Kinematics Study of Swashplateless Propellers

Flying drones between buildings in a city demands high maneuverability. In rotor systems, the swashplate can cause the direction of rotor thrust to deviate from the rotor axis, resulting in vector thrust effects. However, the swashplate system necessitates multiple servos for operation, making the aircraft overly complex and reducing reliability and maintainability, especially for small multi-rotor drones. Visionary scientists have proposed a design for a two-bladed rotor that can achieve cyclic pitch variation without the requirement of servos, relying solely on inertia. The lag-pitch hinges on both sides of the blade are tilted and asymmetric. As the blade lags or leads, the angle of attack (AoA) of one blade increases while the other decreases. By accelerating and decelerating the RPM once during a 360-degree rotation, the blades can complete AoA changes within a single cycle, enabling cyclic pitch variation. In this study, we designed various swashplateless propellers and conducted kinematic, fluid dynamic simulations, and preliminary experimental tests. The results are intriguing. Perhaps it is feasible for swashplateless propellers to generate a tilted thrust vector. In fact, the absence of a swashplate mechanism may lead to a notable increase in vibrations within the propeller system.