Kaman K-17

The Kaman K-17 was a two-seat experimental helicopter built by Kaman in the late 1950s to try out a cold jet rotor system. Rather than an engine turning the rotor through a gearbox, a Blackburn built Turbomeca Turmo turbine drove a compressor that supplied cold compressed air to jets at the rotor tips, and the escaping air spun the rotor. Jane's All the World's Aircraft lists a main rotor 37 feet across, an empty weight of 431 kilograms, a cruise speed of 148 kilometres per hour and about two hours of endurance. It sits among Kaman's experimental rotorcraft of the period, alongside the K-16B tiltwing and the gas turbine K-225, and shows the company testing tip jet propulsion beyond its usual rotor designs.