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Aviation History
1953
1953 - 0112.PDF
no FLIGHT, 23 January 1953 BRISTOL TYPE 171 • A general description of this versatile 4/5-seater having been given on page 104, we may concentrate here on presenting the salient performance data and other particulars. The main rotor diameter is 48ft 6.7m and the disc area 1,860 sq ft. Maximum rotor r.p.m. are 287. The Alvis Leonides LC23HMV Mk73 power plant has a i-hr rating of 465/485 h.p. at 3,000 r.p.m. at 7,500ft, and gives the machine a maximum level speed—again at i-hr rating—of 133 m.p.h., the corresponding rotor r.p.m. being 269. At the 5-min rating of 550/570 h.p. at 3,200 r.p.m. the maximum level speed is 141 m.p.h. at 287 rotor r.p.m. The service ceiling is 19,000ft and the hovering ceiling, within the ground cushion, 7,900ft. Empty and gross weights are 3,630 lb and 5,200 lb respectively, the weight break-down being: aircraft empty, 3,630 lb; pilot, 170 lb; fuel (60 gal), 432 lb; oil (4 gal), 36 lb; payload, 932 lb. Bristol Type 171. The World's Helicopters Westland-Sikorsky S-51 (known in the British Armed Services as the Dragonfly). WEIGHTS 2,500 lb to 6,000 lb FAIREY PRESSURE-JET GYRODYNE • Of the two original experimental Fairey Gyrodynes built in 1947 and 1948, one was destroyed; the other, following a period of inactivity, is being rebuilt for further experimental and development flying in connection with the next and larger Fairey product, the Rotodyne. Comparatively minor alterations to the airframe and engine, and the provision of a new rotor head and blades, should allow the machine to be converted to pressure-jet power at the blade tips. The Leonides piston engine is already positioned and horizon tally mounted in such a way that it could conveniently be adapted to drive a compressor located beneath the rotor. On the original machine—a cut-away drawing of which appears on page 106— the spacious fuselage bay beneath the rotor contains the gearbox for rotor and airscrew drives. In the converted machine pressure air would be led up through the rotor shaft and a much simplified head, and out via the blade spars to the tip jets. The Gyrodyne has stub wings and a tailplane and rudder assembly similar to those on a conventional fixed-wing machine, and on the starboard side is the forward-facing airscrew. With tip- jet power, torque correction is no longer called for, but an airscrew is still needed for directional control when hovering. In forward flight the airscrew provides thrust and the conventional tail sur faces take over. The forward thrust together with the lift of the wings enables the rotor to be unloaded at cruising speed, and the machine (so far as the rotor is concerned) becomes an Autogiro. WESTLAND-SIKORSKY S-51 • The general description of the S-51 appearing on page 103 may be supplemented here by the following notes on dimensions, weights and performance. The main rotor diameter is 48ft and the overall length (blades extended) 57ft ojin. The Leonides engine gives a top speed at sea level cf 103 m.p.h., a cruising speed of 85 m.p.h., and a hovering ceiling within the ground cushion of 7,000ft. Without ground effect the hovering ceiling is 4,600ft. Cabin dimensions are: length, 8ft 4in; depth, 4ft 3m; width (pilots), 4ft 5m; width (passengers), 4ft 8 in. Doman YH-31.
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