H.Nowarra, G.Duval Russian Civil and Military Aircraft 1884-1969

The first powered aircraft to be designed by O. K. Antonov, a glider enthusiast, was a helicopter which stemmed from the same basic idea utilised by Sikorski, that of co-axial rotors. Construction commenced at the Lessner works in St. Petersburg in 1909. The intention was that the machine be lifted by two multi-blade rotors, each blade being made of a triangular piece of aluminium with one point at the hub and pivot points at hub and tip, where it was attached to a large ring. By lowering the pitch of the blades they formed discs, and it was thought that these would permit the machine to descend safely in the event of failure of the 35 h.p. Anzani engine, which also provided forward propulsion by means of a tractor propeller. The helicopter was completed in 1910, but gave a somewhat disappointing performance, and Antonov, suffering from the stresses of overwork during the project, became distraught and destroyed the machine.