The Wright R-975 Whirlwind was a series of nine-cylinder, air-cooled radial aircraft engines built by the Wright Aeronautical division of Curtiss-Wright. These engines had a displacement of about 975 cu in (15.98 L), and power ratings ranging from 300 hp (220 kW) to 550 hp (410 kW), depending on variant and rating basis. They were the largest members of the Wright Whirlwind engine family to be produced commercially, and they were also the most numerous.