Coming close on the heels of its Wasp radial engine, Pratt & Whitney developed a larger version named the Hornet A. The U.S. Military designated the engine the R-1690.
First flown in 1927, the U.S. Navy wanted the Hornet as a replacement for the heavy Packard engines in its torpedo and bomber aircraft. The result was so dramatic, the Navy announced it would cease buying water-cooled engines.

models

• R-1690-11: 700 hp (521 kW)
• R-1690-13: 625 hp (465 kW)
• R-1690-52: 750 hp (559 kW)

specifications

• 9 cylinder, air-cooled, radial
• displacement: 1,690 cubic inches (27.7 litres)

used by

• Martin B-12
• Douglas O-38
• Sikorsky S-43