North American P-51 Mustang XP-51D

The XP-51D was not a new design but the conversion of three existing airframes to cure the most criticised flaw of the razorback Mustang: poor visibility to the rear. In late 1942 the tenth production P-51B-1-NA was taken off the assembly line and, from the windshield aft, its rear fuselage formers were cut down to the same height as those forward of the cockpit, the new line fairing into the vertical tail. A blown plexiglass canopy was fitted over that lowered spine, drawing on the moulding techniques developed in the United States for streamlined bomber nose transparencies, together with a simpler windscreen whose angled bullet-resistant panel and two flat side pieces improved the forward view. Wind tunnel tests on a wooden model had confirmed the aerodynamics beforehand.

Two P-51B-10-NAs modified in the same way joined that first aircraft, making up the three examples covered by the designation. The powerplant remained the Packard V-1650-7, the licence-built version of the Rolls-Royce Merlin 60 series with a two-stage, two-speed supercharger, as used by the production P-51D and P-51K. Since these were not prototypes of a different airframe but the pattern for the version about to enter production, the experimental designation was dropped and the aircraft were redesignated P-51D-NA.

What was tested on these three aircraft became the most widely produced Mustang variant: P-51D production totalled 6,502 aircraft at Inglewood and 1,600 at Dallas, 8,102 in all. The reference material gives no flight dates or individual serial numbers for the three conversions, and this text does not invent them.