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Aviation History
1945
1945 - 2165.PDF
FLIGHT NOVEMBER IST, 1945 The First Freedom ? Preparing for Post-war Qliding : Two New Sailplanes Described ••*» THERE appears to be a reasonable chance that, inthe not too distant future, the ban1 on gliding byprivate individuals will be lifted. Certainly, "glid-ing freedom'' is, in present circumstances, likely to be the first to be obtained by the amateur, who may have to wait for quite a while before he is permitted to go his own way in power-driven aircraft. Furthermore, it is even possible that the ex-Service or ex-A.T.A. pilot may, apart from the question of finance, actually prefer to take up a " new " sport rather than to return, so to speak, to his E.F.T.S. days with any types of light aircraft which may be available. At least for the first year or two it is probable that the great majority of gliding club members will be those who already have adequate flying experience, and it would seem that the immediate need will be for dual and solo high-efficiency gliders rather than for primary gliders. The few of the latter that are available should be adequate for the training of the inexperienced. No medium or high- performance types have been built in this country for the last six years, and very few were built even before the war. So there should be quite a useful market both here and abroad for sailplanes. Pre-war light aircraft pilots will no doubt remember the little single-seater built by Chilton Aircraft, of Hungerford. After a "war" of sub-contracting, this firm is now going ahead with the construc- tion of a sailplane, since only in glid- ing can an" immediate market be seen for any aircraft. The firm has chosen the Olympia as a type worth develop- ment. Olympic Specification It may be remembered that when the 1940 Olympic Games were planned, soaring was included amongst the competitive sports, and it was decided that all should fly an identical aircraft. A committee was formed to lay down the basic requirements of this aircraft. Interestingly enough, this committee limited the wing-span in order to obtain an easily handled machine, and stipulated a minimum weight in order to discourage cheese-paring. An amply wide cockpit, dive-brakes limiting the terminal velocity to 124 m.p.h., and a severe set of strength requirements were also included in the specification. In all, this specification demanded a robust and sensible machine. There were eight entries from various countries and the Olympia sail- plane was the winner of this competition. Generally conventional in layout, the Olympia has a number of interesting features which make for ease of assembly and maintenance, and it is fully aerobatic. Research suggests that the guU-wing is not necessarily as THE CHILTON OLYMPIA DIMENSIONS AND WEIGHTS Span 49.3ft. Length 22ft. Wing area 161 sq.ft. Wing loading Aspect Ratio Weight empty Load ... Structure weight/all-up weight .. Structure-weight wing area PERFORMANCE Best gliding angle (L/D) efficient as had previously been supposed, and the wing- shape of the Olympia is of normal design, with a taper ratio of 2.6 to 1 and a dihedral angle of 2.5 deg. The section at the root is Gottingen 549, thickened to 16 per cent, of the chord to allow the use of a deep spar, with a tip section of Gottingen 676 to give better stalling char- acteristics. To obtain good fore and aft control and stability the tail surfaces are larger and further from the wing than has been previously usual. Small but important points, such as rudder-pedal adjustability and a manually operated tab trimmer, have been included, and the instru- ment panel, including, in the standard aircraft, an A.S.I., a variometer, a turn and bank indicator, an altimeter and a compass, can be quickly removed if the machine must be left unattended after a cross-country. There is a compartment behind the pilot for the mounting of a barograph. The Olympia is small and the design subscribes to the modern theory which is aimed primarily at obtaining a good L/D ratio at higher speeds in the interests of " pene- tration." In earlier designs efforts were made to obtain the lowest possible sinking speeds near the stall, with the result that efficiency went to pieces at high cruising speeds. Quite a large number of Olympias—believed to be about 1,000 were built in Germany—for Luftwaffe training, but, not un- naturally, Chilton Aircraft have had to put in a lot of hard work in "Angli- cisation'' and in making the various fittings more suitable for production. Service pilots who have flown German- built Olympias have been enthusiastic about their performance and stability. Six of the first machines off the pro- duction "line" are, incidentally, to be supplied to the Derbyshire and Lan- cashire Flying Club. 3.48 Ib. sq. ft.15 3S3 Ib.209 Ib. 0.62S2.19 Ib./sq. 't. Minimum sinking speed ... Stalling speed LOAD FACTORS C.P. forward Diving Pull-out Inverted flight In gusts of 33ft. per sec 25 : I at45 m.p.h. 2.2ft. per sec.at 39 m.p.h. 31 m.p.h. 102 105.5 2 CHILTON OLYMPIA : SPAN - 49ft. 4ins. LENGTH - 22ft. WING AREA 161 sq. ft. Private Venture Another interesting sailplane, named the Wanderlust, of new design, is be- ing built in their own time by two draughtsmen, T. E. Brown and K. W. Radbarn, employed by Miles Aircraft. This aircraft, incidentally, is being built without machine tools. The most noticeable feature of the Wanderlust is rB" small size. The question of size has been discussed at great length in the past, and the makers consider that the smallest machine possible, with medium all-round per- formance and good cross-country performance, is required for reasons of handling ease. Since the Wanderlust has been primarily designed for cross-country work, the maximum mileage per hour with the lowest sinking speed was aimed at, and the machine had to be manoeuvrable at 36 m.p.h. and efficient at 90 m.p.h. It had also to be able to land in the smallest possible space. Cloud flying is inevitable, with the risk of building up excessive speed, so means had to be found of limiting this. The wing loading had to be kept high in order to obtain a good cruising speed, together with penetration in a high wind. It was on this foundatiSfc that the Wanderlust was designed. The wing is fitted with extended aerofoil section flaps
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