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.

[3][6][7] An even more powerful version, the R-975E-3, was also introduced that year, with greater supercharging and a still higher RPM limit, and was progressively refined until the final model of 1935 could reach 450 hp (336 kW) for takeoff.

It powered a wide variety of civil utility aircraft, such as the Beechcraft Staggerwing, and various airliners, such as the Ford 4-AT-E Trimotor and the Lockheed 10B Electra.

In addition, it powered U.S. military training aircraft including the North American BT-9 and Vultee BT-15 Valiant for the Army and the Curtiss-Wright SNC Falcon for the Navy.

A military version, the R-975-46, could reach 550 hp (410 kW), and was used in Piasecki's HUP Retriever and H-25 Army Mule helicopters.

The engine was built in Spain as the Hispano-Suiza 9Q or Hispano-Wright 9Q without modification apart from the use of Hispano's patented nitriding finishing process and, on one version only, the 9Qdr, an epicyclic output speed reducer.

Comparable engines Related lists The following Federal Aviation Administration type certificate data sheets, all available from the FAA's Regulatory and Guidance Library Archived 2016-11-12 at the Wayback Machine: