Usage Conditions May Apply Usage Conditions Apply There are restrictions for re-using this media. For more information, visit the Smithsonian's Terms of Use page. IIIF provides researchers rich metadata and image viewing options for comparison of works across cultural heritage collections. More - https://iiif.si.edu View Manifest View in Mirador Viewer Usage Conditions May Apply Usage Conditions Apply There are restrictions for re-using this media. For more information, visit the Smithsonian's Terms of Use page. IIIF provides researchers rich metadata and image viewing options for comparison of works across cultural heritage collections. More - https://iiif.si.edu View Manifest View in Mirador Viewer Usage Conditions May Apply Usage Conditions Apply There are restrictions for re-using this media. For more information, visit the Smithsonian's Terms of Use page. IIIF provides researchers rich metadata and image viewing options for comparison of works across cultural heritage collections. More - https://iiif.si.edu View Manifest View in Mirador Viewer Usage Conditions May Apply Usage Conditions Apply There are restrictions for re-using this media. For more information, visit the Smithsonian's Terms of Use page. IIIF provides researchers rich metadata and image viewing options for comparison of works across cultural heritage collections. More - https://iiif.si.edu View Manifest View in Mirador Viewer Usage Conditions May Apply Usage Conditions Apply There are restrictions for re-using this media. For more information, visit the Smithsonian's Terms of Use page. IIIF provides researchers rich metadata and image viewing options for comparison of works across cultural heritage collections. More - https://iiif.si.edu View Manifest View in Mirador Viewer

The XR-7755-3 is the largest, most powerful reciprocating aircraft engine in the world. During World War II, the U.S. Army Air Forces requested an engine with high takeoff power and low fuel consumption for a yet-to-be designed long-range bomber and transport. Lycoming began designing the engine in early 1944, and it was ready for testing by mid-1946. It featured nine dual-lobe overhead camshafts, which shifted axially for takeoff and cruising efficiency, and a two-speed, geared, dual-rotation propeller drive.

Lycoming built two XR 7755-3 prototypes. The company and the Army successfully tested them, but neither engine ever flew in an airframe. The proven reliability of the new gas turbine engines introduced after World War II made the XR 7755-3 obsolete before it could be fully developed. This artifact is the sole survivor.

 Display Status

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

Boeing Aviation Hangar
Object Details
Date 1945 Country of Origin United States of America Type PROPULSION-Reciprocating & Rotary Manufacturer Lycoming (Williamsport, Pennsylvania)
 Physical Description Type: Reciprocating, Radial, 36 cylinders, nine 4-cylinder banks, liquid cooled Power rating: 3,729 kW (5,000 hp) at 2,600 rpm Displacement: 127 L (7,755 cu in) Bore and Stroke: 162 mm (6.375 in.) x 171 mm (6.750 in.) Weight: 2,783 kg (6,130 lb) Dimensions Diameter 154.9 cm (61 in.), Length 308.2 cm (121.35 in.)
 Inventory Number A19781379000 Credit Line Transferred from the U.S. Air Force Museum. Data Source National Air and Space Museum Restrictions & Rights Usage conditions apply
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