The Challenges of Extremely Quiet Propulsion
This paper focuses on design considerations for “extremely low noise”, electric propeller driven aircraft and the challenges of achieving such low noise. Propeller noise theory will be briefly reviewed, followed by parametric studies of key design variables that are important for low noise, such as tip speed, number of blades, disk loading, etc. Other challenging factors that may negate noise reduction design strategies, such as unsteady blade loading, will also be presented. These results are intended to give guidance that may be helpful to designers and to demonstrate how current tools can be used in a fast and simple manner to obtain propeller noise predictions.