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Aviation History
1942
1942 - 1477.PDF
JULY I6TH, 1942 FLIGHT 61 VOICES FROM THE PAST Recorded Talks by Schneider Trophy Contest Designers and the Winning Pilot A '' TECHNICAL hitch'' was responsible for the country hearing on the radio, on July 6th, the voices of the three men who had most to do with the winning of the Schneider Trophy Seaplane Contest in 1931, the third time in succession, thus making the trophy the property of Great Britain. Jack Northrop, the well- known American aircraft designer, was to have broadcast in the "I am an Aircraft Designer" series, but was pre vented, for technical reasons, from giving his talk. Instead the B.B.C. broadcast records, made at the time by Vickers, of brief talks given after the race by Mr. R. J. Mitchell, Vickers-Supermarine chief designer, Mr. A. J. Rowledge, who designed the Rolls-Royce racing engine fitted in the Supermarine S.6B seaplane, and Fit. Lt. (now Group Cap tain) J. N. Boothman, who piloted the S.6B to victory. To those who knew the late R. J. Mitchell intimately it was something of a shock and rather sad suddenly to hear the familiar voice, and to reflect that the genius who gave us not only the Schneider machines but the Spitfire has gone from us for ever. The recorded talk by Mr. R. J. Mitchell follows: — "In the design of a seaplane of this type, the one out standing and all-important requirement is speed. Every d&Aure has to be sacrificed to this demand, the result of mis is that every part of the aircraft just, and only just, fulfils its requirements. A very exact knowledge is there fore essential of the functioning of the details, requiring an enormous amount of research and investigation. It is not good enough to follow conventional methods of design ; it is essential to break new ground and to invent and evolve new methods and new ideas. '' The important aim of the designer is to reduce air resistance. Of the total air resistance of the S.6B as much as seventy per cent, is brought about by the friction between the air and the surface of the aircraft. The shapes of the fuselage and floats are such that air resistance is very little higher than that of the purest streamline form. The floats are made so small, for the load they have to carry, that their reserve buoyancy is less than forty per cent. The usual reserve buoyancy for seaplane floats is about one hundred per cent. No Contra-props "The problems of float design are further increased by the enormous torque developed by the engine. The effect of this torque is to raise one float and depress the other, regulting in the aircraft swinging off its course if the balance not maintained in some way. This is overcome by carry ing a larger load of fuel in one float than in the other, calling for a very sensitive device to ensure that the balance of fuel is maintained during flight. The underwater lines of the floats are of extreme importance. Before taking the air the aircraft must accelerate to a speed of over one hundred miles an hour—almost equivalent to the world's speed record on the water. The floats must run perfectly smoothly ; any instability at high speed would be fatal. "The cooling of the engine presents many interesting features ; the usual methods employed, either by air cooling or by honeycomb radiators, have very high air resistance. On the S.6B the engine is cooled without adding any air resistance. The cooling water is circulated over both sur faces of the wings and most of the surface of the floats, the covering being of a special double-skin construction. Similarly the oil is circulated along the sides of the body and over the surface of the fins. During flight heat equiva lent to 1,000 h.p. is being transmitted to the air from these surfaces. The S.6B has been aptly described as a flying radiator. t " The air controls and stability in flight must be exactly right. The pilot must be very efficiently protected from the enormous air pressure and from exhaust fumes. He must get a very adequate supply of fresh air and he must have a very good view. '' I must express the very greatest admiration for the pilots of the High-speed Flight of the Royal Air Force who carried out trials and operated these machines. Their job required great courage and great skill, and they played a very important part in developing the machines to their final state. "The question is often asked: Will higher speeds be attained in the future? I feel quite sure they will. The problems of still higher speed are no more intense at this stage than they have been at any stage in the past. For the present, however, it is generally considered that high speed development has served its purpose. It has accumu lated an enormous amount of information which is now being used to improve the breed of everyday aircraft. It is helping to develop our great air liners and ocean-going flying boats, and is thus bringing closer together outlying parts of the British Empire. This, indeed, is an objective worthy of all our greatest efforts." Developed in 7 Months In his talk Mr. A. J. Rowledge paid a tribute to Lady Houston, but for whose generosity the S.6B might never have been built. There had been indecision until she made her offer to defray the cost, and that left only seven months in which to develop the "R" engine to the new standards required for the 1931 contest. At a conference between the Supermarine and Rolls-Royce firms, and the Air Ministry, the Rolls-Royce engineers undertook to in crease the horse-power of the engine by 400 h.p., thus bringing it up to 2,300 h.p. Flight Lieutenant Boothman flew the Schneider course at an average speed of 340.8 m.p.h.- In the broadcast record ing he described his experiences in the following words: — "The first lap was flown at full throttle, and the turns were taken rather wide in order that there should be no risk of disqualification. After about one and a half laps the water temperature started to rise above the maximum allowed for the race, and so the throttle had to be eased back slightly for the remainder of the contest. Weather conditions were good, visibility excellent, and over the sea the air was smooth, but near Southsea, where the course was slightly Inland, bumpy air was experienced. Bumps on high-speed aircraft are rather disconcerting, because instead of the aircraft moving gently up or down, one experiences a sudden jar that could be felt right throughout the aircraft's structure. In view of this, after the fourth lap I flew out to seaward at Southsea in order to miss these disturbances. After about twenty minutes the cock pit became very hot and stuffy, and I was glad of the breathing tube which led a draught of cold air on to my face. "During the fifth lap my legs began to get slightly cramped owing to the small cockpit; I rested my knees on the side of the fuselage. However I quickly moved them when I found that the cockpit walls were blistering hot, I considered the cramp was the lesser evil. During the last lap the engine was still giving the same healthy noise and the aircraft was still flying perfectly, the combination in spite of its higher speed being much smoother than a normal aircraft. "Round at the last turn I opened the throttle full out once more for the final four or five miles to the finish, and then a climbing turn and an amble back to Calshot on about a quarter throttle at two hundred miles an hour ; the final closing of the throttle; left-hand gliding turn, an alighting and the last Schneider Trophy Contest was over. Later, the same aircraft—in the hands of Fit. Lt. G. H. Stainforth, A.F.C., established the world's record for speed with 407.5 miles per hour."
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