One of the primary weaknesses of early jet fighters was their voracious appetite for fuel, resulting in a short range and a limited endurance as compared to conventional piston-engined fighters. In March of 1944, the Bell Aircraft Corporation was asked by the USAAF to construct a jet fighter with extended radius to overcome some of these limitations. A Letter Contract for two prototypes was issued on March 29, 1944. The designation XP-83 was assigned.
Bell had actually been working on an interceptor design since March of 1943 under the company designation of Model 40. In April, in response to the USAAF's requirement, the Model 40 was reconfigured as a long-range escort fighter. The Bell Model 40 retained the basic overall configuration of the earlier P-59A Airacomet, the first US jet-propelled aircraft. Twin General Electric I-40 (J33) turbojets were installed in housings underneath the wing roots, adjacent to the fuselage. This arrangement had the advantage in that no appreciable asymmetric forces were exerted if one engine went out. In addition, no fuselage space was occupied by engines, leaving internal fuselage capacity free for fuel tankage and armament.
The rather large and bulky fuselage was of all-metal semimonocoque construction. A fully-retractable tricycle undercarriage was fitted. Internal fuel capacity was a capacious 1150 US gall. In addition, a pair of 250 US gall drop tanks could be carried. The ailerons were hydraulically-operated, and the flaps were electrically-controlled. A pressurized cabin was provided. The cockpit had a small, low canopy with a very sloping windscreen. The proposed armament was to be six 0.50-in machine guns with 300 rpg, all guns being mounted in the nose. However, alternative armament schemes of four 20-mm or 37-mm cannon and even a battery of 20 (!!!) 0.50-in machine guns were also considered.
A USAAF contract for two XP-83 prototypes was awarded on July 21, 1944, confirming the Letter Contract of March. Serials were 44-84990 and 44-94991. Only seven months after the awarding of the contract, the first prototype (44-84990) was flown on February 25, 1945 by chief Bell test pilot Jack Woolams. The aircraft proved to be underpowered and somewhat unstable. The close proximity of the turbojets was found to have the unintended side effect of allowing the hot jet exhaust gases to buckle the tailplane during run-ups on the ground unless fire trucks were standing by to spray cooling water on the rear fuselage.
The second prototype (44-84991) flew on October 19, 1945. It had a slightly different bubble canopy and a somewhat longer nose to accommodate a heavier armament of six 0.60-inch T17E3 machine guns. This aircraft was used in gunnery tests at Wright Field in Ohio.
The tailplane overheating problem was cured by modifying the tailpipes so that they angled outwards. Wind tunnel tests showed that an 18-inch extension of the vertical tail would cure the stability problems, but it is not certain whether or not this modification was actually carried out.
The performance of the XP-83 was rather disappointing, and no series production was ordered. Apart from its range, the XP-83 offered no significant advantages over the Lockheed P-80 Shooting Star which was already in production, and further work on the XP-83 project was abandoned.
Following the abandonment of work on the XP-83, the two prototypes were used for a short time as test beds for other development work. The first XP-83 was used in a ramjet engine test program, in which a pair of experimental ramjets were slung under the wings. It was intended that the aircraft would be able to fly on ramjet power only, once sufficient flying speed was obtained. A hatch was cut in the belly to provide entry into the aft fuselage, and an engineer's station was provided in the fuselage behind the pilot. However, on September 14, 1946, just as the test program was beginning, one of the ramjets caught fire during a test flight, forcing pilot Chalmers Goodlin and engineer Charles Fay to parachute to safety. The XP-83 was destroyed in the ensuing crash.
The second XP-83 survived until 1947, at which time it was scrapped.
Specification of the XP-83:
Two 4000-lb.st. General Electric J33-GE-5 centrifugally-fed turbojets. Performance: Maximum speed was 522 mph at 15,660 feet. Range on internal fuel was 1730 miles at 30,000 feet. With two 250-Imp.gall drop tanks, range was 2050 miles. Initial climb rate was 5650 feet per minute, and an altitude of 30,000 feet could be reached in 11.5 minutes. Service ceiling was 45,000 feet. Weights were 14,105 pounds empty, 24,090 pounds loaded, 27,500 pounds maximum. Dimensions were wingspan 53 feet 0 inches, length 44 feet 10 inches, height 15 feet 3 inches, wing area 431 square feet.
Sources:
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Fighters of the United States Air Force, Robert F. Dorr and David
Donald, Temple Press Aerospace, 1990.
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The American Fighter, Enzo Angelucci and Peter Bowers, Orion, 1987.
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War Planes of the Second World War, Fighters, Volume 4, William Green,
Doubleday 1964.
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American Combat Planes, Third Enlarged Edition, Ray Wagner, Doubleday,
1982.
- Bell Aircraft Since 1935, A. J. Pelletier, Naval Institute Press, 1992.
