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Aviation History
1909
1909 - 0394.PDF
JULY 3, i(,09. entirely sound and quantitatively, probably, as accurate as the present state of the measurements of wind pressures permitted. The writer determined, however, to withhold publications until the feat of soaring flight had been per- formed by man, partly because he believed that, to ensure safety, it would be necessary that the machine should be equipped with a motor in order to supplement any deficiency in wind force. The feat would have been attempted in 1902 by Wright Brothers if the local circumstances had been more favourable. They were experimenting on " Kill Devil Hill," near Kitty Hawk, N.C. This sand hill, about 100 ft. high, is bordered by a smooth beach on the side whence come the sea breezes, but has marshy ground at the back. Wright Brothers were apprehensive that if they rose on the ascending current of air at the front and began to circle like the birds, they might be carried by the descending current past the back of the hill and land in the marsh. Their gliding machine offered no greater head resistance in proportion than the buzzard, and their gliding angles of descent are practi- cally as favourable, but the birds performed higher up in the air than they. Professor Langley said in concluding his paper upon " The Internal Work of the Wind " : " The final application of these principles to the art of aerodromics seems, then, to be that while it is not likely that the perfect aerodrome will ever be able to dispense altogether with the ability to rely at intervals on some internal source of power, it will not be indispensable that this aerodrome of the future shall, in order to go any distance—even to circumnavigate the globe without alighting—need to carry a weight of fuel which would enable it to perform this journey under conditions analogous to those of a steamship, but that the fuel and weight need only be such as to enable it to take care of itself in exceptional moments of calm." Now that dynamic flying machines have been evolved and are being brought under control, it seems to be worth while to make these computations and the succeeding explanations known, so that some bold man will attempt the feat of soaring like a bird. The theory underlying the performance in a rising wind is not new, it has been suggested by Penaud and others, but it has attracted little attention, because the exact data and the manoeuvres required were not known and the feat had not yet been performed by a man. The puzzle has always been to account for the observed act in very light winds, and it is hoped that by the present selection of the most difficult case to explain — i.e., the soaring in a dead horizontal calm—somebody will attempt the exploit. The following are deemed to be the requisites and manoeuvres to master the secrets of soaring flight:— ist. Develop a dynamic flying machine weighing about i lb. per ?q. ft. of area, with stable equilibrium and under perfect control, capable of gliding by gravity at angles of i in 10 (5fc) in still air. 2nd. Select locations where soaring birds abound, and occasions where rising trends of gentle winds are frequent and to be relied on. 3rd. Obtain an initial velocity of at least 25 ft. per sec. before attempting to soar. 4th. So locate the centre of gravity that the apparatus shall assume a negative angle, fore and aft, of about 30. Calculations show, however, that sufficient propelling force may still exist at o°, but disappears entirely at +• 40. 5th. Circle like the bird. Simultaneously with the steering, incline the apparatus to the side toward which it is desired to turn, so that the centrifugal force shall be balanced by the centripetal force. The amount of the required inclination depends upon the speed and on the radius of the circle swept over. 6th. Rise spirally like the bird. Steer with the horizontal rudder, so as to descend slightly when going with the wind and to ascend when going against the wind. The bird circles over one spot because the rising trends of wind are generally confined to small areas or local chimneys, as pointed out by Sir H. Maxim and others. 7th. Once altitude is gained, progress may be made in any direction by gliding downward by gravity. The bird's flying apparatus and skill are as yet indefinitely superior to those of man, but there are indications that within a few years the latter may evolve more accurately proportioned apparatus and obtain absolute control over it. It is hoped, therefore, that if there be found no radical error in the above computations, they will carry the con- viction that soaring flight is not inaccessible to man, as it promises great economies of motive power in favourable localities of rising winds. The writer will be grateful to experts who may point out any mistake committed in data or calculations, and will furnish additional information to any aviator who may wish to attempt the feat of soaring. ® © -:': •""• .':"-"'•' •""••.. ;" THE VALUE OF MODEL FLYER CLU3S. AN altogether admirable move has been made towards the establishment of clubs for the encouragement of sport with model flyers in various parts of the country, the first town to take the matter up being Blackpool, where Mr. J. Kemp, of Cookson Street, is inviting other enthusiasts to join with him in establishing a club of this character. The idea is to stimulate interest in the subject of aviation, and to induce a practical interest in the building of models, not only by the inauguration of exhibitions from time to time, but also by the institution of competitions at frequent intervals. Such clubs as these could do a very great deal of useful work in preparing the way for the new era that is assuredly coming, not only by popularising the idea of human flight amongst the general public, but also by instilling a fair amount of specific knowledge on the subject into the minds of the younger members of the community. Particularly in the larger seaside towns, and also in other well-populated districts where facilities exist for competitions between machines of all types and size, model flyer clubs have plenty of good work and a very enjoyable time before them. This is a development of which we spoke in our leading article of May 1st, at the time when Mr. V. E. Johnson suggested the substitution of model flyers—with their seashore contests—for diabolo as the juvenile sport for this summer. Mr. Johnson then offered, it will be remembered, to start the ball rolling in the matter of prizes, by giving one for the best flight made by a model constructed by any schoolboy of strictly British nationality. 30
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