The Douglas F4D Skyray (later redesignated F-6 Skyray) is an American carrier-based fighter/interceptor designed and produced by the Douglas Aircraft Company. It was the last fighter produced by the Douglas Aircraft Company prior to its merger with McDonnell Aircraft to become McDonnell Douglas. Number built: 422. 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, (1,211.744 km/h). 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 The last Skyrays were withdrawn from service in February 1964, although a handful continued to be flown for experimental purposes by National Advisory Committee for Aeronautics (NACA) up to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. 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. The D-571-1 had a relatively thick wing with no conventional fuselage save for a pod-like cockpit in a forward position. A total of four 20mm cannons extended forward of the leading edge of the wing, alternative armaments consisted of spin-stabilized rockets. The design study had harnessed the designs and research of the German aerodynamicist Alexander Lippisch, who moved to the United States following the end of World War II; his work had been examined by several of Douglas' design team. 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. For more details on the development and operational history of the Skyray, click here. Variants XF4D-1 Prototypes; redesignated YF-6A in 1962, two built. F4D-1 (Specifications below) Single-seat fighter aircraft, production model; redesignated F-6A in 1962, 420 built. F4D-2 Re-engined F4D-1 with the J57-F-14, 100 on order cancelled. F4D-2N F4D-2 version with extended nose housing twin radar scanners, project only evolved into the F5D Skylancer.
