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Aviation History
1919
1919 - 0957.PDF
JULY 17, 1919 for a deeper and therefore stronger main girder, which gives it an advantage for the larger sizes. Incidentally it is also more difficult and expensive to produce. The balance between advantage and disadvantage therefore depends upon the particular function required from an aeroplane, and also on the skill of the designer in overcoming the peculiar difficulties of this problem. But the general conclusion is that the monoplane is most suited for the very small aero plane ; the biplane for all general sizes, and probably the triplane for the very large sizes. Experience during the War in general bears this out, although there have been instances which might be taken as contradictory to this statement. The importance of the successful use the Germans made of their Fokker- monoplane should not be exaggerated, as the real reason for this success was the production in large numbers of a good single-seater with a rotary engine copied from the French Gnome, combined with the new synchronised guns, and a fresh method of attack. When we tested the aeroplane ourselves, and compared it with our own under similar con ditions, its performance was, in fact, very little superior to the " B.E.2C " against which it was so effective. Our designers, on the other hand, made a very successful triplane fighter with a similar sort of engine. The main objectives of the designer in this case were handiness and view ahead. Handiness was obtained by very small span, and view by placing the pilot so that his eye was in the line of the centre plane. However, as far as this country was concerned, the general decision was the selection of the biplane as the simplest and soundest type for all ordinary work. Climb requirements.—The most valuable quality in a war aeroplane and the one most difficult to supply is, no doubt, climb. Practically all other considerations are opposed to fast climb, such as high superficial loading, direct drive engines, high speed and long range. But the demand by pilots for a high rate of climb, both as a protection against anti-aircraft fire and to increase their fighting capacity, was so great ^that this quality had to be provided. The range of guns, or rather their power of accurate shooting at a height, increased in an astonishing degree during the War. In the early days a height of 3,000 ft. was reasonably safe, and aeroplanes could do their work at that height. Then it was increased to 6,000, 10,000 and 15,000 ft. By the end of the War shooting even at 20,000 ft. was unpleasantly accurate. Whenever a new type of aeroplane appeared which could operate at an increased height, it was immune for a period, and could do its work almost unmolested, and in some cases without being perceived ; but this period seldom lasted long, and sometimes even before the new type was appearing in sufficiently large numbers to count seriously it was outranged. The same state of affairs applied to the height at which fighting took place, which gradually increased from year to year up to 20,000 ft. In order that the pilot could fight in a satisfactory manner he required a good rate of climb as well as the uppermost position. The difficulty of providing climb in an aeroplane during the first two years of the War was enhanced by the constant increase in the number of accessories required to enable the extra military functions to be carried out. These accessories added largely to the weight and also to the air resistance, and it was not until specially designed aeroplanes appeared that the position became satisfactory. Interaction of engine and aeroplane design.—Progress in aero plane was very much bound up with the progress in engine design ; in fact, it can be broadly stated that during the whole of the War the aeroplane designers were waiting upon the engine designers, and as soon as any new engine was developed to a satisfactory point it was but a short time before aeroplanes were in service, making the maximum use of such an engine, or at any rate a thoroughly effective use. It is interesting to compare German practice with our own. The Germans realised at an early stage the necessity of large engines, and they concentrated their attention on the production of a first-class but simple type of motor. This had a straight row of six cylinders of an average weight per horse-power, neither excessively heavy nor particularly light. They standardised this type at a comparatively early date, and consequently made early advances in production and reliability. Our policy was by no means so definite, and our engine designers worked on a number of different types : air-cooled rotary, radia', and in V, water-cooled, 8-cylinder, 12 cylinders The Douglas-Pennant Case A SECOND White Paper (Cmd. 254) has been issued by the Air Ministry containing a further number of letters IBSEI in V, and 6 cylinders in line. At no time did we rigidly standardise a single type. In consequence we had far bigger difficulties in production, and on the whole our motors were not so reliable. Ultimately, however, we progressed much further than the Germans, both in the power of the engine and in the reduction of weight per horse-power. The reduction of weight of the aeroplane per horse-power can be obtained in either of two ways : (1) by having a very powerful engine of average weight per horse-power, so powerful that the weight of the pilot and his military gear is relatively an unimportant factor ; or (2) by having an engine of ve,ry light weight per horse-power. This point is best illustrated by a short analysis in weight per horse-power, comparing two aeroplanes which are both single-seated fighters, and of the same lbs. per horse-power. Large aeroplane— lbs./h.p. 300 h.p. engine, weight .. .. .. 3| 2 hours' fuel, oil and tanks . . . . .. 1 \ Pilot and gear .. .. .. .. .. 1 Aeroplane structure weight .. .. .. 3 Total weight, 2,700 lbs. Small aeroplane. 200 h.p. engine, weight Fuel, oil and tanks Pilot and gear Aeroplane structure weight lbs. 'h.p. 'I J 3 Total weight, 1,800 lbs. The first type has a large water-cooled engine, is economical in fuel, and by reason of the size of the engine, the pilot and his gear account for only a small proportion of the total weight ; whereas on the small aeroplane the engine is a light weight air-cooled engine of heavier consumption, and the weight of pilot, etc., is a much larger proportion of the whole weight. The two aeroplanes would practically give the same per formance, but the smaller probably would be the better 1917 rro Fig. 7. fighter because of its greater manoeuvrability. There are many other factors to take into account, such as reliability, pilot's view, ease of manufacture, etc., all of which must be considered before coming to a decision as to which is the better type. Generally speaking, the tendency during the War was towards the heavier aeroplane, although there were two periods when the light-weight engine reversed this. One was when the 80 Le Rhone Sopwith Pup supplanted the 140 R.A.F. B.E. 12, and the two 100 h.p. pushers D.H. 2 and F.E. 8 ; the other was when the small air-cooled Wasp engine was competing with the 275 water-cooled Rolls-Royce Falcon. (To be continued.) relating to the termination of the appointment of the Hon. Violet Douglas-Pennant as Commandant of the Women's Royal Air Force. 959
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