igned airframe was also produced
and as a result of an overview of the plane a new low drag section of wing replaced the laminar-flow design, the oil cooler was also replaced with a heat exchanger and the cockpit canopy
was stretched to reduce drag further. With a simpler structure and the removal of equipment no longer deemed necessary and the use of new lightweight materials being used a significant
reduction in the planes weight was achieved. Both prototypes were powered by different engines with a 1,695-hp Packard Merlin V-1650-7 engine powering the XP-51F and a 1,140-hp Rolls-Royce
Merlin 145m powering the XP-51G. Two P-51J prototypes of a similar design were ordered, however only one was finished and this would be powered by a Allison V-1710-119, 1,720-hp engine.
As a result of the prototypes the P-51H appeared powered by the V-1650-0 Packard Merlin, this was to be both the last production Mustang and the fastest with a top speed of 487 mph.
Further improvements had been made to the plane and as a result the plane was 40% lighter than the last Mustang in war time service the P-51D.
Another permutation of the P-51 was the P-82 Twin Mustang which was two aircraft merged together, however this didn't see service in World War 2.
A grand total of 14,819 Mustangs were built by the time production ended, seeing service with China, Netherlands and a few were also supplied to the American Volunteer Group (AVG) in China.
The end of the war didn't see the end of the Mustang as it remained in service with the US in some capacity until 1951, although under a different designation of F (fighter) - 51. In fact
the last Mustang was retired from the Dominican Air Force in 1984.