Design
of the L-49 Constellation began in 1939, when Pan American Airways
and Transcontinental & Western Air (later Trans World Airlines) issued a design
requirement for a 40-passenger airliner for their long-range routes. The first L-49 flew in 1943.
U.S. Army Air Force commandeered at least 22 of
the aircraft off the assembly line, designated them as the C-69,
and used them as transports.
When the war
ended, production of civil aircraft began under the designation L-049
using components intended for C-69 production. The first
"true" civil Constellation was the L-649 with more
powerful engines and seating 48 - 64 passengers.
The
next improvement of the Constellation was the L-749 or C-121.