F4D/F-6 Skyray: The Navy’s Delta Wing Interceptor

An F-6 Skyray at Quantico Marine Base, circa 1990. The initial designation was F4D, which can confuse some search engines and return links related the the F-4D Phantom II. (Photo by Robert Sacchi)

History

In 1947 the U.S. Navy put out a requirement for a supersonic high-altitude interceptor. Douglas Aircraft Company designer Ed Heinemann developed the F4D Skyray. On June 17 Douglas Aircraft Corporation put forward their proposal. The D-571–1 plan had a delta wing which was a novel concept that interested the U.S. Navy. The Navy selected the D-571–1 plan for further development.[i]

The Navy gave Douglas a contract for two prototypes on December 16, 1949. The F4D prototype made its first flight on January 21, 1951. This was test pilot Larry Peyton’s first and last flight in a Skyray. Peyton was primarily a transport pilot and found the aircraft had some problems. Test pilot Russ Thaw took over flight testing the Skyray after Douglas corrected some of the issues Peyton found with the aircraft. [ii] Heinemann received the 1953 Robert J. Collier trophy for designing the Skyray.[iii]

On October 3, 1953 Lieutenant Commander James B. Verdin flew a Skyray to set an airspeed record of 752.9 mph (1,205 km/h). On October 15 Bob Rahn flew a Skyray on a 100-kilometer (62.1 mile) closed course at 728.11 mph (1,172.3 km/h) setting another speed record.[iv] On June 5, 1954 the first production F4D-1 became the first aircraft to sustain Mach 1 in level flight.[v] In May 1958 Marine Corps Major Edward N. LeFaive flying a Skyray set a time to climb record of 49,221 feet (15,000 meters) in 2 minutes and 36 seconds. This was one of a series of time to climb records Major LeFaive set in a F4D.[vi]

On November 19, 1958 Marine Corps Second Lieutenant Philip M. Schmitt was practicing an emergency landing at El Toro Marine Air Base. The F4D overshot the runway and crashed into the path of a passenger train. The train derailed. All 135 people on the train and 2 ndLt. Schmitt escaped serious injury.[vii]

In 1958 the Naval Ordinance Test Systems (NOTS) organization used a Skyray to launch a microsatellite into orbit. NOTS gave up after 6 unsuccessful attempts.[viii]

On October 21, 1960 a broken wire on a rudder caused an F4D-1 to crash. Lt. Jan M. Graves was killed in the accident.[ix]

The Navy deployed some Skyrays during the Cuban Missile Crisis but they were never involved in combat.[x] Skyraiders won some U.S. Navy and U.S. Air Force competitions where it competed against the most advanced U.S. interceptors of its day. The Department of Defense changed the Skyray’s designation from F4D to F-6 in September 1962. The Skyray was the first and last delta wing carrier aircraft for the U.S. Navy. It was also the last Douglas fighter accepted by the military. Douglas built 420 Skyrays.[xi]

[i] Military Factory.com, https://www.militaryfactory.com/aircraft/detail.asp?aircraft_id=638, last accessed 3/16/26.

[ii] Airvectors.net, http://www.airvectors.net/avskyray.html, last accessed 3/16/26.

[iii] National Air & Space Museum.

[iv] Airvectors.net, http://www.airvectors.net/avskyray.html, last accessed 3/16/26.

[v] Military Factory.com, https://www.militaryfactory.com/aircraft/detail.asp?aircraft_id=638, last accessed 3/16/26.

[vi] Airvectors.net, http://www.airvectors.net/avskyray.html, last accessed 3/16/26.

[vii] Madera Tribune, Volume 67, Number 136, 20 November 1958, https://cdnc.ucr.edu/cgi-bin/cdnc?a=d&d=MT19581120.2.3&e=-------en--20--1--txt-txIN--------1, last accessed 3/16/27.

[viii] Vectorsite.net, https://web.archive.org/web/20070805072633/http://www.vectorsite.net/avskyray.html, last accessed 3/16/26.

[ix] China Lake Alumni.org, http://www.chinalakealumni.org/Accidents.htm, last accessed 3/16/26.

[x] Airvectors.net, http://www.airvectors.net/avskyray.html, last accessed 3/16/26.

[xi] Airvectors.net, http://www.airvectors.net/avskyray.html, last accessed 3/16/26.

USMC Skyray, Bu. №134815. (Wikipedia)

Background and Epilogue

Ed Heinemann’s inspiration for the Skyray was the designs of Dr. Alexander Lippisch. Dr Lippisch proposed some advanced concepts for high speed aircraft. These included the Me 163 Komet, tailless interceptor. Another Lippisch design was the DM-1 which had a delta wing.[i]

The Skyray showed the advantages and disadvantages of delta wing aircraft. The Skyray had excellent performance and good maneuverability at high speeds. The tradeoff was difficult handling at low speeds. Low speed handling difficulty is a big disadvantage for carrier-based aircraft.

With no horizontal tail, pilots used the elevons on the trailing edge of the wing to control pitch and roll. Pilots seemed to have a love it or hate it opinion of the Skyray.

As with most interceptors it had limited multirole capability. It didn’t have an air-air refueling system, which limited the Skyray’s range. The age of the interceptors ended with the 1960s. The last Skyrays on active duty were at the Navy Test Pilots School at Patuxent River, Maryland. Their purpose was to give pilots familiarity with how an unstable aircraft flew.

[i] “Delta” refers to the triangular shape, which is the symbol for the Greek letter delta.

F-6 Skyray vs MiG-19

© 2020 Robert Sacchi

Originally published at https://hubpages.com on August 17, 2020.