Engine, Wright Whirlwind R-760-E2 (J-6), Radial 7

Type: Reciprocating, 7 cylinders, radial, air-cooled

Power rating: 239 kW (320 hp) at 2,200 rpm

Displacement: 12.39 L (755.93 cu in.)

Bore and Stroke: 127 mm (5.0 in.) x 139.7 mm (5.5 in.)

Weight (dry): 259 kg (570 lb)

Charles Lawrance designs for air-cooled engines began in 1915. In 1921, his own small company’s J-1 149 kW (200 hp) engine was designed for a Navy contract. 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, with the fully supercharged, high compression R-760-E2 certificated in December 1935. However, the most famous of these models was the J-5 which powered Lindbergh’s Spirit of St. Louis.

The first model in the seven-cylinder Wright Whirlwind R-760 (J-6) series was certificated in 1929. The J-6 powered aircraft such as the Stinson SM-2AC, Waco CRG/CSO, Curtiss-Wright CW Sedan 15-D, Curtiss-Wright Travel Air 4-D/10-2. Other R-760 engines powered aircraft such as the St. Louis PT-15, Howard UC-70C, Fairchild UC-88, Fairchild JK-1, Fairchild F-45, and Naval Aircraft Factory N3N-1/-3.