Rolls-Royce aircraft piston engines test stand. The Buzzard was an enlargement of the Kestrel of Condor size, developed in its most extreme form into the Rolls-Royce R racing engine used for the Schneider Trophy competition. The Vulture of 1939 was essentially two Peregrines on a common crankshaft in an X-24 configuration, both of these types being deemed unsuccessful. The Rolls-Royce Merlin, and later the development of the Buzzard, the Rolls-Royce Griffon were the two most successful designs for Rolls-Royce to serve in the Second World War, the Merlin powering RAF fighters the Hawker Hurricane, Supermarine Spitfire, fighter/bomber de Havilland Mosquito, Lancaster and Halifax heavy
Rolls-Royce Crecy fighter. Studies on the de Havilland Mosquito also showed it to raise complex problems with Crecy installation. In 1942 Rolls-Royce Hucknall received a North American P-51 Mustang for engine installation trials. This prompted a series of studies for a Crecy version and the Mustang turned out a more suitable mount than the Spitfire. However these studies were not taken further. As the possibility of a flight-worthy engine approached, on 28 March 1943 Hawker Henley "L3385" was delivered to Hucknall for fitting with a Crecy. However the engine never became available and the aircraft remained at Hucknall until when it was