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Aviation History
1910
1910 - 1063.PDF
DECEMBBR 24, 1910. ITycHr] CORRESPONDENCE. *.* The name and address of the writer (not necessarily for publication) MUST in all cases accompany letters intended for insertion, or containing queries. Correspondents communicating with regard to letters which they have read in FLIGHT, would much facilitate ready reference by quoting the number of each such letter. NOTE.—Owing to the great mass of valuable and interesting corre-r dence which we receive, immediate publication is impossible, each letter will appear practically in sequence and at the earliest possible moment, CAN WE FLY FASTER? [970] Re (g\t,), I thank "Well-wisher" for his comments on my letter. He is quite right as to the bottom of the car giving a lift, it does give an appreciable lift, and, as in a boat, the closing up of the stream behind it after the greatest diameter of the car has passed gives a thrust. In my models I accentuate this thrust by placing two tractor screws, one on each side of the caT, just aft of the greatest diameter. I am now building a model—I think the tenth —5 ft. long, so as to get some idea of the thrust and horse-power required for a full-sized machine, and will send further particulars as soon as experiments are complete. Manchester Street. W. LE MAITRE. SMALL MONOPLANE. [971] Having been a reader of FLIGHT for some months, I thought I would take the opportunity of asking you a few questions about a small monoplane I am building. Do you think a 4 or 6-h.p. motor cycle engine will drive it ? The size is as follows: total length, 22 ft. ; total width, 22 ft. ; width of planes, 4 ft. 6 ins. It has 114 sq. ft. supporting surface. E. Grinstead. A. BINGHAM. [It is invoking great difficulty to attempt to fly with low powers, and there is certainly no justification for believing that a man- carrying machine of only 114 sq. ft. surface could be successful with 6-h.p.—ED.] THE MILITARY FARMAN. [972] With greatest deference I beg to challenge Mr. Roe's statement (927) that " the standard Military Farman, which is nothing but the ordinary Farman with extended planes, has been made successfully by several English manufacturers." Clapham Common. ALAN BUCHANAN (Paulhan's British Mechanic). AERODYNAMIC RESISTANCE. [973] Permit me to again encroach on your valuable space, to further pursue the philosophy of the problem of aerodynamic support as indicated in my letter of August 6th last, and published under No. 847 in your issue of October 29th. My closing words, " when once in motion," in this letter, admits Newton's law, and the initial launching of the aeroplane in the air, D wave, which when once created needs only to be maintained by the compensation of its energy losses, due to internal friction in the wave itself. The character of the wave would, I believe, be something like Fig. Ill, and my contention would furnish an adequate explanation to the admitted upward trend of the air in front of Ihe plane— otherwise difficult to explain or understand. This upward trend being in reality nothing else but the forefoot—if you will pass the expression—of the wave crested some miles away, as the case might be.* In connection with this problem the case of the steamship is interesting, where the minimum resistance is encountered when the wave travels with the ship, and the maximum resistance when the ship is faster or slower than its wave. The former case requiring only a maintenance, the latter more or less constant reproductions of the waves. Whether this possible difference in the speed of the ship and its wave will appear in the case of the aeroplane, I do not know, but it is reasonable to suppose that in this case, where the wave is created for a purpose and by the plane, the relative velocities of plane and wave are equal. However, to complete my case, I may venture the suggestion that a positive or negative drift—respectively represented by a smaller or larger than i Fig. II.—might be responsible for an acceleration or retardation of the wave in relation to the plane. Equal angles o and 8 would then represent maximum efficiency. In the case of the hydroplane you mention, the problem is of course analogous to that of the aeroplane. And if in both cases the speed (power) is reduced, the displacement of water or air is reduced, i.e., less mass of the fluid is for the moment engaged by the planes than is necessary for their dynamic support, with the consequent necessity for them to fall back upon static support more or less. I believe the above views are original, and I beg to put them forward through the columns of your valued paper in the hope that, right or wrong, they might serve their purpose as a contribution to the knowledge of the problem of flight. Leeds. E. MED4N. * The suggestion of a wave motion was to my knowledge first published by Dr. Ing. F. Bendemann in an article in " Zeitschrift des Vereines Deutscher Ingenieure," for May 14th, 21st, 28th, and June 4th, 1910, page 857, where Dr. B. refers to the similarity of the wake of the aeroplane to the stern-wave of a ship, and -the rise of air in front of the plane to the ship's stem-wave. THE "DAILY MAIL" PRIZE. [974] I note your leader this week dealing with the encourage ment of " all British " machines in connection with the Daily Mail ,£10,000 race. As the Royal Aero Club are at present engaged upon the task 01 . drawing up the rules to govern this contest, may I beg to suggest to them a scheme by which the "all British" machine may be Fig. 1 • Fig.n. Ftg.m. or which is the same, the initial creation of the wave, of course, requires the exercise of a force. This force, if constantly applied, would justify the h.p. formula you give, but in such case would mean a continuous reproduction of the wave. But the wave, once created, travels in the direction (and the opposite) of the plane, and it is now my contention that the plane rides upon the crest of this encouraged and the contest put upon a thoroughly fair and even basis for all competitors, whether rich firms or independent and oft times impecunious experimenters. The scheme consists solely of handicapping the various machines according to their predetermined speed through still air (maximum), independent of horse-power or area, monoplane or biplane. This I06l
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