A system and method for reducing a psychoacoustic penalty of acoustic noise emitted by an aircraft, including a plurality of propulsion assemblies coupled to the aircraft, wherein each of the plurality of propulsion assemblies includes a motor, and a plurality of blades defined by a propeller, wherein the plurality of blades can define an asymmetric blade spacing; a control subsystem coupled to the aircraft and communicatively coupled to the motor of each of the plurality of propulsion assemblies, wherein the control subsystem is operable to rotate each of the plurality of propulsion assemblies at a different frequency to modulate the acoustic power distribution of the emitted acoustic signature.

A system and method for reducing a psychoacoustic penalty of acoustic noise emitted by an aircraft, including a plurality of propulsion assemblies coupled to the aircraft, wherein each of the plurality of propulsion assemblies includes a motor, and a plurality of blades defined by a propeller, wherein the plurality of blades can define an asymmetric blade spacing; a control subsystem coupled to the aircraft and communicatively coupled to the motor of each of the plurality of propulsion assemblies, wherein the control subsystem is operable to rotate each of the plurality of propulsion assemblies at a different frequency to modulate the acoustic power distribution of the emitted acoustic signature.

Herein provided are systems and methods for synchrophasing multi-engine aircraft. A phonic wheel is coupled to a first propeller of a first engine of the aircraft. A sensor is disposed and configured for producing a signal in response to passage of first and second position markers on the phonic wheel. A control system is communicatively coupled to the sensor for obtaining the signal, and configured for: determining an expected delay between two subsequent signal pulses of the signal; identifying from within the plurality of signal pulses a particular pulse associated with the second position marker; determining, based on a particular time at which the particular pulse associated with the second position marker was produced, that a rotational position of the first propeller corresponds to a reference position at the particular time; and performing at least one synchrophasing operation for the aircraft based on the rotational position of the first propeller.

Sounds are generated by an aerial vehicle during operation. For example, the motors and propellers of an aerial vehicle generate sounds during operation. Systems, methods, and apparatus may actively adjust the position and/or configuration of one or more propeller blades of a propulsion mechanism to generate different sounds and/or lifting forces from the propulsion mechanism.

Sounds are generated by an aerial vehicle during operation. For example, the motors and propellers of an aerial vehicle generate sounds during operation. Systems, methods, and apparatus may actively adjust the position and/or configuration of one or more propeller blades of a propulsion mechanism to generate different sounds and/or lifting forces from the propulsion mechanism.

A tandem tiltrotor aircraft in which the tiltrotor assemblies are operably coupled at the forward and aft ends of the fuselage of the aircraft is disclosed. The tiltrotor assemblies are capable of rotating between a vertical lift position and a horizontal flight position. The in-line location of the tiltrotor assemblies allow the aircraft to have the vertical take-off and landing capabilities, and, in combination with the at least one wing, can be used in horizontal flight. The nacelles can be disposed on the fuselage they are coaxial in forward flight and do not add to the drag profile like wing-tip nacelles would. When wing-borne flight is desired some or all of the rotors can rotate down so the thrust vector is in a generally horizontal plane.

A tandem tiltrotor aircraft in which the tiltrotor assemblies are operably coupled at the forward and aft ends of the fuselage of the aircraft is disclosed. The tiltrotor assemblies are capable of rotating between a vertical lift position and a horizontal flight position. The in-line location of the tiltrotor assemblies allow the aircraft to have the vertical take-off and landing capabilities, and, in combination with the at least one wing, can be used in horizontal flight. The nacelles can be disposed on the fuselage they are coaxial in forward flight and do not add to the drag profile like wing-tip nacelles would. When wing-borne flight is desired some or all of the rotors can rotate down so the thrust vector is in a generally horizontal plane.

A dynamic rotor-phasing unit can phase rotors in-flight for dynamic rotor tuning and in an idle state for aircraft storage. The input and output shafts can be clocked (e.g., rotated) from 0 degrees apart to in excess of 360 degrees apart or from 0 degrees apart to 140 degrees apart. Such rotation can minimize the footprint of an aircraft for stowing purposes, as the rotor blades can be folded to fit within a smaller area without disconnecting the drive system. Additionally, the unit can allow tiltrotor blades to be clocked during flight, which can allow the live-tuning of the aircraft's rotor dynamics. A fail-safe rotary actuator can rotate a stationary planet carrier to clock the input shaft and the output shaft. Alternatively, an actuator can position a slider housing to clock the input shaft and the output shaft.

A dynamic rotor-phasing unit can phase rotors in-flight for dynamic rotor tuning and in an idle state for aircraft storage. The input and output shafts can be clocked (e.g., rotated) from 0 degrees apart to in excess of 360 degrees apart or from 0 degrees apart to 140 degrees apart. Such rotation can minimize the footprint of an aircraft for stowing purposes, as the rotor blades can be folded to fit within a smaller area without disconnecting the drive system. Additionally, the unit can allow tiltrotor blades to be clocked during flight, which can allow the live-tuning of the aircraft's rotor dynamics. A fail-safe rotary actuator can rotate a stationary planet carrier to clock the input shaft and the output shaft. Alternatively, an actuator can position a slider housing to clock the input shaft and the output shaft.

Apparatus for controlling multi-rotor vehicle vibrations and related methods are disclosed herein. An example apparatus includes a vibration level detector to determine a vibration level of a frame of a vehicle based on data received from a sensor of the vehicle, the vehicle including a rotor. The apparatus includes a rotor operation analyzer to determine an operational parameter of the rotor based on the vibration level. The apparatus includes a communicator to transmit an instruction including the operational parameter to a controller of the rotor.