| P-76 | |
|---|---|
 XP-39E, the prototype of the P-76 | |
| General information | |
| Type | Fighter aircraft |
| Manufacturer | Bell Aircraft Corporation |
| Status | Did not enter mass-production |
| Primary user | United States Army Air Forces |
| Number built | 0 (3 prototypes built as XP-39Es) |
| History | |
| First flight | 1942 |
| Developed from | Bell P-39 Airacobra |
TheBell P-76 was the proposed designation for a production model derivative of the XP-39E, a single-engine Americanfighter aircraft prototype ofWorld War II.
On 26 February 1941 theUnited States Army Air Corps (USAAC) placed a contract with Bell for two prototypes (41-19501 and41-19502) that were intended to be a major improvement on preceding P-39s. In particular, the XP-39E was intended to address the poor high-altitude performance of the Airacobra.
The performance issues of previous P-39 variants were to be addressed by incorporating a new wing design with a lowerwing loading, a more powerful engine and redesigning thetailfin. The wing span was increased to 35 ft 10 in (10.9 m) and the total wing area to 236 ft2 (21.9 m2), was to be wider and thicker, with a symmetricalairfoil; the section chosen wasNACA 0018 at the wing-root tapering to anNACA 23009 at the tip. (While the new wing was sometimes referred to as having alaminar flow profile, that was not technically the case.)[1] The greater internal dimensions of the wing allowed an increase in the fuel capacity to 150 US gallons (568 L).[2] The engine bay was modified to accept a more powerfulengine in lieu of theAllison V-1710. Its origins lay in a 1941 project to equip three P-39Ds (41-19501, 41-19502 and42-7164) with theContinental V-1430-1 liquid-cooledsupercharged engine. The resultant XP-39E had a symmetrical airfoil wing with square wingtips, an elongatedfuselage to accommodate the larger engine, and revised air intakes andradiators. In addition, each of the three prototypes featured a different, redesigned version of the P-39 tailfin.
Since the Continental engine was not available at rollout, theprototypes flew with a new variant of the V-1710, the Allison V-1710-E9. This version, which had the military designation of V-1710-47, used a two-stage mechanicalsupercharger to increase the engine power at altitude. (After the Continental V-1430 failed to live up to its potential, a later version of the V-1710, the Allison V-1710-93, was used in theXP-63A.)[2]
The prototypes performed well and 4,000 P-39Es were ordered for the USAAF. However, the order was postponed to permit Bell to manufacture theBoeing B-29 Superfortress, under license. Many elements of the P-39E were subsequently incorporated in theP-63 Kingcobra, a parallel program to develop an enlarged version of the Airacobra; the XP-63 first flew in December 1942. While the P-39E was retrospectively redesignatedP-76, it never entered production.
General characteristics
Performance
Armament
Related development
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