Pratt & Whitney Wasp Jr. R-985-AN-14B "Dancing Engine"


Display Status:

This object is on display in the Mary Baker Engen Restoration Hangar at the Steven F. Udvar-Hazy Center in Chantilly, VA.

Pratt & Whitney Wasp Jr. R-985-AN-14B "Dancing Engine"

Collection Item Summary:

Begun in 1925 by former Wright Aeronautical employees as a spinoff from a machine tool company, Pratt & Whitney became one of the world’s largest manufacturers of aircraft engines, and the Wasp Jr. is one of the most successful reciprocating engines ever built. Pratt & Whitney introduced it as a complement to the highly successful Wasp and Hornet families of engines in 1930. The Wasp Jr. was essentially a Wasp of reduced dimensions. Pratt & Whitney and its licensees manufactured over 39,000 versions of the R-985 until 1953 for a wide variety of military and commercial aircraft, including light transports, trainers, sport aircraft, and helicopters.

The R-985-AN-14B powered the McDonnell XHJH-1 and XHJD-1 Whirlaway helicopters and the Avro Anson V trainer. This Wasp Jr.-aptly nicknamed "The Dancing Engine"- has been sectionalized and motorized to demonstrate the movements of its internal components.

Collection Item Long Description:

Data Source

National Air and Space Museum

Restrictions & Rights

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


Credit Line

Transferred from the Naval Aviation Museum


Overall - aluminum and steel.


Height: 117.5 cm (46.25 in.), Width: 117.5 cm (46.25 in.), Depth: 109.4 cm (43.06 in.)

Country of Origin

United States of America



Physical Description

  • Type: Reciprocating, Radial, 9 cylinders, air cooled
  • Power rating: 336 kW (450 hp) at 2,300 rpm
  • Displacement: 16.1 L (985 cu in)
  • Bore and Stroke: 132 mm (5.2in.) x 132 mm (5.2 in.)
  • Weight: 309 kg (682 lb)


PROPULSION-Reciprocating & Rotary

Inventory Number