Kaman K-225

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. 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. This aircraft is now at the Smithsonian Institution in Washington, D.C.

Variants

 * K-125 : first prototype
 * K-190 : improved prototype version of K-125 and licensed in April 1949
 * K-225 : improved prototype version of K-125 (and K-190) and licensed in July 1949
 * YH-22 : United States Aircraft designation for one K-225 bought evaluation.
 * XHTK-1: United States Navy designation for two K-225s bought for evaluation.
 * XHTK-1G: Designation for one K-225 evaluated by the United States Coast Guard