The Pratt & Whitney R2800 Double Wasp is an American twin-row, 18-cylinder, air-cooled radial aircraft engine. It is one of the most famous radial engines and known for its large application in American aircraft. The first F4U Corsair applied a R2800 engine was recorded as the first U.S. single-engine fighter to flew in a speed over 400mph(640km/h) in a level flight in Oct.1944. With continuous improvements, R2800 is also used in many long-range patrol planes due to its reliability, even in many restored old military fighters. It is still seen usage around the world currently.