North American Mustang in RAF-RAAF-SAAF-RNZAF-RCAF & Foreign Service

In April 1940 the British Purchasing Commission, arranging for supplies of armaments from the U.S.A., requested the North American aviation concern to build the Cuniss P-40 Kittyhawk under licence. The firm at once made a counter suggestion, offering to build a new fighter of superior performance, but powered bv the same 1,150 h.p. Allison V-1710-39 engine. To this the Com­mission agreed, subject to the proposed aircraft being completed within 120 days; North American met this deadline with a margin of three days, although at this stage the prototype was certainly not in flyable condition, and indeed it was May 1941 before it first took to the air.
The NA-73, as it was then known, featured wings wiih laminar flow aerofoil section to reduce drag—a new feature on a fighter aircraft. The second prototype, carry­ing the full armament of two 0.50 in. machine guns in the nose beneath the engine, with two more in the wings alongside four 0.30 in. guns, was shipped to the United Kingdom for testing, where it proved to be the best fighter so far received from the United States, though the Allison engine failed to endow the aircraft with sufficient altitude performance to allow its employment as a fighter in the Western European area. However, the heavy armament and high maximum speed of 382 m.p.h. at low level, coupled with good manoevreability, suggested its use for tactical reconnaissance duties, and named the Mustang I it was ordered into production for the R.A.F., modified to carry an F-24 camera behind the pilot.