US 12,280,885 B2
System and method for aircraft noise mitigation
JoeBen Bevirt, Santa Cruz, CA (US); Gregor Veble Mikic, Santa Cruz, CA (US); Jason Ryan, Santa Cruz, CA (US); Alex Stoll, Santa Cruz, CA (US); Rob Thodal, Santa Cruz, CA (US); and Jeremy Bain, Santa Cruz, CA (US)
Assigned to Joby Aero, Inc., Santa Cruz, CA (US)
Filed by Joby Aero, Inc., Santa Cruz, CA (US)
Filed on Oct. 7, 2020, as Appl. No. 17/065,172.
Application 17/065,172 is a division of application No. 16/430,163, filed on Jun. 3, 2019, granted, now 10,843,807.
Claims priority of provisional application 62/679,411, filed on Jun. 1, 2018.
Prior Publication US 2021/0078715 A1, Mar. 18, 2021
Int. Cl. B64D 31/06 (2024.01); B64C 11/50 (2006.01)
CPC B64D 31/06 (2013.01) [B64C 11/50 (2013.01); B64C 2220/00 (2013.01)] 11 Claims
OG exemplary drawing
 
1. A system for reducing a psychoacoustic penalty of acoustic noise emitted by a tiltrotor aircraft by reducing the tonality of the acoustic spectrum emitted by the aircraft during operation, comprising:
a tiltrotor aircraft comprising a right wing and a left wing;
a plurality of propulsion assemblies coupled to the aircraft, said plurality of propulsion assemblies located at different locations on said aircraft, said plurality of propulsion assemblies operable between a hover arrangement and a forward arrangement, wherein each of the plurality of propulsion assemblies comprises:
a motor, and
a plurality of blades defined by at least a first propeller, wherein the first propeller is coupled to the motor and rotates at a rotation frequency, wherein the plurality of blades defines an asymmetric blade spacing, wherein said plurality of propulsion assemblies comprises:
a right wing mounted right side rotor assembly;
a left wing mounted left side rotor assembly
a right side rear rotor assembly; and
a left side rear rotor assembly; and
a control subsystem coupled to the aircraft and communicatively coupled to the motor of each of the plurality of propulsion assemblies, wherein the control system is operable to control the plurality of propulsion assemblies to generate thrust in a hover mode, thereby generating a thrust distribution around the tiltrotor aircraft in the hover mode, and wherein the control subsystem is operable to control the rotation frequency of the first propeller of each of the plurality of propulsion assemblies in a spread-RPM mode, and wherein the control system is operable to determine acoustic signature data, and wherein the control system is further operable to control the phase of the propellers of the plurality of propulsion assemblies relative to each other in a phase controlled mode, and wherein the control system is operable to maintain the thrust distribution around the tiltrotor aircraft in the hover mode by adjusting the pitch angle of each of the plurality of propulsion assemblies based upon the respective rotation frequency in order to maintain a desired thrust for each of the plurality of propulsion assemblies, wherein at least one of said plurality of propulsion assemblies rotates at a different rotation frequency than another of said plurality of propulsion assemblies.