An Investigation of Piloting and Flight Control Strategies on Generic eVTOL Noise

A preliminary investigation of impact of piloting and flight control strategies on maneuver noise is conducted on a generic eVTOL configuration undergoing a 50 knot level-turn maneuver. The piloting strategy involved control of aircraft pitch to change split between rotor lift and wing lift, while the control strategy involved comparing a rotor thrust control with fixed pitch rotors operating with variable rotation rate and a rotor thrust control strategy with variable pitch rotors operating at constant angular velocity. With the rotors operating in the low tip-Mach number flow regime, it was revealed that broadband noise due to airfoil self-noise dominates the noise levels overwhelmingly. The turbulent boundary layer trailing edge noise contributed the most, with blade stall found to result in significant addition to noise levels (nearly 10 dBA). Deterministic noise was found to be sensitive to rotor thrust control strategies, with control biases offering an additional layer of influence over individual rotor tip-Mach number and thrust levels. Individual rotor thrust and trim were found to be important parameters controlling deterministic noise, while combined rotor thrust levels was found to be the important influence over time-averaged broadband noise levels.