Turboprop on 20 September 1945. From their experience with the Trent, Rolls-Royce developed the Rolls-Royce Clyde, the first turboprop engine to be fully type certificated for military and civil use, and the Dart, which became one of the most reliable turboprop engines ever built. Dart production continued for more than fifty years. The Dart-powered Vickers Viscount was the first turboprop aircraft of any kind to go into production and sold in large numbers. It was also the first four-engined turboprop. Its first flight was on 16 July 1948. The world's first single engined turboprop aircraft was the Armstrong Siddeley Mamba-powered Boulton
Vickers Valiant military aircraft. It was followed by the Vanguard, a passenger turboprop designed in 1959, and the Vickers VC10, a jet passenger aircraft in 1962, also used as a military transport and tanker by the RAF. The Valiant was a conservative design of the era, having a shoulder-mounted wing and four Rolls-Royce Avon RA.3 turbojet engines, each providing up to of thrust, installed in pairs in fireproof bays in each wing root. The design of the Valiant gave an overall impression of a plain and clean aircraft with simple aerodynamics. George Edwards described the Valiant appropriately and simply as an "unfunny"