Enigine, Radial 9, Wright Whirlwind J-4-B

Type: Reciprocating, 9 cylinders, radial, air cooled

Power rating: 149 kW (200 hp) at 1,800 rpm

Displacement: 12.9 L (788 cu in.)

Bore and Stroke: 114 mm (4.5 in.) x 140 mm (5.5 in.)

Weight: 218 kg (480 lb)

Charles Lawrance started designs for an air-cooled engine in 1915, designing his first 149 kW (200 hp) J-1 for a 1921 Navy contract. The Navy wanted a better engine for use on aircraft carriers, needing a compact lightweight engine not plagued with water leakage problems. After Lawrance’s company was absorbed by Wright Aeronautical in 1923, the J-1 progressed through stages, as the Whirlwind J-3, J-4, J-5, and J-6 series. Used in Lindbergh’s Spirit of St. Louis, the J-5 was the most famous.

The Wright J-4 incorporated improvements based on service with preceding models. J-4 engines powered such aircraft as the Fairchild FC-1 and FC-2, Fokker Universal, Laird Commercial LC-B200, Stearman C2B and C3B, and Stinson Detroiter SB-1.

This Wright J-4 engine was the first type of engine that Northwest Airlines used in its original Contract Air Mail and Passenger run between Minneapolis, Minnesota, and Chicago, Illinois, in October 1926 with a Stinson Detroiter four-place biplane.