Pratt & Whitney R-4360 Wasp Major

The Pratt & Whitney R-4360 Wasp Major is an American 28-cylinder, four-row radial piston aircraft engine designed and built during World War II and the last of the Pratt & Whitney Wasp family. At 4,362.5 cubic inches, about 71.5 litres, it was the largest-displacement piston aviation engine mass-produced in the United States and, at up to 4,300 horsepower, the most powerful. Its prototype first ran on 28 April 1941, and production engines were built from 1944 to 1955, 18,679 in all. Four rows of seven air-cooled cylinders, each offset slightly from the one ahead, earned it the nickname corncob, but the layout caused thermal problems and a heavy maintenance load, and turboprops soon supplanted it.