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Aviation History
1920
1920 - 0814.PDF
JULY 22, 1920 A NOVELTY IN AEROPLANE WINGS THE Wax has proved that performance—that is, speed and, to a certain extent, climb—is chiefly a matter of loading per horse power. Commercial aviation is also, or will be in the future, a matter of loading per horse power—with this difference : performance was obtained by cutting down loading per horse power to the smallest attainable figure. The commercial aeroplane, on the other hand, will have to aim at carrying as great a load per horse power as possible for the sake of economy. This is an axiom to which we have frequently called attention in the columns of this journal. As in so many other things, a compromise has to be made between conflicting desiderata, and, in the case of com- mercial aircraft, this compromise will take the form of carrying-a load somewhat smaller than the maximum power load possible in order to keep the speed up te certain com- mercial figures. Thus it is known that for a loading of 40 lbs./h.p. the maximum speed of the ordinary aeroplane is only about 60 m.p.h. Now a commercial aeroplane flying, for instance, between London and Paris, may frequently encounter a head wind of some 30 m.p.h. 11 the maximum speed of the machine is only 60 m.p.h. it would, therefore, take about eight hours to do the journey. This is obviously too slow to enable the machine always to beat the boat and train service on the score of speed. To do this success- fully a machine of higher speed must be used. But higher speed means less load per horse power, hence a commercial compromise must be made, and it is obvious that the machine which, for a given speed, will carry the greatest load per horse power is the best commercial proposition. A novel form of aeroplane wing, which appears to go a long step towards improving the economy of commercial flight, is just about to be introduced by the Commercial Aeroplane Wing Syndicate, Ltd., whose offices are at 34-36, Gresham Street, E.C.2. This wing, of which the aerodynamic data are given in the following table, is the outcome of many years of experiment and research, and although in its present form the wing marks a great improvement on the ordinary. aerofoil for load carrying at moderate speeds, it does not, in the opinion of the inventors, represent the maximum attainable. ' Tests at East London College on Alula Wing No. 328-8 (Double-arched Model), 4 ins. by 36 ins. at 40 ft. per sec. H4 0> o o S£ S J> uo-o tao 318 o I 23 45 6 8 9 oo •191 •241 •290 •338 •386 •432 •476 •521 •566 •621 7-.o io-5 133 15-8 18-3 20-6 22-2 22-85 22-9 22-5 •575•496 •447 •432 •418 •406 •395 •398 •388 •381 8 bo-U < c" IO II 12 13 14 15 I6 1718 19 •660 • 709 • 761 •799 •823 •827 •822 •814 •800 •784 IJ" 21-8 20-9 19-85 18-8 17-5 16-1 14-6 12-9 10-8 8-6 •378 •371 •365 •35O •34° •335 •335 •34O •352 •369 and we understand that very satisfactory results are being obtained. A reference to the accompanying table will show that not only is the maximum lift coefficient unusually high, but the maximum L/D and the lift coefficient corresponding to maximum L/D are also extremely good. The maximum lift coefficient is -827 and occurs at an angle of incidence of 15°. As the maximum lift coefficient of the ordinary wing is somewhere between -5 and -6 it will be seen that, for the same landing speed, the wing area can be reduced to about three-fourths that necessary with the ordinary wing. This is not the only, nor perhaps the greatest, advantage of the Alula wing, as it is called by the designers. The maxi- mum L/D (to which scale correction still has to be added) is as high as 22-9, which compares favourably with the orthodox wing, and the lift coefficient corresponding to this maximum L/D is -566, or as high as the maximum lift coefficient of the average wins. This, it will be seen, makes for economy of flight, especially in machines carrying a high load at moderate speeds. It is not the intention of the Commercial Aeroplane Wing Syndicate, Ltd., to enter the constructing trade as corn- Two views of a scale model showing application of an Alula wing The accompanying photographs show a model wing of this series, from which some idea of the shape of the wing may be formed. The chief characteristics are the straight trailing edge, the negative dihedral leading edge, the deep camber, and the wash-out in chord camber and incidence towards the tip. In addition to the scale model wind tunnel tests, full scale experiments have been made for some time by the technical staff of the Blackburn Aeroplane & Motor Co.^ of Leeds, in order to determine the agreement between model and full scale work. These trials are still in progress. petitors, but rather to issue licences for the use of Alula— wings by aircraft manufacturing firms, and enquiries from bona fide constructors are invited. The wing, it might be added, can be used in machines of orthodox design if desired, and the general arrangement illustrated by our photographs is a suggestion by Mr. Booth of the Blackburn Technical Staff for one way of utilising the new wing. Time does not allow of a more detailed reference to the wing in the present issue, but we hope to return to the subject in a subsequent issue of FLIGHT. M. Poulet in Batavia M. POULET is back at Batavia in the Dutch East Indies, and on July 13, gave some exhibition flights on his Caudron, the proceeds to go to the fund for the benefit of Vedrine's family. He hopes to continue his flight to Australia next month. The New York—Alaska Flight ALTHOUGH they started from New York on July 16, the 4 Dek machines, piloted by U.S. Army officers, were not able to progress very rapidly on their journey to Alaska, being held up for three days by thunderstorms at Erie, Pennsylvania.814
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