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Aviation History
1915
1915 - 0385.PDF
0 0 FLIGHT" PRIZES OF MERIT. WE print below an interesting communication to which a Fi IGHT Certificate of Merit has been awarded, and take the opportunity of reminding our readers of the main lines of the scheme, in which there are absolutely no rules, and no competition in the strict sense of the word. Whenever the Editor considers that a reader has sent in an especially interesting and carefully prepared communication which may be either in the form of a letter or an article, he will recommend the award of a prize, and the correspondent will' receive a little certificate of merit accompanied by a cheque for tr. It should not be difficult for any student of model aeronautics to win one of these prizes, but it will not be so easy that anvone can pick them up by merely writing a hasty note. They are prizes of merit and we have no intention of awarding them unless the communication is meritoriously above the average. To be meritorious ii is not necessary that the communication should be either lengthy or complicated, but it is necessary that it should show real miff! thought, an understanding of the subject written about, and be a good attempt to lucidly express the information in a way that can readily be understood by ottu-i*. Some subjects are adequately dealt with by a letter, others are lietter suited to a short article, while, with others again, the merit of the information may lie in the neatness and accuracy of a set of sketches, drawings, or photographs that illustrate how one may make something that is worth while making. THE BEST LENGTH FOR A FUSELAGE. By JOHN F. LEEMING. ALTHOUGH the following experiments cannot pretend in any way to be conclusive, the subject to which they are intended to relate presents an interesting problem. To our correspondent belongs the credit of appreciating the importance of this problem, and of having endeavoured to obtain some experimental data on the .subject with tin apparatus at his disposal. Although, as we have said, the research itself is inadequate, we commend the simple character of the initial test, and for this and the above-mentioned reason have awarded the FLIGHT Certificate of Merit.—ED. Both the tractorplanes were accurately weighed beiore and after the flights, while as every part on the one was the exact replica of the corresponding part on the other, the question of resistance was practically avoided. Each model weighed ; or.*., had a span of 24 inches, a chord of 3 inches, and was driven by one 8- inch Chauviere tractor. No. 1 was 38 inches long, and No. 2 30 inches long. No. 2 would rise and fly Ho to 90 yds. moderately steady, The following experiments were made to discover whether the gliding angle and stability of a model were improved when the tail was placed near to, or at some distance from, the centre of gravity on the aeroplane : in short, to find which position was best. On a full-sized aeroplane a more sensitive control is obtained by having the tail well away ; but, on a model where there is no pilot to manoeuvre the machine, this would seem to be an undesirable factor. The aeroplane with a good high gliding angle will obviously take less power to fly than one with a low angle ; therefore, it is of considerable importance for the model designer to know whether by putting the tail far away he is improving the machine or not. The instruments used to investigate this problem were four paper gliders, made from waterproof cartridge paper, and weighted with Harbutt's plasticine, which is by far the best material for the purpose. Every glider had exactly the same shape of planes, loading area, and aspect ratio, the only difference being the length offuselage. For the purpose of reference they were lettered, and each model was given eight trials (under the same conditions as the others) before the results were arrived at. For the wind test they were launched in an artificial draught caused by a large fan, and the results carefully checked by several flights out of doors. The span of each glider was 6 inches, the chord 1 inch, the weight '04 oz. (approx.) in rough weather A did best, being not so sensitive to the gusts which strike the tail as C and D. The machine with the best angle was also A, it was in fact by far the best. Two rubber-driven tractorplaneS, constructed in the same manner, but with a l"ng fuselage and a short one, fully bear these trials out—the one with the short fuselage flying with two less strands of rubber than its rival. For flying while No. I showed a strong tendency to land after the first 10 yds. or so, as if it had not enough power ; when to Stop this the tail was altered, great trouble was met with owing to the machine slipping backwards, no happy medium Iteing obtainable. When two strands of rubber were added, No, 1 certainly flew better than before, but it never equalled No. 2, which, having a less number Of strands, remained in the air longer. Therefore, as in the gliders, a short fuselage is best. Glider A. Glider B. Glider C. (Glider D. Length oi fuselage I in. Length offuselage 2 ins. Very good glider ; angle about Not such a good glider as A ; I in 9; flew quite straight, slightly slower, very quickly. Length oi fuselage 3 ins. Has a strong inclination to "switch-back"; quite slow. Ivength offusev'age 4 ins. To get the best result) with this model, ti ore weight had to be added : Hew q\m< well, but so sensitive to the tail that very few straight flights were obtainable. Wind Test. Wind Test. WindTest. Wind Test. Rocked laterally badly ; easy model to launch. a very Very unstable: rocks so badly Moderately stable ; has a strong that sometimes the model turns tendency to oscillate longi tudinally. Difficult to launch ; also it had a similar tendency to (ilidci C. completely over. ® ® The Laachester Trophy for Model Gliders. IT is announced in the annual report of the Aeronautical Society that it is hoped to publish before long full details regarding the important competition, having for its object the improvement of aerofoil efficiency, which is being organised. The chief award will be a trophy presented by Mr. F. W. Lanchester. ® ® Tests of Models In Wind Channel. IN the same report it is noted that the model competition to M undertaken, in co-operation with the Kite and Model Aeroplane Association, under the control of the Society's Kesearch Com mittee, has been postponed for a time, but will be taken up again at an early opportunity. 385
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