The North American F-82 Twin Mustang is the last American piston-engine fighter ordered into production by the United States Air Force.
Based on the North American P-51 Mustang, the F-82 was originally designed as a long-range escort fighter for the Boeing B-29 Superfortress in World War II.
The war ended well before the first production units were operational.
In the postwar era, Strategic Air Command used the aircraft as a long-range escort fighter.
Radar-equipped F-82s were used extensively by the Air Defence Command as replacements for the Northrop P-61 Black Widow as all-weather day/night interceptors.
During the Korean War, Japan-based F-82s were among the first USAF aircraft to operate over Korea.
The first three North Korean aircraft destroyed by U.S. forces were shot down by F-82s, the first being a North-Korean Yak-11 downed over Gimpo Airfield by the USAF 68th Fighter Squadron.
Initially intended as a very long-range (VLR) escort fighter, the F-82 was designed to escort Boeing B-29 Superfortress bombers on missions exceeding 2,000 mi (3,200 km) from the Solomon Islands or Philippines to Tokyo, missions beyond the range of the Lockheed P-38 Lightning and conventional P-51 Mustangs.
Such missions were part of the planned U.S. invasion of the Japanese home islands, which was forestalled by the surrender of Japan after the atomic bombings of Hiroshima and Nagasaki and the opening of Soviet attacks on Japanese-held territory in Manchuria.
In October 1943, the North American Aircraft design team began work on a fighter design that could travel over 2,000 mi (3,200 km) without refuelling.
It consisted of a twin-fuselage design, parallel to the experimental German Messerschmitt Bf 109Z “Zwilling.”
Although based on the lightweight experimental XP-51F, which would later become the P-51H Mustang, it was actually a new design.
North American Design Chief Edgar Schmued incorporated two P-51H Mustang fuselages lengthened by the addition of a 57 in (1,400 mm) fuselage plug located behind the cockpit where additional fuel tanks and equipment could be installed.
These were mounted to a newly designed centre wing section containing the same six .50 calibre (12.7mm) M3 Browning machine guns as a single-engine Mustang, but with more concentrated fire.
The first XP-82 prototype was equipped with a removable centreline gun pod housing eight additional .50 calibre M3 Brownings, but this did not feature on production aircraft.
An even more powerful centreline gun pod containing a 40 mm (1.6 in) cannon was considered but was never built.
The outer wings were reinforced to allow the addition of hardpoints for carrying additional fuel or 1,000 lb (450 kg) of ordnance.
The two vertical tails were also from the XP-51F but incorporated large dorsal fillets for added stability in case of an engine failure.
The aircraft had a conventional landing gear with both wheels retracting into bays under each fuselage centre section.
The XP-82 was to be powered by two Packard-built Rolls-Royce V-1650 Merlin engines.
Initially, the left engine was a V-1650-23 with an additional gear in the propeller reduction box to allow the left propeller to turn opposite to the right propeller, which was driven by the more conventional V-1650-25.
In this arrangement both propellers would turn upward as they approached the centre wing, which in theory would have allowed better single-engine control.
This proved not to be the case when the aircraft refused to become airborne during its first flight attempt.
After a month of work North American engineers finally discovered that rotating the propellers to meet in the centre on their upward turn created sufficient drag to cancel out all lift from the centre wing section, one quarter of the aircraft’s total wing surface area.
The engines and propellers were then exchanged, with their rotation meeting on the downward turn, and the problem was fully solved.
The first XP-82 prototype (44-83886) was completed on 25 May 1945 and made the type’s first successful flight on 26 June 1945.
This aircraft was accepted by the Army Air Forces on 30 August 1945, whose officials were so impressed by the aircraft, while still in development, that they ordered the first production P-82Bs in March 1945, fully three months before its first flight.
The XP-82 prototypes, and production P-82Bs and P-82Es, retained both fully equipped cockpits so that pilots could fly the aircraft from either position, alternating control on long flights, while later night fighter versions kept the cockpit on the left side only, placing the radar operator in the right position.
Although some P-82B airframes were completed before the end of World War II, most remained at the North American factory in California waiting for engines until 1946.
As a result, none saw service during the war.
Like most versions of the P-51 Mustang, the first two prototype XP-82s as well as the next 20 P-82B models were powered by British-designed Rolls-Royce Merlin engines, re-engineered for increased durability and mass-production, and built under license by Packard.
These provided the fighter with excellent range and performance; however, the Army had always wanted to give the Twin Mustang a purely American and stronger engine than the foreign-designed P-51’s V-1650 (built at Packard plants, dismantled after the war).
In addition, the licensing costs paid to Rolls-Royce for each V-1650 were being increased by Britain after the war.
It therefore negotiated in August 1945 with the Allison Division of the General Motors Corporation for a new version of the Allison V-1710-100 engine.
This forced North American to switch subsequent production P-82C and later models to the lower-powered engines.
It was found that Allison-powered P-82 models demonstrated a lower top speed and poorer high-altitude performance than the earlier Merlin-powered versions.
The earlier P-82B models were designated as trainers, while the “C” and later models were employed as fighters, making the P-82 one of the few aircraft in U.S. military history to be faster in its trainer version than the fighter version.
In 1948, the 3200th Proof Test Group at Eglin AFB, Florida, fitted the 4th F-82B Twin Mustang with retractable pylons under the outer wings capable of mounting 10 High-Velocity Air Rockets (HVAR) each, which folded into the wing under surface when not in use.
This installation was not adopted on later models, the standard “tree” being used instead.
The 13th aircraft was experimentally fitted with a centre wing mounted pod housing an array of recon cameras, and was assigned to the 3200th Photo Test Squadron, being designated, unofficially, the RF-82B.
Variants
NA-123
Basic Development design.
The NA-123 design was presented by North American Aircraft to the USAAF in February 1944.
The design for the new aircraft was for a long-range fighter to penetrate deep into enemy territory.
Its immediate role would be to escort the B-29 Superfortress bombers used in the Pacific Theatre of Operations against Japan.
The USAAF endorsed it at once.
A letter contract to construct and test four experimental XP-82 aircraft (P-82 designation) gave way in the same month to an order for 500 production models.
XP-82 / XP-82A
Prototype.
The USAAF accepted the first XP-82 in August 1945 and a second one in September.
Both were equipped with Packard Merlin V-1650-23 and V-1650-25 engines.
The third experimental aircraft, designated XP-82A, had two Allison V-1710-119 engines.
It was accepted in October 1945.
There is no evidence that the XP-82A was ever actually flown, due to problems with the Allison engines.
The fourth XP-82A prototype (44-83889) was cancelled.
P-82B
Planned production version.
With the end of World War II, production plans were cut back significantly.
Against the 500 P-82Bs initially planned, overall procurement was finalized on 7 December 1945 at 270 P-82s.
Included were 20 P-82Bs already on firm order and later allocated to testing as P-82Z.
The USAAF accepted all P-82Zs in fiscal year 1947.
Two aircraft were accepted in January 1946, four in February 1947, and 13 in March 1947.
By December 1949, no P-82Bs (by then redesignated F-82Bs) remained in the Air Force inventory.
These P-82Bs were basically similar to the XP-82 but differed in having provisions for under wing racks.
P-82C
Night fighter version.
A P-82B, (44-65169) modified in late 1946, for testing as a night interceptor.
The P-82C featured a new nacelle (under the centre wing section) housing an SCR-720 radar.
The SCR-720 was the same radar installation which was carried aboard the Northrop P-61 Black Widow, a considerably larger aircraft.
The right-hand cockpit became the radar operator’s position. The production version was designated P-82G.
P-82D
Night fighter version.
Another P-82B (44-65170) modified with a different radar, the APS-4.
The APS-4 was a much smaller set than the SCR-720 and operated in the 1.18 in (30 mm) waveband.
As like the P-82C, the right-hand cockpit became the radar operator’s position.
The production version was designated P-82F.
F-82E
Escort fighter version.
The F-82E followed the F-82B, which it so closely resembled.
They were equipped with two counter-rotating Allison liquid-cooled engines, V-1710-143 and V-1710-145.
The first four F-82Es were redesignated as F-82As and were allocated for engine testing.
After production delays by engine problems and additional testing, F-82Es entered operational service in May 1948.
The Air Force accepted 72 F-82Es in fiscal year 1948 (between January and June 1948), and 24 in fiscal year 1949 (22 in July 1948, one in October, and one in December).
North American F-82F Twin Mustang night fighter
F-82F/G/H
Night fighter versions.
A nacelle beneath the centre-wing that housed radar equipment
(F-82F’s AN/APG28 and F-82G’s SCR-720C18)
Automatic pilot and a radar operator replacing the second pilot.
When winterization was added to the F or G, it became an F-82H.
Entered operational service in September 1948.
One F-82G was accepted in fiscal year 1948 (February 1948), all other F-82s (F, G, and H models) in fiscal year 1949.
The last F-82G and six winterized F-82Hs were received in March 1949.
Specifications
Crew
Two
Length
42 ft 5 in (12.93 m)
Wingspan
51 ft 3 in (15.62 m)
Height
13 ft 10 in (4.22 m)
Wing area
408 sq ft (37.9 m2)
Empty weight
15,997 lb (7,256 kg)
Max take-off weight
25,591 lb (11,608 kg)
Powerplant
1 × V-12 liquid-cooled piston engine Allison V-1710-143,
2,250 hp (1,680 kW) in War emergency rating,
RH rotation fitted to port
Powerplant
1 × V-12 liquid-cooled piston engine Allison V-1710-145,
2,250 hp (1,680 kW) in War emergency rating,
LH rotation fitted to starboard
Propellers
4-bladed Aeroproducts A-542F-D1 constant-speed fully feathering propeller (LHS)
Aeroproducts AL-542F-D1 constant-speed fully feathering propeller (RHS), 10 ft 11 in (3.33 m) diameter
Performance
Maximum speed
461 mph (742 km/h, 401 kn) at 21,000 ft (6,400 m)
Cruise speed
286 mph (460 km/h, 249 kn)
Range
2,240 mi (3,600 km, 1,950 nmi)
Service ceiling
38,900 ft (11,900 m)
Armament
Guns
6 .5 in (12.7 mm) M3 Browning machine guns
Rockets
25 x 5 in (130 mm) rockets
Bombs
4 x 1,000 lb (450 kg) bombs.
