title: Kaman K-225
text: # Kaman K-225
  
  The Kaman K-225 is an American experimental helicopter developed by Kaman Aircraft. One example 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. 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 first gas turbine-powered helicopter in December 1951. This aircraft is now at the Smithsonian Institution in Washington, D.C.
  
  A standard K-225 is preserved in the New England Air Museum at Windsor Locks Connecticut.
  
  In 1953, the Turkish Army purchased one Kaman K-225 helicopter and a K-225 was the first helicopter flown in Turkey.
  
  ## Variants
  
  ### K-125
  
      first two-seat prototype with 125 hp (93 kW) Lycoming O-390-3 engine and moulded plywood fuselage and bubble canopy.
  
  ### K-190
  
      improved prototype with 190 hp (140 kW) Lycoming engine, certified in April 1949
  
  ### K-190A
  
      open frame three-seat helicopter, powered by a 175 hp (130 kW) Lycoming O-435-C engine. Type certified on April 15, 1949.
  
  ### K-190B
  
      four-seat version.
  
  ### K-225
  
      improved model, powered by a 225 hp (168 kW) Lycoming O-435-A2 engine, certified on September 16, 1949.
  
  ### K-5
  
      designation for K-225 with Boeing T50-BO-2 model 502 engine.
  
  ### YH-22
  
      United States Air Force designation for one K-225 bought for evaluation.
  
  ## Specifications (K-225)
  
  Data from
  
  General characteristics
  
  * Crew: two
  * 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)
  
  Performance
  
  * Maximum speed: 73 mph (117 km/h, 63 kn)
  