The Wright R-1820 Cyclone is a nine-cylinder, air-cooled radial aircraft engine introduced in 1931. Developed from earlier Cyclone designs, it began at 575 hp and eventually reached 1,525 hp in some versions. Its best-known application was the Boeing B-17 Flying Fortress, but the family also powered transports and helicopters.[1]Wright R-1820 CycloneNational Museum of the US Air Force · nationalmuseum.af.mil · Accessed 2026-09-13Open source details[2]Vertol CH-21B WorkhorseNational Museum of the US Air Force · nationalmuseum.af.mil · Accessed 2026-09-13Open source details
Growth of the Cyclone
The R-1820 extended Wright's late-1920s engine work with a larger, more powerful design. The preserved R-1820B at the US Air Force museum represents the early 575 hp standard. By the Martin B-10 installation, the R-1820-33 delivered 775 hp. Subsequent development substantially increased output while retaining the nine-cylinder radial arrangement.[1]Wright R-1820 CycloneNational Museum of the US Air Force · nationalmuseum.af.mil · Accessed 2026-09-13Open source details
Transport applications
A 675 hp R-1820-17 replaced the original Hornet engine in a Bellanca C-27A in 1934, creating the C-27B. The extra power allowed a larger payload without materially changing speed or range. The other C-27As and earlier Y1C-27s subsequently received 750 hp Cyclones and became C-27Cs.[3]Bellanca C-27BNational Museum of the US Air Force · nationalmuseum.af.mil · Accessed 2026-09-13Open source details
Bomber service
The Douglas B-18A used two 1,000 hp R-1820-53 engines. Developed from the DC-2 transport, the B-18 represented a twin-engine application alongside the four-engine B-17. As newer bombers displaced the B-18 from front-line service, surviving aircraft continued in transport and anti-submarine roles.[4]Douglas B-18 BoloNational Museum of the US Air Force · nationalmuseum.af.mil · Accessed 2026-09-13Open source details
Rotary-wing use
The engine's career extended into the tandem-rotor H-21 helicopter. The US Air Force museum lists a 1,425 hp R-1820 in its CH-21B, whose long fuselage could accommodate twenty equipped troops or twelve litter patients with attendants. The type served with American, French, Canadian and West German armed services. The H-21 first flew in 1952, placing this helicopter application more than twenty years after the original Cyclone's introduction.[2]Vertol CH-21B WorkhorseNational Museum of the US Air Force · nationalmuseum.af.mil · Accessed 2026-09-13Open source details