Assessment of swashplateless rotor systems for sensor carrying drones: An investigation into control, efficiency, and feasibility

Abstract

This thesis investigates two rotorhead configurations, a fully articulated dual hinge and a semi-rigid teetering hinge rotor, for potential use in swashplateless helicopters or drones, aiming to expand the understanding of their respective mechanical and aerodynamical behaviours. Experiments were conducted on a fixed test rig designed for easy interchangeability between the two rotor types. Both rotors were tested with identical blades at fixed pitch angles of 8°, 10°, and 12°, using the same control system. Three test types were performed. First, a constant roll input was applied while rotor speed varied from 500 to 3000 RPM, across three increasing roll magnitudes. Second, a step response test measured the time required for the rotor to transition from maximum to minimum roll output, assessing dynamic response. Third, a roll sweep test was conducted at approximately 2500 RPM using stepwise increases in roll input. High-speed video analysis was used to observe dynamic behaviour. Results show that the fully articulated dual hinge rotor provides more effective thrust vectoring across all roll inputs and RPMs, while operating at significantly lower vibration levels. Both rotors exhibited similar energy consumption and roll rates. While the dual hinge rotor’s improved thrust control and smoother operation suggest advantages for general purpose drones and helicopters, especially those carrying sensitive sensors and equipment, the semi-rigid teetering hinge rotor’s simplicity and robustness is attractive for applications where mechanical reliability, weight reduction, and ease of maintenance are prioritized. Further exploration of teetering rotor concepts, especially in alternative configurations and with a further optimized control system, may reveal additional potential not fully captured in this study.