Background By 1960, several major British programmes in the field of military transport aircraft had been terminated or curtailed, such as the
Short Belfast and the
Vickers V-1000; according to author Derek Wood, these outcomes had been largely due to a lack of meaningful support from their principal customer, the
Royal Air Force (RAF). Proposals were received from various manufacturers. The
British Aircraft Corporation (BAC) decided to offer two designs; the BAC.222, which was a local development of the American
Lockheed Hercules, and the indigenously developed BAC.208, which would have been furnished with deflected-thrust engines and multiple lift fans. According to Wood, the BAC.222 proposal had good long-term production prospects and represented an excellent solution to the requirement; he also noted that Lockheed and BAC aggressively lobbied for its construction.
Selection There was a lengthy interval between the submissions and the British government making decisions regarding the requirement. A second issue of the requirement called for the presence of four deflected thrust engines, which were to be suitably augmented by several lift engines housed underneath the wings to allow the aircraft to achieve a viable
Vertical Takeoff and Landing (VTOL) capability. Armstrong Whitworth issued revisions of their AW.681 proposal to accommodate this new need; these revised submissions incorporated
vectored thrust nozzles and
boundary layer control (BLC) amongst other features; there was also considerable interest in adopting the
Rolls-Royce Pegasus engine. BAC also revised their designs in line with the requirement change, although Wood notes that Armstrong Whitworth had already emerged as the front runner for selection around this time. On 5 March 1962,
Julian Amery, the
Aviation Minister, announced that the Government had authorised the go-ahead for the HS.681 and that, in addition to a detailed project study being conducted, a
prototype of the aircraft was projected to perform its
maiden flight during 1966. Armstrong Whitworth pursued a last-minute effort, promoting the development of a non-STOL version of the HS.681, designated the HS.802. To achieve lower costs, this proposal would have had the same wings and engines as had been used on the
HS.801 Nimrod maritime patrol aircraft. Wood notes that the redesign, while likely being cheaper, came at the sacrifice of the type's STOL capabilities. Wood critiqued the programme and its cancellation, attributing some responsibility to overly-ambitious requirements of the RAF that had pushed the limit of aircraft capabilities, as well as the failure to settle those requirements. ==Design==