In 1912, Boris Yuryev created a helicopter that contained, for the first time, a tail rotor in addition to a single main rotor. It is assumed Yuryev had a stronger understanding of aerodynamics than most inventors at the time as he was a pupil of a famous aerodynamicist, N. Ye. Zhukovskii. The introduction of the tail rotor was significant as it helped combat the torque from the main rotor. Based on Newton's third law of motion, if the main rotor is moving in a counterclockwise direction, then the fuselage (body of the helicopter) will move in a clockwise direction. The tail rotor prevents the helicopter from spinning in a circle and also helps improve directional control.

After his tail rotor contribution, Yuryev continued to help improve the design of the helicopter. Yuryev was a leading researcher at the Central Aerohydrodynamic Institute (TsAGI) in Moscow for almost 30 years. His work specifically focused on the development of propellers and helicopters. By the end of his work, he was the Lieutenant-General of Aviation Engineering Sciences and was elected an Academician of the Academy of Sciences of the U.S.S.R.

Text Sources:

Soviet Helicopter. (1959). Retrieved from https://www.flightglobal.com/FlightPDFArchive/1959/1959%20-%200151.PDF. 

Valavanis, K. P. (2007). Advances in unmanned aerial vehicles: state of the art and the road to autonomy.Berlin: Springer.

Image Source:

https://vanhornaviation.com/products/206oh-58-tail-rotor-blades/