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Aviation History
1912
1912 - 0488.PDF
fycHTj JUNE I, 1912. B WILBUR RIGHT, 1867-191! WORDS cannot express the loss that the world of aviation suffers m the decease, on May 30th, of Wilbur Wright, the greatest of all inventors of the flying machine and the first of all pilots. Although hardly unexpected during the past few days by reason of the nature of the illness, nevertheless the sad event has been all too sudden, for while there was life there was hope, as foreshadowed last week in our pages, but, as now known, doomed to disappointment. Wilbur Wright was born in 1867, at Dayton, in Ohio, and his father, a broad-minded bishop, was the first to encourage the inventive and mechanical genius of his two sons. Their first serious engineering achievement was the building of a printing machine, but subsequently they transferred their attentions to bicycle making, for they possessed in a marked degree the American trait of making a useful and up-to-date occupation out of their hobby and conducting it on quite serious lines. When, in 1896, Lilienthal met his untimely end, Wilbur Wright was inspired by the brief notice of the catastrophe that appeared in the Press to take a momentary and somewhat passive interest in the subject that Lilienthal had made his own especial study. He took down from the shelf of his library Marey's classic work on Animal Mechanism," which he had already read several times as a boy. From this some what casual act, the momentary interest in the occasion received a new lease of life, and the passive concern in the subject with which it was associated served as the incubator of a vitally active germ. More modern works relating to aeronautics were read, and his brother Orville, being equally interested with himself, they decided together to try and follow in Lilienthal's footsteps. It seemed to Wilbur Wright that the main reason why the problem of flight had remained so long unsolved was thai no one had been able to attain any adequate practice. Lilienthal himself, who, of all experimenters, alone could be said to have had any practice in the air at all, had only spent an aggregate of about five hours in the air, made up of flights lasting a few seconds each in duration, according to Wilbur Wright's reckoning. Having made up their minds to take up the subject, they attacked the problem in a characteristically practical _^^- way, immediately proceeding to build a glider of some two hundred square feet area, which they calcu lated would be capable of support in the air at about eighteen miles an hour. Initially their idea was to fly this machine as a kite on the side of a hill, with a pilot on board, so that experience in riding the air might be obtained without actual motion over the ground. They built their first machine in 1900, but lack of suitable material caused them to cut down the area to 165 sq. ft. It was a biplane constructed on the trussed bridge principle employed by Octave Chanute, who had been responsible for the introduction of gliding in America and who later on took a personal interest in the Wrights' experiments. Krom the first, the Wright glider showed unmistakeable evidence of keen practical originality. It was designed so that the pilot should lie prone on the lower deck, which would decrease head resistance and eliminate pendu lum action arising from the underhung body assumed by Lilienthal. Instead of balancing the machine by an acrobatic displacement of the pilot's position, as was Lilienthal's custom, the Wrights fitted their glider with a simple contrivance for warping the wings so that equilibrium might be maintained by differential dynamic reaction. There was an interesting point, too, in the trussing of the machine, whereby all the tie wires could be tightened simultaneously merely by shortening two of them. These, and many other features, showed conclusively that Wilbur Wright had brought into the field of aviation a wonderfully clear thinking and active brain. He realised the necessity of practical experiments as the sole reliable foundation of progress, but he knew also the essential importance of understanding his subject as far as possible before he began the labour of practical work in the field. Their first trials with the 1900 machine took place at Kitty Hawk, in North Carolina, and, in general, the results were satisfactory, although the supporting velocity and angle of incidence were both considerably greater than had been estimated. Tests of lift and drift also led them to suppose that they might have made the camber of their planes too small. These earlier experiences included flying the glider as a kite with the pilot on board, and also several free flights down the side of a hill called the Kill Devil sand hill, which has a 10" slope. In 1901 they completed a larger glider, having an area of 308 sq. ft., with the camber increased from one-twenty-second to one-twelfth the chord. The results, at first, were unsatisfactory, the machine exhibiting considerable unsteadiness in the air. It was their first investigation into the causes of this defect that led them conclusively to establish the retrograde movement of the centre of pressure at very small angles of incidence, and thereby to erect for all time a kind of danger sign, as it were, to warn the constructors of future machines. As the result of their experience in 1901, Wilbur Wright formulated the following conclusions, which he subsequently pub lished :— "I. That the lifting power of a large machine held stationary in a wind a small distance from the earth is much less than the Lilienthal table and our own experiments would lead us to expect. When the machine is moved through the air as in gliding, the discrepancy seems much less marked. "2. That the ratio of drift to lift in well-shaped surfaces is less at angles of incidence of 5° to 12° than at an angle of 3°. " 3. That in arched surfaces the centre of pressure at 900 is near the centre of the surface, but moves slowly forwards as the angle becomes less until a critical angle, varying with the shape and depth of the curve, is reached, after which it moves rapidly towards the rear till the angle of no lift is - "^Smtii 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 operator. " 5. That the head-resistances of the framing can be brought to a point much below that usually estimated as necessary. " 6. That tails, both vertical and horizontal, may with safety be eliminated in gliding and other flying experiments. " 7. That a horizontal position of the operator's body may he assumed without excessive danger, and thus the head-resistance reduced to about one-fifth of the upright position. CL*<—'" "8. That a pair of superposed or tandem surfaces nas less lift in proportion to drift than either surface separately, even after making allowance for weight and head-resistance of the connections." In the interim, between the experiments of 1901 and those of 1902, the Wrights conducted laboratory experiments, the results of which have not yet been made public. Their r902 glider was again a biplane, having an area of 305 sq. ft., a span of 32 ft., and a chord of 5 ft. There was an elevator in front, and two vertical tail planes at the rear. At a later period, a single rudder of half the area was substituted for the fixed tail planes. This model also had straight spars in the main wings, whereas those built previously had had them arched like gulls' wings. No complete record was made of all the glides, but as many as I ,ooo may have been made during the season. The longest glide lasted 26 sees., and covered 6224 ft. Having brought their gliding experiments to a pitch of perfection that satisfied them, they decided to take the momentous step of building an engine-driven machine. Not being able to find an engine suited to their requirements, they proceeded therefore to make one for themselves, a four-cylinder four-cycle petrol motor designed on simple but in some respects original lines. Their 488
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