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Aviation History
1963
1963 - 0240.PDF
228 WE8TLAND HELICOPTERS... of the S-51 four-seater. By 1950 an improved variant powered by an Alvis Leonides and known as the Westland-Sikorsky WS-51 Dragonfly had entered production for the RAF, Royal Navy and overseas customers. A total of 139 were delivered. There was obviously not going to be another Westland fixed-wing design to follow the Wyvern, but diversification had kept employ ment steady, by far the largest new interest being the mushrooming Subsidiary Normalair Ltd, specializing in all kinds of environmental control systems. The basic job of making airframes trickled on, but it is doubtful if even the Westland board knew how important to the company helicopters would become. In 1950 work began on a British version of the Sikorsky S-55. The appellation "Westland-Sikorsky" was dropped, and when the first Yeovil-built machine flew on March 27, 1954, it was known simply as the Westland Whirlwind. It was this machine which really set Westland Aircraft on the rotary-wing path, and both piston-engined and turbine-engined examples are still being built. Limited success was achieved in 1955 with an improved Dragonfly known as the Widgeon. Most of the modifications centred upon the nose and forward fuselage, the structure and layout being re modelled to increase the utility of the payload space and make provision for carrying a stretcher or an additional seat. A much more ambitious project was the Westminster, which flew in June 1958. This was the first real essay by the company into the design of a helicopter, although the sound decision was taken to lean on the vast experience of their US licensee and use the dynamic parts—main motor, tail rotor and inter-rotor transmission—of the big Sikorsky S-56. The rest of the machine was entirely new, how ever, and in place of two Double Wasp engines Westland installed a pair of much lighter and more powerful Napier Eland turbines. There was never any real Government support for the Westminster, and when Westland also assumed responsibility for the Rotodyne the lat ter was deemed by the Ministry of Aviation to hold forth greater potential and the Westminster programme was terminated. But the fact remains it was a superb flying machine, and did everything asked of it; and its speed/range/load performance surpassed that of any helicopter now flying or under development today outside the Soviet Union. So much for the past. There is plenty of present, as the rest of this account will show; but the future is as yet far from certain. For many years BEA have studied brochures in a search for the ideal airline helicopter, and at one time—October 1961—the Boeing-Vertol 107 appeared the clear favourite. Accordingly Westland concluded a licence-agreement with Boeing to enable them to support and, if sufficient business were forthcoming, to make the 107 in England. Nevertheless, the relationship with Sikorsky has not suffered, and possible lines of future development are touched on in the concluding paragraphs. Whirlwind During the past decade this familiar helicopter has been Westland Aircraft Ltd's staple breadwinner. Several hundred —the exact figure is restricted—have been delivered to the British Services, and at the time of writing a further 107 have been exported. A Whirlwind HAR.10 carrying four Nord SS.II missiles employed in an air-to-surface role. Firing trials have been successfully completed FLIGHT International, 14 February I%i Powerplant of the original Sikorsky S-55 was the 600 h.p. Prnt & Whitney R-1340 Wasp. A unique feature when the design appeared in 1949 was that the engine was installed right in the nose, where it was accessible to a man standing on the ground. The transmission was taken back at 34° to the horizontal, the drive shaft passing between and behind the two seats in the lofty flight deck to the single lifting rotor set above the unobstructed box for the payload. The Russian Mikhail Mil' chose an identical layout for his Mi-4 series. Many S-55s were built with both the Wasp and with the 700 h.p. Wright R-1300 Cyclone, and Sikorsky-built machines of both types were given to the Royal Navy in 1952 under the MDAP programme. The first Whirlwinds were powered by the Wasp, and the following is the present list of piston-engined versions:— Series 1 Whirlwind HAR.l, Wasp engine, Royal Navy; HAR.2, Wasp, Royal Air Force; HAR.3, Cyclone, Royal Navy; HAR.4, After six years of production the Whirlwind was dramatically rejuvenated by conversion to turbine power. Westland and de Havilland Engines (now Bristol Siddeley Engines) removed the piston engine, clutch and fan unit and replaced them with a single Gnome free-turbine engine mounted horizontally in the nose, to port of the centreline. An auxiliary gearbox aft of the power turbine reduces the output speed from 6,000 to 2,900 r.p.m. and turns the drive to the required 34° angle. The resulting Mk 10 (civil Series 3) Whirlwind is appreciably lighter (enabling it to carry a much larger payload), has a higher performance, and offers a quieter and smoother ride than its piston-engined predecessors. The first Whirlwind to fly with turbine power was a conversion with a General Electric T58 engine (from which the Gnome was derived), and it flew on February 28, 1959. A British-built Gnome was substituted in September 1959, and in April 1960 Westland received a large order for Gnome-Whirlwinds for the RAF. The new machine was designated HAR.10, and the contract not only called for a substantial batch to be built at Yeovil but also for most of the Whirlwinds already in RAF service to be brought up to HAR.10 standard. This task of conversion was assigned to Westland's Bristol Helicopter Division at Weston. Large numbers of Mk 10 Whirlwinds are now in service with both Transport and Coastal Commands, and they performed nobly during the recent very severe weather. The Coastal Command rescue machines are painted yellow, and can carry ten people in the main cabin. The Transport Command aircraft are camouflaged and can be equipped to carry four Nord SS.ll wire-guided missiles,
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