Wright Cyclone series

Wright Cyclone was the name given to a family of air-cooled radial piston engines designed by the Wright Aeronautical Corporation and used in numerous American aircraft in the 1930s, 1940s and 1950s.

Background
The Wright Aeronautical Corporation was formed in 1919, initially to develop liquid-cooled Hispano-Suiza V8 engines under license. In 1923 the Wright purchased the Lawrance Aero Engine Company, and with the purchase Charles Lawrance came to Wright as the Vice-President. Later that year the US Navy awarded Wright a contract to develop two new air-cooled radial engines. The first, called the P-1, was a 9-cylinder single row design of 1652 cuin displacement that was derived from an earlier Lawrence design, it produced 400 hp. The second, the P-2, had the same 1652 cuin displacement as the P-1, but was an improved design that produced 435 hp. Neither engine entered production, with the Navy selecting the superior Pratt & Whitney R-1340 Wasp, so in 1926 work started on the improved 1750 cuin design, which became the R-1750 Cyclone.

Cyclone family
R-1300 Cyclone 7 (1942)
 * 7-cylinder single row air cooled radial
 * Bore x stroke: 6+1/8 x
 * Displacement: 1301 cuin
 * Power output: 800 hp

R-1750 Cyclone (1926)
 * 9-cylinder single row air cooled radial
 * Bore x stroke: 6 x
 * Displacement: 1750 cuin
 * Power output: 500 - 525 hp

R-1820 Cyclone (1932)
 * 9-cylinder single row air cooled radial
 * Bore x stroke: 6+1/8 x
 * Displacement: 1823 cuin
 * Power output: 575 - 1525 hp

R-2600 Cyclone 14 (Twin Cyclone) (1935)
 * 14-cylinder two row air cooled radial
 * Bore x stroke: 6+1/8 x
 * Displacement: 2603 cuin
 * Power output: 1400 - 1900 hp

R-3350 Cyclone 18 (Duplex Cyclone) (1937)
 * 18-cylinder two row air cooled radial
 * Bore x stroke: 6+1/8 x
 * Displacement: 3347 cuin
 * Power output: 1800 - 2800 hp

R-4090 Cyclone 22
 * 22-cylinder two row air cooled radial
 * Bore x stroke: 6+1/8 x
 * Displacement: 4090 cuin

Note: the designations refer to the engine configurations as follows: "R" = Radial, followed by the approximate displacement in cubic inches.