Aeroacoustic Modeling of an eVTOL Slowed Rotor Winged Compound Aircraft

Piasecki Aircraft Corporation (PiAC) and Continuum Dynamics, Inc. (CDI) are investigating noise levels of the PA890, an emergent eVTOL slowed rotor winged compound (SRWC) configuration using the CHARM/PSU-WOPWOP aeroacoustic analysis. While the adoption of electric drive eliminates engine noise, this design allows several operational degrees of freedom that permit it to further mitigate noise mechanisms associated with conventional single rotor helicopters, including: lift compounding to offload the main rotor; reduction of main rotor RPM in cruise; and a dual mode (antitorque/pusher) tail rotor that allows alternate modes of operation for targeted forward flight conditions, with significant potential for noise reduction. This paper provides an overview of an acoustics analysis of the PA890 eVTOL SRWC configuration, including a comparison to an existing single rotor civil helicopter; and the principal noise mechanisms affecting each type of aircraft and the opportunities offered by the SRWC configuration to mitigate them. Ongoing work to further clarify important noise mechanisms is also outlined.