The Hawker Siddeley P.1154 was a planned supersonic vertical/short take-off and landing (V/STOL) fighter aircraft designed by Hawker Siddeley Aviation (HSA). Developed alongside the subsonic and smaller Hawker Siddeley P.1127/Kestrel, the P.1154 was derived from the P.1150. The P.1150 proposal did not meet NATO Basic Military Requirement 3 and, consequently, the P.1154 was born. This Mach 2-capable platform retained plenum chamber burning previously designed for the P.1150. Although the technical winner out of eleven submissions, follow-on testing and production for the P.1154 did not proceed as a result of political strife.

Meanwhile, HSA considered modifying the airframe for a joint specification for an aircraft by the RAF and Royal Navy. Between 1961 and 1965 the two services harmonised their specifications to preserve design commonality. However, the RAF's desired configuration was to take precedence over that of the Royal Navy's. A number of proposals were submitted – at one stage, a twin-Spey design was considered, then rejected. Following the Labour government's coming to power in 1965, the project was cancelled. The Royal Navy would acquire the F-4 Phantom, while the RAF continued to foster development of the P.1127 (RAF), leading to the successful Harrier family.

[edit] Development

[edit] NATO requirements

In 1961, during the development of the V/STOL P.1127 and Kestrel, HSA considered the feasibility of a supersonic V/STOL aircraft. This was influenced by a general perception at the time that supersonic aircraft held significantly more value than subsonic aircraft. Consequently, on 13 April 1961, HSA decided to conduct preliminary work on a supersonic P.1127 under the guidance of Ralph Hooper.^[1] The aircraft, designated P.1150 and 50% larger than the P.1127, would employ plenum chamber burning (PCB) – essentially an afterburner in the previously cold forward nozzles – in the engine.^[1][2