Douglas C-54 Skymaster (DC-4, R5D)
Other designations were DC-4, R5D.
Douglas produced this four-engine transport about twice the size
of the DC-3 and, in 1938. It
proved too expensive to maintain, so airlines agreed to suspend
development in favor of the less complex DC-4, but it was not
put into commercial service until 1946. Its military derivative
was the C-54 "Skymaster" transport, ordered by the U.S.
Army Air Forces in 1942.
Douglas built 1,241 a special C-54C, nicknamed
the "Sacred Cow" by the White House press corps, became
the first presidential aircraft, ordered for Franklin D. Roosevelt.
The U. S. Navy (USN) designation for this aircraft was R5D Skymaster.
Postwar, commercial airliners placed
more than 300 civilian DC-4 transports for use as airliners. DC-4s and
used C-54s carried more passengers than any other four-engine
transport to date. Some were still operating around the world until at least 1998.