The Wright R-1820 Cyclone 9 is an American radial engine developed by Curtiss-Wright, widely used on aircraft in the 1930s through 1950s. It was produced under license in France as the Hispano-Suiza 9V or Hispano-Wright 9V, and in the Soviet Union as the Shvetsov M-25. Design and development The R-1820 Cyclone 9 represented a further development of the Wright P-2 engine dating back to 1925. Featuring a greater displacement and a host of improvements, the R-1820 entered production in 1931. The engine remained in production well into the 1950s. The R-1820 was built under license by Lycoming, Pratt & Whitney Canada, and also, during World War II, by the Studebaker Corporation. The Soviet Union had purchased a license for the design, and the Shvetsov OKB was formed to metricate the American specification powerplant for Soviet government-factory production as the M-25, with the R-1820's general design features used by the Shvetsov design bureau for many of their future radials for the Soviet air forces through the 1940s and onwards. In Spain the R-1820 was license-built as the Hispano-Suiza 9V or Hispano-Wright 9V. The R-1820 was at the heart of many famous aircraft including early Douglas airliners (the prototype DC-1, the DC-2, the first civil versions of the DC-3, and the limited-production DC-5), every wartime example of the Boeing B-17 Flying Fortress and Douglas SBD Dauntless bombers, the early versions of the Polikarpov I-16 fighter (as the M-25), and the Piasecki H-21 helicopter. The R-1820 also found limited use in armoured vehicles. The G-200 variant developed at 2,300 rpm and powered the strictly experimental M6 Heavy Tank. D-200 Diesel The Wright R-1820 was converted to a diesel during World War II by Caterpillar Inc. as the D-200 and produced at 2,000 rpm in the M4A6 Sherman. Variants Notes: Unit numbers ending with W indicate engine variants fitted with water-methanol emergency power boost systems. Hispano-Suiza 9V The Hispano-Suiza 9V is a licence-built version of the R-1820. Hispano-Suiza 9Vr9V with reduction gear Hispano-Suiza 9Vb Hispano-Suiza 9Vbrvariant of the 9Vb with reduction gear Hispano-Suiza 9Vbrsvariant of the 9Vb with reduction gear and supercharger Hispano-Suiza 9Vbsvariant of the 9Vb with supercharger Hispano-Suiza 9Vdvariant of the 9V Hispano-Suiza 9V-10 driving fixed-pitch propeller Hispano-Suiza 9V-11as -10 but RH rotation Hispano-Suiza 9V-16 driving variable-pitch propeller, LH rotation Hispano-Suiza 9V-17as -16 but RH rotation Applications Vehicles M4A6 tank M6 heavy tank Engines on display Preserved Wright R-1820 engines are on