Continental (Wright Whirlwind) R-975-46A, Radial 9 Engine

Type: Reciprocating, 9 cylinders, radial, air cooled

Power rating: 410 kW (550 hp) at 2,400 rpm

Displacement: 16 L (975 cu in.)

Bore and Stroke: 127 mm (5.0 in.) x 140 mm (5.5 in.)

Weight: 331 kg (730 lb)

Charles Lawrance designs for air-cooled engines began in 1915. In 1921, his own company’s J-1 149 kW (200 hp) engine was designed for the Navy. Wanting a better, compact, lightweight engine not plagued with water leakage problems for use on aircraft carriers; the Navy encouraged the 1923 merger with the larger Wright Aeronautical Corporation. The Lawrance engine then progressed through the Wright Whirlwind J-3, J-4, J-5, and J-6 series, the most famous being the J-5 which powered Lindbergh’s Spirit of St. Louis.

This improved J-6 engine was designed by Wright and built under license by Continental Aviation and Engineering Corporation. Post-World War II R-975 engines powered Kaman and Piasecki helicopters, as well as the McDonnell XV-1 convertiplane. In the early 1960s, this engine powered U.S. Navy Piasecki HUP-2 and HUP-3 helicopters. The HUP helicopters were variously utilized for shipboard utility and rescue duties; some were modified for anti-submarine warfare missions.