The third Twin Mustang prototype, the XP-82A, had been fitted with a pair of Allison V-1710-119 engines of 1500 hp each, driving propellers rotating in the same direction. The serial number was 44-83888. This brought the Mustang design full circle.
At first sight, it seems difficult to understand just WHY the USAAF would ever want to go back to the Allison engine, when the Merlin engine worked so well. However, at the end of the war, the British economy was severely crippled and Rolls Royce was forced to charge a substantial license fee for its Packard-built Merlin. This increase, coupled with the Air Force's desire to develop US-designed liquid-cooled engines, led to the decision to switch to the Allison engine. All the remaining production Twin Mustangs ended up being powered by these Allison engines.
In order to cover the period which elapsed before the first jet fighter aircraft could be available, on October 10, 1946 the USAAF ordered a hundred P-82Es, the production version of the XP-82A. Serials were 46-255/354, and the company designation was NA-144. Power was applied by a pair of supercharged Allison V-1710-143/145 engines rated at 1600 hp each. Unlike the early V-1710s that powered the P-39 Airacobra and the P-40 Warhawk, these engines were cleared to 3200 rpm for takeoff, where the rating was 1600 hp. With water-alcohol injection, maximum power output was 1930 hp at sea level and 1700 hp at 21,000 feet. As the dual designation implied, these engines were handed, with the -143 engine being mounted in the left fuselage, the -145 engine in the right fuselage. The propeller blades moved toward each other at the top.
The first P-82E flew on February 17, 1947. Maximum speed of the P-82E was 465 mph at 21,000 feet. Normal range was 2504 miles, with maximum range being 2708 miles. Service ceiling was 40,000 feet, and the initial climb rate was 4020 feet per minute. Weights were 14,914 pounds empty and 24,864 pounds maximum. Dimensions were wingspan 51 feet 3 inches, length 38 feet 1 inches, height 13 feet 10 inches, and wing area of 408 square feet.
Serials of P-82E:
46-255/354 North American P-82E Twin Mustang c/n 144-38141/38240 Redesignated F-82E in 1948. 0256 owned by Wally Fisk of Minnesota 0262 at USAF History and Traditions Museum, Lackland AFB, TX.