The First to Go Up and Down
The Hawker Siddeley Kestrel was not a naval aircraft. But the British airplane had a profound impact on U.S. naval aviation: It was the progenitor of the widely flown Harrier-series vertical/short takeoff and landing (VSTOL) aircraft. Indeed, the U.S. Marine Corps has been the largest user of these highly successful VSTOL planes.
The aircraft was initiated by Hawker Siddeley in 1957 as a private venture and given the company designation P.1127.1 Many previous efforts had been made to develop VSTOL combat aircraft, including the U.S. Navy-sponsored Lockheed XFV-1 and Convair XF2Y-1 Pogo.
But the Kestrel offered the promise of a practical VSTOL configuration, employing a vectored-thrust engine to achieve vertical flight. The Royal Air Force placed an order for six Kestrel prototypes, the first of which rose vertically for the first time on 21 October 1960 and flew its first horizontal takeoff and conventional flight on 13 March 1961. The six prototypes were provided with progressively uprated versions of the Bristol Siddeley Pegasus engine as well as aerodynamic changes.