Russian born engineer Nicolas Florine built one of the first successful tandem rotor helicopters. The rotors turned in the same direction but were tilted in opposite directions to cancel torque reaction. Boulet (1984) describes the various mechanical aspects of the machine. Florine's first aircraft was destroyed in 1930, but he had a second design flying successfully by 1933, which made a flight of over 9 minutes to an altitude of 15feet. This exceeded d'Ascanio's modest flight duration record of the time. Yet, Florine's designs suffered many setbacks, and work was discontinued into the preWorld War 2 years. His machines were ultimately destroyed during the war.