by Sean Sims
Many of us have seen the recent news of North American XP-82 Twin Mustang #44-83887 returning to the skies after nearly 70 years (the only remaining airworthy example in the world), but few of us know the storied, short service career of the Twin Mustang. This amazing aircraft amassed an intriguing history during the half decade it took to the skies for the United States.
Birth of the Twin Mustang
Figure 1. P-51D “Mad Max” by Sean Sims
In the early 1940s, as World War II raged on, the United States Army Air Forces (USAAF) saw the need for a new very long range (VLR) fighter aircraft that would be used to escort the Boeing B-29 Superfortress bombers on missions exceeding 2,000 miles. One of the superstars of World War II, the North American P-51 Mustang had a range of only 1,650 miles with external tanks.
In all probability the designers at North American said, “The Mustang is great. What would be better? Two Mustangs!” and began researching bolting two Mustangs together in 1943. In theory that would be a pretty simple approach. In practice they determined many modifications would be necessary. In the end the Mustang and the Twin Mustang shared only 20% commonality.
The first change was made when the designers calculated the extra fuel necessary for the VLR mission, this required increasing the length of the fuselage by 57 inches for additional fuel storage. The added weight of the extra fuel required a stronger wing. With all of the above mentioned modifications, the undercarriage also underwent a full redesign.
The central wing was used to consolidate the P-51s standard six 50-caliber Browning heavy machine guns. The tail surface was joined inboard with no external horizontal stabilizer and the vertical stabilizers were enlarged to provide extra command over the increased thrust.
Two cockpits were included to combat pilot fatigue on the VLR missions. The pilot in command sat in the left cockpit and the co-pilot sat in the right cockpit similar to all other two pilot aircraft. In later models, a radar operator replaced the co-pilot.
Figure 2. P-82 US Air Force Photo
North American’s proposal was approved by the USAAF on 7 January 1944 and two prototype aircraft were started. By March of 1944 the USAAF was so impressed by the design proposal alone (the first prototype didn’t fly until 15 April 1945!) they issued a contract for five-hundred P-82B-model aircraft. They requested the addition of an optional gun nacelle to be mounted under the central wing section containing eight 50-caliber heavy machine guns bringing the total to fourteen. The USAAF also called for four underwing pylons capable of carrying jettisonable fuel tanks, up to twenty 5-inch rockets or 4,000 pounds of bombs (which was roughly the same payload as a World War II medium bomber, e.g. North American B-25 Mitchell or Martin B-26 Invader).
The Twin Mustang was competing against several other aircraft development projects such as:
Lockheed XP-58 Chain Lightning, an enlarged version of Lockheed P-38 Lightning, intended to be a long-range fighter
Fisher XP-75 Eagle, initially designed as a fast climbing interceptor, utilized co-axial contra-rotating propellers
Consolidated Vultee XP-81, a combined turbojet and turboprop fighter intended to serve as a long-range escort
Updated Northrop P-61E Black Widow, which eventually became the Northrop F-15 Reporter photographic reconnaissance aircraft
McDonnell XP-67 Moonbat, a technologically advanced, twin-engine single-seat fighter intended to serve as a high-speed, long-range interceptor
World War II Draw Down
World War II in Europe ended in May of 1945 with Japan surrendering later that year in August. This caused a reassessment of all on-going military projects with many being cancelled as the post-war draw-down of forces began. North American saw their Twin Mustang project production order cut from 500 to just 20 airframes.
Initially the Twin Mustang utilized the same engine as the P-51 Mustang, the V-12 Rolls-Royce Merlin V-1650 (built under license by Packard). However, the USAAF had to pay a licensing fee for every Merlin installed. In an effort to reduce costs, in August 1945, they approached the Allison Division of the General Motors Corporation and requested a new version of the Allison V-1710-100 engine (the same engine used in the P-38, P-39 and P-40). The Allison-powered P-82 models demonstrated a lower top speed and poorer high-altitude performance than the earlier Merlin-powered versions. The Allison engine was also less reliable and less serviceable. Allison engine versions of the Twin Mustang started being delivered in November 1947. In the end, the Allison-powered P-82 cost 35% more than the Merlin version. This gives the Twin Mustang the rare achievement of being one of a few aircraft in United States military history to be slower in its production version that its trainer/prototype.
Saving grace for the Twin Mustang project came from the Northrop P-61 Black Widow. Developed in the early 1940s, the Black Widow was seen as a stopgap aircraft filling the night fighter/reconnaissance role until a suitable jet-powered aircraft could be produced. Development delays impacting the Northrop XF-89 Scorpion (a jet-powered interceptor which finally entered service in the 1950s) and Curtiss-Wright XF-87 Blackhawk (which lost the jet-powered interceptor role to the Scorpion) projects meant the Black Widows had to remain in service and were rapidly reaching the end of their designed operational timelines. Procured and built for wartime duty, no long-term plans for use had been made; spare parts for example were being supported by cannibalization of Black Widows stored at Davis-Monthan Air Force Base and other storage depots across the US.
Figure 3. P-82C US Air Force Photo
North American convinced the USAAF that the P-82 Twin Mustang could fill the night fighter/reconnaissance role. A pair of P-82Bs were selected for conversion to the night fighter role and these became the P-82C and P-82D models. The primary difference between these models was the radar system. The C-model used the SCR720 series radar while the D-model had the newer APS-4 series (both mounted in nacelles under the center wing section and extending past the propeller to avoid interference). Many P-82Bs were already built and their engine-less airframes were sitting in storage at North American Aviation’s production facility in Inglewood, California.
Operational Status
The first Twin Mustangs began to reach squadrons during 1948. In June of that year, the United States Army Air Forces became the United States Air Force and all P-designated aircraft (for pursuit) were changed to F-designated aircraft (for fighter), and the Twin Mustang became F-82 rather than P-82.
The final Twin Mustang rolled off the North American production line in March 1949. What started as a 500 aircraft order in 1944, based on a plan alone, resulted in a mere 273 P-82/F-82s produced.
The F-82 E-model was manufactured as an all-weather day fighter with a total of 100 produced.
The F-model was outfitted with the APS-4 radar and was a dedicated night fighter with a total of 100 produced.
The G-model was equipped with the SCR720 radar and was similarly a dedicated night fighter with a total of 50 produced.
With the beginning of the Cold War in the mid-1940s the USAF established the Strategic Air Command (SAC), responsible for strategic bombers and intercontinental ballistic missiles, and the Air Defense Command (ADC) responsible for defense of the United States through the use of radar stations and interceptor aircraft.
The first E-model was delivered to SAC’s 27th Fighter Wing (552nd, 523rd, and 524th Squadrons) at Kearney Air Force Base, Nebraska in March of 1948. With an internal fuel range of greater than 1,400mi the E-model Twin Mustang was capable of flying from London to Moscow, loitering for 30 minutes, and returning when equipped with external fuel tanks; the only American fighter capable of such a feat at the time.
F-model Twin Mustangs entered service with ADC’s 325th Fighter Group (317th, 318th, and 319th Squadrons) at Hamilton Field, California and McChord Air Force Base, Washington along with the 51st Fighter Group (16th, 25th, and 26th Squadrons) and the 52nd Fighter Group (2nd and 5th Squadrons) at Mitchel and McGuire Air Force Bases, New Jersey in September of 1948.
The final production model, the F-82G, an all-weather radar-equipped night fighter, started service with the 347th Fighter Group (4th, 68th and 339th Squadrons) in Japan as part of the Far East Air Forces (FEAF).
Unsung Hero of the Korean War
Figure 4. F-82G NMUSAF US Air Force Photo
On 27 June 1950 Twin Mustang G-models assigned to FEAF were the first assets to respond to North Korea’s invasion of South Korea and claimed the first three air kills of the Korean War. The Twin Mustang was the only fighter aircraft assigned to FEAF capable of reaching the entire Korean peninsula from bases in Japan. While assigned to provide fighter cover for C-47 and C-54 transports flying American personnel out of Kimpo Airfield in Seoul, F-82G #44-383 assigned to the 347th Fighter Group, 68th Fighter Squadron, piloted by Lieutenants William Hudson and Carl Fraser shot down a North Korean Yak-7U. Not only was this the first air kill of the Korean War, it was also the first aerial victory by the newly-formed United States Air Force.
Luck had brought the Twin Mustang to service, and luck had placed the Twin Mustang in Japan as the only asset capable of reaching Korea. As the only long-range fighter in the area, the Twin Mustang saw extensive service in Korea through November of 1951 when the air war in Korea became increasingly dominated by new jet-powered fighters on both sides.
On 10 July 1950, F-82s participated in one of the biggest strikes of the war against ground targets in North Korea. Joined by Douglas B-26 Invaders and Lockheed F-80 Shooting Stars, the aircraft hit massive amounts of North Korean road traffic. An estimated 117 trucks, 38 tanks and seven personnel carriers were destroyed, along with a large number of enemy troops killed when the B-26s destroyed a bridge at Pyongtaek causing a massive traffic jam.
Twin Mustang Sunset
A short two years after joining SAC, in February 1950, the F-82E Twin Mustangs were retired from bomber escort duty in favor of the Republic F-84E Thunderjet (with aerial refueling capability). A small number were modified to G-models and sent to Korea (as replacement aircraft) and some were modified to H-models and sent to Alaska as replacement aircraft while the remainder were stricken as surplus. Twin Mustangs assigned to ADC started to be replaced by the Lockheed F-94A Starfire as well in June 1951.
Starting in the early 1950s, Twin Mustangs (filling the night ground-attack role) in Korea were phased out in favor of Douglas B-26 Invader and Northrop F-89 Scorpions. Some were sent to Alaska, but sadly most were sent to a reclamation storage depot. One reason many Twin Mustangs were sent to the depot was a direct result of USAF planning. The Twin Mustang, from the beginning, was selected as a short-term stop-gap aircraft. No provision had been made for an adequate supply of spare parts, as the aircraft was not expected to remain in operational service once jet-powered aircraft were available.
F-82s sent to Alaska were converted to fly in cold weather, re-designated as F-82Hs, and were assigned to the Alaskan Air Command, 5001st Composite Group (449th Squadron) at Ladd Air First Base. Twin Mustangs assigned to Alaska operated further north than any other USAF fighter aircraft of the period. By 1952 they were escorting SAC B-36 Peacemaker bombers near the most northern tip of Alaska a mere 1,000mi south of the North Pole.
At the same time, due to the lack of an established supply chain, Twin Mustangs were limited in flight time. Occasionally F-82s were tasked with long-range, highly dangerous reconnaissance flights over the Bering Sea given that the range of the Twin Mustang was much greater than that of the F-94. The H-models were not outfitted for the photo reconnaissance mission, so the radar operator took photos from the right cockpit using handheld cameras. Later on, rather than a radar operator in the right seat, the aircraft normally carried an experienced flight mechanic. Many pilots were forced to land in remote locations on crude landing strips due to high-hour aircraft being kept flying with salvaged parts. Having the mechanic in the right seat meant they could usually repair the aircraft well enough to get airborne again and return to base.
The final operational Twin Mustang #46–377, originally configured as a G-model that served in Japan then converted to an H-model at Ladd Air Force Base, Alaska, was officially retired at Elmendorf Air Force Base, Alaska on 12 November 1953 ending the Twin Mustang’s short five year career.
Other Twin Cockpit Aircraft
Throughout World War II several aircraft manufacturers explored mating two fuselages of existing aircraft together, but only two notable projects resulted in an actual aircraft being produced. The North American P/F-82 Twin Mustang (which we just discussed above) and the Heinkel He 111Z “Zwilling” (which translates to twin) based on the He 111 medium bomber.
Figure 5. Heinkel He 111Z Public Domain
This experimental aircraft was essentially two He 111 airframes joined together by a new center section wing and powered by five Junker Jumo 221F engines. Initially designed to tow the Messerschmitt Me 321 glider it was subsequently modified in the Z-2 and Z-3 variants to be a heavy bomber that could carry nearly 4,000 pounds of ordinance 2,500mi.
The He 111Z was piloted from the port fuselage which also carried the first mechanic, radio operator and a gunner. The starboard fuselage retained flight controls and related essential equipment but carried the observer, second mechanic and another gunner. The aircraft had a very short service career with only 9 confirmed aircraft all of which were shot down or destroyed.
Twin Mustang Achievements
The Twin Mustang has many noteworthy achievements. Not only was it the first aircraft to score an aerial kill in Korea, but that same kill was the first of the United States Air Force (formerly the United States Army Air Force). The F-82 is also the last propeller-driven fighter acquired in quantity by the U.S. Air Force.
Figure 6. P83B “Betty Jo” at NMUSAF by Sean Sims
The Twin Mustang is also responsible for the longest non-stop flight of a piston-powered/prop-driven military fighter aircraft. F-82B “Betty Jo” (#44-65168) flew from Hickam Field, Hawaii to New York, a distance of 5,051mi over 14 hours and 33 minutes on 27-28 February 1947. Betty-Jo averaged a top speed of 347mph (faster than the top speed of most World War II fighters). Four oversized, jettisonable 310 gallon fuel tanks were required to achieve this range. Flight dynamics were somewhat hampered when three of the fuel tanks refused to release. "Betty-Jo" was named after pilot Lt Colonel Robert Thacker's wife. LtCol Thacker was aided by copilot Lt John Ard.
Remaining Twin Mustangs
Sadly all but five F-82s were eventually scrapped.
Two are at the National Museum of the USAF:
F-82B Twin Mustang “Betty Jo”, AF s/n #44-65168, is currently on display in the Cold War gallery.
F-82B (modified and marked as the G-model that scored the first aerial kill in Korea) Twin Mustang, AF s/n #44-65162, is on display in the Korean War gallery.
The USAF History and Traditions Museum in San Antonio, Texas maintains an E-model, AF s/n #46-0262, which is currently on display as a “gate guard” at Lackland AFB.
And two are privately held and undergoing restoration:
XP-82 Twin Mustang, AF s/n #44-83887, recently returned to flight status with the B-25 Group based in Georgia and led by Tom Reilly. This aircraft, a single fuselage and parts of the second XP-82, were located for many years on the farm of Walter Soplata in Newbury, Ohio. Tom Reilly took possession in April 2008 and moved everything to Douglas Municipal Airport in Douglas Georgia. Additional airframe parts were sourced from Alaska, Colorado, and Florida; a left-turning engine was located in Mexico City; control components from California; and other items fabricated were fabricated in Georgia as part of the restoration.
F-82E Twin Mustang, AF s/n #46-0256 is currently under restoration to flight status by James Harker in Anoka, Minnesota. This aircraft was an intact airframe formerly located at the Walter Soplata farm in Newbury, Ohio.
The big issue with flying the F-82 is that the two engines spin in opposite directions. The left rotating engines are all but impossible to find, and the left hand propellers are no longer available.
Sidebar
Series Model Variants
XP-82 - Prototype Designation; two aircraft produced with the Merlin engines
XP-82A - Third Experimental Prototype Designation; single aircraft produced with the Allison engines
P-82B - Base Production Fighter Version; based on XP-82 prototypes; 20 aircraft produced of the 500 originally ordered
P-82Z - P-82B models set aside for testing and pilot training; 20 aircraft produced
P-82C - Prototype night fighter; center nacelle housing SCR720 radar system
P-82D - Prototype night fighter; center nacelle housing APS-4 radar system
P/F-82E - All-Weather Day Fighter/Escort; first four designated P/F-82A used for testing; 100 aircraft produced
P/F-82F - Night fighter; center nacelle housing SCR720 radar system; 100 aircraft produced
P/F-82G - Night fighter; center nacelle housing APS-4 radar system; 50 aircraft produced
F-82H - Cold Weather Model converted from E, F and G models for use in Alaska
