The Wasp Major was Pratt & Whitney Aircraft's last and largest piston engine. Its cylinders were in four rows, arranged in a spiral for better cooling. Initially producing 2,237 kW (3,000 shp), later models developed 3,207 kW (4,300 shp). It was reliable in flight, but required extensive and time consuming checks at startup and shutdown.

The gigantic Convair B-36 strategic bomber was likely planned around this engine, which used six R-4360s along with four turbojets. The Wasp Major saw service at the end of World War II in late Boeing B-29s that were actually early B-50s, and was used on the Boeing B-50 "Lucky Lady" when it made the first non-stop around the world flight in 1949.

This artifact powered a Boeing Model 377 Stratocruiser, one of the last generation of large propeller-driven commercial airliners. It is a Q.E.C. (Quick Engine Change) unit, complete with engine cowling, designed for rapid engine changes to minimize aircraft out-of-service time.

 Display Status

This object is not on display at the National Air and Space Museum. It is either on loan or in storage.
Object Details
Date Circa 1949 Country of Origin United States of America Type PROPULSION-Reciprocating & Rotary Manufacturer Pratt & Whitney
 Physical Description Type: Reciprocating, 28 cylinders, radial, air cooled, four rows Power rating: 2,424 kW (3,250 hp) at 2,700 rpm Displacement: 71.5 L (4,360 cu. in.) Bore and Stroke: 146 mm (5.8 in.) x 152 mm (6 in.) Weight: 1,626 kg (3,584 lb) Dimensions Diameter 139.7 cm (55 in.), Length 245.1 cm (96.5 in.)
 Materials Aluminum, Magnesium, Steel, Rubber, Plastic, Copper, Stainless Steel, Paint, Textile
 Inventory Number A19910072000 Credit Line Gift of June Freemanzon Data Source National Air and Space Museum Restrictions & Rights Usage conditions apply
For more information, visit the Smithsonians Terms of Use.