On 7 January North American presented a bold design based on the successful P-51. North American's idea of joining two standard, well proven, P-51 fuselages (complete with engine) was not unique. It was reminiscent of the Heinkel 111Z transport and glider tug, a "Siamese Twin" arrangement of two Heinkel 111 bombers, built by the Germans earlier in the war. In any case, North American's plane proved to be the sole American example.
The XP-82 made its first flight on 6 July 1945.
Few of the 40 F-82s available to the Far East Air Forces in mid 1950 were combat ready. In July, Fifth Air Forces (The Fifth was the largest air force under FEAF) spared three F-82s of the 68th Fighter All Weather Squadron for operations over Korea, but the planes proved of little value except against known and fixed targets. In addition, FEAF's F-82 operations (like ADC's, ADC resumed major air command status in January 1951) were hampered by parts shortages and maintenance troubles. If Fifth Air Force continued to use F-82s over Korea, only 60 days of extra supply support could be expected. Hence, although a few of SAC surplus F-82Es went to FEAF, all F-82s were withdrawn from combat in February 1952. Despite limited use, the F-82s managed to leave a solid war record. They destroyed 20 enemy planes (4 in air fights, 16 on the ground). They scored the first aerial victory in Korea on 27 June 1950, downing a Soviet built Yakovlev-11.
The F-82 was the last propeller-driven fighter acquired in quantity by the USAF. It appears to be two Mustang fuselages on one wing, but in reality it was a totally new design. Its purpose was to provide a fighter carrying a pilot and co-pilot/navigator to reduce fatigue on long-range bomber ecsort missions. Delivery from production did not begin until early 1946, too late for WW II. After WW II, radar-equipped F-82s were used quite extensively by the Air Defense Command as replacements for the P-61 night fighter.
During the Korean Conflict, Japan-based F-82s were among the first USAF aircraft to operate over Korea. The first three North Korean airplanes destroyed by U.S. forces were shot down by all-weather F-82G interceptors on June 27, 1950.
The North American P-82 Twin Mustang was the last piston-engined fighter ordered by the USAAF. It was conceived late in 1943, when it was realized that the very long distances over which single-seat fighters were operating in the Pacific were imposing very great strains on their pilots. It was not uncommon for fighter pilots to spend up to eight hours in their cockpits on maximum-distance missions. Pilots would often return from such missions drenched in sweat and would be so exhausted that they would have to be lifted from their cockpits.
It seemed that a fighter with a second seat for a copilot might be a good idea. North American Aviation came up with the idea of joining two Mustang fuselages together by a constant-chord wing midsection and a rectangular tailplane, using standard port and starboard outer wings. The project was given the company designation of NA-120.
On January 7, 1944, the USAAF ordered four prototypes under the designation XP-82. The twin fuselages were basically similar to that of the P-51H, but were lengthened by some 57 inches by inserting additional sections with integral dorsal fins in front of the tailplane. All parts of the wing had to be completely redesigned internally to carry the very much greater gross weight and to accommodate the increased fuel capacity. The center wing section carried a full set of flaps and was stressed to carry heavy external loads on either one or two pylons. The outer wings were stressed for two pylons. Because of the greater rolling inertia, each aileron was increased in length and divided into inner and outer sections to prevent binding of the hinges under high g-loads.
The engines were 1860 hp Packard Merlin V-1650-23/25 liquid-cooled Vees driving oppositely-rotating Aeroproducts propellers. Each main undercarriage leg was attached to the front wing spar under the outboard side of each fuselage. The wheels retracted inwards under the fuselage and wing. Armament consisted of six 0.5-inch Browning MG 53-2 machine guns with 300 rpg mounted in the new wing center section. These guns could be augmented by a central pod below the wing, with 8 additional machine guns installed.
The two cockpits with dual controls had the same bubble canopies as the P-51H. The port cockpit housed the pilot and was equipped with a full set of flight and engine instruments. The starboard cockpit housed the navigator/copilot and was equipped with only a limited set of instruments, sufficient only for basic control of the plane. At an early stage, it was suspected that once the war was over, the Packard Motor Car Company would be unlikely to continue the manufacture of V-1650 Merlin engines. Furthermore, the Allison V-1710 had by that time matured into an engine which, without a turbosupercharger but with two stages of gear-driven blowers could give excellent performance at high altitudes. Consequently, the V-1710-119 was specified for the third and fourth prototypes, which were to be designated XP-82A. XP-82 serial number 44-83887 flew for the first time on April 15, 1945, piloted by J. E. Barton. The other XP-82 (44-83886) followed shortly thereafter. At first, there were problems with excessive drag, which was eventually traced to the fact that the propellers turned toward each other during their upward sweep. This tended to stall the center section of the wing. The problem was cured by switching the engines, so that the blades met during their downward trajectory. The performance was excellent, the XP-82 retaining all the excellent qualities of the P-51: high speed, excellent maneuverability, and heavy firepower. Maximum speed of the XP-82 was 468 mph at 22,800 feet. Normal range was 1390 miles, with maximum range being 2600 miles. Service ceiling was 40,000 feet, and an altitude of 25,000 feet could be attained in 6.4 minutes. Weights were 13,402 pounds empty, 19,100 pounds normal loaded, and 22,000 pounds maximum. Dimensions were wingspan 51 feet 3 inches, length 39 feet 1 inches, height 13 feet 10 inches, and wing area of 408 square feet.
At an early stage, it was suspected that once the war was over, the Packard Motor Car Company would be unlikely to continue the manufacture of V-1650 Merlin engines. Furthermore, the Allison V-1710 had by that time matured into an engine which, without a turbosupercharger but with two stages of gear-driven blowers could give excellent performance at high altitudes. Consequently, the V-1710-119 was specified for the third and fourth prototypes, which were to be designated XP-82A.
The third Twin Mustang prototype (44-83888) was completed as the XP-82A and was fitted with a pair of Allison V-1710-119 engines of 1500 hp each, driving propellers rotating in the same direction. This change to the Allison brought the Mustang design full circle. The serial number was 44-83888. The Allison installation now looked not unlike that of a Merlin, because the -119 engine had an updraft inlet and an injection-type carburetor upstream of the two-stage supercharger, so that the inlet was on the underside of the engine behind the spinner. The inlet was about a foot further back than with the Merlin.
There is no evidence that the XP-82A was ever actually flown, due to problems with the Allison engines. The other XP-82A prototype (44-83889) was cancelled.
The P-82B was one of the hottest piston-engined fighters of the war. Maximum speed was 482 mph at 25,100 feet. Normal range was 1390 miles at 227 mph, 1280 miles with a 4000-pound bomb load. Service ceiling was 41,600 feet, and an altitude of 20,000 feet could be attained in 7 minutes. Weights were 13,405 pounds empty, 19,100 pounds normal loaded, and 22,000 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.
The first Twin Mustangs began to reach the squadrons during 1948. In June of that year, the P-designation was changed to F, and the Twin Mustang became F-82 rather than P-82. The F-82E entered service in the long-range bomber escort role with the 27th Fighter Group (522nd, 523rd, and 524th Squadrons) of the Strategic Air Command. They spent their brief life flying alongside B-29s, and were replaced by jets in 1950.
In 1948, the F and G night-fighter versions of the Twin Mustang began to replace the Northrop F-61 Black Widow in service with the Air Defense Command. They were painted all-black and had flame-damped exhausts. The first Air Defense Command unit to take delivery of the F-82F was the 325th Fighter Group (317th, 318th, and 319th Squadrons) based at both Hamilton Field, California and McChord AFB, Washington, the 51st Fighter Group (16th, 25th, and 26th Squadrons) and the 52nd Fighter Group (2nd and 5th Squadrons) based at Mitchel AFB and McGuire AFB, New Jersey. In 1949, the 347th Fighter Group (4th, 68th, and 339th Squadrons) stationed in Japan received F-82Gs. The 449th Squadron of the 5001st Composite Group based at Ladd AFB in Alaska received the "cold-weather F-82Hs.
By the middle of 1949, the Twin Mustang was in widespread service, some 225 E, F, and G models being on strength. It was anticipated that the service life of the Twin Mustang would be relatively brief, since the F-82 was seen as only an interim type, filling in the gap only until adequate numbers of jet fighters could be made available. In 1950, some units based in the USA were already beginning to replace their Twin Mustangs with jets.
On June 25, 1950, the Korean War broke out. The Twin Mustangs based in Japan were immediately thrown into combat to stem the North Korean advance. They were the only fighter aircraft available with the range to cover the entire Korean peninsula from bases in Japan. They provided fighter cover for the C-54 and C-47 transports flying in and out of Kimpo Airfield near Seoul. On June 27, 1950, an F-82G (46-383) of the 68th Fighter Squadron of the 347th Fighter Group flown by Lieut. William Hudson (pilot) and Lieut. Carl Fraser (radar operator) shot down a North Korean Yak-7U. This was the first air-to-air kill of the Korean War, and, incidentally, the first aerial victory by the newly-formed United States Air Force. Squadron records have been lost, and memory is unreliable, and it is possible that Lt. Hudson was actually flying 46-601 that day. Later that same day, an F-82G (46-392) flown by Major James Little of the 339th Fighter Squadron of the 347th Fighter Group shot down a North Korean Yak-9. Records are unreliable, and some experts maintain that Major Little actually was the first to kill.
The Twin Mustang saw extensive service in Korea until November of 1951, serving in both escort and ground attack roles. However, the F-82 played a secondary role as compared with its distinguished predecessor, the single-engined F-51. As more jets became available, the F-82s were withdrawn from combat and phased out of service.
TheOn June 27, 1950, Lt. William Hudson, flying an F-82G, became the first pilot of the new U.S. Air Force to claim the first American aerial victory of the Korean war.
The last Twin Mustang was retired from service in mid-1953.
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