Armstrong Whitworth Apollo Armstrong Whitworth Apollo The Armstrong Whitworth AW.55 Apollo was a 1940s British four-engine turboprop airliner built by Armstrong Whitworth at Baginton. The aircraft was in competition with the Vickers Viscount but was beset with engine problems and only two were built. The requirement resulted from the Brabazon Committee's Type II design, calling for a small, medium-range pressurized aircraft to fly its less-travelled routes which became Air Ministry Specification C.16/46 for an aircraft able to carry 24-30 passengers over 1,000 mi (1,610 km) at a cruising speed of . The resulting design was the AW.55 Apollo, a low-wing cantilever monoplane with
Vickers Viscount TAA. Unstated was the requirement for both airlines to have identical equipment. The first North American airline to use turboprop aircraft was Trans-Canada Air Lines (TCA), with a small fleet of Type 700 Viscounts. Initially, TCA was cautious of the Viscount due to the turboprop engine being a new technology, and there had been a preference for acquiring the piston-engined Convair CV-240 instead; praise of the Viscount from pilots and a promise from Vickers to make any design changes desired by TCA persuaded it to procure the Viscount instead. On 6 December 1954, the first Viscount was delivered to Canada