C-121

C-121 stands in the designation system of the United States Air Force (USAF) valid from 1948 to 1962 for the following four-engine propeller - driven transport and reconnaissance aircraft made by the US manufacturer Lockheed :

• C-121A for the military version of the Lockheed Constellation
• VC-121A, B for the military VIP version of the Lockheed Constellation
• C-121C, E, G, J for military versions of the Lockheed Super Constellation
• EC-121 Warning Star for Airborne Warning and Control System (AWACS) versions of the Lockheed Super Constellation
• WC-121N for the military weather reconnaissance version of the Lockheed Super Constellation
• YC-121F for four military test copies of the Lockheed Super Constellation with turbo prop drive