Wright R-975 Whirlwind

R-975 Whirlwind
A Continental-built R-975 from a Sherman tank
Type	Air-cooled 9-cylinder radial piston engine
National origin	United States
Manufacturer	Wright Aeronautical
Built by	Continental Motors
Major applications	Beechcraft Staggerwing North American BT-9 Vultee BT-15 Valiant M4 Sherman tank Piasecki HUP Retriever M18 Hellcat
Produced	1929-1950s
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 of 300–450 hp (220–340 kW). 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. Some of these produced as much as 550 hp (410 kW).

The R-975 powered the American World War II M18 Hellcat tank destroyer which was claimed to have been the fastest tracked armored vehicle until the introduction of the turbine powered M1 Abrams in the 1980s.^[1]