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Aviation History
1931
1931 - 1356.PDF
FLIGHT, DECEMBER 25, 1931 times the total travel (actually even more) would be re-quired to make the fully-stalled landing a feasible pro- position." A modification of the fully-stalled landing was the" pancake landing," in which the shock of impact was lessened by flattening out the gliding path before themachine touched. This entailed reversed elevator con- trol. To flatten out from a steep glide the control stickhad to be pushed forward. Dr. Lachmann described a novel technique of landing theoretically worked out inGermany by Dr. Wilhelm Schmidt, but as the theoretical arguments were rather involved, while a wing section veryunsuitable in other respects (sudden drop in lift curve after stall) had to be used, and the actual manoeuvre appearedmuch more complicated than a normal side-slip landing, we need hardly deal with this part of the paper here. THE DISCUSSION In reply to questions raised in the discussion, the lec-turer said that he regretted very much indeed the absence of Professor Melvill Jones, yet at the same time he wasglad, as Professor Melvill Jones was so much an acknow- ledged expert that he (Dr. Lachmann) would have feltdiffident in answering any of the questions of others before him. Replying to Mr. McKinnon Wood, he said that hewas sorry to hurt this gentleman's feelings, but he had not meant to detract from the value of the controlled slot andaileron ; he only meant to infer that it had not main- tained its position, but had been supplanted by the auto-matic slot and interceptor. With regard to the question which had been raised about the position of the tailplane,he said he strongly advised designers of low-wing mono- planes to place the tailplane as high as possible, thoughprobably on top of the fuselage was sufficient in the case of biplanes. In reply to another speaker, he said thereprobably was an optimum useful span for the slot, and he thought that this was most likely between 25 and 30 per cent, of the semi-span of the wing. In reply to the suggestion that ailerons might be don<away with and interceptors substituted, he said that inter- ceptors could be used for lateral control, but he did notthink they were effective for getting a machine out of a prolonged fiat spin. In answer to Dr. Thurston, he saidthat in the picture of the very large birds Dr. Thurston had appeared to see only the alula, whereas he himselihad been most struck by the multi-slot feather formation at the ends of the wings. After Mr. Wimperis (Director of Scientific Research) hadseconded the vote of thanks to the lecturer and announced the fact that the new 12-ft. vertical wind tunnel hadthat same day started working successfully at Farnborough, Dr. Pleinis, of the D.V.L., read a short paper, illustratedwith lantern slides, describing the work which had recently been done in Germany on the same subject, particularlyby mass loading of the wing tips with water containers and investigating the behaviour of the machine when thiswater was released. He also showed a short film depicting the behaviour of wool tufts attached along each spar onthe bottom wing of a biplane, when that wing was stalled. Capt. Hover, of the Aeronautical Department of theNorwegian Navy, also contributed to the discussion, and described a certain amount of the work which his depart-ment had been doing. The machine to which he referred had previously been shown on the screen by Dr. Lachmann,and Capt. Hover described how on two occasions a flat spin had been developed with this machine, in the firstplace at 25,000 ft. and in the second place at 3,000 ft., and in each case the machine had spun right down to thewater without damage to the pilot. After the lecture some 40 guests attended a small dinnergiven at the Royal Aero Club by Mr. Handley Page. AMERICA'S NEW WATER TANK: The model towing tank at Langley Field, Virginia, is 2,040 ft. long, 24 ft. wide and 12 ft. deep. The car is built of welded steel tube and runs on pneumatic tyres inflated to ,125 lb. pressure. ^0 maximum speed of 50 m.p.h. can be attained. 1270 •-•-•: •:;-;•.;.-r..V '.: : .=
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