PK-13 NA.P-51D Mustang (Mustang Mk. IV/P51-D)

In January 1940, the British Government requested North American Aviation to build under licence another company's design. North American however, proposed a completely new fighter - the Mustang, producing the first prototype in 117 days.

Early machines entered service with the R.A.F. in July 1942 fitted with the Allison engine. Performance, excellent at low level, was not suitable for normal fighter operations and the aircraft were used on ground attack missions only.

Little interest was shown by the U.S.A.A.F. until the Rolls Royce Merlin 61 engine was successfully fitted as an experiment. An order for several thousand aircraft using Packard built Merlins followed, the P51.D. version becoming perhaps the best propeller driven fighter of W.W.2.