First flown 1949, K-225 was one of Kaman's early production models. 11 produced initially with 225 hp piston engine; 1 delivered to Turkey and a second to Mississippi State. Other 9 leased as crop dusters since there was no market for them. Navy order for 3 more saved company from serious financial problems. 1 modified later with Boeing turboshaft engine became first turbine-powered helicopter to fly. Tested extensively before acquired by Navy. K-225 had rotor system developed by Kaman which used two intermeshing rotor blades--called synchropter blades. Later developed as observation helicopter for Navy and became HOK-1; also, 29 trainer version HTK-1s delivered to Navy 1951-3. An HTK-1 later modified with 2 gas turbine engines and became first twin-turboshaft helicopter. Jul 59, Kaman delivered last piston-powered helicopter, a HH-43A crash rescue helicopter. HH-43B was first Kaman production model to be equipped with gas turbine engine, Lycoming T53-L-1B. With availability of gas turbine engines, Kaman stopped using synchropter blades in favor of a single rotor. Reasoning was that with gas turbine, power was cheaper, and single-rotor design required less deck space, was more streamlined, and could go faster-- important in rescue operations. Rotor diam 38 ft; length 23 ft; height 11 ft; weight 1800 lbs empty, 2500 lbs gross; max speed 72 mph.