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Aviation History
1916
1916 - 0147.PDF
FEBRUARY 17, 1916 ALL communications in connection with this section should be addressed to the Model Editor, «' FUGHT," 44, St. Martin's Lane, London, W.C. Correspondents are requested to write on one side of the paper only. Experiments with Divided Tall Models By G. H. KILSHAW, Liverpool Aero Research Club. BEFORE starting a description of the various designs of divide 1 tail models experimented with, it may be mentioned that the first of these was suggested after a series of interesting stability experiments with paper gliders, the notes being published in " FLIGHT," Nos. 210 and 211, January, 1913. It appeared that this design was capable of adaption to a military type machine, model. J model 3 1?2odel £. rrc«ifel.4 K.li^ie Perspective views showing the development of Mr. Kilshaw's experiments. some of the chief points likely to be of advantage being :—I. Clear view ahead, enabling free forward gun fire. 2. Increased stability. 3. Employment of a short fuselage. 4. No disturbing influence from propeller draught on the tail. The first machine (1913) is shown in scale at Fig. 1 ; it had a span of 34 ins. and a total length (front of plane to rear of tail) of 17 ins., and a carved propeller 11 ins. diam. and 20 ins. pitch. A clear idea of the reversed camber employed at the tail ends is shown in sketch Fig. 2. In Model 2 these were discarded owing to the reaction bringing the main weight more forward than was thought advisable, although the stability shown was very good, especially while banking. In Model 2, the length of flight was better, showing greater efficiency, there being no apparent difference in the stability, the only alteration being the omission of the shaded tail portions in Fig. I. A S ft. 8 ins. span scale model built to Model 2 design is shown, being exhibited in the Holt Secondary School, Liverpool, 1913, and the Y.M.C.A. Hall, Mount Pleasant, Liverpool, 1914. There was noticed, however, in the previous two machines mentioned, a certain amount of sluggishness, and although Model 2 showed improvement in this respect, it was decided to pursue this question further. The most likely cause of this was thought to be due to the close proximity of the main planes in relation to the tail, and with this in mind Model 3 was designed and built, and is shown to scale in Fig. 3. In order to give as much clearance between the main and tail surfaces as possible, the main planes were swept forward from the centre, and in order to counteract any tendency to spin were retreated near the tips, with a negative angle of incidence. Results with either single or twin propellers were not very encouraging, the directional stabilty being very poor, with increased sluggishness. In order to properly test this, the tail surfaces were detached, and fitted with a forward elevator, the model was flown as a twin canard type, as shown in Fig. 4. It proved an exceedingly ineffi cient flyer, as demonstrated by amount of the power required to mike her fly. Keeping this in mind, and reverting back to the previous models, 1 and 2, it was at last decided to do away with the overhanging portions of the main planes, and to increase the tail plane surfaces sufficiently to make the loading of the machine comparatively light. Thus was evolved Model 4, shown to scale in Fig. 5, and the Plans, to scale, of Mr. Kilshaw's models. results were immediately satisfactory, and a decided improvement on the previous machines. Fitted as a twin-propellered model she showed up very well, with good stability and excellent climbing abilities, besides proving a very good wind fighter. The only thing deemed to need improvement was her rather rakish appearance, which was more pronounced when in the An exhibition scale model- air. In fact this earned for her the rather misplaced name, " The Angry Wasp." She seemed, however, more to suggest a dragon fly. Another thing introduced into this machine was a small forward vertical surface, which certainly improved the model's flying. To improve her appearance no great alterations had to be made, and Model 5 came into being. The main features of Model 4 were kept in view, and were in fact identical except for a rounding-off of the supporting surfaces. As experiments for a design of machine suited for fighting (offensive purposes) these tests ended here, but I see no reason why an efficient tractor could not be made incorporating this type. [The above contribution has been awarded a " FLIGHT" Certifi cate of Merit. It will be recalled that Mr. Kilshaw was awarded the first of these certificates for his work on paper gliders referred to above.—ED.] 147
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