Development of Dual Rotor Propulsion System for Contra-Rotating Propeller Drive

Propulsion using propellers is common in the marine and aerial industries. Conventional methods of rotating two propellers coaxially while maintaining a constant speed difference include the use of two separate electric motors, or rotating them in opposite directions using mechanical gears. In this paper, we propose a simplified counter-rotating propeller mechanism with a dual-rotor motor system driven by a single electric motor and controlled by a single inverter. The proposed system is designed so that both rotors operate at a constant speed ratio, which improves the propeller propulsion efficiency. In addition to increasing propulsion efficiency, this design has the important advantage of significantly reducing the overall weight of the system, especially when applied to marine and aerial propulsion systems that utilize contra-rotating propellers.