Kaman K-225

This Kaman K-225 was the first helicopter to fly with a gas turbine driven transmission. Turbines offered important advantages for helicopters including reduced weight, improved reliability, easier maintenance and higher power-to-weight ratios, which allowed for larger useful loads, increased safety and lower operating costs. In 1949, Kaman built the K-225 commercial model, primarily for use as a crop-duster. The Navy ordered two to evaluate the advantages of the intermeshing rotor system and the novel blade mounted servo-flap control system.In 1951, Kaman replaced the reciprocating engine that originally powered this K-225 with a Boeing 502-2 gas turbine to demonstrate the potential of jet-powered helicopters to the Navy. The K-225 served as the prototype for Kaman's successful HOK series of military helicopters, which incorporated a cabin in place of the open cockpit. The engine currently on the aircraft is not original.