|John J. Floherty, Aviation From the Ground up, Lippincott 1960|
The Kaman Huskie had an unusual rotor configuration, twin counter-rotating two blade rotors that intermeshed, thereby eliminating the need for a tail rotor. It first flew in 1947 powered by a piston engine which soon gave way to a gas turbine power. In this configuration it entered military service in 1952 and was used till the early seventies, and finally retired in 1975. It was well suited to rescuing downed airmen and was often used for firefighting.