Military Wiki
XHTK-1 modified with a Boeing 502 (YT50) turboshaft engine
Role Experimental helicopter
Manufacturer Kaman Aircraft
First flight 15 January 1947
Status Retired
Primary user United States Navy, United States Coast Guard
Number built 7
Unit cost

The Kaman K-225 was an experimental helicopter developed by Kaman Aircraft. One was modified to become the world's first gas turbine powered helicopter.

Design and development

The K-125 was Charles Kaman's first helicopter, which utilized intermeshing rotors and Kaman's patented servo-flap stability control.[1] The K-125 first flew on 15 January 1947.

The K-190 and K-225 were an improved versions of the K-125, which first flew in April and July 1949 respectively. The U.S. Navy bought two and the Coast Guard one for $25,000 each. The United States Air Force evaluated one K-225 with the designation YH-22.

A modified K-225 equipped with a Boeing 502 (YT50) turboshaft engine became the world's first gas turbine powered helicopter in December 1951.[2] This aircraft is now at the Smithsonian Institution in Washington, D.C.



first prototype
improved prototype version of K-125 and licensed in April 1949
improved prototype version of K-125 (and K-190) and licensed in July 1949
United States Aircraft designation for one K-225 bought evaluation.
United States Navy designation for two K-225s bought for evaluation.
Designation for one K-225 evaluated by the United States Coast Guard

Specifications (K-225)

K-225 displayed at the New England Air Museum, Windsor Locks, Connecticut, in June 2005

Data from [3][4]

General characteristics

  • Crew: 2
  • Length: 22 ft 5 in (6.83 m)
  • Height: 11 ft 0 in (3.35 m)
  • Empty weight: 1,799 lb (816 kg)
  • Gross weight: 2,703 lb (1,226 kg)
  • Powerplant: 1 × Lycoming O-435-2 6-cyl. air-cooled horizontally opposed piston engine, 225 hp (168 kW)
  • Main rotor diameter: 2× 38 ft 0 in (11.58 m)


  • Maximum speed: 73 mph (117 km/h; 63 kn)

See also



  1. "Hall of Fame/Inventor Profile: Charles Kaman"
  2. Boeing Model 502 Gas Turbine Engine
  3. Eckland, K.O. (2009-03-07). "American Airplane Ka-Ku". usa: Retrieved 8 May 2012. 
  4. Kaman K-225, Smithsonian National Air and Space Museum, cit. 28. 1. 2013

External links

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