The Pratt & Whitney R-985 Wasp Junior was a radial engine widely used in American aircraft starting in the 1930s at 300 hp. It was a scaled-down version of the original R-1340, and the second in the Wasp family. By the 1940s, the R-985 produced 450 hp and was used in thousands of military and civilian aircraft. Production of 39,000 engines spanned from 1930 to 1953.
Some of the aircraft using the engine included the Airspeed Oxford, Avro Anson, Beech 17 Staggerwing, Beech 18, De Havilland Canada DHC-2 Beaver, Grumman Goose, Lockheed L-10 Electra, Lockheed 12 Electra Junior, Vought Kingfisher, Vultee BT-13 Valiant, North American Yale and the Sikorsky S-51 helicopter.
This engine is installed in the twin-engined Beech 18 on display at the Museum.