Patent ID: 8287422

Claim:
A model helicopter comprising a drive mechanism, the drive mechanism comprising: a battery powered motor comprising a toothed motor shaft; a main rotor comprising a main shaft aligned with the motor shaft, the main shaft including a main gear; and a reduction gear assembly comprising four lower first gears arranged around the motor shaft, a lower outer ring gear meshed with the first gears, four lower second gears each being smaller than the first gear and fixed to top of the first gear, four upper third gears, an upper outer ring gear meshed with the third gears, four upper fourth gears each being smaller than the third gear and fixed to top of the third gear, the fourth gears being meshed with the main gear, and four shafts each axially passing through the fourth gear, the third gear, the second gear, and the first gear so that a revolution of the motor shaft rotates the main shaft via the first gears, the fourth gears, and the main gear.