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Pratt & Whitney R-985 Wasp Junior

The Engine  Specifications

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.


9-cylinder, air-cooled radial
displacement: 985 cubic inches (16.1 liters)
Bore x stroke: 5 3/16 x 5 3/16 in
 Models  Used by
R-985-AN-4: 450 hp (336 kW)
R-985-AN-5: 450 hp (336 kW)
R-985-25: 450 hp (336 kW)
R-985-48: 450 hp (336 kW)
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page updated 06 December 2007



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Kenneth W Shanaberger 2000 - 2010