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Aviation History
1934
1934 - 0158.PDF
FLIGHT, FEBRUARY ;lfS, JJ&S4 tests on similar installations (with supercharged andgeared engine), the one having no ring cowl and no baffles, whilst the other had N.A.C.A. cowl and baffles. In thelatter case there was a reduction of nearly 50 deg. F. in the maximum cylinder head temperature and an increaseof speed of 15 m.p.h., under conditions of constant power and r.p.m., constant fuel consumption and constant den-sity altitude. MR. HOLLIS WILLIAMS said there was one interestingpoint in the paper which rather revised his ideas of how rings and the N.A.C.A. cowling worked. It was interestingto see working out in full scale a physical phenomenon which one knew must be true, i.e., that if a ring cowlingwere working properly, symptoms of vibration, wind-screen chatter, and so on, would disappear, and there would belaminar flow. One could feel the warm air down the sides of the fuselage, and that was one of the best methods oftelling whether a cowling was working properly. It had always seemed to him that to secure the peculiar pheno-menon of laminar flow it was necessary to rely on the sluicing of the air at the back of the ring. There was ahigh-velocity air stream rejected from the back of the ring, and that tended to pack the air down on to the bodyand produce the laminar flow. It had been stated by Mr. North that in tests carriedout in America, where the slots had been filled up behind the N.A.C.A. cowling, the drag was reduced. That upsetthe ideas which he (Mr. Hollis Williams) had had ; it meant that the war-time cowlings were as good as anythingnow produced, and he was not sure that this was not a fact. The point was whether the slot was absolutely neces-sary for the high-speed sluicing which gave the laminar flow. MR. NORTH, replying to the discussion, suggested that part of the difficulty which had arisen was due to the unavoidable doubt as to what was an N.A.C.A. cowling. He had quoted extracts from the statements of the N.A.C.A. at the time they had produced their cowling, in order to try to show what was in fact in their minds prior to the publication of Mr. Townend's results, and what they had produced. The line of the cowling was a .'•continuation of the shape of the fuselage. It was, there- 'fore, not surprising under those circumstances that the •filling up of the slot, which was a horizontal and not a .vertical slot, had the effect of reducing resistance. But if one filled up the slot of the Townend Ring the drag in- creased tremendously. One could regard that as being the fundamental difference between the N.A.C.A. cowling and the Townend Ring. Then Mr. Fedden has referred to the Douglas fittedwith the N.A.C.A. cowling. Mr. North did not know whether it fell within the definition which the N.A.C.A.themselves had laid down in their reports. When he had said that the N.A.C.A. cowling caused other troubles as Death of Fit. Lt. R. E. H. Allen IT is with the greatest regret that we have to record the untimely death of Fit. Lt. Ralph Eric Herbert Allen, 'A.M.I.A.E., M.I.Ae.E., R.A.F.O. After being knocked down by a motor car in Whitehall on Friday, February 9, he died in Westminster Hospital on the following Sunday. Allen was a well-known and cheerful person in aviation circles. He kept his own " Bluebird " at Han worth and flew consistently for his own pleasure and often, it is under- stood, for the Metropolitan Police. He was employed at Scotland Yard as an assistant engineer where the extensive knowledge he gained in the Royal Air Force of ground transport vehicles made him very valuable. Born in 1892, he joined the R.N.A.S. in 1914, and served throughout the war in France and on Coastal Defence duties. From 1919 to 1925 he was an engineer officer and instructor in the R.A.F., and subsequently worked at the Air Ministry until 1928. He also designed and patented many specialised vehicles in connection with aviation. His loss will be felt keenly both by his employers and his many friends ; to them we offer our sincerest sympathy. Mr. Shackleton's illness His many friends will be sorry to hear that Mr. W. S. Shackleton recently had to undergo an operation. He is at present in the London Clinic, 20, Devonshire Place, London, W.I, where he is, at the time of writing, progressing favourably, and there is, we are informed, no cause to anticipate complications. For the benefit of well as heating, he was quoting Mr. Fedden. There again, the importance of that was that Mr. Fedden's figures, where he had shown that there had been overheating with the N.A.C.A. cowling, arose from direct comparisons with some installations of the Townend Ring, and certainly, from what he himself had said on the matter, he had found that the temperatures were considerably greater with the N.A.C.A. cowling than with the Townend Ring. But in these matters one was not dealing with things that were so precise that one could be compared with another. No doubt there was a very large number of installations- which conformed to the original definition of the N.A.C.A. cowling, and which functioned well, particularly at the very high speeds at which the machines were working. When Mr. Fedden had said that there was no engineer- ing difference between the Townend Ring and the N.A.C.A. cowling, because both had a forward component, Mr. North was unable to understand it. The mere fact that both had an upward component was only a sort of manifesta- tion of the pressure distribution and something which was inevitable from the position in which the ring was placed. He did not think the fact that the Townend Ring gave a large upward force and also gave a drag had any more significance than the fact that if one took a slice from a streamline body, the nose might have an upward com- ponent, although the back part had a drag ; it was a question of cause' and effect. The interesting suggestions made by Mr. Townend with regard to methods of experiment would be very helpful. As a matter of fact, one did not find very much difficulty in hitting off these things in the wind tunnel now ; it was much easier intuitively to know how to set about the job than to explain how to do it. He could give some figures with regard to the bulbous nose which would surprise and interest Mr. Townend. Some wings were tested by them- selves in free air. With the one-tenth scale polygonal ring, using the bulbous nose, the drag was 18.26 lb., and with the one-fifth scale ring it was 17.72 lb., showing practically no scale effect. When the bulbous nose was removed, the drag was 31 on the one-tenth scale and 22 on the one-fifth scale. So that there was increased drag when the bulbous nose was taken off and a very large scale effect. But he could not give an explanation ; this was far more Mr. Townend's province than his own. He agreed with Mr. Hollis Williams' remarks with re- gard to the general steadying up of the flow when the ring was functioning satisfactorily. Finally, commenting on Mr. Fedden's emphasis of the importance of the shape of the after body, Mr. North said there was a great deal in the paper which he had not had time to read at the meeting, and he, too, had referred to the importance of the shape and size of body. He agreed with Mr. Fedden as to the sort of effects produced when there was a badly shaped body behind a ring. s sany of our readers who might like to make inquiries, the telephone number of the London Clinic is Welbeck 4444. Major Mealing's accident MAJOR MEALING'S marriage to Miss Cournede has un- fortunately had to be postponed owing to an accident, Major Mealing having fallen from a ladder and hurt his spine. We hope that his injuries will prove to be less serious than they seem, and that he will soon be able to leave the Nightingale Nursing Home, Twickenham. U.S.A. air mail contracts cancelled ON February 9, President Roosevelt, through the U.S. Postmaster General, issued an order cancelling all domestic air mail contracts on the ground that sufficient evidence of collusion and fraud in securing them was believed to exist. The Army Flying Corps was placed at the disposal of the Postmaster General for the carrying on of the air mail services. Col. Lindbergh sent a telegram to the Piesident, in the course of which he said: "Your order cancelling all air mail contracts condemns the largest por- tion of our commercial aviation without a just trial." It " does not discriminate between the innocent and the guilty, and places no premium on honest business." According to Col. Lindbergh, America has been leading the world in commercial aircraft, engines, equipment, and organisation of air lines, and the greatest part of this pro- gress has, he says, been brought about through the air mail, subsidised by the Government. 158
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