By 1930, Pratt & Whitney's Wasp was producing 500 hp (372 kW) and the company decided to develop the Wasp Junior to compete in the 300 - 400 hp (220 - 300 kW) market.

The first R-985 produced 300 hp and flew in 1930. By the end of World War II, improved R-985s produced 450 hp and were used in thousands of military and civilian aircraft.

The R-985 was in production from 1930 through 1953. Over 39,000 were produced.

models

• R-985-AN-4: 450 hp (336 kW)
• R-985-AN-5: 450 hp (336 kW)
• R-985-25: 450hp (336 kW)
• R-985-48: 450 hp (336 kW)

specifications

• 9-cylinder, air-cooled radial
• displacement: 985 cubic inches (16.1 litres)
• Bore x stroke: 5 3/16 x 5 3/16 in

used by

• Beech AT-11 Kansas
• Vultee BT-13 Valiant
• North American BT-14 Yale
• Beech C-45 Expeditor
• Grumman G-164 AgCat
• de Havilland Canada DHC-2 Beaver
• Lockheed L-10 Electra
• Beech Model 17 Staggerwing
• Vought OS2U Kingfisher
• Sikorsky R-5