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F4D (F-6A) Skyray

The F4D was the only delta-wing design to enter service aboard US carriers, along with the tail-winged Cutlass. The single-place Douglas Skyray was named after the undersea manta ray it resembled. It was on the leading edge of aircraft design, could climb to 40,000 feet in two minutes and reach Mach 1 during a dive.

Analysis of data captured in Germany after World War II indicated that the delta-shaped wing would take the most advantage of jet propulsion for fast-climbing interceptor fighters. In 1948, Douglas signed a contract to build the F4D-1. Nicknamed "the ten-minute killer," the Skyray broke five world's time-to-height records. On 3 October 1953 a prototype XF4D-1 captured the world absolute speed record of 752.9 mph (642 knots). In 1953, the Skyray was co-winner with North America's Super Sabre of the prestigious Collier Trophy.

Lieutenant Commander James F. Verdin set a world speed record of 752.943 mph over a three-kilometer course in an F4D Skyray. This was a first for a carrier aircraft in its normal combat configuration. On 16 September 1952, Douglas test pilot Bob Rahn broke the 100-kilometer closed-course record in the Skyray with a 728.114-mph mark. On 23 February 1954, Douglas' Bob Rahn reached 10,000 feet in 56 seconds in an F4D Skyray. Although Bob Rahn is probably best known for his record-setting flights in the 1950s in the Douglas F4D Skyray, his life in the air produced many more experiences.

The focus of U.S. military aviation in the 1950s was the development of offensive nuclear capability, and, correspondingly, the ability to defend against nuclear attack. The Marine Corps would do both. The U.S. Navy realized its ship formations were vulnerable and embarked on its own line of air defense development. By 1956, it had three planes as its mainstay. Two were the McDonnell F3H-2N and -2M Demon. The third was of a much more radical nature - the Douglas F4D-1 Skyray.

The Douglas F4D-1 Skyray was a graceful, tailless, delta-wing fighter designed to meet a challenging specification: climb to 40,000 feet within five minutes to intercept a bomber before it reached its target. The F4D was the hottest plane the Navy had at the time. Acceleration and climb were breathtaking. Without external stores, a clean "Ford" (as it was quickly dubbed) could be climbed initially at 540 knots at 70 degrees nose up angle. The climb requirement meant a thicker, less loaded wing; thus, level top speed was limited. Pitch and roll was done through unconventional "elevons," but the Skyray had none of the traditional flaps for reducing speed. Slow flight was helped by free moving, leading-edge slats.

The fire control system with its Westinghouse APQ-50 radar was designed to use unguided 2.75- inch rockets. The fire control system necessarily had to be simple to use (although its 600 vacuum tubes would be a maintenance headache). Single targets could be locked onto from up to 25 miles, but actual detection ranges were perhaps half that against another F4D. In theory, the system's analog computer would guide the pilot to a lead-collision firing position slightly forward of the target's beam. Then, at the last instant, a few seconds before a midair collision (about 900-2,000 foot range), when catastrophe appeared inevitable and as the radar scope flashed collapsing circles, the pilot mashed a trigger, hurling up to four 19 shot pods worth of fiery rockets off ahead. However, if the pilot missed on any little angle, speed, or course adjustment, or if the radar was a wee bit out of alignment, the rockets would go all for hell and gone.

In addition to cannon and rockets, the Skyrays were fitted with a pair of Navy-designed heat-seeking AIM-9B Sidewinder missiles. The Sidewinder was a simple, low-cost missile with twice the speed of sound (Mach 2). About nine feet long and five inches in diameter, the 165-pound missile homed onto the infrared exhaust emissions of the target's engines. This weapon was visually fired at about one-half to two-and-one-half miles range in the target's aft quadrant. Once the pilot determined he was within range (by radar or visually), he listened for a buzzy growl in his headphones. This meant the missile's seeker head had detected an infrared signal which hopefully was not that of the sun, clouds, or warm areas on the ground, all of which could confound proper guidance of these early Sidewinders. Even with these limitations, the Sidewinder was a cheap (under $5,000 each), reliable, easy-to-use weapon that was very effective against non-maneuvering targets. Over the next four decades, it was destined to become the most successful air-to-air missile ever made. More than a dozen versions were produced by the U.S. and it was copied by the Soviet Union and China. It was a distinct improvement over the unguided 2.75" rockets and 20mm guns.

On the positive side, there were many other important innovations in the Skyray. The radar system was mounted on rails for a single, easy removal. One hundred percent oxygen was now required at all times and was provided via a five liter liquid oxygen system. There were provisions for a partial pressure suit for flights above 50,000 feet where a pilot could die if pressurization was lost.

A selective identification feature was now incorporated into the plane's 1FF set. The pilot could select any one of 64 discrete codes which were sent out in answer when his 1FF was interrogated, and his unit and plane number could also be transmitted. The set was "turned on" for U.S-based radars on 1 February 1959, and it was now possible for controllers instantly to identify individual cooperating aircraft.

Possibly the best innovation from the pilots' perspective was a new Navy-developed navigation aid called TACAN. TACAN (tactical air navigation) was a line-of-sight aid with 126 channels and a bearing accuracy of better than one degree. Distance was accurate to 600 feet at close ranges and within two percent at long range. It gave a very accurate magnetic bearing, as well as distance, in a single system. Pilots, at last, had an instantaneous picture of their position, without having to resort to tedious calculations or confusing sound signals.

The engine was powerful, with 16,000 pounds of thrust on afterburner. This generated additional thrust by injection of fuel just aft of the last turbine stage. In the Pratt and Whitney J57-P-8 engine, its use quadrupled fuel flow while increasing thrust from 10,200 pounds to 16,000 pounds. Finally, there was a Martin-Baker ejection seat. Provided the pilot was above 120 knots and 50 feet altitude, pulling a D-ring between his legs initiated an automatic sequence of canopy release, seat firing by explosive charge (with a frequent concomitant compression fracture of the spine), and a parachute deployment. It was a vast improvement over the F3D in which the crew had to collapse the pilot's seat, grab a bar, and swing out of a belly escape hatch.

Instead of a flat approach begun at 250 feet altitude, the Skyray started down from 600 feet on a fixed glide path that the pilot tracked by use of a reflected beam of light. To overcome the swept wing jets' poor low-speed handling and slow engine response from idle, the pilot flew the approach with power in a constant landing attitude - at 132-137 knots or about 1.17 times stalling speed - by using his angle-of-attack indicator rather than airspeed. The Skyray was flown firmly onto the deck without changing power, and this stabilized approach to touchdown proved to he the key to successful carrier landings with high performance aircraft.

All-weather fighter design had moved rapidly in the 1950s, and the Ford's lack of a usable aerial refueling system to use with the KC-130F tanker plane then coming into service, minimal air-ground capability, and its inability to shoot down aircraft head-on doomed it to a short service life in the Marine Corps. Moreover, the all-weather mission itself placed extremely high demands on the single pilot who had to fly on instruments at sonic speeds, while simultaneously operating and interpreting a radar scope. With these limitations in the late 1950s, two dozen Navy and Marine squadrons would have to make do with F4Ds in this configuration.

The VF-102 DIAMONDBACKS were established on July 1, 1955 in Jacksonville, Florida. The first aircraft to carry the distinctive DIAMONDBACK markings was the McDonnell F2H Banshee, a twin-engine fighter-bomber with four 20MM internal cannons. The DIAMONDBACK's inaugural cruise took place aboard the USS RANDOLPH (CV 15) in July 1956. After the deployment the squadron transitioned to the Douglas F-4D-1 Skyray. This aircraft, in addition to the internal cannons, carried the new AIM-9B "Sidewinder" missile. The squadron's outstanding performance in the Skyray resulted in their entry into the 1958 "All Navy Weapons Meet." After a final cruise with the Skyray aboard the USS FORRESTAL (CV 59) in 1960, the DIAMONDBACKS moved to NAS Oceana, Virginia and transitioned to the F-4B Phantom.

In 1957, VMFA-314 received the new F-4D Skyray and was designated VMF(AW)-314. During that same year, the squadron officially became the BLACK KNIGHTS, and was awarded the Commandant's Aviation Efficiency Trophy. Additionally they deployed throughout the Far East both on land as well as onboard the fast attack carriers USS Hancock and USS Ticonderoga. In 1961, the squadron became the first Marine squadron to transition to the new F-4B Phantom II.

On 25 February 1958, Lieutenant Colonel Gordon E. Gray was the first VMF(AW)-53 pilot to transition to the Skyray. By July, transition training was in full swing, using new F4D-ls fresh off the production line. After logging more than 48,000 hours in service with -531, the old F3D Skyknights departed in mid-year along with their radar operators. For VMF(AW)-531, the four-year Skyray era was a brief one.

On 26 July 1958, VMF-513 received the F-4D "Skyray" aircraft. In October of 1962 VMF(AW)-513 was relocated from NAS Atsugi Japan to MCAS El Toro, California. The outfit was effectively disbanded in Japan and reformed in El Toro under a new C.O., who organized new pilots and maintenance Marines to operate the now "old" F-4D Skyrays while the Flying Nightmares awaited delivery of the brand new F-4B Phantom II. This occurred in early 1963.

The Fighting BLACKLIONS of VFA-213 were commissioned on 22 June 1955 at NAS Moffett Field , California . The BLACKLIONS flew the F-2H3 Banshee during their first deployment aboard USS BON HOMME RICHARD (CV-31). They transitioned to the F-4D Skyray for their next two deployments on USS LEXINGTON (CV-16). By their third WESTPAC deployment aboard the "LEX," they were flying the F-3H2 Demon.

In 1957 and 1958, a Skyray-equipped squadron was named the top interceptor squadron in the North American Air Defense Command, although it was the only Navy unit assigned to the Air Force-dominated command.

Douglas built 421 Skyrays, including two prototypes, and they continued to roll out of the El Segundo, Calif., plant until December 1958. After 1962, it was designated the F-6A and served Marine and Navy carrier squadrons until February 1964.

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Page last modified: 07-07-2011 02:31:23 ZULU