Developed during WWII the Pratt and Whitney R 4360 is the largest and most powerful mass produced piston engine in the United States. The R 4360 is a four row 28 cylinder, seven per row, air cooled radial engine and produced a maximum of 3000 to 4000 hp and weighed about 3,500Ibs. Almost 19,000 were produced between 1944 and 1955.
Unfortunately for the radial engine and the R4360 in particular the 1940's saw the invention and development of the jet engine which in time would come to dominate the application in fighters and bombers alike, especially with the spectre of the Red threat on the horizon.
Still the R 4360 found it's way onto numerous aircraft during the 40's and 50's and still flies to this very day on racing aeroplanes. Noteworthy Military applications of the R 4360 include the Hughes XF -11, the Hughes HFB-1 (H4) Hercules Spruce Goose (both featured in Martin Scorcese's biopic of Howard Hughes, "The Aviator"), the elegant Martin JRM-2 Mars Flying Boat, the Boeing B-50, and the Convair B-36 Strategic Bomber.
Commercial Applications include the Boeing Model 377 Stratocruiser, and the Aerospacelines B-377 Mini, Super and the Pregnant Guppy.
Racing Applications include the FG2 Corsair, Super Corsair and the Hawker Sea Fury, "Dreadnought."