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Aviation History
1924
1924 - 0052.PDF
the disparity between ideal and real values may arise. As stated at the beginning, these causes are not entirely unique to aircraft material, but become of greatest importance in this aircraft because of the smaller margin allowed for such like defects. Granted the existence of the defects or imper fection, the question arises at once as to whether the margin provided is sufficient to be safe. No simple answer can be given to this question. For some materials and under certain conditions the answer would be easily the opposite of that for other metals in other conditions. What is certain is that in general it is none too great, taking ail in all. A second question naturally arises when it is asked how- may the margin be made most effective—or (what amounts to much the same thing) how may the defects be rendered most ineffective. Again there is no golden gospel that preaches salvation for all cases, but certain beneficial lines of action have been indicated earlier. In the first place, it is a very good rule to decide that a material shall be used only in that state in which it possesses the most satisfactory combination of maximum stress and ductility. There are definite limits to the possibilities in respect of both types of property, and these should be carefully respected. High maximum stress in the absence of adequate ductility does not constitute strength, but weakness. Hardened metals—whether hardened by working, as in aluminium, or by quenching, as in alloy steels—are not ductile or tough. The values of both properties can, however, be markedly improved by reheating the metal to suitable temperatures. The most suitable temperature depends upon the nature of the metal, the type of hardening, the degree of hardening, and the purpose to which the part is to be put, but it is a good and sound rule to make the re heating temperature as high as possible. Besides its direct effect upon the toughness and ductility of a metal, this process also has decidedly beneficial effects upon the elastic limit, proof stress, fatigue range and freedom from internal stress. For the purely metallurgical defects such as inclusions, nothing need be said here, as the aircraft constructor cannot do any thing practical with them that has any remedial effect. H H m J3 REMINISCENCES OF THE EARLY DAYS OF AVIATION AT BROOKLANDS* IN 1919 I was travelling from London to Cambridge. An R.A.F. pilot, who was looking out of the window of the dining car, remarked on the curiously-shaped piece of water we were passing. I looked out, and saw that we were passing the flooded Lea Marshes. My thoughts went back to ten years before, and the work which was done on this marsh by Mr. A. V. Roe and his assistants. All this pioneer work is now largely forgotten. The memories of those days of hard work and high hopes, some of the hopes fulfilled and some of them disappointed, made me consider that it would be well that I should write them down while still fairly fresh in my mind. As I thought of the men who had done the work, I began to realise that most of them had paid the penalty of pioneers, and could never relate their memories. So I am endeavouring to tell you of those days, drawing on memory only, and not referring to any periodicals or diary. If, as a result, I omit the work of any pioneer or cast a slight on the work of anyone, I ask indulgence. All memories are apt to be distorted by time, and events take a personal perspective instead of historical sequence. On July 13, 1909, Mr. A. V. Roe made a hop of about 100 ft. length on his triplane fitted with a 9 h.p. Jap motor-cycle engine. This was the first flight on an all-British aeroplane. Two days later this was repeated, and a photograph of the flight was published in the Daily Mail of the following day. It was not much of a flight : just a hop with a minor crash, but it was a beginning. The triplane was a curious con struction showing much originality, and more nearly resembled modern machines than did any other aeroplane of that date. The Lea Marshes was far from being an ideal aerodrome. The ground was divided by three fences. The two parts near the railway arches, which served as hangar and workshops, were covered with stumps of wood, used to tether donkeys and goats. The further portion was of fair surface but small, probably about 10 acres, and was bounded on two sides by water, on the other sides by Lea Bridge Road and a fence. Those were days of toil. Every hop meant a crash. The procedure was as follows. At 4 or 5 a.m. we assembled and carefully wheeled the triplane out of the railway arch down the tow-path beside the River Lea—a difficult job, as there was a small gate to pass through, and the tow-path was narrow. Having pushed the triplane to a suitable corner of the ground, amid the jeers of the onlookers, we endeavoured to start the engine, which usually took 15 minutes. Mr. Roe, having given the word " Let go," allhis assistants seized tools, pieces of timber, and other appliances, to repair the inevitable smash. One kept a cycle and a fire extinguisher handy, and followed as close as possible in case of fire, which was not infrequent. When the landing took place after a hop, which might be anything from 10 to 120 yards, if a miracle had occurred and the machine was still intact, the process was repeated until the inevitable crash took place. We then partly dismantled the triplane and carried it home, amid further jeers from the onlookers. Then work started, and we worked for days in the very damp and dark railway arches to prepare for the next crash. The average programme was two weeks' work, a 50-yards hop, crash, and work again. At first no one with any sense stopped to watch the madmen, but after M. Bleriot had crossed the Channel we had another • Abstract of paper read by Mr. R. L. Howard-Flanders, before the Institution of Aeronautical Engineers on January 11, 1924. difficulty—that of sightseers. On one occasion the trams and 'buses were stopped and the police complained, so Mr. Roe had police persecution added to his other difficulties. The story of Brooklands aerodrome commenced with Mr. A. V. Roe's attempts in 1908, but the first real flights were made by Paulhan in October, 1909, and shortly afterwards the aerodrome commenced its activities, with Messrs. Astley, Lane, and Neale. Mr. Ravnham came to the aerodrome to learn construction in December, 1909. The original sheds had no windows, so we had to take the shutters down for light, and during the cold winter we had an old bucket with a coke fire to warm the handles of the tools. It was an awful time : mud floor, leaky roof (we used the sheds before the roofs were finished), cold, long hours and floods. However, the coke fire cheered us a lot, because the smoke made us think it was warm. The Lane monoplanes were a very promising type, well made and of fair design. The chief point of note was the undercarriage. The wheels were in forks, which allowed them to track and also move fore and aft, this latter motion giving the shock-absorbing vertical motion. It was not unlike the front forks of a Triumph motor-cycle reversed. These monoplanes had biplane tails, the lower plane fixed and upper plane hinged to act as an elevator. The results were rather poor on account of interference. However, I saw some good flights with these. The first aeroplane designed and built at Brooklands was the Neale " Pup," a monoplane of 29 ft. span and 5 ft. chord with aileron control. The engine was a 9 hyp. Jap without auxiliary exhaust posts, and was geared down 3|- to 1 with a spur gear, so the propeller shaft lay on top of the crankcase between the cylinders. The motor unit was heavy—about 14 lbs. per h.p. The whole machine, with Mr. Raynham in the seat, and petrol and oil for two hours, weighed 450 lbs. The factor of safety was high—probably about 7, but the undercarriage—on the lines of a Bleriot—was weak. The planes had too little camber—about 2 ins. for the under surface and 6 ins. for top surface, with a parabolic curve drawn by eye from a small drawing. This gave 45 lbs. per h.p., 3£ lbs. per sq. ft., which, with the inefficient camber, prevented sustained flight. The streamline was good, so the machine could be got off the ground without trouble, but it sank back to earth after a short hop. By Easter, Brooklands was a very busy place. The Petre Brothers brought their monoplane, which was a marvellous piece of construction The fuselage, spars and ribs were of lattice-girder construction, riveted together with copper boat nails and rooves, the material being ash and swamp elm, no wires being used except for external bracing. The con struction was light and rigid ; the cross-sectional areas were insufficient to take the compression forces, hence it was not strong. It was unsuitable for experimental use. because a slight smash strained every joint. The outstanding feature was the position of the engine and propeller. The engine was just between the main spars, driving a long shaft of 2-in. 16 s.w.g. tube with universal joints at each end, to the propeller in the tail. As the tail skid was long, to protect the propeller and fix the height of the tail, the angle of the main plane was variable. The pilot sat in front. This monoplane was engined with a 40 h.p. N.E.C. two-stroke engine, which gave much trouble and little power—probably about 25 h.p.
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