Lycoming R-680-BA, Radial 9 Engine

Type: Reciprocating, 9 cylinders, radial, air cooled

Power rating: 179 kW (240 hp) at 2,000 rpm

Displacement: 11 L (680 cu in.)

Bore and Stroke: 117.5 mm (4.625 in.) x 114.3 mm (4.5 in.)

Weight: 225 kg (505 lb)

Operating as a subsidiary of the Auburn Auto Company, Lycoming produced its first aircraft engine, the R-645, in 1929. Begun in 1930, the R-680 used Stromberg carburetors and Scintilla magnetos in a straightforward design including two valves in each cylinder with aluminum alloy heads shrunk to barrels machined with integral cooling fins from steel forgings. The engine’s overall reliability established the company as a design and manufacturing leader, and one of the world’s largest producers of aircraft engines. The Aviation Corporation (renamed Avco in 1947) acquired Lycoming in 1932 to add its engines to the corporation's range of aeronautical products, which included Stinson aircraft and Smith variable-pitch propellers.

The R-680 series powered various models of the Stinson Reliant cabin plane of the 1930s and the Boeing PT 13 Kaydet trainer of World War II. Overall, Lycoming manufactured over 26,000 R-680 engines. This R-680-BA, an early model in the R-680 series, first appeared in 1932.