Armstrong Whitworth Apollo

The Armstrong Whitworth AW.55 Apollo was a four-engine turboprop airliner built at Baginton, Coventry, to meet the Brabazon Committee Type II requirement for a small pressurised aircraft to carry 24 to 30 passengers over about 1,000 miles. It was a low-wing monoplane with a retractable tricycle undercarriage, and it was designed around the Armstrong Siddeley Mamba engine, which was not yet producing the power expected when the prototype first flew on 10 April 1949. The aircraft proved unstable and underpowered, and repeated engine trouble ended a trial passenger programme after a single proving flight to Paris in March 1951. Development was abandoned in June 1952 in favour of the rival Vickers Viscount, and only two were built. Both ended their days as research and test airframes, the second used at the Empire Test Pilots' School for multi-engine training.