Lockheed C-121 Constellation

The Lockheed C-121 Constellation was a military transport version of the Lockheed Constellation. A total of 332 aircraft were constructed for both the United States Air Force and United States Navy for various purposes. Numerous AWACS versions were also constructed. The C-121 later saw service with smaller civilian operators until 1993.

Design and development

Lockheed's first attempt at a military version of the Constellation airliner had been unsuccessful. This was largely due to the problems encountered by the Wright R-3350 engines that powered the aircraft. After the war, the few military Constellations built (designated C-69) were retrofitted by Lockheed for use in the post-war airline industry as the L-049.

In 1947, Lockheed unveiled a more economical Constellation. The L-749 as it was known, had extra fuel capacity and a more economical version of the R-3350. However, Lockheed had lost 1200 workers that same year. By 1948, production of the L-749 was at a near halt. It was then that the United States Air Force (USAF) signed a contract with Lockheed for ten L-749A aircraft designated the C-121A. The United States Navy (USN) had also placed an order for two AWACS versions of the L-749A designated the PO-1W (later WV-1). The first L-749A variants off the production line were for the US military.