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Aviation History
1934
1934 - 0570.PDF
FLIGHT, JUNE 7, 1934 A REWARD : Mrs. C. C. Walker making Mr. P. G. Lucasa presentation in recognition of his display in the Hawker " Haxt." (FLIGHT Photo.) manoeuvres should be made, but also how they should not be made, is both educative and amusing. Mr. R. A. C. Brie handled an Autogiro in a manner which proved its wonderful utility. He stood still in the air and landed vertically, flew fast and slow, took off in a very short space and climbed rapidly. He was flying the latest C.30 direct- controlled type (7-cyl. " Genet Major "). A contrast was given by Mr, P. G, Lucas, a test pilot of Hawker Aircraft Co., Ltd., in the company's demonstration " Hart " (" Kestrel VI "). Mr. Lucas not only " roared up " the aerodrome, following with an almost incredibly sustained climb, but also showed that the " Hart " could fly quite comparatively slowly. Since the De Havilland Aircraft Co. took over the direc- tion of the London Aeroplane Club many amenities have been added to those originally provided there. For example, the swimming bath is an attraction, and this was enhanced on Sunday by a bathing costume parade and a swimming demonstration by Miss Betty Blanks, the 100 yd. Southern Counties Breast Stroke Champion for 1932. The visitors were entertained to a tea dance in the clubhouse, and they could also sit comfortably on the terrace while they watched various amusing events, like the wheelbarrow race, which was won by Mr. Humble and his passenger ; the hat-trimming competition for men, which was won by Mr. Graham MacKinnon ; the bottle race by Mr. Bishop, of the Reading Aero Club, who steered his passenger, Mrs. Higgs, along a tortuous course and disturbed the least number of bottles ; and finally a pilot's obstacle race, which was won by Mr. W. Yamamoto. During the aiternoon, Nos. 18 and 57 (Bomber) Squadrons, R.A.F., and Nos. 600 and 601 Squadrons, A.A.F., flew over in the course of exercises, forming part of their practice for the R.A.F. Display at Hendon. The machine park was also open so that the visitors could inspect the many machines—over 40 of which arrived during the afternoon—and there they evinced great interest in the many types, among which was the " Martlet " (" Genet ") in which Mr. E. M. Wright won the arrival competition. It was disappointing, however, that the D.H. 86 four-engined airliner, or Diana, as she is called by Imperial Airways, which had been expected, could not be brought over. STALLING" A Summary of the Twenty-second Wilbur Wright Memorial Lecture, given by Professor Melvill Jones before the Royal Aeronautical Society places could be more suited to the delivery of the Wilbur Wright Memorial Lecture than the Science Museum, South Kensington, and last Thurs- day evening Professor Melvill Jones spoke almost in the shadows of the original Wright machine and of the Supermaxine S.6b. The lecturer was introduced by Mr. C. R. Fairey, President of the R.Ae.S., who also presented the year's awards, which are given elsewhere. The Lecture Were it not for the dangers inherent in the stall, the art of flying would probably have been mastered in very early times, and until this phenomenon is thoroughly understood aviation will not be free to play the great part it is destined to play. Knowing that some inexplicable reason lay behind the previous tragedies, the Wright brothers decided never to leave the ground by more than a few feet until the trap had been discovered, and this decision marks the real beginning of the present era of flight. They discovered that at slow speeds either wing was liable to start a sudden rearward and downward motion, and countered this tendency by interconnecting the rudder and wing warping controls, very much after the manner in which slots and flaps are experimentally arranged to-day. From that time the development of the light petrol engine enabled pilots to fly safely above the stall, and accidents were attributed to an " error of judgment." But, after the war, it was realised that a phenomenon which was responsible for two-thirds of the fatal accidents merited at least a careful study, and the Aeronautical Research Committee started upon a research campaign. We now know how to avoid the worst dangers, and, the first urgency having passed, scientists may settle down to study the stall in an atmosphere of calm. But the variations, almost inexplicable, in the reactions of different machines show that the problem is far from being com- pletely solved. Two different kinds of experiment have been used— those on models and orr machines in actual flight. Pilot psychology cannot be allowed for in the first, and the difficulties of dealing with three velocities in the second have been considerable. The work at Farnborough and the courage of the persons concerned in this work have rarely been adequately praised. Calculation, based on wind tunnel experiments, showed that the spin was exceedingly sensitive to yawing moments, and this explained the failure of the ailerons to check it and the importance of good rudder control. Afterwards came the Handley-Page slot and the " interceptor," so that the discoveries of the Wrights were, in effect, re- discovered. The next thing was to find out exactly what happened to the air flow over a stalled and semi-stalled wing. In 1912, Professors Bairstow and Melvill Jones, working with the old wind tunnel at the N.P.L., were shocked by the " precipice curves " indicating the complete and sudden loss of lift at low speeds, and these curves are still fair examples of the three typical ways in which aerofoils behave. At Cambridge, in 1932, however, a new technique was developed, in which undamped balances gave the greatest and least forces rather than the mean fluctuations, and, from this, results were obtained which show up some aspects of the stall in a new light. It was found that aerofoils could be divided into three main groups, according to the way in which lift and drag varied during the stall. In the first the lift rises and the drag increases slightly at incidences above 7 deg., whilst at 17 deg. lift falls and drag rises suddenly. In the second, severe fluctuations persist over an incidence range of some 5 or 6 deg., and the onset of these fluctuations coincides with the passage of the incidence of maximum mean lift. In the third, the fluctuation increase does not occur until an incidence several degrees greater than that of maximum lift, which passes without any marked fluc- tuations. A study of the flow changes over an aerofoil shows that the first noticeable sign of approaching stall is the forma- 570
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