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Aviation History
1911
1911 - 0148.PDF
[/ycHT FEBRUARY 18, 191 I. CORRESPONDENCE. V The name and address of the writer (not necessarily for publication) MUST in all cases accompany letters intended foi insertion, or containing queries. Pendulum Stability. Correspondents communicating with regard to letters which they have read in FLIGHT, would much facilitate ready reference by quoting the number of each such tetter. NOTE.—Owing to the great mass of valuable and interesting corre spondence which we receive, immediate publication is impossible, but each letter will appear practically in sequence and at the earliest possible moment. " Farman Type" Aeroplanes. [1065] 1 have received a letter from the Farman Brothers, who have done so much to bring aviation to its present stage, in reference to the publicity given lately to copies of their machine in this country. They ask me to point out in the Press that whilst they have taken no steps to stop the copying, they think that the limit is reached when in certain notices of copies of their machine a statement appears that " this type of flying machine holds most of the important records for duration flights, passenger-carrying and cross-country work." The Farman Brothers ask me to point out that the Inter national records for duration in the air and distance are held by the Henry and Maurice Farman machines respec tively, and that it is not correct to describe any unlicensed copy of their machine as being of their types. February 8th. G. HOLT THOMAS. Endurance Prize. [1066] Mr. E. Manville is to be congratulated not only for giving a very liberal prize, but for the fact that an endurance prize will do more good to aviation than several prizes awarded for speed alone. It is to lie hoped that other public-spirited persons who contemplate giving prizes will follow Mr. Manville's lead. I have been considering Uie possibilities of an endurance prize, and think one could not improve upon the following scheme, the winner to be the one who gains the greatest number of marks awarded on the following plan :— 40 marks for speed. 40 marks for the lowest petrol consumption per unit of weight. 20 marks for the lowest oil consumption per unit of weight. The unit of weight would be taken on the combined weight of the aeroplane, engine, aviator, passenger, petrol, and everything; in fact, the weight in the air. The marks for each aviator are easily found. The highest marks under each heading would be given to the best man, and the others would receive marks in proportion. The more you consider it the more you will discover all kinds of opportunities for securing useful information. The monoplane and the triplane could be fairly compared to see whether there is any advantage of the one over the other ; the chain drive compared with the direct drive ; plane areas. In fact, there is no limit to the important knowledge one could secure. I would very much like to be favoured with the opinion of yourself and your readers on this scheme. H. V. ROE. Flight Golf. [1067] Some time ago you suggested the game of " Flight Golf." I have not heard whether it has made much headway and think that there are some disadvantages about that particular game ; no doubt you had in your mind at the time the great popularity of ordinary golf. Though not so popular now, the game of bowls has long been known and seems to me particularly suitable for a substitute—there is plenty of bias on the " bowls ! " A " jack," in the shape of a pilot flyer, could be started in the ordinary way and would have the advantage of proving that the flight was possible, it would not be necessary then to encounter a side wind. Not nearly so much ground would be required for this game, an important point, as most model enthusiasts know, also there would be plenty of time for winding up as this could be done while necessarily waiting for one's turn. I should very much like to hear whether any of your readers have tried " Flight Golf," and if they noticed the drawbacks to which I have alluded. Thatcham, Berks. E. T. HAYNES. [1068] Mr. Kelham has curious ideas as to what a pendu lum is, according to his letter (1027), which appeared in the issue of your indispensable paper for January 21st, 1911. I have always understood that a pendulum was a swinging weight, and that a man pivoted at his armpits would corre spond to a pendulum. As to the machine " invented " by Planes, Ltd., this system of stability was discovered and found wanting by Bleriot, Saulnier, and Farman (monoplane), long before this firm was heard of, and the patent taken out by this firm was for a device to raise or lower the bottom plane of a bi plane up and down the struts, and not to obtain stability by a low centre of gravity, although the illustration to the specification showed a machine with all the weight under the bottom plane. Also, machines of this type are notoriously difficult to handle. Croydon. R. H. BUCKWELL. Dipping Front Edge. [1069] I should like to make a few remarks about the theory of the dipping edge of an aerofoil, through your valuable correspondence columns. First of all, how was this idea of the dipping-edge originated ? Surely it was copied from the bird's wing. Now this has to be of some appreciable thickness to take the force—it is in fact a little cantilever. In my opinion the dipping-angle found is of no importance, and that it is part of the stream line formation necessary to eliminate excessive head resistance of the girder. Figs. 1 and 2 illustrate more clearly what I mean. Now as the centre of pressure is close to the leading edge, the phenomenon of the dipping-edge resulted. To further illustrate my theory ;—On the Antoinette machine the girder is about the middle of the plane—and the dipping-edge nearly disappears ! See Fig. 2. Barrow-in-Furness. CLAUD W. PIDCOCK, [Our correspondent appears to somewhat misunderstand the conception of a dipping front edge. It is determined by the attitude of the plane in flight, not by its camber. Any cambered plane can be driven through the air with a dipping front edge and the theoretical advantage of doing so we have already explained,—ED,] 150
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