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Aviation History
1914
1914 - 0154.PDF
FEBRUARY 7, 1914. A Simple Tractor Monoplane. THE accompanying scale drawings and the following particulars of a small model tractorplane are sent us by Mr. R. Pinniger. The main planes are constructed of 18 s.w.g. piano wire, and the tail and rudder of 20 s.w.g. The fuselage is made from ru-in. poplar, with ^Vin. °y -rV>n- bamboo for the struts. The landing chassis consists of a skid of hickory, to which a vertical strut is attached by means of a T-socket, which is also bound higher up to the bearing and one of the longitudinals. Pinnlger's tractor monoplane Further, a piece of bamboo is attached as shown at C, and the axle is fixed rigid on to the skid. The wheels are 2 ins. in diameter, and were obtained from Messrs. J. Bonn and Co. The bearing is constructed from a T-piece of brass, as shown in the drawings. The tractor screw is 10-in. diameter and 18-in. pitch. The reason why an opening is left in the central part of the trailing edge of the main plane and the join-up is made towards the leading edge is that it leaves the trailing edge more flexible, and enables a small angle of incidence to be given to the main plane if desired. Edited by V. E. JOHNSON, M.A. Mr. R. V. Tlvy's Steam-Driven Model. We give this week an illustration of this model, a brief account of which appeared in our last monthly report under The Eristol and West of England's Aero Club's model notes, p. 129. Mr. Tivy, in his communication accompanying the photograph says: "The loading will probably strike you as being quite abnormal. How ever, the machine rose at quite a low speed when it was driven by a rubber motor, the loading then being 17-6 oz. per sq. ft. At the time of leaving the ground fully half of the wing ^as at a negative angle. As mentioned in the report, the speed at which the model will leave the ground with the engine on board has been found to be about 20 m.p.h. My contention is that for a given engine power a ' Weiss' wing will carry about double the loading employed on the power-driven machines of the present day, and I do not think that the experiments with a full-size ' Weiss' machine which are, I believe, to be conducted will disprove my assertion. " The difficulties I have experienced so far with my steam plant have been entirely concerned with my lamp, and I must ask you to keep an open mind (as I am trying to do) as regards the possi bilities of a plant of this kind, until my experiments have proceeded a little further." Referring to our correspondent's last statement, we do not quite understand it. If the inference is that we are asked to keep an open mind re the possibilities of this type of plant in general, and not our correspondent's in particular, then there is no necessity for us to do so at all, because the writer has in his possession a blow lamp which is perfectly satisfactory and efficient. We quite under stand Mr. Tivy's difficulties in this respect: it is the crux of the whole problem, and it took, we believe, Mr. H. H. Groves some three years to solve it experimentally ; but the problem is a solved one, and Mr. Groves has published the results of his experiments, with respect to which Mr. Tivy is at liberty to take the fullest advantage. Mr. Tivy adds that he hopes to exhibit the model at Olympia ; we trust that he will do so, and that we shall have an opportunity of seeing the plant running (in the annexe, say). Something of this kind would greatly add to the interest of the Show in general. Mathematical Formulae for Model Workers. " For some time past it has appeared to me," writes Mr. A. E. Wollard, "that, in spite of the fact that many model makers are experimenting with regard to shape of planes, aspect ratios, cross sections, &c, it has been extremely difficult to take advantage of the data so gained. " To be able to make proper use of this data, I contend that it is necessary to put the deductions into correct mathematical formula?. Also, if the world is to benefit by the model makers' experiments, it is absolutely necessary to arrive at some definite basis on which to make any calculations that may be required. " It would doubtless be an easy task for an experienced mathematician to compile formulae, but although I know that there are many aeromodellists who have studied mathematics, the absence of formulas in connection with model work—and I should judge that from Mr. Handley Page's recent lecture that the same formulas would be applic able to full-sized machine work— suggests that they are either non - existent or are of such an incorrect and inconsistent character that it would be unwise to publish them. " In writing this I know that I am laying myself open to criticism, and perhaps some will think, even though they do not voice their remarks, that for all formulas required why not use those compiled by Eiffel, Lanchester and other experts. My answer to this is that model makers want to find out for them selves the basic principles, and even if the results should prove Mr. R. V. Tivy's steam-driven model.
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