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Langley-Manly-Balzer Radial 5 Engine


Display Status:

This object is on display in the Early Flight exhibition at the National Air and Space Museum in Washington, DC.

Collection Item Summary:

Commissioned by Dr. Samuel P. Langley, this engine powered his unsuccessful airplane, known as the Langley Aerodrome A. It was the first internal combustion engine specifically designed for an aircraft. In its original form, the 1899 engine was a 6 kW (8 hp), air-cooled rotary designed and built by Stephen M. Balzer of New York City, N.Y. It derived from his automobile engine of 1894, and was never reliable, only running for a few minutes.

After being redesigned and successfully rebuilt as a water-cooled radial by Charles M. Manly, Langley's assistant, it had the best power-to-weight ratio (1.5 kg/kW or 2.4 lb/hp) of any engine in the world until 1906, and ran for up to 10 hours duration. Manly damaged his eyesight while brazing engine parts, and nearly drowned while piloting the last attempted flight of the Aerodrome on December 8, 1903. The Wright Brothers were successful on December 17.

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


  • Charles M. Manly
  • Stephen M. Balzer


Credit Line

Deposit by the Smithsonian Institution




  • 3-D: 104.1 × 91.4 × 88.9cm (41 × 36 × 35 in.)
  • Support: 104.1 × 120.7 × 47cm (41 in. × 47 1/2 in. × 18 1/2 in.)

Country of Origin

United States of America



Physical Description

  • Type: Reciprocating, 5 cylinders, radial, water-cooled
  • Power rating: 39.1 kW (52.4 hp) at 950 rpm
  • Displacement: 8.85 L (540 cu in.)
  • Bore and Stroke: 127 mm (5 in.) x 140 mm (5.5 in.)
  • Weight (wet): 95.2 kg (209.6 lb)


PROPULSION-Reciprocating & Rotary

Inventory Number