History
Background
With the Curtiss P-40 Warhawk entering production in 1940, Curtiss began an ambitious effort to develop a superior aircraft that could replace the P-40. The US Army Air Corps (USAAC) was interested in supporting these efforts and awarded a contract to fund the development of potential successors.
Curtiss initially designed the XP-46 prototype, which shared similarities with the P-40, except it was built to be smaller and equipped with an inward-retracting undercarriage. The XP-46 took its first flight on February 15, 1941, but it offered no meaningful performance improvements over the P-40 and was outright rejected by the USAAC.
After the XP-46 did not secure production orders, Curtiss shifted focus to a new design: the Model 88, later designated the XP-53 by the Army. This model was intended to use a Continental XIV-1430-3 engine. However, engine development issues led to the cancellation of the XP-53 before it could be built.
Curtiss then moved on to the development of Model 90, which was designated XP-60. At the Army’s request, the XP-60 was initially designed to be powered by a Rolls-Royce Merlin engine and include laminar-flow wings, a type of airfoil designed to reduce drag and make the aircraft fly faster. Curtiss produced four airframes during this project, which resulted in nine different designations: XP-60, XP-60A, YP-60A, P-60A, XP-60B, XP-60C, XP-60D, XP-60E, and YP-60E. These versions represented Curtiss’ long and desperate attempts to develop a worthy successor to the P-40—efforts that lasted until late 1944.
XP-60A - Model 95A
As concerns about the shortage of Packard-built Merlins grew, the XP-60 program was not doomed, as the Army recognized its potential despite the disappointing performance of the previous XP-60 prototype. Consequently, the Army officially requested Curtiss to develop the experimental XP-60A, XP-60B, and XP-60C, each featuring different powerplants, during a meeting on January 2, 1942.
The development of the XP-60A began under the company designation Model 95A. This variant was considered a new iteration of the XP-60, featuring the original P-40 wing but mounted on a completely redesigned fuselage and powerplant that did not resemble the P-40. The aircraft was set to incorporate a 1,425 hp Allison V-1710-75 engine paired with a General Electric B-14 turbo-supercharger, necessitating extensive modifications to the nose and fuselage contours to accommodate the new powerplant. The armament was reduced from eight to six .50-caliber machine guns, and a four-bladed propeller was fitted.
Initial ground taxi tests for the XP-60A took place in late October 1942, but a fire broke out in the engine due to inadequate cooling around the exhaust manifold shrouds. After prompt repairs, the turbo-supercharger system was removed, and standard exhaust stacks were installed in preparation for its maiden flight.
The XP-60A made its first flight on November 1, 1942, but it fell short of expectations regarding its promised high speed and climb rate. Although plans were in place to test a revised turbo-supercharger system, development was halted on November 6, 1942, as the Army shifted its focus to the R-2800 engine. The XP-60A was eventually dismantled, with some components repurposed for the XP-60C and XP-60E variants, which utilized the R-2800 powerplant.
The lackluster performance of the XP-60A led the Army to cancel an order for 1,950 P-60As equipped with turbo-supercharged Allison V-1710-75 engines in January 1942, along with an order for 26 YP-60As intended as service test models, which was also canceled on July 19, 1943. Only one YP-60A was built, but it was later rebuilt and completed as the YP-60E.
The XP-60B, designated Model 95B, was planned as an identical version of the XP-60A but with a different Wright SU-504-2 turbo-supercharger on the Allison V-1710-75 engine. However, this aircraft was never completed as the XP-60B and was instead finished as the XP-60E with a Pratt & Whitney R-2800 engine.
As the Army’s interest in the XP-60 program waned, Curtiss continued to advocate for the program’s potential by developing the Curtiss XP-60C and XP-60E with their respective powerplant.
