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
British Aerospace Sea Harrier in 1973, and are now popularly recognised as aircraft carriers. Almost immediately upon their construction, a ski-jump was added to the end of the 170-metre deck, enabling the carriers to effectively operate a small number of V/STOL jets. The Royal Air Force's Hawker Siddeley Harrier GR1s had entered service in April 1969. A navalised variant of the Harrier was developed by Hawker Siddeley to serve on the upcoming ships; this became the Sea Harrier. In 1975, the Royal Navy ordered 24 Sea Harrier "FRS.1" (standing for 'Fighter, Reconnaissance, Strike') aircraft, the first of which entered service in 1978. During this