Pratt & Whitney Wasp Jr. R-985-AN-39A, Radial 9 Engine

Type: Radial, 9 cylinders, supercharged, air-cooled

Power rating: 336 kW (450 hp) at 2,300 rpm

Displacement: 16.1 L (985 cu in)

Bore and Stroke: 132 mm (5.2 in.) x 132 mm (5.2 in.)

Weight: 292.8 kg (645 lb)

The Wasp Jr. R-985 was the third engine type designed by Pratt & Whitney Aircraft, following the Wasp R-1340 and Hornet R-1690, all of which were nine-cylinder engines. The Wasp Jr. was designed to compete at lower power and was virtually a Wasp of reduced dimensions, as the details of construction were followed closely throughout. First certificated in January 1930 at 224 kW (300 hp), the R-985 was designed for light transports, trainers, sport aircraft, and helicopters. A number of models were made, most at 298 kW (400 hp) or higher power.

Powering a wide variety and large number of well known military and commercial aircraft such as the de Havilland Beaver and Lockheed Electra, the Wasp Jr. was one of the most successful reciprocating engines ever built in its power class. The R-985-39A powered the Beech C-45G and C-45H aircraft.