The Republic XP-72 was an American

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 ...

fighter-interceptor developed by

Republic Aircraft The Republic Aviation Corporation was an American aircraft manufacturer based in Farmingdale, New York, on Long Island. Originally known as the Seversky Aircraft Company, the company was responsible for the design and production of many important ...

as a progression of the

P-47 Thunderbolt The Republic P-47 Thunderbolt is a World War II-era fighter aircraft produced by the American company Republic Aviation from 1941 through 1945. It was a successful high-altitude fighter and it also served as the foremost American fighter-bombe ...

design. The XP-72 was designed around the

Pratt & Whitney R-4360 Wasp Major The Pratt & Whitney R-4360 Wasp Major is an American 28-cylinder four-row radial piston aircraft engine designed and built during World War II. First run in 1944, at , it is the largest-displacement aviation piston engine to be mass-produced in ...

28-cylinder

air-cooled Air-cooled engines rely on the circulation of air directly over heat dissipation fins or hot areas of the engine to cool them in order to keep the engine within operating temperatures. In all combustion engines, a great percentage of the heat ge ...

radial engine The radial engine is a reciprocating type internal combustion engine configuration in which the cylinders "radiate" outward from a central crankcase like the spokes of a wheel. It resembles a stylized star when viewed from the front, and is ca ...

with a

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 ...

mounted behind the pilot and driven by an extension shaft from the engine. The armament consisted of six

.50 caliber This is a list of firearm cartridges which have bullets in the to caliber range. *''Length'' refers to the cartridge case Case or CASE may refer to: Containers * Case (goods), a package of related merchandise * Cartridge case or casing, a ...

(12.7 mm) wing-mounted Browning AN/M2 machine guns and underwing racks for two 1,000 lb bombs; Alternative armament packages included two 37 mm M4 autocannons with four .50 caliber AN/M2s, or four M4 autocannons.

Design and development

The XP-72 development paralleled that of another Republic design, the XP-69 that was to be powered by an experimental 42-cylinder Wright R-2160 liquid-cooled inline radial engine mounted in the nose of the aircraft and driving

contra-rotating Contra-rotating, also referred to as coaxial contra-rotating, is a technique whereby parts of a mechanism rotate in opposite directions about a common axis, usually to minimise the effect of torque. Examples include some aircraft propellers, res ...

propeller A propeller (colloquially often called a screw if on a ship or an airscrew if on an aircraft) is a device with a rotating hub and radiating blades that are set at a pitch to form a helical spiral which, when rotated, exerts linear thrust upon ...

s. The XP-69 was intended for high altitude operations and featured a pressurized cockpit and armament of two 37 mm cannon and four

50 caliber This is a list of firearm cartridges which have bullets in the to caliber range. *''Length'' refers to the cartridge case length. *''OAL'' refers to the overall length of the cartridge. *''Bullet'' refers to the diameter of the bullet. Some m ...

machine guns. As the XP-72 displayed greater promise than the XP-69, the XP-69 was cancelled on 11 May 1943 and an order for two XP-72 prototypes was placed on 18 June 1943.

Operational history

The XP-72 flew for the first time on 2 February 1944, equipped with a four-bladed propeller. The second prototype was completed on 26 June 1944 and was equipped with an Aero-Products

contra-rotating propeller Aircraft equipped with contra-rotating propellers, also referred to as CRP, coaxial contra-rotating propellers, or high-speed propellers, apply the maximum power of usually a single piston engine, piston or turboprop engine to drive a pair of ...

. As the XP-72 displayed exceptional performance during flight tests, an order for 100 production aircraft was awarded. The order included an alternate armament configuration of four 37 mm cannon. By this time,

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 ...

had progressed to where the need was for long-range escort fighters and not high-speed interceptors. Furthermore, the advent of the new

turbojet The turbojet is an airbreathing jet engine which is typically used in aircraft. It consists of a gas turbine with a propelling nozzle. The gas turbine has an air inlet which includes inlet guide vanes, a compressor, a combustion chamber, and ...

-powered interceptors showed greater promise for the interceptor role. Thus, the production order for the P-72 was cancelled.

Specifications (XP-72)

References

Notes

Citations

Bibliography

* Bodie, Warren. "The Whine of the Jug". ''Wings Magazine'' (Vol. 4, No. 4), August 1974, pp. 33–39. * Freeman, Roger A. ''Thunderbolt: A Documentary History of the Republic P-47''. London: Macdonald & Jane's (Publishers) Ltd., 1978. . * Green, William. ''War Planes of the Second World War - Fighters (Volume Four)''. London: Macdonald & Co.(Publishers) Ltd., 1961. . * Green, William and Gordon Swanborough. ''WW2 Aircraft Fact Files: US Army Air Force Fighters, Part 2''. London: Macdonald & Jane's (Publishers) Ltd., 1978. . * Jarski, Adam and Robert Michulec. ''P-47 Thunderbolt, P-35/P-43/XP-72 (Monografie Lotnicze 26)'' (in Polish). Gdynia: AJ-Press, 1996. .

External links

{{USAF fighters P-072 Republic P-72 Single-engined tractor aircraft Aircraft with contra-rotating propellers Low-wing aircraft Aircraft first flown in 1944