Douglas F6 / F4D-1 Skyray

US Navy interest in German delta-wing research led, in 1947, to the design by Douglas of a carrier-based interceptor with a variation of the pure delta wing. Approval of the Douglas design was signified by the award of a contract for two Douglas XF4D-1 prototypes on 16 December 1948, the first making its maiden flight on 23 January 1951 powered by a 2268kg thrust Allison J35-A-17 engine. This represented an emergency powerplant, resulting from delays in development of the Westinghouse J40 turbojet which had been the planned engine. Both prototypes were flown subsequently with the XJ40-WE-6 developing 3175kg thrust and the XJ40-WE-8 which had a rating of 5262kg with afterburning, but problems with this engine programme led to final selection of the Pratt & Whitney J57 engine for production aircraft.

The F4D Skyray was a cantilever mid-wing monoplane, the wing of modified delta configuration incorporating elevons to serve collectively as elevators or differentially as ailerons. The tail unit had only swept vertical surfaces, landing gear was of retractable tricycle-type. The pilot was accommodated well forward of the wing.

The potential of the F4D was demonstrated effectively by the second prototype on 3 October 1953, then powered by the XJ40-WE-8 turbojet, which set a new world speed record of 1211.746km/h.

The first production F4D-1 was flown on 5 June 1954, powered by a Pratt & Whitney J57-P-2 turbojet developing 6123kg thrust with afterburning, but it was not until 16 April 1956 that deliveries began, initially to US Navy Squadron VC-3. The 419th and last production aircraft was delivered on 22 December 1958, but in the intervening period a change had been made by installation of the higher-rated J57-P-8 engine. All aircraft retained the F4D-1 designation, the popular (derived) name being Ford.

The new Douglas factory at Torrance (Plant B-6) in May 1954 was in volume production with both the AD-5 and 6 Skyraider and the F4D-1 Skyray, the latter with the J57 turbojet with afterburner. This leaves the El Segundo division almost clear to turn out twin-jet Skywarriors. Navy contracts for the Skyray were sufficient to keep Torrance busy until the end of 1956. Reports came to the effect that a new variant, the F4D-2, was being developed "with some configuration changes." After manufacture at Torrance, Skyrays are put aboard a flat truck and taken to El Segundo, where final operational equipment is installed preparatory to flight testing.

At the peak of its utilisation, the Skyray equipped 11 US Navy, six US Marine and three reserve squadrons, but none was used operationally. The type survived in first-line service until the late 1960s, with two front-line squadrons not converting to the type until 1964. It was redesignated F-6A in September 1962.

Gallery

F4D
Engine: 1 x Pratt & Whitney J57-P-8B turbojet, 64.5kN / 9700 lb with afterburner
Max take-off weight: 11340 kg / 25001 lb
Empty weight: 7268 kg / 16023 lb
Wingspan: 10.21 m / 33 ft 6 in
Length: 13.93 m / 45 ft 8 in
Height: 3.96 m / 12 ft 12 in
Wing area: 51.75 sq.m / 557.03 sq ft
Ceiling: 16765 m / 55000 ft
Range: 1931 km / 1200 miles
Crew: 1
Armament: 4 x 20mm cannons, 1814kg of weapons on six hardpoints

F4D-1
Engine: Pratt & Whitney J57-P-2 turbojet, 9,7001b. thrust
Wingspan: 33 ft. 6 in
Length: 42 ft.
Loaded weight: approx. 16,000 lb.
Max. speed: approx. 750 m.p.h.
Ceiling: 50,000 ft.
Endurance: 45 min.
Armament: 4x20 mm. Cannon
Bombload: 2x 1,000 lb. bombs, 6 pods of 7x2.75 in. rockets or 4 pods of 19x2.75 in. rockets.
Crew: 1