Hawker Siddeley P.1127 GR.1" designation. The Harrier went on to become a successful aircraft in British service, and was exported to several nations, often seeing usage as a carrier-based aircraft. The P.1127/Kestrel was an experimental V/STOL aircraft, which served as the forerunner for the production of the Hawker Siddeley Harrier and the wider Harrier Jump Jet family. It served to demonstrate an entirely original technique of flight, as well as to trial a brand new type of engine in the form of the Pegasus turbofan engine. Despite this, the aircraft employed a principally conventional structure which, according to Mason, lent itself favourably to
Harrier Jump Jet of the upgraded "Sea Harrier FA2"; this version entered operational service on 2 April 1993. The Sea Harrier was also procured by the Indian Navy, the first Indian Sea Harriers were entered squadron service during December 1983. As early as 1973, Hawker Siddeley and American aviation manufacturer McDonnell Douglas were jointly working on development of a more capable version of the Harrier. Early efforts concentrated on the development of an improved Pegasus engine, designated the "Pegasus 15", which was being tested by Bristol Siddeley. During August 1981, the program received a boost when British Aerospace (BAe) and McDonnell Douglas signed