Editing Douglas C-54 Skymaster (section)

==Design and development==
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[[File:Douglas C-54 Skymaster in flight, circa in 1943.jpg|thumb|A USAAF Douglas C-54 (s/n 41-37271), circa 1943]]

With the looming entry of the United States into World War II, in June 1941{{citation needed|date=May 2020}} the War Department took over the provision orders for the airlines for the [[Douglas DC-4]] and allocated them to the United States Army Air Forces with the designation '''C-54 Skymaster'''. The first, a C-54, flew from [[Clover Field]] in [[Santa Monica, California]] on 14 February 1942.<ref name=Tinker>{{cite web|url=https://www.tinker.af.mil/News/Article-Display/Article/1132101/tinker-history-douglas-c-54-skymaster/ | title= TINKER HISTORY: Douglas C-54 Skymaster | work= Tinker Air Force Base | date= 24 March 2017 |publisher=Greg L. Davis, Tinker Air Force Base, 24 March 2017|access-date=23 June 2020}}</ref>

To meet military requirements, the first civil production aircraft had four additional auxiliary fuel tanks in the main cabin, which reduced the number of passenger seats to 26. The following batch of aircraft, designated C-54A, were built with a stronger floor and a cargo door with a hoist and winch. The first C-54A was delivered in February 1943. The C-54B, introduced in March 1944, had integral fuel tanks in the outer wings, allowing two of the cabin tanks to be removed. This change allowed 49 seats (or 16 stretchers) to be fitted. The {{awrap|C-54C}}, a hybrid for Presidential use, had a C-54A fuselage with four cabin fuel tanks and C-54B wings with built in tanks to achieve maximum range.

The most common variant was the C-54D, which entered service in August 1944. Based on the C-54B, it was fitted with more powerful R-2000-11 engines. With the C-54E, the last two cabin fuel tanks were moved to the wings which allowed more freight or 44 passenger seats.

Aircraft transferred to the [[United States Navy]] were designated '''Douglas R5D'''. With the introduction of the [[1962 United States Tri-Service aircraft designation system|Tri-Service aircraft designation system]] in 1962, all R5Ds were re-designated C-54.