suitable aircraft to meet its demands. Initially, design efforts were focused upon a twin-engine design intended for military use, which was internally designated as the AW.66. As it was recognised that the aircraft held sales potential within the civil market, a civilian-oriented variant, designated AW.65, was also designed alongside the military design; the AW.65 principally differed from the AW.66 via the installation of full-section doors at each end of the fuselage to enable rapid loading and unloading operations. However, a lack of available finance contributed to the company's decision to abandon all work towards meeting the military requirement; despite this setback, Armstrong Whitworth had already decided to proceed with developing the civil variant as a private venture. The company believed that the type would have significant appeal to the growing short-haul air freight sector of both the European and American markets. At that time, no other aircraft had been purpose-designed for such a purpose. As work continued, the AW.65 was extensively redesigned, including the adoption of four Rolls-Royce Dart turboprop engines; the resulting aircraft being designated as the AW.650. On 8 January 1959, the first Argosy performed its maiden flight. It appeared during that year's Farnborough Airshow, by which point five aircraft were flying, having cumulatively amassed about 400 flight hours between them. Certification-related testing of the type was reportedly completed during September 1960. In December 1960, the Argosy received type certification from the American Federal Aviation Administration (FAA), authorising the aircraft's entry to commercial service. 10 of the initial civil version, the Series 100, were built; construction of these aircraft had commenced months prior to receiving certification so that deliveries could commence as soon as possible. Further development While the RAF had lost interest in any acquisition of the original AW.66 design, the service still needed to procure a replacement for its obsolete piston engined transport fleet, including the Vickers Valetta and Handley Page Hastings. During 1959, the British Air Ministry released a new specification that called for a military derivative of the AW.650, the envisioned aircraft was intended to serve in multiple roles, including as a medium-range transport, paratroop and supply aircraft. The resultant design, which was designated AW.660, was significantly different from the AW.650. Changes included the sealing of the nose door, its location being instead occupied by the radome of a weather radar unit, while the rear doors were substituted for by an alternative clamshell style