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 R-975 was a nine-cylinder engine in the J-6 series. Versions of the R-975 ranged from 224 to 354 kW (300 to 475 shp), and powered aircraft such as the Consolidated BT6, Stearman BT3/YPT-9C, North American BT-9/A/B/C/D, Vultee BT-15, Lockheed 10, Beech D-17R and 18R, and Ford 4-AT-E. The R-975 also had autogiro, airship, and tank applications.

 Display Status

This object is not on display at the National Air and Space Museum. It is either on loan or in storage.
Object Details
Date Circa 1930 Country of Origin United States of America Type PROPULSION-Reciprocating & Rotary Physical Description Type: Reciprocating, 9 cylinders, radial, air-cooled Power rating: 224 kW kW (300 hp) at 2,000 rpm Displacement: 16 L (975 cu in.) Bore and Stroke: 127 mm (5.0 in.) x 140 mm (5.5 in.) Weight: 250 kg (550 lb) Dimensions Diameter 119.4 cm (47.0 in.), Length 105.3 (41.4375 in.) (Dimensions for R-975D)
 Inventory Number A19690365000 Credit Line Transferred from United States Navy, Naval Supply Center. Data Source National Air and Space Museum Restrictions & Rights Usage conditions apply
For more information, visit the Smithsonians Terms of Use.