Less than a decade after the development of the first practical rotorcraft of any type with the autogyro, in the Soviet Union, Boris N. Yuriev and Alexei M. Cheremukhin, two aeronautical engineers working at the Tsentralniy Aerogidrodinamicheskiy Institut, constructed and flew the TsAGI 1-EA single rotor helicopter, which used an open tubing framework, a four-blade main rotor, and twin sets of 1 meters diameter anti-torque rotors; one set of two at the nose and one set of two at the tail.