Pratt & Whitney R-1690 Hornet A

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.


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


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

used by

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