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C-54 Skymaster
Role	Military transport aircraft
Manufacturer	Douglas Aircraft Company
First flight	14 February 1942
Introduction	1942
Retired	1975
Primary users	United States Army Air Forces United States Navy United States Air Force
Produced	1942–1947
Number built	1,170
Developed from	Douglas DC-4

The Douglas C-54 Skymaster was a four-engined transport aircraft used by the United States Army Air Forces in World War II and the Korean War. Like the Douglas C-47 Skytrain, the C-54 Skymaster was derived from a civilian airliner, the Douglas DC-4. Besides transport of cargo, the C-54 also carried presidents, prime ministers, and military staff. Dozens of variants of the C-54 were employed in a wide variety of non-combat roles such as air-sea rescue, scientific and military research, and missile tracking and recovery. During the Berlin Airlift it hauled coal and food supplies to West Berlin. After the Korean War it continued to be used for military and civilian uses by more than 30 countries. This was one of the first aircraft to carry the President of the United States.

With the entry of the United States into World War II, in June 1941 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.

To meet military requirements the first civil production aircraft had four additional auxiliary fuel tanks in the main cabin which reduced the passenger seats to 26. The following batch of aircraft were designated C-54A and were built with a stronger floor, cargo door with a hoist and winch. The first C-54A was delivered in February 1943. With the introduction of the C-54B in March 1944 the outer wings were changed to hold integral fuel tanks allowing two of the cabin tanks to be removed, this allowed 49-seats (or 16 stretchers) to be fitted. The C-54C was a hybrid for Presidential use, it had a C-54A fuselage with four cabin fuel tanks and the 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, it was a C-54B with more powerful R-2000-11 engines. With the C-54E the last two cabin fuel tanks were moved to the wings which would allow more freight or 44 passenger seats.

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