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 Viscount the Vickers Vanguard. The Vanguard drew extensively from the knowledge and design of the Viscount, and likewise maintained its advantage of lower operating costs over pure jet-powered aircraft, but its disadvantage in being slower than jet aircraft became increasingly critical as jets became more available over time. Regular passenger flights were launched by BEA in 18 April 1953, the world's first scheduled turboprop airline service. BEA became a large user of the Viscount, as well the rival Handley Page Dart Herald; by mid-1958 BEA's Viscount fleet had carried over 2.75 million passengers over 200,000 flight hours. Following BEA's launch of