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Aviation History
1918
1918 - 0123.PDF
JANUARY 31, 1918. Rbvcil £Tero Cla of the United Kh^gdoi OFFIC8AL NOTICES TO ME.MBERS BE Presentation to the Club. MESSRS. BURROUGHES AND WATTS have very kindly presentedto the Clnb one of their best quality Billiard Tables in oak, fitted with their celebrated Patent Steel vacuum cushions. THE FLYING SERVICES FUND, administered by THE ROYAL AERO CLUB.THE Flying Services Fund has been instituted by the Royal Aero Club for the benefit of officers and men of the RoyalNaval Air Service and the Royal Flying Corps who are incapacitated on active service, and for the widows anddependants of those who are killed. The fund is intended for the benefit of all ranks, butespecially for petty officers, non-commissioned officers and men.Forms of application for assistance can be obtained from the Royal Aero Club, 3, Clifford Street, New Bond Street,London, W. 1. . .... Subscriptions. £ s. d.Total subscriptions received to Jan. 22nd, 1918 12,538 8 2 Staff and Workers of Gwynnes, Ltd. (fifty-fifth contribution) .. .. ,'. -.'. 10 11 II Total, January 29th, 1918 .. 12,549 o H. E. PERRIN, Secretary.3, Clifford Street, New Bond Street, W. 1. 'J WEB J \ [As a number of letters reach us signed with initials only,some of which do not give a complete address, we would point out that such communications cannot be dealt with in ourcolumns. Full name and address, which will not be published, must always be given.—ED.] W. R. H. D. (N.Z. Engineers).—The static thrust of anair screw is no criterion on which to judge the thrust obtain- able with a given engine. It is quite conceivable that a screwwhich gives a high static thrust will give a small thrust when mounted on a machine travelling through the air, andsimilarly an air screw may be very efficient in flight but give a fairly low static thrust. This is, however, a question whichspace does not allow of discussing in these columns. From the formula 550 x HP. x E,1 - ^ it will be seen that if the efficiency of the propeller remainsthe same, the thrust obtainable with a given engine depends only on the translational speed. Thus, if on a certain machinefitted with this engine the thrust is found to be T lbs. at a speed of v ft. per sec, if the efficiency of the new air screwis the same as that of the old, the thrust on another machine built for a speed of* -zv ft. per sec. will be only T : 2. To givea numerical example : Suppose your engine develops 50 h.p. and is installed in an aeroplane which flies at 80 ft. per sec,and that at that speed the propeller efficiency is • 70. The thrust T will then equal 550 x 50 x-70 . 8o - 24° o 1Ds. Now suppose that the same engine is put into another machinedesigned to fly at 160 ft. per sec, and that the propeller for this speed also gives an efficiency of 70 per cent. The thrustwill then be . 550 X50 X70 160 = 120-3or just half of the thrust delivered in the slower machine. W. S. (R.G.A.).—The machine in the illustration you referto is a BE2C. The twin-engine machine in the Gallay radiator advertisement is a Dyott biplane, flown at Hendonin 1915. We believe that Gamages stock compressed-air motors suitable for model aeroplanes, G. E. P. (Boston).—The meaning of the letters BE, RE, FE,and SE has already been explained in these columns, but for the benefit of our many new readers it may be repeated here.The letters BE were adopted in the first place to signify Bleriot Experimental, as the machines of this type were fittedwith tractor screws. In the same manner FE represents Farman Experimental, the " pusher" type with enginebehind. RE indicates Reconnoitring Experimental, and SE Scouting Experimental. The formula o.4<f-N is no longerany criterion of the power output of an aero engine, since with the improved efficiency now obtained all engines developconsideiably more power than that indicated by above formula. In his book on aero engines Mr. G. A. Burls suggests thatapproximately correct results may be obtained by altering the formula to o&dFH, or 50 per cent, more than the powergiven by the R.A.C. formula. For an engine of so low power as 40 h.p. there would probably be no gain attending theemployment of two air screws instead of one, as any gain there might be in the efficiency would probably be counteracted bythe loss in the transmission gear necessary when two screws were employed. No definite answer can be given to thequestion of the type of sockets employed for inter-plane struts of the "I" type, as the various makers use different methods.A detailed description with scale drawings of the Avro triplane was published in our issue of April 1st, 1911, a copy of whichcan be obtained from the offices of " FLIGHT " ; the price isis. 6d. post free. The roll shown in your diagrams has been done on Nieuport scouts, and is, we believe, known as the" apple turn-over." H. J. U. (Surrey).—The red, white, and blue stripes onaeroplanes are identification marks. We should not like to say this machine is the fastest in the world, although it iscertainly very fast ; no figures relating to its may, however, be published. The Sopwith " Camel " has not, as you appear tothink, its top plane sloping down ; on the contrary, the top plane is straight and the bottom plane is set at a dihedralangle or sloping up. Under certain conditions a four-bladed propeller may be more efficient than a two-bladed, especiallyfor transmitting high power, as the employment of four blades allows of keeping the diameter somewhat smaller. G. A. (Hampstead).-—Generally speaking the BE2E andthe RE8 are a good deal alike. Apart from the engine, however, there are minor differences. For instance, theplacing of the wings is farther back on the RE8 than on the BE2E owing to the longer engine. The tail also is somewhatdifferent, and the seat back of the RE8 is placed farther back than the back seat of the BE2E. For identification purposesthe deH2 and the FE8 can best be distinguished by the formation of the tail booms. In the former the tail boomsare of similar formation to those of the Henry Farman, while in the FE8 they are parallel in plan but converge to a pointat the tail when seen from the side. We have not published any large scale drawings of a Curtiss " Wireless." F. E. T. (St. Albans).—See reply to G. E. P. (Boston). 119
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