Two turboprop aircraft of much larger size than the Vickers Viscount were constructed in the United Kingdom. These were the Vickers Vanguard, with a gross weight of 146 500 pounds, and the Bristol Britannia, with a gross weight of 185 000 pounds. In early 1953, not long after the Viscount entered service with British European Airways (BEA), discussions began to initiate the design of a successor. Both BEA and Trans-Canada Airlines were interested in a generally similar aircraft; compromise in design to satisfy the views of these two operators resulted in the low-wing configuration and 'double-bubble' fuselage to provide a large underfloor cargo hold beneath the main cabin.
The power plant considered originally for inclusion in the design was the Rolls-Royce Dart. But Rolls-Royce intimated that development of a new engine, the RB.109, was then well under way and it (later known as the Tyne) was chosen to power this new transport. Construction was entirely conventional except for the wing, which introduced integrally machined skins of light alloy to provide spanwise stiffening at low cost, and three shear webs instead of the single spar in the Viscount wing. When tied together by closely spaced ribs it produced a rigid box structure and outboard of the centre-section it was sealed to form integral fuel tanks.
The first flight of the prototype Vanguard, as the new aircraft had been named, came on 20 January 1959. Because of the normal development program of a new civil airliner - coupled with delays caused by problems with the new power plant - it was not until 01 February 1961 and 01 March 1961 that these aircraft began regular service with Trans-Canada Airlines and BEA respectively. By then, turboprop-powered airliners had been surpassed by the introduction into service of economical turbojet-powered airliners such as the Boeing Model 707. Consequently production ended after the original orders had been completed: 20 for BEA and 23 for Trans-Canada Airlines.
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