Kinner R-5 / R-53 / R-55 / R-56 / R-540
The Kinner R-5 is an American five cylinder radial engine for light general and sport aircraft of the 1930s. The R-5 was a development of the earlier Kinner B-5, with slightly greater power and dimensions. The main change was the increase in cylinder bore from 117 mm (4.625 in) to 127 mm (5 in) and an increase in cylinder stroke from 133.3 mm (5.25 in) to 139.7 mm (5.5 in). This led to a corresponding increase in displacement from 7.2 liters (441 cu in) to 8.8 liters (540 cu in). The R-5 was a rough running but reliable engine and the R-5 and its derivatives were produced in the 1,000s, powering many World War II trainer aircraft, its military designation R-540.