The P-51H (NA-126) was the final production Mustang, embodying the experience gained in the development of the XP-51F and XP-51G aircraft. This aircraft, with minor differences as the NA-129, came too late to participate in World War II, but it brought the development of the Mustang to a peak as one of the fastest production piston-engine fighters to see service.
The P-51H used the new V-1650-9 engine, a version of the Merlin that included Simmons automatic supercharger boost control with water injection, allowing War Emergency Power as high as 2,218 hp. Differences between the P-51D included lengthening the fuselage and increasing the height of the tailfin, which reduced the tendency to yaw. Service access to the guns and ammunition was also improved. The canopy resembled the P-51D style, over a raised pilot's position, and the aircraft was given a new propeller with wider, uncuffed blades and rounded tips to allow the additional power to be utilized more effectively. This propeller was similar to the one used on some later production P-51Ds and the majority of postwar F-51Ds.
With a new airframe several hundred pounds lighter, extra power, and a more streamlined radiator, the P-51H was faster than the P-51D, able to reach 472 mph at 21,200 ft.
The P-51H was designed to complement the P-47N as the primary aircraft for the invasion of Japan, with 2,000 ordered to be manufactured at Inglewood. Production was just ramping up with 555 delivered when the war ended.
Additional orders, already on the books, were canceled. With the cutback in production, the variants of the P-51H with different versions of the Merlin engine were produced in either limited numbers or terminated.
Although some P-51Hs were issued to operational units, none saw combat in World War II and, in postwar service, most were issued to reserve units. One aircraft was provided to the RAF for testing and evaluation. Serial number 44-64192 was designated BuNo 09064 and used by the U.S. Navy to test transonic airfoil designs and then returned to the Air National Guard in 1952. The P-51H was not used for combat in the Korean War despite its improved handling characteristics, since the P-51D was available in much larger numbers and was a proven commodity.
Model Scale 1:27
Air National Guard