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Pratt & Whitney Hornet R-1860-B Radial Engine


Display Status:

This object is on display in the Boeing Aviation Hangar room at Steven F. Udvar-Hazy Center in Chantilly, VA.

Pratt & Whitney Hornet R-1860-B Radial Engine

Collection Item Summary:

The Pratt & Whitney Hornet series occupies a significant place in the development of reliable and powerful engines for both commercial and military operators. The series began with the 1926 development of the air-cooled R-1690 for the U.S. military, and was Pratt & Whitney’s second major engine, following the Wasp, another 1926 development. This early version of the Hornet allowed the first practical torpedo plane, the Martin T4M which carried a 909 kg (2000 lb) torpedo for a range of 1079 km (665 miles).

First certificated in 1929, the R-1860-B was a larger version for use in civil and military aircraft in the United States and abroad. Pratt & Whitney manufactured this particular R-1860-B Hornet for the U.S. Army Air Corps in 1932. The engine is most closely associated with the Sikorsky S-40 and S-41B flying boats. Subsequently, Pratt & Whitney engines powered nearly every flying boat built by Sikorsky.

Collection Item Long Description:

Data Source

National Air and Space Museum


Do not reproduce without permission from the Smithsonian Institution, National Air and Space Museum


George Willgoos


Credit Line

Found in the collection


Diameter 144.6 cm (56.93 in.), Length 113.7 cm (44.78 in.)

Country of Origin

United States of America



Physical Description

  • Type: Reciprocating, 9 cylinders, radial, air-cooled
  • Power rating: 429 kW (575 hp) at 1,950 rpm
  • Displacement: 30.5 L (1,860 cu in.)
  • Bore and Stroke: 159 mm (6.3 in.) x 171 mm (6.8 in.)
  • Weight: 377 kg (831 lb)


PROPULSION-Reciprocating & Rotary

Inventory Number