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Aviation History
1914
1914 - 0253.PDF
MARCH 7, 1914 An Edited by V. E. JOHNSON, M.A. Attempt to find the most suitable Wing Shape for Model Monoplanes of the Loaded Elevator Type. By JOHN M. HERON. The experiments were carried out with wings of 30-in. span and 4^-in. chord fitted to a 36-in. A-type frame ; the elevator employed was oval in shape, uncambered, of 3^-in. span and 2-in. chord. The motive power was two 10-in. bent wood propellers, with eight strands of A-in. strip rubber to each. Experiment 1.—A rectangular wing with £-in. camber (Fig. 1). Flight very erratic, great tendency to dive, no lateral stability, the model frequently diving sideways and alighting on the wing tip. Experiment 2.—A similar wing to No. I, but with the tips up turned 1 in. (Fig. 2). Flight still erratic, with a decided tendency to dive, but great lateral stability, the model quickly righting itself, even when launched at an angle of 45° to the horizontal. Experiment 3.—A semi-crescent shape wing with \-'va. camber. Tips upturned I in. and retreated 1 in. from the leading edge (Fig. 3). Flight steady but with a slight tendency to dive. Great lateral stability. Experiment 4.—A crescent shape wing with \ in. camber at the centre, gradually decreasing to a wash-out at 3 ins. from the tip, nai PLAN ELEVATION no 2 ^= PLAIN ^ LLLVATION no 3 w PLAN ^ LLLVATION FIG 4 ELEVATION i in. reverse camber ij ins. from the tip. Tips upturned 1 in, (Fig. 4). Flight very steady, with no tendency to dive. Great lateril stability. This model was not upset by even strong gusts of wind. Deductions.—A flat wing such as No. I posesses little lateral stability, because when struck by a side gust the tip is either lifted or depressed, and the model, being unable to right itself, dives side ways to the ground ; whereas a wing with upturned tips such as Nos. 2, 3, and 4, when struck by a side gust, immediately it starts to dive sideways, is brought back to the horizontal position by the upward curve of the tip. Again, a rectangular wing shape such as Nos. 1 and 2 have a tendency to dive because any decrease in speed of flight of the model brings the weight of the elevator into play, the nose tends to fall, and the model dives until the speed of flight increases sufficiently to enable the model to elevate once more, this diving and elevating continuing until the driving power of the rubber motor is expended ; whereas a crescent shaped wing with its retreated tip and its reverse camber, such as No. 4, overcomes this tendency to dive in same manner as the upturned tip overcomes the sideways dive, the model when launched rising in the air and gradually, as the power of the motor becomes expended, planing giacefully to earth. [With regard to the diving referred to above, a great deal depends on the position of the e.g. and the correct sine and setting of the elevator. When one sees models of types 2 and 4 flown by expert flyers of these respective types, it is not unfrequently very hard to say which shows the greatest longitudinal stability. Type No. 4 has undoubtedly the greater possibilities.] Some Suggestions let 1914 Competitions. The Royal Aero Show at Olympia will very soon be here, and the results of the model competitions, with their lessons, will be, ere long, a thing of the past. Whether club secretaries generally will wait until the results of these competitions are known before drawing up their summer programme, I do not know. Probably, in any case, some dates will, at any rate, be left open. How ever, apart altogether from any considerations referring to the above, it appears to the writer that, broadly speaking, something in the way of finality has been reached by our present methods, and that it would be as well to break fresh ground, in some directions at any rate. I have no doubt that during the present summer most, if not all, of the present "records " will be broken, and some ntw ones of an entirely different character will be established. We are also bound to have some very interesting and probably very exciting and closely contested competitions of a sporting character between the differ ent clubs for the Farrow Shield, which should do much to keep existing clubs "going," and even add to their number. The two trophies offered by Sir John and Lady Shelley for power-driven models will, we hope, also lead to some interesting and valuable results, to say nothing of the forthcoming Exhibition competitions. But if we mean, if we really want, the model aeroplane to play that part in the development of the full-sized machine of the future which it both should and could play, and if we want the clubs and the movement generally to receive and to continue to receive proper official recognition and support, it is no use whatever standing still. It is no good whatever having the same kind of competitions year after year, whether the competitors be many or whether they be few. We must progress. We must keep on moving. We may not, as a matter of fact, we no doubt shall not, always be moving forwards, sometimes we may go back ; it may be neces>ary to do so in order to find a new road, a new path, which leads farther than the par ticular cul-de-sac in which we temporarily find ourselves. Above all, it appears to be a matter of the greatest importance to learn from the designer and constructor of actual full-sized machines what " types" appear to him to be likely types for the future, and to concentrate on those types, rather than on ones which, no matter how interesting or attractive in " model " form, stand no practical chance of being used in full sized work. So far as aviation in this country is concerned, its most valuable asset (at present at any rate) undoubtedly appears to lie in the military aeroplane, both for land and water use. Such naturally divide themselves into two distinct types, the speedy scout and the swift but le*s speedy type of fighter. As to whether the first named should be either armed or armoured is a much debated question ; but in both cases there is no difference of opinion about one point, and that is that both must have considerable flexibility in the matter of speed; and the further removed from what is known as the " tangent" machine, which has practically none, the better. So far as the "fighter" is concerned, one of the most important items in connection with it is its ability to fire in every direction as far as possible. It should certainly be able to fire astern, as well as ahead. Suppose you are (purpo-ely) running directly away from your enemy; having this power to fire directly astern, then you most certainly have him, who is firing directly ahead, at a decided disadvantage. You are flying away from his shots, he is flying directly in'o the teeth of yours. He is also firing directly into the relative wind, whilst you are not. Every shot you fire helps you on, owing to the recoil. Every shot he fires retards him for the same reason. Now the above considerations pave the way, I think, to two very interesting competitions, one for " Variation in Speed." The prize to go to the machine proving itself capable of flying the slowest as well as the fastest, or since it would not probably win " at both ends," to the machine exhibiting the greatest range of speed. There will no dou'it be some diffi culties in connection wiih measuring the speeds and so on. But if we are going to be deterred by such matters as this, we might just 253
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