The Skyraider was originally designed in the 1940s by Ed Heinemann of the Douglas Aircraft Company, as a simpler alternative to the XBTD-1. At the time of the first prototype's flight on 18 March 1945, it was the largest production single-seater aircraft. The low-wing monoplane design started with a Wright R-3350 radial engine, later upgraded multiple times. Its distinctive feature was the presence of seven hardpoints on each wing, enabling it to carry a tremendous amount of ordnance for its size.
Although the Skyraider came into production too late for World War II, it turned out to be of great value in the Korean War, since its weapon load and 10-hour flying time far surpassed the jets that were available.
It 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 4-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 a R-3350-26WB engine.
Production ended in 1957 with a total of 3,180 built. However, in 1962 the existing Skyraiders were redesignated A-1D through A-1J and later used by both the USAF and the Navy in the Vietnam War.
In addition to serving during Korea and Vietnam as an attack aircraft, it was modifed into the first airborne early warning aircraft to see service off aircraft carriers. It served in this function in the USN and Royal Navy, being replaced by the E-1 Tracer and Fairey Gannett respectively in those services.
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