The American engine of war production was running at full throttle in 1943. The pace of warplane making reached a peak and the Mustang-maker North American Aviation was employing more than 84,600 factory workers in its Inglewood, California, Dallas, Texas, and Kansas City, Missouri plants. The company was on its way to building more warplanes—fighters, trainers and bombers—than any other American airplane maker in the Second World War.
In that same year the flight test air crew and engineers were bringing the giant new Boeing B-29 Superfortress bomber through its performance evaluations and early teething problems. The plane, in great numbers, was destined for the very long ranging attacks of the American bombing campaign against Japan in the final months of the war. There would be many problems associated with the precedent-setting mission of the new bombers, not least being the matter of providing effective fighter escort protection for them over the vast expanse of ocean from the massive Tinian air base in the Marianas to the Japanese home islands and back.
Only the North American P-51 Mustang, of all the fighters in the USAAF inventory, was capable of making the long, and arduous trip, but doing so on a routine daily basis was believed to be too much to expect of the fighter pilots who would have to sit for eight hours or more and be ready to defend their charges in combat. The fatigue factor would simply go beyond excessive. To deal with the problem, the design engineers of North American got busy on a unique solution, a new, ultra-long-range fighter that would carry a second pilot to share the flying duties.
The new plane would be designated the P-82 and referred to as the “Twin Mustang.” Basically, the design incorporated the fuselages of two P-51H Mustangs which were connected by a constant-chord wing. Their tails were joined by a single rectangular tailplane and standard port and starboard outer wing sections were employed. The plane was flown by a pilot in the port fuselage sections; the copilot sat in the starboard cockpit. Both of the cockpits were, however, fully equipped, enabling the pilots to fly the plane from either cockpit and spell each other on very long flights.
The so-called Twin Mustang was actually a new design. Mustang designer Edgar Schmued added a 57” fuselage plug immediately behind the cockpit areas of each fuselage, to accommodate the installation of additional fuel tanks and other equipment. The new centre wing section was an entirely new design and would house the M2 Browning machine-gun armament. The outer wing sections were substantially strengthened to carry new hard points for additional fuel drop tanks or up to 1,000 lb of ordnance. New, enlarged dorsal fillets were added to the two vertical tail fins to increase stability in the event of an engine failure.
The P-82 was designed to be powered by two Packard-built V-1650 Merlin engines which would ultimately be replaced with Allison V-1710 engines of 1,600 horsepower each, with counter-rotating propellers. The first two prototype aircraft and the next twenty P-82B models were, in fact, powered by the Packard Merlins. In early testing engineers found the arrangement inadequate, requiring a major monthlong rethink. This, coupled with an increase in the licensing cost paid to Rolls-Royce for each Packard-built Merlin made in the United States, led the U.S. Army to negotiate an agreement with the Allison Division of General Motors for a new version of the V-1710-100 engine, a slightly lower- powered engine than the Merlin it was replacing. North American was then required to switch to the all new Allison for installation in all P-82C and later models of the plane. Subsequent performance testing then established that the Allison-powered P-82s had a lower top speed and less efficient high altitude performance than their Merlin-powered predecessors. The earlier Merlin P-82s were relegated to trainer roles.
Each main landing gear leg was attached to the front wing spar beneath the outboard side of each fuselage, the wheels retracting inward under the fuselage and wing. Initially, the plane would be armed with six .50-calibre machine-guns mounted in the centre wing section.
Early design work on the new plane began in October 1943 with a fundamental range requirement of 2,000 miles without refuelling. Work was started on the two prototype XP-82s in January 1944 and the first flight came on June 26th 1945 and the aircraft was accepted by the Army Air Force on August 30th. AAF officials had been so impressed with the aircraft in its early development that they placed the initial order three months before the first flight of the prototype.
At North American Aviation, the approach to getting a new aircraft type into the air was a cautious, careful, reasoned affair. In the case of the XP-82 prototype, the initial step toward the flight test was an official engineering acceptance inspection made on May 25th 1945 at the Inglewood plant, at Mines Field, which is now the Los Angeles International Airport site.
NAA test pilot Joe Barton was scheduled to take the prototype up on her first flight from the 4,500 main runway at Mines, and no one involved that day was expecting any trouble. But when Barton had completed a series of taxi tests and ground runs at gradually increasing speeds, he turned the factory-fresh Twin Mustang onto the runway to begin its first ever actual take-off roll. As the plane neared lift-off speed he pulled back on the control stick as far as he dared, and then as far as he could, and the airplane remained firmly on the ground. Over several days he tried repeatedly to make the plane take-off, without success. The technical brains of the company met to consider the problem. Chief Engineer Ray Rice, chief of the engineering technical section Larry Waite, aerodynamicist Ed Horkey, chief test pilot Ed Virgin, Mustang designer Edgar Schmued, and Mustang test pilot / Merlin engine specialist Bob Chilton were all in attendance. Chilton tried to make the bird fly. It wouldn’t. Once again, Joe Barton tried a new series of take-off tests, to no avail.
When the weekend came, Barton and Ed Virgin decided to try and fly the plane in the relatively quieter, less busy hours of Saturday and they had most of the fuel off-loaded to see if improved acceleration from the reduced weight might help. The pressure was on to get the seemingly recalcitrant machine airborne. Roaring down the runway, Barton brought the stick back more and more until it was nearly fully back when, without warning, the big plane suddenly leapt off the ground and was instantly at an altitude of fifty feet. The surprised Barton quickly recovered and safely continued the short flight.
Chilton: “The engines were set up with the propellers rotating towards each other. Dut to the direction of travel, a stall was set up with the airplane center section. Then they swapped engines left to right and right to left. I flew it ten days later and it became like a normal P-51.”
Horkey: “What was happening was that we had propellers rotating in different directions on the left and right engines. For some reason, which I can’t remember, we started with the blades moving upward in front of the center section. What this does, particularly at high angles of attack, is to create upward flow approaching the leading edge of the center section of the wing. You also have normal upflow ahead of the wing. The two upflows would add together and we got an early stall. The center section area represented a large portion of the wing area. So what was happening was that we were stalling out early and just not getting enough lift. It wasn’t any mysterious vacuum holding it down or anything like that. It was just a standard stall or the wing section. I remember taking a ride during this period in one of the fuselages, and we had tufts on the wing. You could see the stalled flow. It would also happen at high-speed turns. We changed the [propeller] rotations to go down in the middle and we had the problem solved.”
Work progressed through the year, but delays in delivery of engines to the waiting airframes at Inglewood plant meant that none of the P-82s would see service in the war.
The order book of North American showed 500 of the new planes to be built as P-82Bs, but with the end of the war on September 2nd, the order was cancelled except for twenty of the aircraft. During their construction in 1946, it was decided to fit two of them with large radar nacelles under the centre wing section to test them in the night-fighter role. The night-fighters were built with a modified starboard cockpit for a radar- intercept observer instead of a copilot.
With the expansion of a procurement budget, the order was then increased to 250, with 100 being built as long-range escort fighters and 150 as night-fighters. The P-82s would soon replace aging Northrop P-61 Black Widows, which suffered a persistent shortage of spare parts along with a seemingly everpresent need for maintenance, making them very difficult and expensive to keep airworthy.
At the height of the Allied round-the-clock bombing offensive against Germany in 1944, the P-51 Mustang showed both sides in the conflict that a well-designed, long-range single engine escort fighter with one pilot could do the job formerly believed to be exclusive to a twin-engined aircraft with a crew of two. But with the advent of the B-29, and the even more extreme long-range requirements of the coming American bombing campaign against Japan, the length of the missions and the very high fatigue factor anticipated for the escort pilots, interest in developing a twin-engined plane for the role was revived.
The development of the Twin Mustang came as the propeller-driven fighter era was ending. With the advent of the new jet fighters and their greatly superior performance, and the atomic bombing of Hiroshima and Nagasaki bringing the war to an end, everything changed. All remaining warplane contracts with American aircraft builders were cancelled. The peace dividend was at hand and very little funding was available for aircraft development. Everyone wanted to forget the war and all thought of new equipment for war.
It came as a huge shock to American military planners, when, during the 1947 Soviet Aviation Day at Tushino, three Tu-4 long-range strategic bombers, exact copies of the big Boeing B-29s interned by the Soviets during the war, appeared over the spectators. U.S. Intelligence knew that the USSR would soon have nuclear weapons and the Americans now knew too that, with the availability of the Tu-4, the U.S. would soon become vulnerable to Soviet nuclear attack. In an interim period during which new jet interceptors were being developed to counter such a threat, the existing Twin Mustangs were pressed into service with the United States Strategic Air Command, to be used as fighter escorts and all-weather air defense interceptors for the bombers of SAC. The first F-82s began operations with SAC at Kearney Air Force Base, Nebraska, in March 1948 with the 27th Fighter Escort Wing.
The mission of the 27th was escort the B-29s, B-50s, or Convair B-36 bombers of SAC on their very long-range missions to the Soviet Union, extremely lengthy flights from bases in Europe or Alaska. In the period between 1948 and the early 1950s, the F-82s were the only operational American fighters capable of shepherding the big bombers on a mission from, say, England to Moscow and back, with a loiter time over the target area of thirty minutes. The Twin Mustang’s service ceiling of 40,000 feet allowed it to stay with the bombers and meet its mission requirement.
With the establishment of the Berlin Airlift and heightened tensions with the Soviets in 1948, the F-82s of the 27th FEW were deployed to McChord Air Force Base, Washington, and put on alert should hostilities break out in Europe. While at McChord, some of their number were detached for temporary duty with the 449th (All-Weather) Fighter Squadron in Alaska, which also flew the Twin Mustang. The pilots of the 27th briefly provided some transition training for the pilots of the 449th before returning to Washington.
The all-weather credentials of the F-82 were certainly confirmed in January of 1949 when the planes of the 27th were ordered to participate in a flypast at Carswell AFB, Fort Worth, Texas, along with many of SACs bomber fleet aircraft. The weather on that particular day was less than ideal. Blizzards raged throughout the Midwest and most major airports were closed. At Kearney AFB, home base to the 27th, the field was completely socked in by blizzard conditions, but still, an early briefing was held for the crews and the planes were readied for the flight to Texas. Runways and taxiways were cleared of the mounting snow and, at the appointed hour the F-82s got airborne and managed a rendezvous with the bombers. The flypast came off as planned and all present were mightily impressed with the performance of the Twin Mustangs in the vilest of weather.
As a part of military budget cutting, the Kearney base was closed in March 1949 and the 27th relocated to Bergstrom AFB, Texas. There, the unit began transitioning into the Republic F-84 Thunderjet and the old F-82s were phased out of active service by September 1950. Most were sent to reclamation, probably to the “airplane graveyard” at Davis-Monthan AFB near Tucson, Arizona. Some, however, went to combat in the Korean War.
The war in Korea broke out on June 25th 1950 when more than 75,000 troops of the North Korean People’s Army began a march south across the 38th parallel into the pro-Western Republic of Korea in the initial military action of the Cold War era. American troops soon entered the conflict on the side of South Korea. U.S. President Harry Truman said at the time: “If we let Korea down, the Soviets will keep right on going and swallow up one place after another.
In the skies over Korea that summer, everything changed. The technology of the 1940s was instantly replaced by a genuine game changer. Swept-wing jet fighters, the Soviet MiG-15 and the American F-86, outstripped the best of the propeller-era fighters, along with the first fighters of the jet age, the straight-winged Republic F-84, Gloster Meteor, and Lockheed F-80. The biggest, best and most sophisticated bomber of the prop-era, the 300-mile-an-hour B-29 too was no longer viable in a time when the opposition could flash by at roughly twice that speed. Either lead, follow, or get out of the way . . . those were the options then for everything in the air that wasn’t a swept-wing jet.
The F-82 air crews on alert at Itazuke Air Base, Japan, in the evening of June 24-25 learned at four in the morning that ground forces of North Korea had invaded their neighbour across the 38th parallel. They were immediately ordered on a reconnaissance mission to report on road and rail activity along the invasion route. They arrived in the area to find it engulfed in cloud cover topped at 8,000 feet. Emerging from the cloud at about 2,000 feet, the Twin Mustangs set course toward Kimpo air base near Seoul in South Korea. En route they spotted great convoys of military vehicles, trucks, and more than fifty tanks heading south. Having completed the recce, the F-82 pilots returned to Japan and a debriefing by staff from General Douglas MacArthur’s headquarters, thus completing the first recorded combat mission of the Korean air war. The intelligence gathered in the flight confirmed the scale of the North Korean invasion force.
From a total of thirty-two Twin Mustangs in the Far East Air Force inventory, twenty-seven were made available by June 27th for use in Korea and they were formed into the 347th Provisional Fighter Group. Before dawn that same day they were airborne providing fighter cover for C-54 Skymaster transport planes carrying civilians out of the country to safety. The mission had been mounted due to concern that fighters of the North Korean Air Force might appear at the Kimpo airfield to shoot down the arriving and departing C-54s. One of the transports had been destroyed on the ground at Kimpo on June 25th by the North Koreans.
The F-82s circled over Kimpo airfield in three flights. At just before noon an assortment of Soviet-built Yak-9s, Yak-11s, and La-7s arrived in the area. A Yak-11 immediately attacked the F-82 of Lt. Charles Moran, damaging one of this vertical stabilizers. The Yak was then set upon by Lt. William Hudson in another of the Twin Mustangs who was able to get in firing position behind the Yak fighter after pulling a high-g turn. His machine-gun rounds struck the North Korean plane, which banked hard right to evade the American. Hudson’s second burst holed the right wing of the Yak, destroying the flap and aileron and setting fire to a fuel tank. The damage prompted the North Korean pilot to bale out, but his observer, who was either dead or badly wounded, went down with the crippled aircraft. The enemy pilot landed on the Kimpo airfield and was surrounded by troops of the South Korean army. He drew his pistol and began firing at the soldiers who quickly returned fire, killing him.
Other F-82 pilots in the area of Kimpo engaged and destroyed two of the La-7s, allowing only two of the enemy aircraft to return to their base that day. The C-54 evacuation operations continued and Lt. Hudson was credited with the first aerial victory of the Korean War.
In that strange, uncertain period between the beginning of hostilities on the Korean peninsula and the arrival and availability of jet interceptors to take over the roles assigned to the F-82s there, the U.S. Air Force faced a serious operational problem. Production of the F-82 Twin Mustang had ceased in April 1948 and no one had planned for the provision of an appropriate supply of spare parts for the small fleet as it had only been built for an interim use and was not intended to remain in service after the new jets came on stream. The entire F-82 inventory amounted to only 182 aircraft and most of them were committed to operational units in the Pacific Northwest, Alaska, and the U.S. east coast. The air force needed the Twin Mustangs immediately to escort B-26 Invader bombers on their raids deep into North Korea, as well as for recce flights in search of ground targets on the Han River. Ground maintenance crews had no alternative to cannibalizing some of their F-82s to keep others airworthy. And the level of activity was high in that week following June 26th 1950, with the planes flying thirty-five sorties that averaged five hours each. The wear and tear on them was considerable.
Some of the pressure on the F-82 crews was relieved in July when some newly arrived Lockheed F-80 Shooting Star jets were able to stifle the progress of the North Korean Air Force in its attempted strikes below the 38th parallel. This enabled the F-82s to fly more escort missions as well as many night intruder missions. In these latter efforts, however, the planes suffered a number of hits, mainly ground fire, in their large, underslung radar radomes. Replacement radomes and radar units were then difficult to access and the ground crews were forced to remove the units, relegating the planes to a day-fighter role. As ground-support aircraft, the Twin Mustangs were most effective, bringing their 4,000-pound bomb and ordnance loads anywhere in the war zone. They also made good use of their six .50 calibre machine-guns against the many ground targets they found.
4th and 68th Squadron F-82s formed part of a major air strike on July 10th against North Korean road traffic of tanks, trucks and personnel carriers, as well as many enemy troops. The bombing objective of the escorted B-26s was an important river bridge whose destruction resulted in an impressive traffic jam for the North Koreans.
Ground support was a vital service being provided by the pilots of the Twin Mustangs throughout July and August. Some 68th Squadron F-82s were patrolling over South Korea during the night of August 27th when their leader received an urgent call for air support from a unit of United Nations ground troops pinned down by concentrated enemy mortar fire. After making initial passes to coordinate their attack with a ground controller, the American pilots spent the next forty-five minutes shooting up the enemy positions, silencing the mortar opposition and killing more than 300 of the North Korean troops.
From October, the use of the Twin Mustangs in Korea was shifted to flying early morning weather recce missions, along with an airfield alert readiness in the Seoul area. Now the bulk of the ground attack missions were being undertaken by F-51 Mustangs, F-80 Shooting Stars, and F-84 Thunderjets.
The situation changed again in December as large units of the Chinese Communist army entered the conflict in support of the North Koreans. Most of the F-82s were then committed to flying armed reconnaissance missions over southern North Korea, checking road activity by the Chinese. Their role was altered again in late January when they were ordered to fly continuous combat air patrols over the main airfields in the area of Pyongyang to monitor Chinese aircraft operations which were threatening the UN front lines.
The earlier operations of the F-82s had put the air and ground crews under considerable stress and strain. By midsummer, though, the liklihood of the planes becoming involved in air-to-air combat had been significantly reduced, largely due to the increasing participation of the F-80s, F-84s, and the F-51 Mustangs, all of whom had become effective in preventing the aircraft of the North Korean Air Force from flying below the 38th parallel.
The use of the F-82 twin-Mustangs in escorting the B-26 missions to targets deep into North Korea brought their substantial and effective firepower in the form of their six .50-caliber machine guns with 400 rounds each and a 4,000-pound ordnance capability into play against the many ground targets available to them. The trips were not without hazard, however, as the F-82s, operating with droppable external fuel tanks, had to frequently drop these tanks due to the risk of fire or explosion should the tanks be hit by enemy ground fire.
By early July the 339th Squadron had been withdrawn from combat operations and reassigned to Johnson Air Base on the island of Okinawa. This was followed by the return of the 4th Squadron to Okinawa, the inactivation of the 347th Provisional Group, and control of the 68th Squadron being assigned to the Eighth Fighter Group. The 339th Squadron had been in combat for just ten days in late June and early July, flying a total of only forty-four combat sorties, actions for which they had been given no training. Throughout July and August, the F-82s of the 68th were required to carry on the battle, attacking enemy trains, vehicles, buildings, and strafing North Korean troops on the roads.
Time was running out for the Twin Mustangs in Korea by August 1951. By the end of the month, only eight of the planes remained operational in Korea as the new Lockheed F-94 Starfire all-weather interceptor was arriving in quantity and assuming much of the responsibilities formerly carried by the F-82s. And by April 1952, all such assignments were being flown by the F-94s. During their Korean War involvement, the Twin Mustangs had accounted for twenty enemy aircraft destroyed, four in the air and sixteen on the ground.
Several of the surviving F-82 Twin Mustangs were reassigned to a cold weather air defence role in Alaska, a mission they were well suited for with their long-range mission capability. There they patrolled the area in a time when the Soviets were regularly flying missions from Siberian airfields to test the air defences of the U.S. in that part of the world. Tensions were high there during and after the Korean War, and the job of responding to the constant testing and threats was shared by the F-82s with F-94 jets which, while much faster, had a far shorter range capability. Most of the F-82s were operated from Ladd AFB near Fairbanks, and from Adak Island.
By the time they arrived in Alaska, most of the Twin Mustangs that had served in Korea were in a badly run-down condition, many of them suffering serious corrosion and, of course, the continuing parts shortage which made maintenance difficult to almost impossible. Some limited long-range recce flying was carried out over the Bering Sea, but it was necessary to bring along an experienced flight mechanic in the right side cockpit to be on hand when the demands of these extremely long flights on the relatively high-time airplanes forced them to make emergency landings in remote and desolate locations. In such instances, the mechanic was normally able to make adequate repairs so the pilot could bring the aircraft back to the Ladd base.
Finally, the shortage of spare parts, and ordinary attrition brought about the ultimate withdrawal of the last operational F-82s, roughly half of which had long since become “hangar queens”, robbed of their precious parts to keep the others in the air. As fewer and fewer the of old machines were capable of being repaired by spring 1953, only a handful remained operational. Most of the planes were declared to be surplus to requirements, put in storage and eventually sent for reclamation and ending up in smelters for recovery of their metal as ingots. Four of the old F-82s were acquired by the National Advisory Committee for Aeronautics (NACA) where they served briefly in research work.
Five examples of the F-82 Twin Mustang are known to still exist. One was for many years a ‘gate guardian’ at Lackland AFB in Texas. It was ultimately acquired by what used to be called the Confederate Air Force, and is now known as the Commemorative Air Force. It was restored to flying condition and operated by the Texas organization until a landing accident in 1987. The plane could be repaired but locating the required replacement propellers and landing gear proved all but insurmountable. In 2009 the aircraft was returned to the U.S. Air Force (the National Museum of the U.S. Air Force, in Ohio) which had loaned it to the CAF originally. The museum staff have since restored it, repainted and marked it to replicate the aircraft that was flown by Lt. Charles Moran, in which he downed a North Korean La-7 on June 27th 1950 near the Kimpo Air Base in Korea.
A second Twin Mustang example survives on display in the Air Force Museum. It is shown in the markings it wore during an historic flight from Hawaii to New York in February 1947. The aircraft, named Betty Jo, made the 4,968-mile trip in fourteen hours and thirty-two minutes at an average speed of 342 mph with Colonel Robert E. Thacker at the controls. The plane carried a combined internal and external fuel load of 2,215 gallons. The achievement remains the longest nonstop flight ever made by a propeller-driven fighter plane. Betty Jo was an F-82B powered by Rolls-Royce Merlin engines. It has been in place at the Air Force Museum since June 1957.
Next on the short survivor list of Twin Mustangs is one of the two prototypes, the XP-82 number 44-83887. Aircraft restorer Tom Reilly of Douglas, Georgia, acquired the remains (a single left-side fuselage and some parts) of this historic aircraft in March 2008. For many years it had lain on the farm of airplane collector Walter Soplata, near Newbury, Ohio. Reilly intends to build a new right-side fuselage and rebuild the entire plane to flying condition.
Another airframe that had been a part of the Soplata collection in Ohio is an F-82E which has been sold to C&P Aviation of Anoka, Minnesota, which is restoring it to flying condition.
The last of the remaining Twin Mustangs, an F-82E, is a current gate guardian at Lackland AFB, Texas, and part of the USAF History and Traditions Museum of San Antonio, Texas.