Wright R-975 Whirlwind

R-975 Whirlwind
A Continental-built R-975 from a Sherman tank
TypeAir-cooled 9-cylinder radial piston engine
National originUnited States
ManufacturerWright Aeronautical
Built byContinental Motors
Major applications
Manufactured1929-1950s
Number built
  • over 7,000 by Wright
  • over 53,000 by Continental

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.

During World War II, Continental Motors built the R-975 under license as a powerplant for Allied tanks and other armored vehicles. Tens of thousands of engines were built for this purpose, dwarfing the R-975's usage in aircraft, where it was overshadowed by the similar Pratt & Whitney R-985. After the war, Continental continued to produce its own versions of the R-975 into the 1950s; the Continental R-975-46A was rated at 550 hp (410 kW) at 2,400 rpm.

The R-975 powered the American World War II M18 Hellcat tank destroyer, which is claimed to have been the fastest tracked armored fighting vehicle ever built.