Bristol Britannia Model 175 Mk 1 (proyecto)

The Model 175 came out of the Brabazon Committee, set up in 1943 to decide which civil aircraft Britain would need after the war: the British had concentrated their industry on heavy bombers and transport construction had been left to the United States. Bristol won the Type I and Type III contracts, and from the Type III — Specification C.2/47, issued in April 1947 — came the project that would become the Britannia.

The Mk 1 was the first of the three prototypes ordered: 48 passengers, a 114 ft (35 m) fuselage, a 120 ft (36.5 m) span and four Bristol Centaurus 662 radials. By October 1947 Bristol had settled on a Centaurus-powered design of 103,000 lb (47,000 kg) gross weight with a 13,300 lb (6,000 kg) payload, limited to 48 seats by the demands of the Karachi–Cairo stage. It was never built: in November 1948 the Type 175 was revised for 74 passengers and a longer span, and BOAC decided that only the Proteus turboprop was viable, which eliminated the Centaurus option.