Douglas F4D Skyray

F4D (F-6) Skyray
Role	Fighter aircraft Type of aircraft
Manufacturer	Douglas Aircraft Company
First flight	23 January 1951
Introduction	1956
Retired	1964
Status	Retired
Primary users	United States Navy United States Marine Corps
Produced	1950–1958
Number built	422
Developed into	Douglas F5D Skylancer

The Douglas F4D Skyray (later redesignated F-6 Skyray) is an American carrier-based supersonic fighter/interceptor designed and produced by the Douglas Aircraft Company. It was the first naval fighter to exceed the speed of sound in level flight and the last fighter produced by the Douglas Aircraft Company prior to its merger with McDonnell Aircraft to become McDonnell Douglas.

Development of the Skyray was started by Douglas during the late 1940s as the D-571-1 design study. It was a delta wing interceptor capable of a high rate of climb as to permit the rapid interception of approaching hostile bombers. Douglas' proposal was selected by Navy officials to fulfil a formal requirement issued in 1948. The decision to adopt the Westinghouse J40 turbojet engine to power it would lead to considerable difficulties later on as this engine would be cancelled prior to entering production. 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 Skyray was declared ready for fleet introduction in April 1956, permitting its entry to service with both the United States Navy (USN) and United States Marine Corps (USMC) shortly thereafter.

The Skyray had a relatively brief service life, during which it never participated in actual combat. Despite this, it was the first carrier-launched aircraft to hold the world's absolute speed record, having attained a top speed of 752.943 mph,^[1][2] (1,211.744 km/h).^[3] It also set a new time-to-altitude record, flying from a standing start to 49,221 feet (15,003 m) in two minutes and 36 seconds, all while flying at a 70° pitch angle. The last Skyrays were withdrawn from service in February 1964, although a handful continued to be flown for experimental purposes by National Advisory Committee for Aeronautics (NACA) up to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 F5D Skylancer was an advanced development of the F4D Skyray that ultimately did not enter service.