In some embodiments, a method, apparatus and computer program for reducing noise from an audio signal captured by a drone (e.g., canceling the noise signature of a drone from the audio signal) using a model of noise emitted by the drone's propulsion system set, where the propulsion system set includes one or more propulsion systems, each of the propulsion systems including an electric motor, and wherein the noise reduction is performed in response to voltage data indicative of instantaneous voltage supplied to each electric motor of the propulsion system set. In some other embodiments, a method, apparatus and computer program for generating a noise model by determining the noise signature of at least one drone based upon a database of noise signals corresponding to at least one propulsion system and canceling the noise signature of the drone in an audio signal based upon the noise model.

A method of reducing the noise generated in-flight by a vortex wake caused by each first blade of a main rotor of a hybrid helicopter. The hybrid helicopter includes a main rotor, at least two wings and at least one propeller. The method enables a stabilized flight phase on the level or with a non-zero aerodynamic slope to be implemented by determining a first value of the pitch of the second blades of each propeller and an angle of incidence of the main rotor as function of the flight conditions, then by applying the first pitch value to each propeller and by applying the angle of incidence to the main rotor so as to direct the vortex wake to limit the noisy interactions between the vortex wake and the other first blades and/or the second blades.

A propulsion system for an aircraft comprises at least first and second propulsors, each propulsor being independently driven by a respective electric motor. The first and second propulsors each comprise respective rotors comprising a plurality of blades. The rotor of the first propulsor (30a) comprises a different number of blades to the rotor of the second propulsor, and the rotors of the first and second propulsors each have a blade pitch varying mechanism.

Vertical take-off and landing (VTOL) aircraft can provide opportunities to incorporate aerial transportation into transportation networks for cities and metropolitan areas. However, VTOL aircraft may be noisy. To accommodate this, the aircraft may utilize onboard sensors, offboard sensing, network, and predictive temporal data for noise signature mitigation. By building a composite understanding of real data offboard the aircraft, the aircraft can make adjustments to the way it is flying and verify this against a predicted noise signature (via computational methods) to reduce environmental impact. This might be realized via a change in translative speed, propeller speed, or choices in propulsor usage (e.g., a quiet propulsor vs. a high thrust, noisier propulsor). These noise mitigation actions may also be decided at the network level rather than the vehicle level to balance concerns across a city and relieve computing constraints on the aircraft.

An aircraft fairing includes a fairing body having an exterior fairing wall and at least one wheel bin. The at least one wheel bin has a side wall extending from an opening in the exterior fairing wall to an end wall. The side wall and the end wall define a cavity of the at least one wheel bin in fluid communication with the opening in the exterior fairing wall. An acoustic resonator is mounted to an outer surface of the side wall of the at least one wheel bin and is in fluid communication with the cavity. The acoustic resonator has a resonant frequency substantially similar to a cavity modal frequency of the at least one wheel bin at an aircraft flight condition.

An urban air mobility (UAM) noise reduction system and method are provided, where the UAM noise reduction system includes a UAM configured to detect and to provide rotation per minute (RPM) information of a propeller and location coordinate information, and a noise canceling device configured to predict a noise canceling sound wave amplitude on the basis of the RPM information of the propeller and the location coordinate information received through the UAM and to output a noise canceling sound wave corresponding to the predicted noise canceling sound wave amplitude to the UAM.

Systems and methods according to embodiments of the present technology vary engine throttle and flight control surfaces (such as high-lift devices, which can include flaps and/or slats) during takeoff, climb, approach, and/or landing of a supersonic aircraft to reduce noise. A representative computing device automatically controls thrust output of the propulsion system according to a schedule of thrust output, such that the thrust output remains below levels at which the jet exhaust becomes supersonic, and such that noise is reduced to comply with noise regulations or other limitations. The computing device also automatically controls the position and configuration of flight control surfaces to compensate for the reduced thrust and to maintain an appropriate climb and/or descent rate.

Noise-abatement for a leading edge wing slat is provided by a noise-abatement airflow shield integral with the lower trailing edge of the slat, wherein the shield is reciprocally autonomously curveable from a substantially planar configuration when the slat is in a retracted position thereof and into a convexly curved configuration when the slat is in a deployed position thereof.

An aircraft fairing includes a fairing body having an exterior fairing wall and at least one wheel bin. The at least one wheel bin has a side wall extending from an opening in the exterior fairing wall to an end wall. The side wall and the end wall define a cavity of the at least one wheel bin in fluid communication with the opening in the exterior fairing wall. An acoustic resonator is mounted to an outer surface of the side wall of the at least one wheel bin and is in fluid communication with the cavity. The acoustic resonator has a resonant frequency substantially similar to a cavity modal frequency of the at least one wheel bin at an aircraft flight condition.

An acoustic system for an Urban Air Mobility (UAM) vehicle may comprise: a first shroud configured to be disposed around a rotor of the UAM vehicle, the first shroud comprising: a radially inner wall configured to be spaced radially outward from a blade tip of a rotary blade of the rotor, the radially inner wall including a perforated portion; and a hollow chamber defined by an internal surface of the first shroud and the radially inner wall.