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Aviation History
1947
1947 - 0751.PDF
MAY 15TH, 1947 439 CUMMARIZED on these pages are two of a series of three ** powers delivered on May 7th at a full-day session of the Tteyo/ Aeronautical Society, held at the Institution of Civil Engineers. They are : (0) " A Sumy of the technical Problems of the Design of Naval Aircraft," by Mr. W. S. Farren, C.fi.. M.A., F.R.S., F.R.Ae.S. (b) "Naval Aircraft and Carrier Equipment," by Mr. L. Boddington. During the same session Cdr. F. M. A. Torrens-Spence. D.S.O., D.S.C., R.N., lectures on operational flying. This, together with the General Discussion, will be dealt with next week. Mr. W. G. A. Perring, F.R.Ae.S., showed films of deck landing. he saw no reason to believe that a high degree of versatility should be incompatible with technical quality. Though some naval aircraft might not attain the highest standard of technical efficiency, in the narrow sense, this was due to exceptionally difficult operational requirements rather than to the fact that they operated from ships, but there were types for which, he believed, a.more thorough exploitation of the potentialities of the carrier could assure technical and operational efficiency perhaps higher than that of comparable land-based aircraft. To this end the carrier designer must make a contribution. i Calculations concerning take-off from the '' higher class '' of carrier did not disclose any outstanding technical problem until we came to aireraft of very high speed, leading to swept-back wings and a low maximum lift. For these, and for the majority of first-line naval air- craft, Mr. Farren believed that take-off would become more and more a responsibility of the carrier. Free take- off would be pracC* able, but an enterprising development of A.T.O. could provide operational advantages far greater than any development of the aircraft which he could fore- see. Using the Carrier's Power The power available in the carrier, he felt, had never been fully exploited on behalf of its aircraft. It could be used directly, he suggested, to project the aircraft into the air under any conditions and at a rate greatly exceeding what could be achieved by any combination of the aircraft's own power plant and catapults and rockets as we knew them. He saw no reason why the many handling prob- lems to be solved could not be overcome. For the second-line ship such ivelopments were not prac- ticable, and free take-off was essential. There seemed no good reason why rockets should be excluded. The present view —that they should be reserved for emergencies—was unlikely to survive. Concerning take-off from this class of carrier, Mr. Farren said that with appropri- ate and economical thrust- weight ratios there was still something to be gained by a rise in lift, but it was doubtful whether elaborate developments in the direction of very high lift coefficients would pay. They would be most useful in emer- Design Problems and Equipment Discussed Before R.Ae.S. gencies, when rocket assistance, .1 far lower economical burden on''the aircraft, was surely acceptable. It was chiefly in the landing of aircraft on carriers that aircraft design had still a long way to go ; this applied particularly to the "higher class" of aircraft, whu h would gain particularly by an improvement in the litt coefficient under approach conditions. It seemed to the lecturer surprising that so little had been done to exploit aerodynamic devices to this end. We needed a relatively high lift coefficient under conditions of entirely satisfac- tory control and therefore, almost necessarily, remote from the condition of the stalled wing. We had still to exploit the potentialities of flaps, slots, spoilers and suction. In the past, approach speeds and conditions were such as to make a small margin, in relation to the inevitable collapse at the stall, an acceptable risk; but in futuie the consequences of a mistake would be too serious. What was needed was freedom from vice at the stall, combined with first-class control at an appreciably higher speed, and a first-class view. The burden was then on the arrester. Even with special aerodynamic devices, the maximum lift coefficient of the "higher class" of aircraft was likely to be low, and there would be a big reward for increasing the speed acceptable by the arrester. A rise of 10 knots in the neighbourhood of 60 knots led to an aircraft gain about equal to that obtainable by raising the maximum lift coefficient by 0.5—namely, an increase in permissible wing loading of 20-25 per cent. The take-off thrust/weight ratio available was likely to suffice for free take-oil usii:._» the full deck length. For the more modest aircraft, where take-off must be JET AIRCRAFT AND FLEET CARRIERS. Assumptions :—Take-off distance 700ft. Carrier wind speed 30 knots. Take-off speed I.I x stalling speed (eng. off). Approach at 1.25 x stalling speed (ene. off). Landing weight 80 per cent of takeoff weight. THRUST/WEIGHT AT TAKE OFF Q-5 8O AIRSCREW - DRIVEN AIRCRAFT AND POCKET CARRIERS. Assumptions :—Take-off distance 400ft. Carrier wind speed 15 knots. Take-off speed 1.0 x stalling speed (eng. off). Approach at 1.1 x stalling speed (eng. off). Landing weight 92 per cent of take-off weight. 1/THRUST/WEIGHT AT .JAKE OFF OS O 6O 91J/1 SPEED INTO ARRESTER (KNOTS) 1O 15 2O 25 3-O MAXIMUM LIFT COEFFICIENT (ENGINE OFF) t-O 1-5 2O 2-5 3O £ MAXIMUM LIFT COEFFICIENT 5 (ENGINE OFF] Two graphs showing relations between wing loading at take-off and max. lift coefficient(eng. off) for fixed values of thrust/weight at take-off and speed into arresters.
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