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Aviation History
1925
1925 - 0687.PDF
OCTOBER 22, 1925 THE " AUTOGIRO " DEMONSTRATION : Our group includes, from left to right, Senor J. de la Cierva,the inventor of the " Autogiro," Air Chief-Marshal Sir Hugh Trenchard, Chief of the Air Staff, Mr. C. LI. Bullock, Private Secretary of the Air Minister, Sir Samuel Hoare, Secretary of State for Air, Air Vice-Marshal Sir Geoffrey Salmond, Air Member for Supply and Research, Capt. Frank Courtney, pilot of the "Autogiro," Air Vice-Marshal Sir Sefton Brancker, Director of Civil Aviation, Mr. W. Sydney Smith,Superintendent of the Royal Aircraft Establishment, and Squadron Leader Rollo Haig. upon it. Perhaps the best way of realising the reason for itsrotation is to picture the " windmill " as being stationary, while the machine is travelling forward. Disregarding forthe moment the two blades which are in a fore and aft position, it will be obvious that the starboard blade is meeting the airleading edge foremost (the direction of rotation being anti- clockwise when viewing the windmill from above), while theport blade is meeting the air trailing edge foremost. The resistance of the blade travelling leading edge foremost issmaller than that of the blade travelling trailing edge fore- most, with the result that the windmill begins to rotate.It will be realised that during flight the blade which is travelling forward is at a greater relative velocity than thattravelling back, the one having the machine's speed added to its own velocity and the other having it subtracted therefrom.In a rigid airscrew the result would be that there would be more lift on one side than on the other. By reason of the blades being hinged, however, they are free to move up anddown, and in doing so virtually increase and decrease their angle of incidence, thus equalising the lift on the two sides.The special feature of the " Autogiro " is that centrifugal force is relied upon to keep the blades outstretched against theaction of the lift, and by slightly arching the blades the designer has attempted to ensure that all the stresses arepurely tensile ones (with, presumably, a slight torque or twisting stress caused by the travel of the centre of pressure.As the chord is small and the wing section carefully chosen, presumably this travel is small, and consequently the torqueis small also.) This, very briefly, is the principle of the " Autogiro." Anumber of interesting problems naturally arise, but with these doubtless the inventor, Senor de la Cierva, will deal in thepaper which he is reading tonight before the Royal Aero- nautical Societv. LONDON AEROPLANE CLUB DURING the month of September the two club D.H." Moths " have flown 88 hours 40 minutes. F. G. M. Sparks, the senior pilot instructor, gave flying instruction for 4Dhours 50 minutes, and G. T. Witcombe, the second instructor, for 42 hours 50 minutes. During the month there werefour davs on which no flying was possible. Since the opening of the club on August 19 last 72 members have received flyinginstruction, and of these several have completed over six hours dual control and three are flymg solo During the ^nding ftober 17 tl. fol ^^ Mr" £CSOAM. Beaumont, E A. Boyd, WEPJohntone, H. R. Thomas SO. Bradshaw, L G. Pollard, AJ L. Angus, N. H. Jones, j. Barros, A. P. Hunt, E. Thomson, A. Lees- Q N Warrick made the granted to a member who has received his flying instructionin the light aeroplane clubs. There were practically four blank days during the week onaccount of fog and rain. The total flying hours for the week were 10 hours 25 mins. This was done on the one machineonly. The machine damaged last week has now been repaired by the De Havilland Company and was handed back to theClub on Saturday. The following arrangements have been made for bookingtimes for flying instruction :— On and after November 1, bookings for flying instructionmay be made for one-hour flights. The total time booked for any one week must not exceed two hours. Bookingscannot be made for more than one week ahead. Owing to the large demands for bookings by the presentmembers and the somewhat long waiting list, it has been decided by the committee not to elect any further membersthis year. 687
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