The Douglas A-1 Skyraider (formerly designated AD before the 1962 unification of Navy and Air Force designations) is a single-seat attack aircraft designed and produced by American aerospace manufacturer Douglas Aircraft Company. It had an unusually long career, remaining in frontline service well into the Jet Age (when most piston-engined attack or fighter aircraft were replaced by jet-powered aircraft), thus becoming known by some as an "anachronism". The aircraft was nicknamed "Spad", after the French World War I fighter.Burgess and Rausa 2009, p. 7.
Development of the Skyraider commenced during World War II as a carrier-compatible, single-seat dive/torpedo bomber that was capable of long endurance missions and possessing relatively high performance for the era. Ordered by the United States Navy (USN) in July 1944, the XBT2D-1 prototype performed its maiden flight on 18 March 1945. Various modifications were made to lighten the airframe to bolster its performance ahead of the Skyraider's entry to service in 1946. While procurement was initially slashed due to the end of World War II, numerous orders for the type were placed, resulting in production continuing through to 1957. The Skyraider was operated by various services, including the USN, the United States Marine Corps (USMC), the United States Air Force (USAF), the Royal Navy (RN), the French Air Force, and the Republic of Vietnam Air Force (RVNAF) amongst others.
Operationally, the Skyraider was principally used as a close air support aircraft; in this capacity, it was extensively used during both the Korean War and Vietnam War, as well as multiple other conflicts. In the Korean theatre, it possessed more endurance while carrying larger quantities of ordnance than any contemporary jet-powered aircraft. The Skyraider also frequently undertook interdiction missions. While not intended for the role, it was not defenseless in air-to-air engagements; on 16 June 1953, a Skyraider shot down a Soviet-built Polikarpov Po-2 biplane, this being the only documented Skyraider aerial victory of the conflict. During the Vietnam War, the type used cannon fire to shoot down two Mikoyan-Gurevich MiG-17 jet fighters of the Vietnam People's Air Force (VPAF). British Skyraiders were deployed during the Suez Crisis while France used its during the Algerian War. It remained in US service until the early 1970s, having been supplanted by newer jet-powered aircraft, such as the Grumman A-6 Intruder.
Design and development The origins of the Skyraider can be traced back to World War II and a decision made in 1943 by the United States Navy's (USN) Bureau of Aeronautics to overturn a long-standing preference for procuring multi-seat aircraft as dive bombers and torpedo bombers; furthermore, the bureau sought to combine both of these missions into a single aircraft type. A requirement was promptly formulated for a carrier-based, single-seat, long-range, high performance aircraft to perform the dive bomber/torpedo bomber mission as a successor to earlier aircraft, including the Douglas SBD Dauntless, the Curtiss SB2C Helldiver and the Grumman TBF Avenger.Parker 2013, p. 33. In response, Douglas Aircraft Company opted to produce a new design to propose; the company's design team was headed by Ed Heinemann. Upon presentation, bureau officials were impressed; accordingly, on 6 July 1944, the company received an order for prototypes under the designation of XBT2D-1.
On 18 March 1945, the first XBT2D-1 conducted its maiden flight, almost four months ahead of schedule. On 7 April 1945, the prototype was delivered to the USN'd Naval Air Test Center (NATC) where a service evaluation was performed;Swanborough and Bowers 1976, p. 176. test pilots allegedly reported that the XBT2D-1 performed better than any dive-bomber to have previously been evaluated. Accordingly, on 5 May 1945, the service ordered the aircraft into quantity production under the designation of AD-1; the type received the Skyraider name around this time as well. Months later, the Surrender of Japan and the end of the conflict led to production being curtailed, but not cancelled. In December 1946, the delivery of the first production aircraft to a fleet squadron, VA-19A, took place.Swanborough and Bowers 1976, p. 177.
In terms of its basic configuration, the AD-1 is a low-wing monoplane, powered by a single Wright R-3350 Duplex-Cyclone 18-cylinder radial engine, capable of producing well over , which was upgraded several times, ultimately attaining . The aircraft had distinctive large straight wings with seven hardpoints apiece. The Skyraider had excellent maneuverability at low speed, and carried a large amount of ordnance over a considerable combat radius. It had a long loiter time for its size, compared to much heavier subsonic or supersonic jets. The aircraft was optimized for ground attack and was armored against ground fire in key locations, unlike faster fighters adapted to carry bombs, such as the Vought F4U Corsair or North American P-51 Mustang, which were retired by US forces before the 1960s.
Shortly after Heinemann began designing the XBT2D-1, a study was issued showing that for every of weight reduction, the takeoff run was decreased by , the combat radius increased by and the rate-of-climb increased by . Heinemann immediately had his design engineers begin a program for finding weight savings on the XBT2D-1 design, no matter how small. Simplifying the fuel system resulted in a reduction of ; by eliminating an internal bomb bay and hanging external stores from the wings or fuselage; by using a fuselage dive brake; and by using an older tailwheel design. In the end, Heinemann and his design engineers achieved more than of weight reduction on the original XBT2D-1 design. The AD-1 was built at Douglas's El Segundo plant in Southern California.
The Navy AD series was initially painted in ANA 623 glossy sea blue, but during the 1950s, following the Korean War, the color scheme was changed to light gull gray and white (Fed Std 595 27875). Initially using the gray and white Navy scheme, by 1967 the USAF began to paint its Skyraiders in a camouflaged pattern using two shades of green, and one of tan. Used by the USN over Korea and Vietnam, the A-1 was a primary close air support aircraft for both the USAF and RVNAF during the Vietnam War. The A-1 was famous for being able to take hits and keep flying thanks to armor plating around the cockpit area for pilot protection. It was gradually replaced from the mid-1960s onwards by the Grumman A-6 Intruder as the USN's primary medium-attack plane in supercarrier-based air wings; however Skyraiders continued to operate from the smaller s.
The Skyraider went through seven versions, starting with the AD-1, then AD-2 and AD-3 with various minor improvements, then the AD-4 with a more powerful R-3350-26WA engine. The AD-5 was significantly widened, allowing two crew to sit side-by-side (this was not the first multiple-crew variant, the AD-1Q being a two-seater and the AD-3N a three-seater); it also came in a four-seat night-attack version, the AD-5N. The AD-6 was an improved AD-4B with improved low-level bombing equipment, and the final production version AD-7 was upgraded to an R-3350-26WB engine.
For service in Vietnam, USAF Skyraiders were fitted with the Stanley Yankee extraction system, which acted in a similar manner to an ejection seat, though with twin rockets extracting the pilot from the cockpit.
In addition to serving in Korea and Vietnam as an attack aircraft, the Skyraider was modified to serve as a carrier-based airborne early warning aircraft, replacing the Grumman TBM-3W Avenger. It fulfilled this function with both the USN and Royal Navy (RN) before being replaced by the Grumman E-1 Tracer and Fairey Gannet, respectively, in those services.
Skyraider production ended in 1957 with a total of 3,180 having been built. In 1962, the existing Skyraiders were redesignated A-1D through A-1J and later used by both the United States Air Force (USAF) and the USN in the Vietnam War.
Operational history
Korean War
The Skyraider was produced too late for use in World War II, but became the backbone of USN aircraft carrier and USMC strike aircraft sorties in the Korean War (1950–1953). The first ADs were sent into action from with VA-55 on 3 July 1950.Mersky 1983, p. 144. Its weapons load and 10-hour flying time far surpassed the jets that were available at the time.Johnson, E.R. "Able Dog." Aviation History, September 2008. The type frequently performed close air support and interdiction operations, the latter being focused on the supply lines of the North Korean Army.
On 2 May 1951, Skyraiders made the only aerial torpedo attack of the war, hitting the Hwacheon Dam, then controlled by North Korea.Faltum 1996, pp. 125–126.Thompson and Dorr 2003, p. 75.
On 16 June 1953, a USMC AD-4 from VMC-1 shot down a Soviet-built Polikarpov Po-2 biplane, the only documented Skyraider air victory of the war.Grossnick and Armstrong 1997, . AD-3N and -4N aircraft carrying bombs and flares, flew night-attack sorties, and radar-equipped ADs carried out radar-jamming missions from carriers and land bases.
During the Korean War, AD Skyraiders were flown by only the USN and USMC, and were normally painted in dark navy blue, leading to it being commonly called the "Blue Plane" by enemy troops.Jordan, Corey C. "Douglas AD-4 Skyraider." A Frozen Hell... The Air War Over Korea, 1950–1953, 2001. Retrieved: 14 July 2011. USMC Skyraiders suffered heavy losses when used in low-level close-support missions. To allow low-level operations to continue without unacceptable losses, a package of additional armor was fitted, consisting of thick external aluminum armor plates fitted to the underside and sides of the aircraft's fuselage. The armor package weighed a total of and had little effect on performance or handling. A total of 128 USN and USMC Skyraiders were lost in the Korean War – 101 in combat and 27 to operational causes. Many of the operational losses were attributed to the tremendous power of the aircraft: Skyraiders that were "waved-off" during carrier recovery operations were prone to performing a fatal torque roll into the sea or the deck of the aircraft carrier if the pilot mistakenly gave the aircraft too much throttle.
Cathay Pacific VR-HEU incident On 26 July 1954, a pair of Skyraiders from the aircraft carriers and reportedly shot down a pair of Chinese People's Liberation Army Air Force (PLAAF) Lavochkin fighters off the coast of Hainan Island while searching for survivors after the shooting down of a Cathay Pacific Douglas DC-4 Skymaster airliner three days previously.
Vietnam War
As American involvement in the Vietnam War began, the A-1 Skyraider was still the medium attack aircraft in many carrier air wings, although it was planned to be replaced by the Grumman A-6 Intruder as part of the general switch to jet aircraft. Skyraiders from and participated in the first US Navy strikes against North Vietnam on 5 August 1964 as part of Operation Pierce Arrow in response to the Gulf of Tonkin Incident, striking against fuel depots at Vinh, with one Skyraider from Ticonderoga damaged by anti-aircraft fire, and a second from Constellation shot down, killing its pilot, Lieutenant Richard Sather.Dorr Air Enthusiast 1988, p. 3.Dorr and Bishop 1996, pp. 34–35.