Vickers Viscount

Development

Origins

The Viscount was a response to the 1943 Brabazon Committee's proposed Type II design for a postwar, small, medium-range, pressurised aircraft to fly less-travelled routes, carrying 24 passengers up to 1,750 mi (2,816 km) at 200 mph (320 km/h). During discussions between the committee and Vickers' chief designer, Rex Pierson, Vickers advocated turboprop power. The committee was not convinced and split the specification into two types, the Type IIA using piston power, which led to the Airspeed Ambassador, and the turboprop-powered Type IIB, which Vickers was selected to develop in April 1945. British European Airways (BEA) was involved in the design and asked that the aircraft carry 32 passengers, instead, but remained otherwise similar.

The first design in June 1945 was based on the Viking with four turboprop engines and 24 seats and designated the VC-2 or Type 453. Later, a double-bubble fuselage was proposed to give extra underfloor cargo space. Neither was pressurised, but the designers soon realised that for economical operation, an altitude above 20,000 ft (6,100 m) was needed. Thus, pressurisation was required. The decision for pressurisation resulted in the double-bubble and elliptical fuselage designs being abandoned. A circular cross-section variant was offered at the beginning of 1946. The resulting 28-seat VC-2 was financed by the Ministry of Supply with an order for two prototypes. Before the contract was signed, though, the government asked for the capacity to be increased to 32. This stretched the fuselage from 65 ft 5 in (19.94 m) to 74 ft 6 in (22.71 m) and meant an increased wingspan of 89 ft (27 m).

The contract for the aircraft to Air Ministry specification C.16/46 was signed on 9 March 1946 and Vickers allocated the designation Type 609 and the name Viceroy. Although Vickers' Experimental Department Manager George Edwards had always favoured the 800 hp Rolls-Royce Dart other engines were considered, including the Armstrong Siddeley Mamba, which the government specified for the two prototypes. The choice of the Mamba engine increased the weight, but Vickers made sure the engine nacelle would fit either the Mamba or Dart. While the Dart progressed better in development, the government asked in August 1947 for the second prototype to be Dart-powered. The second prototype was designated the 630 and was named as the Viscount. The first prototype already under construction was converted to the Dart as a 630, as well.

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 Dart engines for a cruising speed of 275 mph (443 km/h). An order for two prototypes was placed in March 1946, and construction started in the company's Foxwarren Experimental Department. Originally named Viceroy after the viceroy of India, Lord Louis Mountbatten, the aircraft was renamed Viscount following India's independence in 1947. Work took place on replacing the Darts with the Mamba, but this was dropped by the time the prototypes were reaching completion. After Pierson's death in 1948, George Edwards (later Sir George Edwards) took over as chief designer and assumed all technical control over the Viscount project.

Prototypes

The prototype Type 630, registered G-AHRF, made its maiden flight from the grass airfield at Wisley on 16 July 1948, piloted by Joseph "Mutt" Summers, Vickers' chief test pilot. 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, and BEA had placed an order for 20 piston-engined Airspeed Ambassadors in 1947. Retrospectively commenting on Britain's aviation industry, Duncan Burn stated: "Had BEA committed itself to full support of the Viscount... it was quite likely that the smaller version would have gone into production... It was in a sense BEA's lack of enthusiasm for the [Type] 630 which made possible the [Viscount's] success."

Early flight trials, however, showed the qualities of a turboprop, resulting in a February 1949 order from the Ministry of Supply for a prototype of a stretched version with more powerful engines, the Type 700. Meanwhile, the first prototype Type 630 was awarded a restricted Certificate of Airworthiness on 15 September 1949, followed by a full certificate on 27 July 1950, which allowed the aircraft to be placed into trial service with BEA on 29 July to familiarise the pilots and ground crew with the new aircraft. It flew scheduled flights between London and Paris, and London and Edinburgh until 23 August 1950. The 29 July 1950 flight between Northolt and Paris – Le Bourget Airport with 14 paying passengers was the first scheduled airline flight by any turbine-powered aircraft.

The second prototype Viscount, the Type 663 testbed, had two Rolls-Royce Tay turbojet engines, and first flew in RAF markings as serial VX217 at Wisley on 15 March 1950. It was demonstrated at the Farnborough SBAC Show in September and was later used in the development of powered controls for the Valiant bomber.