North American P-51 Mustang variant
North American P-51 Mustang XP-51J
Third prototype of the NA-105 lightweight Mustang programme and the only one with an Allison V-1710-119. As the engine was insufficiently developed, the aircraft was loaned to Allison for engine development work. Two built, none in production.
North American P-51 Mustang sheet
- 2
- Units built
History
The XP-51J closes the trio of lightweight Mustangs derived from model NA-105, the redesign of the P-51D that North American proposed in 1943 and the USAAF accepted. It shares with the XP-51F and XP-51G the lightened airframe — modified cowling, simplified undercarriage with smaller wheels and disc brakes, larger canopy, four .50 in Brownings and some 730 kg less than the P-51D — and the new wing with NACA 66,2-(1.8)15.5 a=.6 airfoils at the root and NACA 66,2-(1.8)12 a=.6 at the tip, in a simple trapezoidal planform.
Its distinguishing feature is a return to the engine maker of the original Mustang: against the Merlins of the other two designations, the XP-51J was fitted with an Allison V-1710-119 and added to the programme as a third prototype. The choice proved premature, since the engine was insufficiently developed, and the aircraft ended up loaned to Allison as a flying testbed for the engine itself rather than exploring what the lightweight airframe could do.
Two aircraft were built. None of the three experimental lightweight types went into production; the practical payoff of the programme came through the P-51H, which embodied the experience of the XP-51F and XP-51G. The reference material gives no flight dates, no performance achieved and no output for the V-1710-119 in this installation, and this text does not invent them.