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Aviation History
1914
1914 - 0204.PDF
FEBROARY 21, 1914- Edited by V. E. Mr. F. Handley Page's Lecture: The Discussion. MJt H H. GKOVES asked the lecturer: (1) What was the real cause of failure in full-sized Canard-type machines ; (2) Why should there be end losses in a. plane (or wing), since the air is sucked in, in the case of a propeller, and a plane is analogous to a propeller with an infinite radius. ,. , . Mr. G. P. Bragg-Smith said he quite agreed with the lecturer, and considered that he had set a good example in recognising that the model had a scientific value. In dealing with the discussion, he thought that although be held different views with regard to lateral stability, he was certainly not confined to the idea that there was only one way of obtaining it. As regards experiments with gliders, undoubtedly they were of scientific value ; but he thought that experiments with a model fitted with a propeller had a greater value, since such enabled you to take into account the propeller thrust, which was one of the most important factors to be reckoned with in a full-sized machine. Taking the case of an automatically controlled aeroplane, the effect of the propeller if placed in the correct position in the vertical plane, which he considered is such that the centre of pressure, centre of gravity and centre of propeller thrust are in a line, then when the propeller stopped, the machine auto matically assumed its gliding angle. He quite agreed with Mr. Handley Page's remarks re propeller behind, and he also believed that if the Canard type of machine were fully developed it would prove far superior to the ordinary type of full-sized machine, with its large plane forward. One reason why the propeller is best placed absolutely in the rear is that the propeller draught not coming in contact with any tail planes, did not affect its stability. In con clusion, he was convinced that the model would prove of greater value in aeronautics, if its lessons were properly appreciated than in any other engineering science, and that, had manufacturers paid more attention to it and recognised its merits, they would have saved themselves a considerable amount of trouble and expense. Mr. F. Mayer : Mr. Handley Page had said that the aim of many designers of stable aeroplanes was the ultimate production of a machine without either front or rear stabilizing planes, with the necessary outrigger or body to support them. The lecturer spoke of having made a step in this direction in his experiments at Hendon, when the empennage of the Handley Page biplane was removed. The speaker had also made some experiments with the same idea in view. The main surface of the models experimented with was of the double curve or S section. Pirection of flight. He found that he was able by such means to produce very stable gliders of 3 to 10 ozs. in weight. These'gliders were quite a success without the use of either any front or rear elevator or damping JOHNSON, M.A. surface. The next step was the building of a power-driven model fitted with one of his early petrol motors, which it was hoped would possess the same characteristics. After a few adjustments and experiments the model did actually fly, but so many difficulties were met with that we were forced to take a backward step and fit a tail plane This had the effect desired—i.e., the resultant model flew well, but the tail plane completely upset the stability of the w^ curve 1 of the main plane, so we removed the turned-up back edges of the main plane, which were really large flaps, and had then left a plane of the ordinary camber. This was found to be an improvement so far as stability was concerned. It seemed as though the w^ sectioned main plane on their own account were very stable, but in conjunction with a tail the stability did not appear to be nearly so good. Referring to the question of weight carried per unit area at a given speed on large and small planes, Mr. Mayer said he had tried two models—one a power-driven one, and the other a model driven by rubber. The rubber-driven model was exactly a quarter the size of the other, and both flew at almost exactly the same speed, which, as near as coul d be measured, was about 17 miles per hour. The large model carried from 2 to 3 oz. more per j square foot than the smaller one. This he partly put down to the fact that the angle of incidence of the rubber model was rather larger than is usual for models of this kind. Both models flew at the same time and in the same attitude. The plan of the surfaces of the S curve model was as per rough sketch. How Long Ought Rubber to Last? A correspondent writes as follows : "Could you kindly tell me how long model aeroplane rubber ought to last ? I use J-inch strip rubber (8 strands), and I have tried several lubricants, but can never get the rubber to last more than a week or two, sometimes the strands burst separately, but several times all eight strands have gone simultaneously, after only being in use a day or two. The rubber used was quite new, and seemed in good condition. My model is 30 ins. long, and I never wind my rubber motor up more than 450 turns. The rubber does not go near the hooks, so these cannot have worn ; it generally breaks in the middle. I should much like to know the best way of preserving it and how long it ought to last ? " Your rubber under such circumstances as the above ought to last quite a good time, with care. We can only conclude it is not good rubber. Refuse any and all rubber which when bought will not stretch to at least eight times its own length without fracture ; in other words you should be able to pull out a piece some 3 ins. long to a length of about 24 ins. I have just performed this actual experiment with some (unused) rubber which I have had for nearly a year (kept in a tin). Large trlplane model by Mr. L. S. Wyatt. 204
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