 near the center. This gave it a tendency 
 to turn itself when started; so that it 
 
 turned too far on one side and then too 
 far on the other. As a result the machine 
 would rise suddenly to about ten feet, 
 and then as suddenly dart for the ground. 
 A sudden dart when a little over a hun- 
 dred feet from the end of the track, or a 
 little over 120 feet from the point at 
 which it rose into the air, ended the flight. 
 As the velocity of the wind was over 35 
 feet per second and the speed of the ma- 
 chine against this wind ten feet per sec- 
 ond, the speed of the machine relative to 
 the air was over 45 feet per second, and 
 the length of the flight was equivalent to 
 a flight of 540 feet made in calm air. 
 This flight lasted only 12 seconds, but it 
 was nevertheless the first in the history 
 of the world in which a machine carrying 
 a man had raised itself by its own power 
 into the air in full flight, had sailed for- 
 ward without reduction of speed, and 
 had finally landed at a point as high as 
 that from which it started. 
 
 ****** 
 
 At twenty minutes after eleven Wilbur 
 tarted on the second flight. The course 
 of this flight was much like that of the 
 first, very much up and down. The 
 speed over the ground was somewhat 
 faster than that of the first flight, due to 
 the lesser wind. The duration of the 
 flight was less than a second longer than 
 the first, but the distance covered was 
 about seventy-five feet greater. 
 
 Twenty minutes later the third flight 
 started. This one was steadier than the 
 first one an hour before. I was proceed- 
 ing along pretty well when a sudden gust 
 from the right lifted the machine up 
 twelve to fifteen feet and turned it up 
 sidewise in an alarming manner. It be- 
 gan sliding ofi" to the left. I warped the 
 wings to try to recover the lateral bal- 
 ance and at the same time pointed the 
 machine down to reach the ground as 
 quickly as possible. The lateral control 
 was more effective than I had imagined 
 
 14 
 
THE 
 
 EARLY 
 
 HISTORY 
 
 O F 
 
 THE 
 
 AIRPLANE 
 
 and before I reached the ground the right 
 wing was lower than the left and struck 
 first. The time of this flight was fifteen 
 seconds and the distance over the ground 
 a little over 200 feet. 
 
 Wilbur started the fourth and last 
 flight at just 12 o'clock. The first few 
 hundred feet were up and down as be- 
 fore, but by the time three hundred feet 
 had been covered, the machine was un- 
 der much better control. The course for 
 the next four or five hundred feet had 
 but little undulation. However, when 
 out about eight hundred feet the machine 
 began pitching again, and, in one of its 
 starts downward, struck the ground. 
 The distance over the ground was meas- 
 ured and found to be 852 feet; the time 
 of the flight 59 seconds. The frame sup- 
 porting the front rudder was badly 
 broken, but the main part of the ma- 
 chine was not injured at all. We esti- 
 mated that the machine could be put in 
 
 condition for flight again in a day or two. 
 While we were standing about discuss- 
 ing this last flight, a sudden strong gust 
 of wind struck the machine and began 
 to turn it over. Everybody made a rush 
 for it. Wilbur, who was at one end, 
 seized it in front, Mr. Daniels and I, who 
 were behind, tried to stop it behind, tried 
 to stop it by holding to the rear uprights. 
 All our efforts were vain. The machine 
 rolled over and over. Daniels, who had 
 retained his grip, was carried along with 
 it, and was thrown about head over heels 
 inside of the machine. Fortunately he 
 was not seriously injured, though badly 
 bruised in falling about against the mo- 
 tor, chain guides, etc. The ribs in the 
 surfaces of the machine were broken, the 
 motor injured and the chain guides badly 
 bent, so that all possibility of further 
 flights with it for that year were at an 
 end. 
 
 u 
 
Some Aeronauticdl Experiments 
 
 By Wilbur Wright 
 
 HE difficulties which obstruct 
 the pathway to success in fly- 
 ing machine construction are 
 of three general classes: (1) 
 Those which relate to the construction of 
 the sustaining wings. (2) Those which 
 relate to the generation and application 
 of the power required to drive the ma- 
 chine through the air. (3) Those relat- 
 ing to the balancing and steering of the 
 machine after it is actually in flight. Of 
 these difficulties two are already to a cer- 
 tain extent solved. Men already know 
 how to construct wings or aeroplanes 
 which, when driven through air at suffi- 
 cient speed, will not only sustain the 
 weight of the wings themselves, but also 
 that of the engine, and of the engineer as 
 well. Men also know how to build en- 
 gines and screws of sufficient lightness 
 and power to drive these planes at sus- 
 taining speed. As long ago as 1893 a ma- 
 chine weighing 8,000 lbs. demonstrated 
 its power both to lift itself from the 
 ground and to maintain a speed of from 
 30 to 40 miles per hour; but it came to 
 grief in an accidental free flight, owing 
 to the inability of the operators to bal- 
 ance and steer it properly. This inability 
 to balance and steer still confronts stu- 
 dents of the flying problem, although 
 nearly ten years have passed. When this 
 one feature has been worked out the age 
 of flying machines will have arrived, for 
 all other difficulties are of minor im- 
 portance. 
 
 The person who merely watches the 
 flight of a bird gathers the impression 
 that the bird has nothing to think of but 
 the flapping of its wings. As a matter of 
 fact, this is a very small part of its men- 
 tal labour. Even to mention all the 
 things the bird must constantly keep in 
 
 mind in order to fly securely through the 
 ail' would take a very considerable trea- 
 tise. If I take a piece of paper, 
 and after placing it parallel with the 
 ground, quickly let it fall, it will not set- 
 tle steadily down as a staid, sensible piece 
 of paper ought to do, but it insists on con- 
 travening every recognized rule of de- 
 corum, turning over and darting hither 
 and thither in the most erratic manner, 
 much after the style of an untrained 
 horse. Yet this is the style of steed that 
 men must learn to manage before flying 
 can become an everyday sport. The bird 
 has learned this art of equilibrium, and 
 learned it so thoroughly that its skill is 
 not apparent to our sight. We only learn 
 to appreciate it when we try to imitate it. 
 Now, there are two ways of learning how 
 to ride a fractious horse: one is to get on 
 him and learn by actual practice how 
 each motion and trick may be best met; 
 the other is to sit on a fence and watch 
 the beast awhile, and then retire to the 
 house and at leisure figure out the best 
 way of overcoming his jumps and kicks. 
 The latter system is the safest; but the 
 former, on the whole, turns out the larger 
 porportion of good riders. It is very 
 much the same in learning to ride a flying 
 machine; if you are looking for perfect 
 safety you will do well to sit on a fence 
 and watch the birds; but if you really 
 wish to learn you must mount a machine 
 and become acquainted with its tricks 
 by actual trial. 
 
 ****** 
 
 My own active interest in aeronautical 
 problems dates back to the death of 
 Lilienthal in 1896. The brief notice of 
 his death which appeared in the tele- 
 graphic news at that time aroused a pas- 
 sive interest which had existed from my 
 
 i« 
 
THE 
 
 EARLY 
 
 HISTORY 
 
 O F 
 
 THE 
 
 AIRPLANE 
 
 childhood, and led me to take down from 
 the shelves of our home library a book 
 on "Animal Mechanism," by Prof. 
 Marey, which I had already read several 
 times. From this I was led to read more 
 modern works, and as my brother soon 
 became equally interested with myself, 
 we soon passed from the reading to the 
 thinking, and finally to the working 
 stage. It seemed to us that the main 
 reason why the problem had remained so 
 long unsolved was that no one had been 
 able to obtain any adequate practice. We 
 figured that Lilienthal in five years of 
 time had spent only about five hours in 
 actual gliding through the air. The won- 
 der was not that he had done so little, but 
 that he had accomplished so much. It 
 would not be considered at all safe for a 
 bicycle rider to attempt to ride through 
 a crowded city street after only five 
 hours' practice, spread out in bits of ten 
 seconds each over a period of five years; 
 yet Lilienthal with this brief practice was 
 remarkably successful in meeting the 
 fluctuations and eddies of wind gusts. 
 We thought that if some method could be 
 found by which it would be possible to 
 practice by the hour instead of by the 
 second there would be hope of advancing 
 the solution of a very difficult problem. 
 It seemed feasible to do this by building 
 a machine which would be sustained at 
 a speed of 18 miles per hour, and then 
 finding a locality where winds of this ve- 
 locity were common. With these condi- 
 tions a rope attached to the machine to 
 keep it from floating backward would 
 answer very nearly the same purpose as 
 a propeller driven by a motor, and it 
 would be possible to practice by the hour, 
 and without any serious danger, as it 
 would not be necessary to rise far from 
 the ground, and the machine would not 
 have any forward motion at all. We 
 found, according to the accepted tables of 
 air pressures on curved surfaces, that a 
 
 machine spreading 200 square feet of 
 wing surface would be sufficient for our 
 purpose, and that places could easily be 
 found along the Atlantic coast where 
 winds of 16 to 25 miles were not at aU 
 uncommon. When the winds were low 
 it was our plan to glide from the tops of 
 sand hills, and when they were sufficient- 
 ly strong to use a rope for our motor and 
 fly over one spot. Our next work was to 
 draw up the plan for a suitable machine. 
 After much study we finally concluded 
 that tails were a source of trouble rather 
 than of assistance, and therefore we de- 
 cided to dispense with them altogether. 
 It seemed reasonable that if the body of 
 the operator could be placed in a horizon- 
 tal position instead of the upright, as in 
 the machines of Lilienthal, Pitcher and 
 Chanute, the wind resistance could be 
 very materially reduced, since only one 
 square foot instead of five would be ex- 
 posed. As a full half-horse-power could 
 be saved by this change, we arranged to 
 try at least the horizontal position. Then 
 the method of control used by Lilienthal, 
 which consisted in shifting the body, did 
 not seem quite as quick or effective as the 
 case required; so, after long study, we 
 contrived a system consisting of two 
 large surfaces on the Chanute double- 
 deck plan, and a smaller surface placed 
 a short distance in front of the main sur- 
 faces in such a position that the action of 
 the wind upon it would counterbalance 
 the effect of the travel of the center of 
 pressure on the main surfaces. Thus 
 changes in the direction and velocity of 
 the wind would have little disturbing ef- 
 fect, and the operator would be required 
 to attend only to the steering of the ma- 
 chine, which was to be effected by curv- 
 ing the foi'ward surface up or down. 
 The lateral equilibrium and the steering 
 to right or left was to be attained by a 
 peculiar torsion of the main surfaces, 
 which was equivalent to presenting one 
 
 » 
 
THE 
 
 EARLY 
 
 HISTORY 
 
 O F 
 
 THE 
 
 AIRPLANE 
 
 end of the wings at a greater angle than 
 the other. In the main frame a few 
 changes were also made in the details of 
 construction and trussing employed by 
 Mr. Chanute. The most important of 
 these were: ( 1 ) The moving of the for- 
 ward main cross-piece of the frame to 
 the extreme front edge; (2) the encasing 
 in the cloth of all cross-pieces and ribs of 
 the surfaces; (3) a rearrangement of the 
 wires used in trussing the two surfaces 
 together, which rendered it possible to 
 tighten all the wires by simply shortening 
 two of them. 
 
 With these plans we proceeded in the 
 summer of 1900 to Kitty Hawk, North 
 Carolina, a little settlement located on 
 the strip of land that separates Albemarle 
 Sound from the Atlantic Ocean. Owing 
 to the impossibility of obtaining suitable 
 material for a 200-square-foot machine, 
 we were compelled to make it only 165 
 square feet in area, which, according to 
 the Lilienthal tables, would be supported 
 at an angle of three degrees in a wind of 
 about 21 miles per hour. On the very 
 day that the machine was completed the 
 wind blew from 25 to 30 miles per hour, 
 and we took it out for a trial as a kite. 
 We found that while it was supported 
 with a man on it in a wind of about 25 
 miles, its angle was much nearer 20 de- 
 grees than three degrees. Even in gusts 
 of 30 miles the angle of incidence did not 
 get as low as three degiees, although the 
 wind at this speed has more than twice 
 the lifting power of a 21-mile wind. As 
 winds of 30 miles per hour are not plen- 
 
 tiful on clear days, it was at once evident 
 that our plan of practicing by the hour, 
 day after day, would have to be post- 
 poned. Our system of twisting the sur- 
 faces to regulate the lateral balance was 
 tried and found to be much more effec- 
 tive than shifting the operator's body. 
 On subsequent days, when the wind was 
 too light to support the machine with a 
 man on it, we tested it as a kite, working 
 the rudders by cords reaching to the 
 ground. The results were very satisfac- 
 tory, yet we were well aware that this 
 method of testing is never wholly con- 
 vincing until the results are confirmed by 
 actual gliding experience. 
 
 We then turned our attention to mak- 
 ing a series of actual measurements of 
 the lift and drift of the machine under 
 various loads. So far as we were aware, 
 this had never previously been done with 
 any full-size machine. The results ob- 
 tained were most astonishing, for it ap- 
 peared that the total horizontal pull of 
 the machine, wliile sustaining a weight 
 of 52 lbs., was only 8.5 lbs., which was 
 less than had previously been estimated 
 for head resistance of the framing alone. 
 Making allowance for the weight carried, 
 it appeared that the head resistance of 
 the framing was but little more than 50 
 per cent, of the amount which Mr. 
 Chanute had estimated as the head re- 
 sistance of the framing of his machine. 
 On the other hand, it appeared sadly de- 
 ficient in lifting power as compared with 
 the calculated lift of curved surfaces of 
 its size. This deficiency we supposed 
 might be due to one or more of the fol- 
 lowing causes: — (1) That the depth of 
 the curvature of our surfaces was insuf- 
 ficient, being only about one in 22, in- 
 stead of one in 12. (2) That the cloth 
 used in our wings was not sufficiently air- 
 tight. (3) That the Lilienthal tables 
 might themselves be somewhat in error. 
 We decided to arrange our machine for 
 
 u 
 
THE 
 
 EARLY 
 
 HISTORY 
 
 O F 
 
 THE 
 
 AIRPLANE 
 
 the following year so that the depth of 
 the curvature of its surfaces could be 
 varied at will and its covering air- 
 proofed. 
 
 Our attention was next turned to glid- 
 ing, but no hill suitable for the purpose 
 could be found near our camp at Kitty 
 Hawk. This compelled us to take the ma- 
 chine to a point four miles south, where 
 the Kill Devil sand hill rises from the flat 
 sand to a height of more than 100 feet. 
 Its main slope is toward the northeast, 
 and has an inclination of 10 degrees. On 
 the day of our arrival the wind blew 
 about 25 miles an hour, and as we had 
 had no experience at all in gliding, we 
 deemed it unsafe to attempt to leave the 
 ground. But on the day following, the 
 wind having subsided to 14 miles per 
 hour, we made about a dozen glides. It 
 had been the original intention that the 
 operator should run with the machine to 
 obtain initial velocity, and assume the 
 horizontal position only after the ma- 
 chine was in free flight. When it came 
 time to land he was to resume the up- 
 right position and alight on his feet, 
 after the style of previous gliding ex- 
 periments. But in actual trial we found 
 it much better to employ the help of two 
 assistants in starting, which the peculiar 
 form of our machine enabled us readily 
 to do; and in landing we found that it was 
 entirely practicable to land while still re- 
 clining in a horizontal position upon the 
 machine. Although the landings were 
 made while moving at speeds of more 
 than 20 miles an hour, neither machine 
 nor operator suffered any injury. The 
 slope of the hiU was 9.5 deg., or a drop 
 of one foot in six. We found that after 
 attaining a speed of about 25 to 30 miles 
 with reference to the wind, or 10 to 15 
 miles over the ground, the machine not 
 only glided parallel to the slope of the 
 hill, but greatly increased its speed, thus 
 indicating its ability to glide on a some- 
 
 what less angle than 9.5 deg., when we 
 should feel it safe to rise higher from the 
 surface. The control of the machine 
 proved even better than we had dared to 
 expect, responding quickly to the slight- 
 est motion of the rudder. With these 
 glides our experiments for the year 1900 
 closed. Although the hours and hours 
 of practice we had hoped to obtain finally 
 dwindled down to about two minutes, 
 we were very much pleased with the gen- 
 eral results of the trip, for, setting out as 
 we did with almost revolutionary the- 
 ories on many points and an entirely un- 
 tried form of machine, we considered it 
 quite a point to be able to return without 
 having our pet theories completely 
 knocked on the head by the hard logic 
 of experience, and our own brains 
 dashed out in the bargain. Everything 
 seemed to us to confirm the correctness 
 of our original opinions — (1) that prac- 
 tice is the key to the secret of flying; (2) 
 that it is practicable to assume the hori- 
 zontal position; (3) that a smaller sur- 
 face set at a negative angle in front of 
 the main bearing surfaces, or wings, will 
 largely counteract the effect of the fore 
 and aft travel of the center of pressure; 
 (4) that steering up and down can be at- 
 tained with a rudder without moving the 
 position of the operator's body; (5) that 
 twisting the wings so as to present their 
 ends to the wind at different angles is a 
 more prompt and efficient way of main- 
 taining lateral equilibrium than that em- 
 ployed in shifting the body of the oper- 
 ator of the machine. 
 
 When the time came to design our new 
 machine for 1901 we decided to make it 
 exactly like the previous machine in the- 
 ory and method of operation. But as the 
 former machine was not able to support 
 the weight of the operator when flown 
 as a kite, except in very high winds and 
 at very large angles of incidence, we de- 
 cided to increase its lifting power. Ac- 
 
 is 
 
THE 
 
 EARLY 
 
 HISTORY 
 
 O F 
 
 THE 
 
 AIRPLANE 
 
 corcjingly, the curvature of the surfaces 
 was increased to one in 12, to confonn to 
 the shape on which LiUenthal's table was 
 based, and to be on the safe side we de- 
 cided also to increase the area of the ma- 
 chine from 165 square feet to 308 square 
 feet, although so large a machine had 
 never before been deemed controllable. 
 The Lilienthal machine had an area of 
 151 square feet; that of Pilcher, 165 
 square feet; and the Chanute double- 
 decker, 134 square feet. As our system 
 of control consisted in a manipulation of 
 the surfaces themselves instead of shift- 
 ing the operator's body, we hoped that 
 the new machine would be controllable, 
 notwithstanding its great size. Accord- 
 ing to calculations, it would obtain sup- 
 port in a wind of 17 miles per hour with 
 an angle of incidence of only three de- 
 grees. 
 
 Our experience of the previous year 
 having shown the necessity of a suitable 
 building for housing the machine, we 
 erected a cheap frame building, 16 feet 
 wide, 25 feet long, and 7 feet high at the 
 eaves. As our machine was 22 feet wide, 
 14 feet long (including the rudder), and 
 about 6 feet high, it was not necessary to 
 take the machine apart in any way in or- 
 der to house it. Both ends of the build- 
 ing, except the gable parts, were made 
 into doors which hinged above, so that 
 when opened they formed an awning at 
 each end and left an entrance the full 
 width of the building. We went into 
 camp about the middle of July, and were 
 soon joined by Mr. E. C. Huftaker, of 
 Tennessee, an experienced aeronautical 
 
 investigator in the employ of Mr. Cha- 
 nute, by whom his services were kindly 
 loaned, and by Dr. A. G. Spratt, of Penn- 
 sylvania, a young man who has made 
 some valuable investigations of the 
 properties of variously curved surfaces 
 and the travel of the center of pressure 
 thereon. Early in August Mr. Chanute 
 came down from Chicago to witness our 
 experiments, and spent a week in camp 
 with us. These gentlemen, with my 
 brother and myself, formed our camping 
 party, but in addition we had in many 
 of our experiments the valuable assist- 
 ance of Mr. W. J. Tate and Mr. Dan Tate, 
 
 of Kitty Hawk. 
 
 ****** 
 
 It had been our intention when build- 
 ing the machine to do most of the 
 experimenting in the following manner: 
 — When the wind blew 17 miles an hour, 
 or more, we would attach a rope to the 
 machine and let it rise as a kite with the 
 operator upon it. When it should reach 
 a proper height the operator would cast 
 off the rope and glide down to the ground 
 just as from the top of a hill. In this way 
 we would be saved the trouble of carry- 
 ing the machine uphill after each glide, 
 and could make at least 10 glides in the 
 time required for one in the other way. 
 But when we came to try it we found that 
 a wind of 17 miles, as measured by Rich- 
 ards' anemometer, instead of sustaining 
 the machine with its operator, a total 
 weight of 240 lbs., at an angle of inci- 
 dence of three degrees, in reality would 
 not sustain the machine alone — 100 lbs. 
 — at this angle. Its lifting capacity 
 seemed scarcely one-third of the calcu- 
 lated amount. In order to make sure that 
 this was not due to the porosity of the 
 cloth, we constructed two small experi- 
 mental surfaces of equal size, one of 
 which was aii'-proofed and the other left 
 in its natural state; but we could detect 
 no difference in their lifting powers. 
 
 80 
 
THE 
 
 EARLY 
 
 HISTORY 
 
 O F 
 
 THE 
 
 AIRPLANE 
 
 For a time we were led to suspect that the 
 lift of curved surfaces little exceeded 
 that of planes of the same size, but fur- 
 ther investigation and experiment led to 
 the opinion that (1) the anemometer 
 used by us over-recorded the true ve- 
 locity of the wind by nearly 15 per cent.; 
 12) that the well-known Smeaton coefJi- 
 [ent of .005 V ^ for the wind pressure at 
 degrees is probably too great by at 
 least 20 per cent.; (3) that Lilienthal's es- 
 timate that the pressure on a curved sur- 
 face having an angle of incidence of 
 three degrees equals .545 of the pressure 
 at 90 degrees is too large, being narly 50 
 per cent, greater than very recent experi- 
 ments of our own with a special pressure 
 testing machine indicate; (4) that the su- 
 perposition of the surfaces somewhat re- 
 duced the lift per square foot, as com- 
 pared with a single surface of equal area. 
 In gliding experiments, however, the 
 amount of lift is of less relative import- 
 ance than the ratio of lift to drift, as this 
 alone decides the angle of gliding de- 
 scent. In a plane the pressure is always 
 perpendicular to the surface, and the 
 ratio of lift to drift is therefore the same 
 as that of the cosine to the sine of the 
 angle of incidence. But in curved sur- 
 faces a verj^ remarkable situation is 
 found. The pressure, ijistead of being 
 uniformly normal to the chord of the arc, 
 is usually inclined considerably in front 
 of the perpendicular. The result is that 
 the lift is greater and the drift less than 
 if the pressure were normal. Lilienthal 
 was the first to discover this exceedingly 
 though our measurements differ consid- 
 erably from those of Lilienthal. While 
 important fact, which is fully set forth 
 in his book, "Bird Flight the Basis of the 
 Flying Art," but owing to some errors in 
 the methods he used in making measure- 
 ments, question was raised by other in- 
 vestigators not onlj' as to the accuracy of 
 Ais figures, but even as to the existence of 
 
 any tangential force at all. Our experi- 
 ments confirm the existence of this force, 
 at Kitty Hawk we spent much time in 
 measuring the horizontal pressure on 
 our unloaded machine at various angles 
 of incidence. We found that at 13 de- 
 grees the horizontal pressure was about 
 23 lbs. This included not only the drift 
 proper, or horizontal component of the 
 pressure on the side of the surface, but 
 also the head resistance of the framing 
 as well. The weight of the machine at 
 the time of this test was about 108 lbs. 
 Now, if the pressure had been normal to 
 the chord of the surface, the drift proper 
 would have been to the lift (108 lbs.) as 
 the sine of 13 degrees is to the cosine of 
 
 13 degrees, or^?^^^ = 24 + lbs.; but 
 
 this slightly exceeds the total pull of 23 
 lbs. on our scales. Therefore, it is evi- 
 dent that the average pressure on the sur- 
 face, instead of being normal to the 
 chord, was so far inclined toward the 
 front that all the head resistance of fram- 
 ing and wires used in the construction 
 was more than overcome. In a wind of 
 
 14 miles per hour resistance is by no 
 means a negligible factor, so that tang- 
 ential is evidently a force of considerable 
 value. In a higher wind, which sustained 
 the machine at an angle of 10 degrees, the 
 pull on the scales was 18 lbs. With the 
 pressure normal to the chord the drift 
 
 proper would have been 
 
 .17 X 98 
 .98 
 
 17 
 
 lbs., so that, although the higher wind ve- 
 locity must have caused an increase in 
 
THE 
 
 EARLY 
 
 HISTORY 
 
 O F 
 
 THE 
 
 AIRPLANE 
 
 the head resistance, the tangential force 
 still came within one pound of overcom- 
 ing it. After our return from Kitty 
 Hawk we began a series of experiments 
 to accurately detennine the amount and 
 direction of the pressure produced on 
 curved surfaces when acted upon by 
 winds at the various angles from zero to 
 90 degrees. These experhnents are not 
 yet concluded, but in general they sup- 
 port Lilienthal in the claim that the 
 curves give pressures more favorable in 
 amount and direction than planes; but 
 we find marked differences in the exact 
 values, especially at angles below 10 de- 
 grees. We were unable to obtain direct 
 measurements of the horizontal pres- 
 sures of the machine with the operator 
 on board, but by comparing the distance 
 traveled in gliding with the vertical fall, 
 it was easily calculated that at a speed of 
 24 miles per hour the total horizontal re- 
 sistance of our machine when bearing 
 the operator, amounted to 40 lbs., which 
 is equivalent to about 2 1/3 horse-power. 
 It must not be supposed, however, that a 
 motor developing this power would be 
 sufficient to drive a man-bearing ma- 
 chine. The extra weight of the motor 
 would require either a larger machine, 
 higher speed, or a greater angle of inci- 
 dence in order to support it, and there- 
 fore more power. It is probable, how- 
 ever, that an engine of six horse-power, 
 weighing 100 lbs., would answer the pur- 
 pose. Such an engine is entirely practi- 
 cable. Indeed, working motors of one- 
 half this weight per horse-power (9 lbs. 
 per horse-power) have been constructed 
 by several different builders. Increasing 
 the speed of our machine from 24 to 33 
 
 miles per hour reduced the total horizon- 
 tal pressure from 40 to about 35 lbs. This 
 was quite an advantage in gliding, as it 
 made it possible to sail about 15 per cent, 
 further with a given drop. However, it 
 would be of little or no advantage in re- 
 ducing the size of the motor in a power- 
 driven machine, because the lessened 
 thrust would be counter-balanced by the 
 increased speed per minute. Some years 
 ago Professor Langley called attention to 
 the great economy of tlirust which might 
 be obtained by using very high speeds, 
 and from this many were led to suppose 
 that high speed was essential to success 
 in a motor-driven machine. But the 
 economy to which Professor Langley 
 called attention was in foot-pounds per 
 mile of travel, not in foot pounds per 
 minute. It is the foot-pounds per min- 
 ute that fixes the size of the motor. The 
 probability is that the first flying ma- 
 chines will have a relatively low speed, 
 perhaps not much exceeding 20 miles per 
 hour, but the problem of increasing the 
 speed will be much simpler in some re- 
 spects than that of increasing the speed 
 of a steamboat; for, whereas in the latter 
 case the size of the engine must increase 
 as the cube of the speed, in the flying ma- 
 chine, until extremely high speeds are 
 reached, the capacity of the motor in- 
 creases in less than simple ratio; and 
 there is even a decrease in the fuel con- 
 sumption per mile of travel. In other 
 words, to double the speed of a steam- 
 ship (and the same is true of the balloon 
 type of airship) eight times the engine 
 and boiler capacity would be required, 
 and four times the fuel consumption per 
 mile of travel; while a flying machine 
 would require engines of less than 
 double the size, and there would be an 
 actual decrease in the fuel consumption 
 per mile of travel. But looking at the 
 matter conversely, the great disadvan- 
 tage of the flying machine is apparent; 
 
 8S 
 
THE 
 
 EARLY 
 
 HISTORY 
 
 O F 
 
 THE 
 
 AIRPLANE 
 
 for in the latter no flight at all is possible 
 unless the proportion of horse-power to 
 flying capacity is very high; but on the 
 other hand a steamship is a mechanical 
 uccess if its ratio of horse-power to ton- 
 nage is insignificant. A flying machine 
 that would fly at a speed of 50 miles an 
 hour with engines of 1 ,000 horsepower 
 would not be upheld by its wings at all at 
 a speed of less than 25 miles an hour, and 
 nothing less than 500 horse-power could 
 drive it at this speed. But a boat which 
 could make 40 miles per hour with en- 
 gines of 1,000 horse-power would still 
 move four miles an hour even if the en- 
 gines were reduced to one horse-power. 
 The problems of land and water travel 
 were solved in the nineteenth century, 
 because it was possible to begin with 
 small achievements and gradually work 
 up to our present success. The flying 
 prolem was left over to the twentieth 
 century, because in this case the art must 
 be highly developed before any flight of 
 any considerable duration at aU can be 
 obtained. 
 
 However, there is another way of fly- 
 ing which requires no artificial motor, 
 and many workers believe that success 
 will first come by this road. I refer to 
 the soaring flight, by which the machine 
 is permanently sustained in the air by 
 the same means that are employed by 
 soaring birds. They spread their wings 
 to the wind, and sail by the hour, with no 
 perceptible exertion beyond that re- 
 quired to balance and steer themselves. 
 What sustains them is not definitely 
 known, though it is almost certain that it 
 is a rising current of air. But whether 
 it be a rising current or something else, 
 it is as well able to support a flying ma- 
 chine as a bird, if man once learns the art 
 of utilizing it. In gliding experiments it 
 has long been known that the rate of ver- 
 tical descent is very much retarded, and 
 the duration of the flight greatly pro- 
 
 longed, if a strong wind blows up the face 
 of the hill parallel to its surface. Our 
 machine, when gliding in still air, has a 
 rate of vertical descent of nearly six feet 
 per second, while in a wind blowing 26 
 miles per hour up a steep hill we made 
 glides in which the rate of descent was 
 less than two feet per second. And dur- 
 ing the larger part of this time, while the 
 machine remained exactly in the rising 
 current, there was no descent at all, but 
 even a slight rise. If the operator had 
 had sufficient skill to keep himself from 
 passing beyond the rising current he 
 would have been sustained indefinitely 
 at a higher point than that from which 
 
 he started. 
 
 ****** 
 
 In looking over our experiments of 
 the past two years, with models and full- 
 size machines, the following points stand 
 out with clearness: — 
 
 1. That the lifting power of a large 
 machine, held stationary in a wind at a 
 small distance from the earth, is much 
 less than the Lilienthal table and our own 
 laboratory experiments would lead us to 
 expect. When the machine is moved 
 through the air, as in gliding, the discrep- 
 ancy seems much less marked. 
 
 2. That the ratio of drift to lift in 
 well-balanced surfaces is less at angles 
 of incidence of five degrees to 12 de- 
 grees than at an angle of three degrees. 
 
 3. That in arched surfaces the center 
 of pressure at 90 degrees is near the cen- 
 ter of the surface, but moves slowly f or- 
 
 
 23 
 
THE 
 
 EARLY 
 
 HISTORY 
 
 O F 
 
 THE 
 
 AIRPLANE 
 
 ward as the angle becomes less, till a 
 critical angle varying with the shape and 
 depth of the curve is reached, after which 
 it moves rapidly toward the rear till the 
 angle of no lift is found. 
 
 4. That with similar conditions large 
 surfaces may be controlled with not 
 much greater difficulty than small ones, 
 if the control is effected by manipulation 
 of the surfaces themselves, rather than 
 by a movement of the body of the oper- 
 ator. 
 
 5. That the head resistances of the 
 framing can be brought to a point much 
 
 below that usually estimated as neces- 
 sary. 
 
 6. That tails, both vertical and hori- 
 zontal, may with safety be eliminated in 
 gliding and other flying experiments. 
 
 7. That a horizontal position of the 
 operator's body may be assumed without 
 excessive danger, and thus the head re- 
 sistance reduced to about one-fifth that 
 of the upright position. 
 
 8. That a pair of superposed, or tan- 
 dem, surfaces has less lift in proportion 
 to drift than either surface separately, 
 even after making allowance for weight 
 and head resistance of the connections. 
 
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