The Douglas XP-48 was a small, lightweight fighter aircraft, designed by Douglas Aircraft in 1939 for evaluation by the U.S. Army Air Corps. Intended to be powered by a small inline piston engine, the contract was cancelled before a prototype could be constructed, due to the Army's concerns about the projected performance of the aircraft.[1]
In the years before the outbreak of World War II, a number of countries became intrigued by the idea of developing a very light fighter aircraft,[2] with these proposals often being derived from the design of racing aircraft. Following the consideration of a modified French Caudron racer by the U.S. Army Air Corps, a proposition that was considered uneconomical,[2] Douglas Aircraft made an unsolicited proposal to the Army Air Corps of their Model 312 design in 1939.[2]
Intended to be powered by a Ranger XV-770 inverted V-12 engine equipped with a supercharger, Douglas' proposal was considered worth pursuing by the Army Air Corps, and on 5 August 1939 a single prototype was ordered. The Model 312 was given the Army designation XP-48, the 48th aircraft type in the Pursuit category.[3]
Closely resembling the later Bell XP-77,[4] the design of the XP-48 featured a wing of remarkably high aspect ratio, and was equipped with a pair of synchronized machine guns for armament,[3] Douglas touted the XP-48 as offering outstanding performance, with a top speed of at least,[3] and, according to Douglas' estimates, possibly as high as .[5]
However, this very aspect of its design was regarded with suspicion by the Army Air Corps.[3] The Ranger engine was suffering from development difficulties and delays and would never prove truly reliable.[6] At the same time, Douglas' performance estimates became increasingly regarded as being over-optimistic.[7] Accordingly, in February 1940 the Army cancelled the XP-48 contract,[3] and without government funding Douglas ceased development of the aircraft.[5]