Thursday, October 8, 2009

The Viscount


The Viscount was a British medium-range turboprop airliner first flown in 1948 by Vickers-Armstrongs, making it the first such aircraft to enter service in the world. It would go on to be one of the most successful of the first-generation post-war transports, with 445 being built.

The design resulted from the Brabazon Committee's Type II design, calling for a small-sized medium-range pressurised aircraft to fly its less-travelled routes, carrying 24 passengers up to 1,750 mi (2,816 km) at 200 mph (320 km/h).[1] British European Airways (BEA) was involved in the design and asked that the plane carry 32 passengers instead, but remained otherwise similar. During development, Vickers advocated the use of turboprop power, believing piston-engines to be a dead-end in aviation. The Brabazon committee was not so convinced, but agreed to split the design into two types, the Type IIA using piston power, and the Type IIB using a turboprop. Vickers won the IIB contracts, while the IIA was the Airspeed Ambassador.

The resulting Vickers Type 630 design was completed at Brooklands by Chief Designer Rex Pierson and his staff in 1945, a 32-seat airliner powered by four Rolls-Royce Dart engines providing a cruising speed of 275 mph (443 km/h). An order for two prototypes was placed in March 1946, and construction started almost immediately. Originally to be named Viceroy, the name was changed after the partition of India in 1947. There was some work on replacing the Darts with the Armstrong Siddeley Mamba, but this was dropped by the time the prototypes were reaching completion.
The prototype Type 630 flew on 16 July 1948. It was awarded a restricted Certificate of Airworthiness on 15 September 1949, followed by a full Certificate on 27 July 1950, and placed into service with BEA the next day to familiarize the pilots and ground crew with the new aircraft. However the design was considered too small and slow at 275 mph (443 km/h), making the per-passenger operating costs too high for regular service.
The second prototype Viscount was named the Type 663 and was built as a test-bed. This aircraft fitted with two Rolls-Royce Tay (turbojet) engines and first flew in RAF Markings as VX217 at Wisley on 15 March 1950. It demonstrated at the Farnborough SBAC Show in September and was later used in the development of powered controls for the Valiant bomber. Subsequently, Boulton Paul Ltd used it as a test bed for electronic control systems until scrapping in the early 1960s.
General characteristics
  • Crew: Two pilots + cabin crew
  • Capacity: 75 passengers
  • Length: 85 ft 8 in (26.11 m)
  • Wingspan: 93 ft 8 in (28.56 m)
  • Height: 26 ft 9 in (8.15 m)
  • Wing area: 963 ft² (89 m²)
  • Empty weight: 41,479 lb (18,815 kg)
  • Max takeoff weight: 72,281 lb (32,786 kg)
  • Powerplant: 4× Rolls-Royce Dart RDa.7/1 Mk 525 turboprop, 2,100 shp (1,566 kW) each
Performance
  • Maximum speed: 352 mph (566 km/h)
  • Range: 1,735 mi (2,790 km)
  • Service ceiling: 25,000 ft (7,620 m)
  • Wing loading: 75 lb/ft² (368 kg/m²)
  • Power/mass: 0.12 hp/lb (0.19 kW/kg)

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