 Rolls-Royce Mustang Mk.X

The North American Mustang Mk.X (as in "Mark.10"; also known as the "Rolls-Royce Mustang") was a British variant of the US North American P-51 Mustang using a Rolls-Royce Merlin engine in an experimental program undertaken by the Rolls-Royce company in 1942.In April 1942, the Royal Air Force's Air Fighting Development Unit (AFDU) tested the Allison V-1710-engined Mustang at higher altitudes and found it wanting, but their commanding officer, Wing Commander Ian Campbell-Orde, was so impressed with its maneuverability and low-altitude speed that he invited Ronald Harker from Rolls-Royce's Flight Test establishment at Hucknall to fly it.