Curtiss K-6, In-line 6 Engine


Display Status:

This object is not on display at the National Air and Space Museum. It is either on loan or in storage.

Collection Item Summary:

Among the most successful early engines marketed in the United States were those designed and built by aviation pioneer and inventor Glenn H. Curtiss in his factory in Hammondsport, New York. The earliest Curtiss designed engines powered his racing motorcycles. The first Curtiss aircraft engine, a 5.2 kW (7 hp) air cooled, V-twin, powered a small dirigible in 1904.

During 1917 and 1918, the Curtiss K-6 (Kirkham-6) was designed under the direction of Charles B. Kirkham, an associate of Curtiss for a number of years who became the company’s Chief Engineer. Following the K-12, a Curtiss competitor for the highly successful Hispano-Suiza engine, the K-6 was introduced as a six-cylinder vertical direct-drive engine using the same cylinder block and the same crankshaft dimensions. Closely following the design of the K-12, the K-6 used K-12 parts wherever possible. Three K-6 engines powered the 1919 tri-motor Curtiss Eagle II airliner.

Collection Item Long Description:


Circa 1918

Inventory Number


Physical Description

  • Type: Reciprocating, 6 cylinders, in-line, water-cooled
  • Power rating: 112 kW (150 hp) at 1,700 rpm
  • Displacement: 9.38 L (572.54 cu in)
  • Bore and Stroke: 114 mm (4.5 in.) x 152 mm (6 in.)
  • Weight: 189.1 kg (417 lb)

Credit Line

Transferred from the Department of the Navy, Bureau of Aeronautics.

Country of Origin

United States of America


Aluminum, Steel, Copper, Rubber, Preservative Coating, Paint, Nickel plating, Textile


Height 119.4 cm (47 in.), Width 81.3 cm (32 in.), Depth 168.9 cm (66.5 in.)

Data Source

National Air and Space Museum

Restrictions & Rights

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


PROPULSION-Reciprocating & Rotary