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Aviation History
1953
1953 - 0099.PDF
FLIGHT, 23 January 1953 97 THE RISE OF THE HELICOPTER . . . rotors had been mounted on a fuselage of the C.30 and W.2 types respectively, with rather more robustness added to the under carriage. The one thing the Autogiro still could not do was hover in still air; but the fulfilment of this desirable and elusive per formance characteristic was now only one step away. Alas^ on December 9th, 1936, Juan de la Cierva—then 41 years of age— was amongst the passengers killed in a DC-3 accident at Croydon and the continuation of his pioneering efforts had to be left to others. At the beginning of 1937, another newcomer made its appear ance at Hanworth, the A.R.III gyroplane designed by Raoul Hafner. Similar in general configuration to the Autogiro, this "direct-control" single-seater powered by a Pobjoy "R" engine of 90 h.p. was characterized by its ability also to take-off and land without a run. A noticeable feature of detail design was that, by contrast with the tilting hub of the Autogiro, the A.R.III had a fixed hub, the inclination of the rotor disc being obtained from a cyclic variation of blade pitch-angle actuated by a conventional control column. Piloted by A. E. Clouston, this well-engineered and highly manoeuvrable aircraft was a rebuild of a prototype which had been damaged during an early test flight the previous year. The ability of rotary-wing aircraft to take off without a run, thus enhancing their potentialities for use on ships, at last resulted in positive action by the Admiralty, for in June, 1937, the Cierva Company received a contract for the supply of five re-designed C.40S. This type was a side-by-side two-seater with a Salmson engine of 180 h.p., and construction was undertaken by the British Aircraft Company, Hanworth. Towards the end of the year, the Weir group decided to con centrate their future rotary-wing activities solely on the helicopter, and their first effort, the W.5, was flown at Dalrymple, Ayrshire, on June 7th, 1938. This, incidentally, was the first successful flight by any helicopter in this country. Designed by C. G. Pullin and piloted by his eldest son, R. A. Pullin, the W.5 had two side-by-side two-bladed rotors with cyclic-pitch control. A single-seater with a 50 h.p. Weir engine, this prototype made over 100 take-offs and landings before it was superseded the following year by the W.6. Helicopters were also occupying the minds of those directly associated with the activities of the Cierva Company. From Dr. J. A. J. Bennett there emerged the conception of the Gyrodyne, whereby, amongst other advantages, the torque from a power- driven single main rotor would be compensated by the thrust of an airscrew laterally offset from the body of the fuselage. A design-study to meet a Naval requirement, and using a Kestrel engine, received the support of the Air Ministry, but was abandoned at the outbreak of war. Meanwhile, the B.A.C.-constructed prototype C.40 had com pleted its acceptance tests and two Naval pilots, Lts. Torin and Illingworth, joined the Cierva school at Hanworth for 50 hours training each. Early in 1939 the first two production C.40S were handed over to the Royal Navy. During October of that year the Weir W.6 helicopter made its maiden flight in Scotland. Although of similar configuration to the W.5, each of its two outrigger-supported main rotors had three blades. Moreover, it was now a two-seater with a Gipsy VI engine located in the nose. The outbreak of war, and a complete lack of Government encouragement and support, soon put an end to all British rotary- wing effort. By mid-1940 both Cierva and Weir had closed down. However, the activities of No. 509 Squadron (C.30S) with Fighter Command on radar calibration duties, coupled with considerable American progress in helicopter research and development over the next three years, ultimately compelled a revision of official outlook. Towards the end of 1943, the Cierva Company re-activated its helicopter interest with C. G. Pullin at the helm. The initial programme was based on an intensive investigation into the The Hafner AR.Iil gyroplane of 1937. The Ciena CAO Autogiro of 1938. Although this aircraft could take off and land without a run, it could not hover in still air. possibilities of using jets as a means of counteracting torque from the main rotor. In 1944 the Bristol Aeroplane Co., Ltd., acquired the rights in the A.R.III Construction Co., and the services of Raoul Hafner to head their newly created helicopter interest. The Fairey Aviation Co., Ltd., created a helicopter branch in June, 1945, with Dr. J. A. J. Bennett as chief technician. By October of that year, the Cierva W.9, a prototype with a single three-bladed main rotor, and employing a jet torque-com pensation device at the tail, had reached the hovering stage. Early in 1946 the Cierva headquarters at Thames Ditton were moved to Eastleigh, a licence agreement having been reached with Cunliffe-Owen Aircraft. Before 1947 was out, the prototypes of the first helicopters to be produced by Bristol and Fairey had been flown successfully. Both four/five seaters, with single three-bladed main rotors, the Bristol 171 with a Pratt and Whitney Wasp Junior was of similar configuration to the Sikorsky S-51, while by contrast the Fairey Gyrodyne (Alvis Leonides) re-introduced the Cierva Company's conception of 1938 by having stub wings, that on the starboard side carrying a variable-pitch airscrew for torque compensation and to assist propulsion. In the following year this prototype captured the then world speed record for helicopters, at 124 m.p.h. Of interest in 1947, also, was the disclosure of a helicopter programme by Westland Aircraft, Ltd., a licence having been acquired from the United States to construct to the well-known Sikorsky designs. With initial concentration on the S-51 type, a considerable number have since been produced, chiefly to meet Service requirements. During 1948 two new Cierva prototypes made their initial flight tests: firstly, the W.14 Skeeter—a two-seater with a single three-bladed main rotor and a torque-compensating rotor at the tail, the power unit being a Gipsy Major; secondly, the W.II Air Horse, the world's largest helicopter, with an all-up weight of 17,500 lb. It was of unusual configuration—the centres of the three three-bladed 47ft diameter main rotors, all three powered by a single Rolls-Royce Merlin 24 engine, were displaced in the form of a triangle. Following a fatal mishap with the first W.II during 1950, the Cierva Company ceased to be active in the helicopter field, all development work under contract to the Ministry of Supply being taken over by Saunders-Roe, Ltd. In 1951, Percival Aircraft, Ltd., announced the formation of a helicopter division and the intention to construct rotary-wing aircraft employing a new conception in power units. The Bristol 171, now powered with an Alvis Leonides engine, was in quantity production, mainly for Service use. Construction of the first helicopter in this country to be equipped with two (Leonides) engines was also completed this year. A 10/12 seater with a tandem three-bladed rotor system, the Bristol 173 made its first flight early in January, 1952. Later in the year the Westland-Sikorsky S-55, an 8/10-seater, was also flown; it is now going into production on a fairly large scale. With a single rotor having three all-metal blades, the power is provided by a Pratt and Whitney Wasp engine.
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