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Aviation History
1926
1926 - 0040.PDF
JANUARY 21, 1926 SOCIETY OF MODEL AERONAUTICAL ENGINEERS ON Tuesday, January 12, before a large gathering of members at the Central Y.M.C.A., Mr. W. E. Evans gave a lecture on " Model Aeroplane Propellers." After emphasising the importance of the propeller, or more strictly speaking, the airscrew, of an aeroplane and the: necessity of drawing a • complete design of same to suit the weight and flying speed of the model to ensure good flights, Mr. Evans proceeded to design a propeller to specification laid down in the rules for the recent propeller competition. This being very clearly and simply done, practical operations in forming the wood block, testing pitch angles, and finally balancing, were demonstrated. Laminated blocks were essential if correct pitch angles were to be depended upon for any length of time. ( A specimen laminated propeller 12 in. in diameter wasshown with pitch angles O.K. after being in use for four years. This concluded the first part of the lecture, the second part followed immediately, and was even more instructive. The subject was " Testing Model Propellers for Static Thrust." The apparatus used for the tests was <>'. exhi^ted, and consisted of a small electric motor to which . was Attached a revolution indicator, these being mounted -on a base-board which, when in use, is suspended by four fine piano wires,from the ceiling of a room. A needle pointer below the baseboard registers the static thrust in ounces and fractions of an ounce on a calibrated scale fixed on a table. The suspension method, together with the slip stream of the propeller travelling away from the apparatus, eliminates all friction. The electric motor and revolution indicator are an improvement upon Mr. Evans's propeller-testing apparatus, which was in use by the Society four years ago when the power was obtained from a compressed-air container. Still further improvements in the machine are contemplated. Many propellers, nearly all of 10 in. diameter, this having been found the most suitable size for the motor, but with different pitches and blade areas, were shown, with accom- panying graphs recording static thrust at various speeds, including a variable pitch propeller with symmetrical blades, a three-bladed propeller, and a four-bladed one. The best graphs indicated thrusts of over 7 oz. at 2,500 revs., an important point being the fact that the maximum blade width had to be not less than 1^ in., and not more than 1-5% in., any excess either way causing the thrust to drop. Another important point not previously realised by most of the members was evident from all the graphs without exception, was that when the speed of the motor was doubled more than three times the thrust was obtained. The highest maximum thrust, 8 oz., was given by a three- bladed propeller, the pitch of which was equal to the diameter, viz., 10 in. The power absorbed by this propeller was only slightly more than that of a two-bladed propeller of same pitch and blade width, whilst an extra 1-oz. thrust was registered, the maximum revs, being 2,500 and 2,750 respectively for the full output of the motor. The four-bladed propeller gave only 1,800 revs., with a maximum thrust of 6J oz. It was apparent, however, that this thrust is comparatively good for the number of revs. The graphs all showed the same characteristic curve and gave members food for thought as to how they were to main- tain their durations of flight with a rubber motor and at the same time increase the speed of their propellers. On January 26, at 7.30 p.m., there will be an ordinary meeting at the Y.M.C.A. Agenda as follows :—(1) Arrange- ment of programme for 1926. (2) Question of reducing subscriptions. (3) A Club Journal (edited by W. E. Evans). (4) Fuselage formula. B. K. JOHNSON, Technical Secretary. Commercial Aviation in Japan THE Japanese Government has been asked for an appro- priation of 2,500,000 yen for the fiscal year 1925 for the purpose of extending the air service between Japan and the Asiatic continent, the Aerial Transportation Co. to receive a subsidy of 500,000 yen, and 2,000,000 yen being used to establish an air service between Osaka and Shanghai, and between Tokyo and Dairen. Royal Aeronautical Society's Lectures MAJOR J. S. BUCHANAN, A.F.R.Ae.S., will give a lecture this (Thursday) evening before the society on " The Schneider Cup Race, 1925." The next meeting will be the joint one with the Institution of Automobile Engineers (Inst.A.E. and not Inst. Ae.E. as, through a slip of the pen, it appeared in our diary of forthcoming events) at the Royal Society of Arts, on February 4. IMPORTS AND EXPORTS, 1924-1925 AEROPLANES, airships, balloons and parts thereof (not shown separately before 1910). For 1910 and 1911 figures see " FLIGHT " for January 25, 1912 ; for 1912 and 1913. see " FLIGHT " for January 17, 1914 ; for 1914, see " FLIGHT " for January 15, 1915 ; for 1915, see " FLIGHT " for January 13, 1916; for 1916, see "FLIGHT" for January 11, 1917;" for 1917, see " FLIGHT " for January 24, 1918 ; for 1918, see " FLIGHT " for January 16, 1919"; for 1919, see " FLIGHT " for January 22, 1920 ; for 1920, see " FLIGHT " for January 13, 1921 ; for 1921, see " FLIGHT " for January 19, 1922 ; for 1922 see "FLIGHT" for January 18, 1923; for 1923, see " FLIGHT " for January 17,1924 ; and for 1924, see " FLIGHT " for January 22, 1925. Imports. Exports. Re-Exports. 1924. 1925. 1924. 1925. 1924. 1925. £ £ £ £ £ £ Jan. ..2,213 3,546 52,239 83,728 2,219 291 Feb. .. 920 985 26,349 85,639 335 20 Mar. 11,381 - 34,113 56,881 509 9,355 Apr... 373 321 56,998 78,041 6,014 6,732 May..3,426 560 125,138 74,844 4,162 15,278 June..1,219 190 87,629 71,009 2,115 667 July..1,510 184 179,292 159,262 2,708 870 Aug... 687 469 247,982 113,054 950 — Sept. 4,383 1,224 67,749 111,237 641 213 Oct. ..2,715 460 143,512 114,563 3,743 855 Nov...2,349 837 100,505 84,163 1,007 2,314 Dec... 108 1,806 90,172 104,745 24 19,004 31,284 10,582 1,210,104 1,137,166 20,698 55,599 m m m m PUBLICATIONS RECEIVED Report Xo. 214.—Wing Spar Stress Charts and Wing Truss Proportions. By E. P. Warner. No. 217.—Preliminary Wing Model Tests in the Variable Density Wind Tunnel of the National Advisory Committee for Aeronautics. By Max M. Munk. No. 218.—Standard Atmosphere—Tables and Data. By W. S. Diehl. U.S. National Advisory Committee for Aeronautics, Washington, D.C., U.S.A. Canadian Patent Office Record. Vol. LIII, No. 51. Decem- ber 22, 1925. The Canadian Patent Office, Ottawa, Canada. Price 25 cents. & M M W AERONAUTICAL PATENT SPECIFICATIONS Abbreviations : Cyl. «= cylinder; i.e. •= internal combustion : m. •= motor.The numbers in brackets are those under which the Specihcations will be printed and abridged, etc. APPLIED FOR IN 1924.Published January 21, 1926 21,768. DETHAVILLAND AIRCRAFT CO., LTD., AND A. E. HAIG. Aerofoils. (244,813.) 22,545. DOUGLAS MOTORS, LTD., and S. L. BAILEY. Pistons. (244,829.)22,806. SPERRV GYROSCOPE CO. H Gyroscopic navigational apparatus. (244,843.)25,660. J. TRSKA. Driving-gear for propellers and engine valve-gear of aircraft. (244,873.)28,539. H. O. SHORT. Sheet-metal hulls for flying-boats and seaplanes (244,898.)30,613. T. M. BARLOW and F. DUNCANSOS. Floats for seaplanes, etc. (244,911). APPLIED FOR IN 1925. Published January 21, 1926.13,214. F. SIEGRIST. Direction-indicators. (244,994.) FLIGHT The Aircraft Engineer and Airships 36, GREAT QUEEN STREET, KINGSWAY, W.C.2. Telegraphic address: Truditur, Westcent, London. Telephone : Gerrard 1828. SUBSCRIPTION RATES " FLIGHT" will be forwarded, post free, at the following rates :— UNITED KINGDOM ABROAD* s. d. s. d. 3 Months, Post Free.. 7 7 3 Months, Post Free .. 8 3 6 „ „ ..15 2 I 6 „ „ ..16 6 12 „ „ ..30 4 ! 12 „ „ ..33 0 • Foreign subscriptions must be remitted in British currency. Chenues and Post Office Orders should be made payable to the Pioprietors of " FLIGHT," 36, Great Queen Street, Kingsway. W.C. 2, and crossed Westminster Bank. Should any difficulty be e perienced in procuring " FLIGHT " from local newsvendors, intending readers can obtain each issue direct from the 1 ublishing Office, by forwarding remittance as above. 40
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