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Aviation History
1953
1953 - 0117.PDF
Bristol Type 173. The World's Helicopters WEIGHTS ABOVE 6,000 lb BRISTOL TYPE 173 • The essential characteristics of this twin-rotor helicopter having been set out on pages 104-105, they may be supplemented here with the following data: rotor diam., 48ft 6.7in; overall length, 78ft 2in; disc loading at gross weight, 2.86 lb/sq ft; engines, two Alvis Leonides Le25HMV Mk 73 (525/545 h.p. at 3,200 r.p.m.); empty weight, 7,800 lb; max. disposable load, 2,800 lb; gross weight, 10,600 lb; cubic capacity for payload, 605 cu ft; passengers, 10; max. cruising speed, 113 m.p.h. at 2,500ft; initial rate of climb, 1,190 ft/min; range with payload of 1,200 lb, 100 miles at 85 m.p.h. at 2,500ft. BRISTOL 181 • The Bristol Company's answer to the B.E.A. helicopter specification is known as the Type 181 and is a scaled-up development of the Type 173, intended to carry 40 passengers. Should it be accepted, B.E.A. would wish to start operation by 1958, which would mean that a C. of A. would have to be obtained by 1957 and test-flying would have to start in 1955. SAUNDERS-ROE AIR HORSE • This large experimental helicopter, a sectioned drawing of which appears on page 106, has the following characteristics: rotor diam., 47ft; overall length 88ft 7in; engine, Rolls-Royce Merlin 24 (1,620 h.p.); empty weight, 12,140 lb; gross weight, 17,500 lb; passengers, 24; max. cruising speed, 116 m.p.h.; initial rate of climb, 790 ft/min. FAIREY ROTODYNE • For more than [two years; past, Fairey's broad plans for a large passenger-carrying helicopter with tip-jet power have been common knowledge, and models exhibited on the firm's stand at Farnborough in 1951 and 1952 gave clues to the convertiplane type of configuration which is in mind for their projected Rotodyne. The latest thoughts are understood to have inspired such a machine, somewhat re-tailored to meet B.E.A. requirements and carrying 30-40 passengers for at least the dis tances and at speeds no less than those indicated in Mr. Peter Masefield's survey. The Rotodyne will thus have the appearance substantially as indicated in our artist's sketch: a load-carrying fuselage capable of accommodating two pairs of seats abreast, some eight rows deep, with, in addition, luggage, mail and toilet space. A simple form of wing, without ailerons, will be mounted above the fuselage (per mitting different hulls to be "bolted-on" if required at a later dace) and will be surmounted by the rotor and its pylon. The two power-units will be slung beneath the wings, and again this will permit buyers a certain flexibility in choice of unit. The power requirements are outlined in a Fairey patent specifi cation. Briefly, a kind of compound turbine or piston engine is required which can provide, at will, shaft horse-power or pressure air, in inverse proportions for the twin-engined Rotodyne. This requirement can quite easily be met if air from common com pressors can be distributed to the tip jets or to the combustion chambers of the turboprops in any proportions selected by the pilot, according to the power requirements of the rotor, and of the airscrews for forward speed. When hovering the rotor takes at least 90 per cent of the power and the airscrews require only sufficient power to give directional control; in cruising flight the conventional tail surfaces take over this duty. Single-engined safety is afforded. The uninterrupted wing would house fuel, and the normal nose- wheel landing-gear would retract into nose and engine nacelles. The Rotodyne conception is thus a true compromise between helicopter, Autogiro and fixed-wing transport. <o ^>' '.':::• Fairey Rotodyne (details unconfirmed). Saunders-Roe Air Horse.
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