The Wright R-3350 Duplex-Cyclone is an eighteen-cylinder, two-row radial aircraft engine with air cooling and a displacement of 3,350 cubic inches. First run in May 1937, it became a major American heavy-aircraft powerplant through its use in the Boeing B-29. Development continued into powerful post-war transport versions.[1]Wright R-3350-23 Duplex-CycloneNational Museum of the US Air Force · nationalmuseum.af.mil · Accessed 2026-09-13Open source details
Development and wartime use
Design work began in early 1936. The development programme and early installations encountered serious backfire problems, but the engine went into large-scale wartime production. The B-29 was its principal military application, while versions also powered the Consolidated B-32 and early Boeing C-97 transports.[2]Wright Cyclone R-3350-57National Air and Space Museum · airandspace.si.edu · Accessed 2026-09-13Open source details
B-29 engine ratings depended on the version installed. The museum's Bockscar, for example, used 2,200 hp R-3350-41 engines. The broader family eventually extended beyond 3,500 hp. The museum's preserved R-3350-23 is presented in its replacement-engine delivery condition, before installation of accessories transferred from the engine being removed.[1]Wright R-3350-23 Duplex-CycloneNational Museum of the US Air Force · nationalmuseum.af.mil · Accessed 2026-09-13Open source details
Turbo-compound development
Post-war turbo-compound versions recovered energy from the exhaust through three turbines geared into the engine's power system. The turbines contributed mechanical power rather than merely driving a supercharger. This arrangement helped extend the useful development of large piston engines during the transition towards turbine-powered airliners.[3]Wright Cyclone R-3350-91TCNational Air and Space Museum · airandspace.si.edu · Accessed 2026-09-13Open source details
Airline and military transports
Turbo-compound Cyclones powered the Douglas DC-7 and Lockheed Super Constellation. The R-3350-91 served the military C-121, and the Smithsonian's -91TC example is rated at 3,250 hp at 2,900 rpm. Its listed weight is 3,690 lb, illustrating the scale of the complete late-generation powerplant.[3]Wright Cyclone R-3350-91TCNational Air and Space Museum · airandspace.si.edu · Accessed 2026-09-13Open source details
The R-3350 also served the C-119 and A-1 Skyraider. Its applications therefore reached beyond long-range bombers and airliners into tactical transport and attack aviation, with different versions tailored to their aircraft's power and installation requirements.[1]Wright R-3350-23 Duplex-CycloneNational Museum of the US Air Force · nationalmuseum.af.mil · Accessed 2026-09-13Open source details