In 1943, the Army asked GE to propose a 13,344 to 17,792 N (3,000 to 4,000 lb) thrust turbojet engine. GE's response was the I-40 (J33), a centrifugal-flow engine that could be produced in a short time, as well as the axial-flow TG-180 (J35), which required a longer development time. First off the block, the I-40 went into service in 1945 in America's first operational jet fighter, the Lockheed P-80A.
To meet wartime needs, production was licensed to the Allison Division of General Motors. When World War II ended, the Army Air Forces re-evaluated its production program, and turned over all post-war production of the J33 to Allison.
The J33 was GE's first turbojet engine of its own design, the last all-centrifugal-flow engine built by GE, and last used in U.S. military combat aircraft. The J33 powered many first generation U.S. military jet aircraft. This engine powered the Lockheed F-80C and TF-80C.