Hawker Siddeley Harrier AV-8As to the AV-8C configuration—the work focused mainly on extending useful service lives and improving VTOL performance. The AV-8C and the remaining AV-8A Harriers were retired by 1987. These were replaced by the Harrier II, designated as the AV-8B, which was introduced into service in 1985. The performance of the Harrier in USMC service led to calls for the United States Air Force to procure Harrier IIs in addition to the USMC's own plans, but these never resulted in Air Force orders. Since the late 1990s, the AV-8B has been slated to be replaced by the F-35B variant of the
Supermarine Type 324 Supermarine Type 324 The Supermarine Type 324 and Type 325 were British two-engined fighter designs proposed as the replacement for the Supermarine Spitfire and Hawker Hurricane. Neither of them nor a revised design - the Type 327 - to carry cannon was accepted for development and production. As an aircraft to succeed the Hurricane and Spitfire then entering service, Air Ministry specification F.18/37 required a 400+ mph (at 15,000 ft) fighter with twelve .303 inch machine gun armament. Hawker Aircraft submitted a single seat, single engine design with two possible engines, the Hawker Tornado powered by the Rolls-Royce Vulture and