The Bell P-76 was the proposed designation for a production model derivative of the XP-39E, a single-engine American
fighter aircraft
Fighter aircraft are fixed-wing military aircraft designed primarily for air-to-air combat. In military conflict, the role of fighter aircraft is to establish air superiority of the battlespace. Domination of the airspace above a battlefield ...
prototype of
World War II
World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...
.
Design and development
On 26 February 1941 the
United States Army Air Corps
The United States Army Air Corps (USAAC) was the aerial warfare service component of the United States Army between 1926 and 1941. After World War I, as early aviation became an increasingly important part of modern warfare, a philosophical r ...
(USAAC) placed a contract with Bell allowing for the purchase of two XP-39Es (''41-19501 and 41-19502'') which were envisaged to be a major improvement on the P-39D series. Because of the number of changes proposed the production model was to be called the Bell P-76.
The Bell P-76 was proposed to address the poor high-altitude performance of the
P-39 Airacobra
The Bell P-39 Airacobra is a fighter produced by Bell Aircraft for the United States Army Air Forces during World War II. It was one of the principal American fighters in service when the United States entered combat. The P-39 was used by the ...
by incorporating a new and thicker wing with a symmetrical
airfoil
An airfoil (American English) or aerofoil (British English) is the cross-sectional shape of an object whose motion through a gas is capable of generating significant lift, such as a wing, a sail, or the blades of propeller, rotor, or turbine.
...
; the section chosen was
NACA 0018 at the wing-root tapering to an
NACA 23009 at the tip. Although the new wing has often been referred to as a
laminar flow
In fluid dynamics, laminar flow is characterized by fluid particles following smooth paths in layers, with each layer moving smoothly past the adjacent layers with little or no mixing. At low velocities, the fluid tends to flow without lateral mi ...
type, this was not the case.
UIUC incomplete guide to Airfoil usage
Retrieved: 9 August 2008 The wing span was increased to 35 ft 10 in (10.9 m) and the area to 236 ft² (21.9 m²), the thicker wing allowing an increase in the fuel capacity to 150 US gallons (568 L).[Bowers 1979, pp.21-25.]
Design of a new Allison V-1710-E9 was also underway. This version, which had the military designation of V-1710-47, used a two-stage mechanical supercharger
In an internal combustion engine, a supercharger compresses the intake gas, forcing more air into the engine in order to produce more power for a given displacement.
The current categorisation is that a supercharger is a form of forced induct ...
to increase the engine power at altitude. However, this engine went through so many design changes that it ended up being almost identical to the later V-1710-93 which was fitted in the XP-63A.engine
An engine or motor is a machine designed to convert one or more forms of energy into mechanical energy.
Available energy sources include potential energy (e.g. energy of the Earth's gravitational field as exploited in hydroelectric power gen ...
in lieu of the V-1710. Its origins lie in the 1941 project to equip three P-39D (41-19501, 41-19502 and 42-7164) with the Continental V-1430-1 liquid-cooled supercharged
In an internal combustion engine, a supercharger compresses the intake gas, forcing more air into the engine in order to produce more power for a given displacement.
The current categorisation is that a supercharger is a form of forced induct ...
engine. The resultant XP-39E had a symmetrical airfoil wing with square wingtips, an elongated fuselage
The fuselage (; from the French ''fuselé'' "spindle-shaped") is an aircraft's main body section. It holds crew, passengers, or cargo. In single-engine aircraft, it will usually contain an engine as well, although in some amphibious aircraft t ...
to accommodate the larger engine, and revised air intakes and radiator
Radiators are heat exchangers used to transfer thermal energy from one medium to another for the purpose of cooling and heating. The majority of radiators are constructed to function in cars, buildings, and electronics.
A radiator is always a ...
s. The three prototypes each had a different tailfin. Since the Continental engine was not available at rollout, the prototype
A prototype is an early sample, model, or release of a product built to test a concept or process. It is a term used in a variety of contexts, including semantics, design, electronics, and Software prototyping, software programming. A prototyp ...
s flew with Allison V-1710-47 engines. In 1942, the XP-39E was redesignated P-76. Although 4,000 aircraft were initially ordered, the order was cancelled to permit the Bell factory to manufacture B-29 Superfortress
The Boeing B-29 Superfortress is an American four-engined propeller-driven heavy bomber, designed by Boeing and flown primarily by the United States during World War II and the Korean War. Named in allusion to its predecessor, the B-17 Fl ...
bomber aircraft under license from Boeing
The Boeing Company () is an American multinational corporation that designs, manufactures, and sells airplanes, rotorcraft, rockets, satellites, telecommunications equipment, and missiles worldwide. The company also provides leasing and product ...
. Many of the lessons learned in the P-76 were implemented in the subsequent P-63 Kingcobra.
Specifications (P-76)
See also
References
Citations
Bibliography
* Bowers, Peter M. "Airborne Cobra Pt.II". ''Airpower magazine, Vol.9, No.1, January 1979.''
{{USAF fighters
Bell XP-46
P-076
Mid-engined aircraft
Single-engined tractor aircraft
Low-wing aircraft