It was a delta wing interceptor capable of a high rate of climb as to permit the rapid interception of approaching hostile bombers.

Aerodynamic issues would also lead to a protracted development cycle, considerable design changes being made even after the maiden flight of a production standard Skyray having taken place in June 1954.

The last Skyrays were withdrawn from service in February 1964, although a handful continued to be flown for experimental purposes by National Advisory Committee for Aeronautics (NACA) up to the end of the decade.

The Skyray originated within a design study, the D-571-1, performed by Douglas and funded by the United States Navy (USN).

It was a fast-climbing pure interceptor that used a delta wing configuration and powered by a pair of Westinghouse J34 turbojet engines, which were equipped with afterburners for bursts of additional acceleration.

A total of four 20mm cannons extended forward of the leading edge of the wing; alternative armaments consisted of spin-stabilized rockets.

[6] In June 1947, the Navy issued a contract to Douglas to proceed with preliminary investigation and engineering works on the concept up to the mockup stage.

A formal operational requirement was issued by the Navy in 1948, however, according to aviation author Tommy H. Thomason, that the contract would be awarded to Douglas from the onset was an apparently foregone conclusion.

[8] Specifics of this requirement included the ability to intercept and destroy an enemy aircraft at an altitude of 50,000 ft (15,240 m) within five minutes of the alarm being sounded.

[11] One criticism produced at this stage was that the nose-up attitude was greater than had been anticipated, necessitating changes to the aircraft's nose and radome to improve the pilot's external visibility.

Douglas' design team had decided to make accommodations to facilitate the use of other engines as a contingency measure;[12] this approach proved to be quite fortunate as the J40 had a particularly troubled development, being eventually cancelled with no production units ever being delivered.

[14] The ensuing delays to the programme led to several other aircraft, such as the North American F-100 Super Sabre and the Mikoyan-Gurevich MiG-19, beating it into operational service.

[1] As a dedicated interceptor, the F4D was unsuited to the multi-mission capabilities that became increasingly in demand, thus the type had a relatively short career in both USN and USMC service.