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Aviation History
1954
1954 - 1381.PDF
Powered gliders by Fouga: (left) the CM 8-R13 Cyclone single-seater powered by a Turbom6ca Pim6n€ turbojet, and (right) the CM 72 (Turbomica Palas) powered development of the CM 71 high-performance two-seater sailplane. THE FUTURE OF SOARING . . . obtained cheaper soaring, it is either at the expense of all the members of clubs since 1930 (and because many old and second hand sailplanes of lower initial cost are still being flown) or at die expense of new members who paid their entrance fees and sub scriptions and were then frightened away, never to return. One flourishing club recently lost 90 members in one year. Now let us examine the extraordinarily small average of 4| hours per year per member. If suitable instruction is available it takes only about four hours and 30 to 50 take-offs and landings before a pupil is fit to go solo, and another 10 to 15 circuits before he is fit to soar and gains his "C." Making full allowances for adverse weather and queues, the average pupil should obtain his A, B and C within 6 or 7 months, and so die beginner should be able to fly about ten hours in his first year. A club's pre occupation with training beginners should therefore not reduce the average member's soaring. We can only conclude that the effort, frustration and expense involved in high-performance soaring is too great. Our present sailplanes and launching methods are totally inadequate to give us what we want: we need equipment which will enable the average club member, flying at week-ends and during a two or three weeks' holiday, to achieve 50 hours of high- performance soaring each year at a cost of not more than £1 per hour. Sailplanes owned by one private owner should be capable of providing him with 100 hours a year, those operated by four partners should provide 400 pilot-hours a year and club-owned sailplanes should equal light-aircraft utilization figures of 400-800 hours per year. In civil aviation the cheapest passenger-mile costs are provided by ever-more-expensive transport aircraft of increased capacity and block speed and hence of increased utilization. The cheapest soaring-hour will be achieved by expensive high-performance two- seater sailplanes and not by cheaper and smaller sailplanes. The latter will never become cheap enough for the soaring they do, unless they are expressly designed for ease and economy of operation as opposed to a small initial cost. The two-seater is the obvious immediate choice for most single private owners, for syndicates of four partners, and for clubs, provided that these machines do not cost twice as much as a single-seater. The present cost of the 50ft high-performance single-seater Spatz-L at £535 and that of its 56ft two-seater brother, the Bergfalke II at £765, show that the two-seater can provide cheaper soaring, because each hour flown by the sailplane is enjoyed by two pilots at the same time. The choice of a two-seater, however, will at the best only double the existing pilot-hours, and we must look to more promising methods to increase the overall utilization of sailplanes. There appear to be only four major methods of achieving this aim, and these are now considered in turn. Thermal-detection.—The development of an airborne thermal- detector with a range of 200 yd would treble one's random chance of finding a thermal and would greatly improve the quality of soaring achievements. The thermal-detection problem can be solved, but it should be attacked on the broadest morphological basis and not just on a narrow front following up the possibilities of a single method. A certain amount of the basic research work and even some of the necessary instruments have been produced by military research stations for entirely different purposes. If the M.o.S. could be persuaded to co-operate, a relatively small amount of money could achieve miracles. Gliding Angles of 1 :100 and 1 : infinity.—K. G. Wilkinson, Dr. A. Raspet and others believe that boundary-layer control by suction through porous surfaces requiring only 1 h.p. or less would enable sailplanes of less than 50ft span to achieve gliding angles of 1 :100 or even 1 : infinity (that is, level flight at constant speed). This would indeed solve the utilization problem and introduce real and unprecedented high-performance soaring. Although the initial cost of such a sailplane would be very high, the cost per pilot-hour would fall to a shilling or two. Dr. Raspet has a project study for a high-performance single- seater (see diagram) of 40ft span where the power and suction for take-off and level flight are provided by the pilot himself. Pedals drive a propeller co-axial to the fuselage boom and suction air is pumped through the hollow propeller and sucked out through apertures on the low-pressure areas at the blade tips. For take-off, the pedals drive the retractable landing wheel as well as the propeller. The successful realization of these theories would be of inestim able value to all aviation and would be more far-reaching than the introduction of the jet engine. Aerial transportation would become the cheapest form of passenger transport, and would approach the economy of canal barges for most types of freight. These theories can be developed and tested to most advantage on sailplanes, rather than in wind tunnels. The Auxiliary-powered Sailplane.—There are many sailplane pilots who imagine that "pure" soaring flight should be untarnished by any form of mechanical power. Yet they use mechanical power to tow their sailplanes to the launching point, to pull out the winch cable and to drive the winch which launches them. Those who can afford it are launched in tow behind a powered aircraft. Not content with this, they have electric motors to drive rate-of-turn indicators, inverters and artificial horizons, and V.H.F. radio. Yet in order that the purist may enjoy one winch launch, a winch driver, a cable-retrieve-vehicle driver, a wing-tip holder and signaller have to work like busy bees, their tasks including starting engines and repairing them when they break down. If our purist is lucky enough to get away on his first launch instead of rejoining the long queue of sailplanes waiting to be launched, two other pilots give up their own chance of flying and set out with a powerful car and trailer to retrieve the purist from his downwind dash. Their road mileage will be at least three times the pilot's own air mileage. Often the purist is heard to express the wish "to soar like a bird, without an engine." Even the most confirmed soaring specialists, such as the albatross, fulmar and condor, do not enlist die aid of others to get themselves into the air or to get themselves home. They launch and retrieve themselves. Evolution has seen many over-specialized purists such as ostriches, dodos and penguins. Look at the sport of sailing in open waters. It has become a popular sport, no longer reserved for the very rich since a small auxiliary motor was added. This enables the yacht to get out of narrow estuaries and harbours by itself and, if becalmed at sea, to return to harbour and get its owners back to work by Monday morning. Its auxiliary can often save it from shipwreck when storm and tide become too strong for its sails. The last cry of these self-styled purists is that this beastly dependence on the work of launching and retrieving crew (who are prevented from flying themselves) fosters "team spirit." Well, let them join rugger, football or hockey teams or, if they really want to soar, let them display "team spirit" in thermals (where they often do their best, in true competition style, to crowd their neighbours into the sink); or let them develop team cross-country soaring, where two sailplanes fly together as a team about 200 yd apart, thus trebling their individual chances of hitting a thermal. Obviously, an auxiliary-powered sailplane will be more expen- size than an orthodox sailplane. Hence it must be a two-seater to reduce the cost per pilot-hour. It must have a good gliding angle (above 1 : 25) and penetration, and a minimum sink not greater than 2.8ft/sec. Hence power-plant and propeller should
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