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The Curtiss P-60 was a 1940s American single-engine single-seat, low-wing
monoplane A monoplane is a fixed-wing aircraft configuration with a single mainplane, in contrast to a biplane or other types of multiplanes, which have multiple wings. A monoplane has inherently the highest efficiency and lowest drag of any wing con ...
fighter aircraft Fighter aircraft (early on also ''pursuit aircraft'') are military aircraft designed primarily for air-to-air combat. In military conflict, the role of fighter aircraft is to establish air supremacy, air superiority of the battlespace. Domina ...
developed by the
Curtiss-Wright The Curtiss-Wright Corporation is an American manufacturer and services provider headquartered in Davidson, North Carolina, with factories and operations in and outside the United States. Created in 1929 from the consolidation (business), consoli ...
company as a successor to its
P-40 The Curtiss P-40 Warhawk is an American single-engined, single-seat, all-metal fighter-bomber that first flew in 1938. The P-40 design was a modification of the previous Curtiss P-36 Hawk which reduced development time and enabled a rapid entr ...
. It went through a lengthy series of prototype versions, eventually evolving into a design that bore little resemblance to the P-40. None of these versions reached production.


Design and development

Following rejection of the XP-46, Curtiss put forward its Model 88 in proposals to 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 ri ...
. The proposal was for an aircraft using the P-40D fuselage and tail assembly with a low drag NACA
laminar flow Laminar flow () is the property of fluid particles in fluid dynamics to follow 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 m ...
wing, the (at the time under development)
Continental I-1430 The Continental XI-1430 ''Hyper engine'' (often identified as the IV-1430) was a liquid-cooled aircraft engine developed in the United States by a partnership between the US Army Air Corps and Continental Motors. It was the "official" result of ...
-3 inverted V-12 engine, and eight wing-mounted 0.5 in (12.7 mm) machine guns. This proposal was accepted and a contract for two
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 prototype ...
s was issued on 1 October 1940 with the aircraft designated XP-53. Within two months the Army Air Corps contacted Curtiss for an aircraft with a laminar wing and the British
Rolls Royce Merlin The Rolls-Royce Merlin is a British liquid-cooled V-12 piston aero engine of 27-litre (1,650 cu in) capacity. Rolls-Royce designed the engine and first ran it in 1933 as a private venture. Initially known as the PV-12, it was later call ...
engine. Curtiss suggested the XP-53 design be used and the second prototype be converted while it was being built; the contract was altered to account for that with the aircraft - known to the company as Model 90 - designated XP-60. A Packard-built V-1650-1 (equivalent to the Merlin Mk XX) as being used on the Curtis XP-40F was to be used. The airframe design for the XP-60 was modified for the different engine, and the main landing gear was changed from the rearward-retracting P-40 design to a new inward retracting version, as used on the XP-46, which allowed a wider wheelbase and a smooth wing surface when the gear was retracted. This aircraft first flew on 18 September 1941 with a
British British may refer to: Peoples, culture, and language * British people, nationals or natives of the United Kingdom, British Overseas Territories and Crown Dependencies. * British national identity, the characteristics of British people and culture ...
Merlin 28 engine. The XP-53 prototype was then converted into a static test airframe for the XP-60. Considering delivery delays of quantities of the Packard-built Merlin engines might occue due to its use in other fighter projects closer to delivery, the use of a turbo-supercharged
Allison V-1710 The Allison V-1710 aircraft engine designed and produced by the Allison Engine Company was the most common United States, US-developed V12 engine, V-12 Internal combustion engine cooling, liquid-cooled engine in service during World War II. Ve ...
-75 engine was considered in its place. This was expected to deliver 394 mph at 25,000 ft. Consequently, on 31 October 1941, a contract for 1,950 P-60A fighters using the Allison engine was awarded with deliveries expected in September 1942.Norton 2008 p81 Flight tests of the XP-60 prototype did not progress smoothly. In addition to landing gear problems, expected top speed was not being met due to shortcomings in the laminar-flow wing surface finish, relatively high
radiator A radiator is a heat exchanger 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 ...
drag (compared to the
North American P-51 Mustang The North American Aviation P-51 Mustang is an American long-range, single-seat fighter and fighter-bomber used during World War II and the Korean War, among other conflicts. The Mustang was designed in 1940 by a team headed by James H. Kin ...
, which was then flying), and lower than specified engine output performance. The P-60A Allison engine was not delivering the requisite 1,500 hp, and now that America was at war following the Japanese attack on Pearl Harbor, delivery of existing designs took precedence over introducing a new design into production. Work on the P-60A was stopped after 20 December 1941, when the USAAF recommended that Curtiss concentrate on license production of
Republic 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 ...
s. The P-60 project was not stopped but a decision was taken to build experimental aircraft on the XP-60 but with different engines. The new order issued on 2 January 1942 specified one XP-60A (Model 95A) with the Allison V-1710-75 engine and a General Electric B-14 turbo-supercharger, one XP-60B (Model 95B) with the Allison V-1710-75 engine and a Wright SU-504-1 turbo-supercharger, and one XP-60C (Model 95C) with the 2,500 hp 36.4 liter displacement Chrysler XIV-2220 16-cylinder V-16 engine. While the wing of the XP-60 would be used, the fuselage was more rounded in cross-section. In February 1942, the production of P-60As was cancelled so that Curtiss could build a further 1,400 P-40s and - to keep its production lines occupied until the P-60 was ready build - the Thunderbolt for the USAAF."Fact Sheet: Curtiss XP-60."
''National Museum of the United States Air Force''. Retrieved: 10 July 2017.
At the time, availability of the Chrysler engine was coming into question, and after Curtiss noted (in April) that either the fuselage would need changes, or several hundreds of pounds of ballast would be needed in the tail of the existing airframe, to balance the heavy engine, a decision was made in September to install a
Pratt & Whitney R-2800 The Pratt & Whitney R-2800 Double Wasp is an American twin-row, 18-cylinder, air-cooled radial aircraft engine with a engine displacement, displacement of , and is part of the long-lived Pratt & Whitney Wasp series, Wasp family of engines. ...
radial engine in the XP-60C. In the meantime, Curtiss installed a Packard V-1650-3 (equivalent of the Merlin 61) in the original XP-60 with a four bladed propeller and the larger XP-60A vertical stabilizer; this aircraft was redesignated XP-60D. The XP-60A first flew on 1 November 1942. While official interest in the type was waning (with the emergence of newer designs), the promise of improved performance from use of the R-2800 engine, resulted in a contract for 500 aircraft, officially designated P-60A-1, with the R-2800 and contra-rotating
propeller A propeller (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 a working flu ...
s; the first 26 to be YP-60A with single rotation propeller. With concern that the contra-rotating propellers would not be available on time (Pratt & Whitney had to modify the engine gearing), in order to get data, the XP-60B was modified to take the R-2800-10 engine with turbocharger driving a four-bladed propeller. As a result of the other prototype variants, this modification was redesignated XP-60E (Model 95D). On 27 January 1943, the XP-60C flew for the first time, powered by an R-2800-53 engine with contra-rotating propellers. The aircraft's flying characteristics were found to be generally satisfactory. The first flight of the XP-60E with the four-bladed propeller was delayed until 26 May 1943 after it was found that due to its lighter weight, the engine installation had to be moved forward compared to the XP-60C. In April 1943, the US Army Air Forces decided to conduct an evaluation of the various fighter aircraft in development and use, in order to eliminate the least desirable models. With four days notice Curtiss was requested to have the XP-60E participate. As the XP-60E was not available, the company hurriedly prepared the XP-60C (at the time being repaired) for the evaluation at
Patterson Field Wright-Patterson Air Force Base (WPAFB) is a United States Air Force base and census-designated place just east of Dayton, Ohio, in Greene and Montgomery counties. It includes both Wright and Patterson Fields, which were originally Wilbur Wr ...
. The XP-60C performed poorly due to flaking wing finish preventing laminar flow and the engine delivering less power resulting in reduction of the production run of 500 aircraft to 20 YP-60A then to just two aircraft. On 6 May 1943, the XP-60D crashed during a dive demonstration. In January 1944, the XP-60E was flown to
Eglin Field Eglin may refer to: * Eglin (surname) * Eglin Air Force Base Eglin Air Force Base is a United States Air Force (USAF) base in the western Florida panhandle, located about southwest of Valparaiso, Florida, Valparaiso in Okaloosa County, Flor ...
for official trials, where USAAF pilots found that it did not compare favorably to contemporary aircraft designs. However, when Curtiss suggested abandoning future work on the P-60 series, the USAAF insisted on completion of at least one of the two aircraft already in production.


Operational history

Somewhat confusingly, the first production aircraft was still designated YP-60A-1-CU, although this was later changed to YP-60E, to conform with the naming of previous prototypes. The YP-60E was powered by a 2,100 hp (1,566 kW) R-2800-18 engine. It also featured a cut-down rear fuselage and
bubble canopy A bubble canopy is an aircraft canopy constructed without bracing, for the purpose of providing a wider unobstructed field of view to the pilot, often providing 360° all-round visibility. The designs of bubble canopies can vary drastically; so ...
for improved visibility. It first flew on 13 July 1944 and was subsequently delivered to
Wright Field Wilbur Wright Field was a military installation and an airfield used as a World War I pilot, mechanic, and armorer training facility and, under different designations, conducted United States Army Air Corps and Air Forces flight testing. Loc ...
. However, as the government's development contract had already been cancelled (June 1943), there was no budget for further modifications, let alone a guarantee of a final purchase order. Consequently, the only production YP-60E completed was scrapped, on 22 December 1944.Dorr and Lake 1990, p. 113. The XP-60E survived to be sold as an entry for the 1947
National Air Races The National Air Races (also known as Pulitzer Trophy Races) are a series of pylon and cross-country races that have taken place in the United States since 1920. The science of aviation, and the speed and reliability of aircraft and engines grew ...
, but crashed during a qualifying flight before the competition was held.


Variants

;XP-53 :Curtiss Model 88; derivative of XP-46 to Request for Data R40-C specifications. Laminar flow wing and Continental XIV-1430-3 engine. Contracted for 1 October 1940; cancelled in favor of XP-60 in November 1941. Two built, one converted to the XP-60, the other used as a static test airframe. ;XP-60 :Curtiss Model 90;
Rolls-Royce Merlin The Rolls-Royce Merlin is a British Coolant#Liquids, liquid-cooled V12 engine, V-12 Reciprocating engine, piston aero engine of 27-litre (1,650 cu in) Engine displacement, capacity. Rolls-Royce Limited, Rolls-Royce designed the engine an ...
engine, armament eight .50-cal (12.7 mm) machine guns. One built, first flight 18 September 1941; modified to XP-60D.Norton 2008, p. 81. ;XP-60A :Curtiss Model 95A;
Allison V-1710 The Allison V-1710 aircraft engine designed and produced by the Allison Engine Company was the most common United States, US-developed V12 engine, V-12 Internal combustion engine cooling, liquid-cooled engine in service during World War II. Ve ...
-75 engine with B-14
turbosupercharger In an internal combustion engine, a turbocharger (also known as a turbo or a turbosupercharger) is a forced induction device that is powered by the flow of exhaust gases. It uses this energy to compress the intake air, forcing more air into th ...
; armament: six .50-cal MG. One built. ;P-60A :Planned production version of XP-60; 1900 ordered, all cancelled. ;YP-60A-1 :Pre-production version of P-60A-1 with single prop. Twenty-six ordered; two built; one rebuilt as YP-60E.Norton 2008, pp. 83–85. ;P-60A-1 :Planned production version of XP-60C with
Pratt & Whitney R-2800 The Pratt & Whitney R-2800 Double Wasp is an American twin-row, 18-cylinder, air-cooled radial aircraft engine with a engine displacement, displacement of , and is part of the long-lived Pratt & Whitney Wasp series, Wasp family of engines. ...
-18 engine and
contraprop Aircraft equipped with contra-rotating propellers (CRP) coaxial contra-rotating propellers, or high-speed propellers, apply the maximum power of usually a single engine piston powered or turboprop engine to drive a pair of coaxial propellers i ...
; armament: four .50-cal MG. 500 ordered; cancelled before any built.Norton 2008, p. 83. ;XP-60B :Curtiss Model 95B; V-1710-75 engine with SU-504-2 turbosupercharger; armament: six .50-cal MG. One built, modified to XP-60E. ;XP-60C :Curtiss Model 95C; planned for Chrysler XIV-2220 engine, built with R-2800-53 and contra-rotating propeller; armament: six .50-cal MG. One built. Rebuilt as XP-60E; original XP-60E rebuilt as XP-60C.Norton 2008, p. 85. ;XP-60D :Rebuilt XP-60 (Curtiss Model 90B);
Packard V-1650 The Packard V-1650 Merlin is a version of the Rolls-Royce Merlin aircraft engine, produced under license in the United States by the Packard Motor Car Company.Gunston 1995, p. 144. The engine was licensed to expand production of the Rolls-Ro ...
-3 engine; crashed 6 May 1943 at Rome Air Depot when tail separated during flight.Norton 2008, p. 82. ;XP-60E :Rebuilt XP-60B. Curtiss Model 95D; R-2800-10 engine; crashed January 1944. XP-60C reconfigured to XP-60E status. ;YP-60E :Modified YP-60A-1 with bubble canopy. First flight 15 July 1944; cancelled 22 December 1944. ;XP-60F :Planned modification of YP-60A-1 with different model of R-2800; cancelled before conversion.


Specifications (XP-60C)


See also


References


Notes


Bibliography

* Bowers, Peter M. ''Curtiss Aircraft, 1907–1947''. London: Putnam & Company Ltd., 1979. . * Dorr, Robert F. and Jon Lake. ''Fighters of the United States Air Force''. London: Temple Press, 1990. . * Green, William. ''War Planes of the Second World War, Volume Four: Fighters''. London: MacDonald & Co. (Publishers) Ltd., 1961 (Sixth impression 1969). . * Green, William and Gordon Swanborough. ''WW2 Aircraft Fact Files: US Army Air Force Fighters, Part 1''. London: Macdonald and Jane's Publishers Ltd., 1977. . * Jones, Lloyd S. ''U.S. Fighters: 1925-1980s''. Fallbrook, California: Aero Publishers, Inc., 1975. . * Norton, Bill. ''U.S. Experimental & Prototype Aircraft Projects: Fighters 1939–1945''. North Branch, Minnesota: Specialty Press, 2008, pp. 80–85. .


External links


Curtiss-Wright P-60


{{USAF fighters P-60
Curtiss P-60 The Curtiss P-60 was a 1940s American single-engine single-seat, low-wing monoplane fighter aircraft developed by the Curtiss-Wright company as a successor to its Curtiss P-40, P-40. It went through a lengthy series of prototype versions, eventua ...
Single-engined tractor aircraft Low-wing aircraft Cancelled military aircraft projects of the United States Aircraft first flown in 1941 Aircraft with retractable conventional landing gear Single-engined piston aircraft