The Curtiss-Wright Corporation was formed in June 1929 by the merger of the Curtiss Aeroplane and Motor Co. and the Wright Aeronautical Corporation. Curtiss-Wright operated in three main divisions: the Curtiss-Wright Airplane Division, which manufactured airframes until it closed down in 1951; the Wright Aeronautical Corporation, which produced aeronautical engines; and the Curtiss-Wright Propeller Division, which manufactured propellers. After 1929, most engines produced by the new company were known as Wrights, while most aircraft were given the Curtiss name, with a few exceptions. During World War I, the Curtiss company produced more aircraft than any other American manufacturer and became the largest aircraft and aircraft engine producer in the world. The Wright Aeronautical Corporation division produced air-cooled radial engines during the war that powered US fighter and bomber aircraft. During the first half of the 1930s, more than half of the company's revenues came from Wright Aeronautical, which provided a cushion that helped the other divisions survive during the Depression. In 1936 the Wright Aeronautical Corporation produced five distinct series of aircraft engines. They were the Wright Cyclones F and F-50; the Wright Cyclone G Series high-powered, nine cylinder radial air-cooled engines; the single-row Whirlwind series of five, seven and nine cylinders; the 14 cylinder Wright double-row Whirlwind Series; and the Curtiss Conquerors.