Disclosed is a system for controlling acoustic radiation from an aircraft. The system comprising a plurality of rotor systems (one or more) and a noise controller configured to regulate acoustic radiation from the plurality of rotor systems. The noise controller can be configured to regulate a commanded flight setting from the flight control system and to output a regulated flight setting to the plurality of rotor systems. Based on the regulated flight setting, the plurality of rotor systems are configured to generate, individually and in aggregate, acoustic radiation having a target acoustic behavior. The target acoustic behavior may be achieved using beamforming techniques to, for example, change the directionality of acoustic radiation from the plurality of rotor systems, or otherwise tune the acoustic radiation to reduce detectability and/or annoyance.

A noise cancelation system for an unmanned aerial vehicle may have an audio capture module, a metadata module and a filter. The audio capture module may be configured to receive an audio signal captured from a microphone, e.g., on a camera. The metadata module may be configured to retrieve noise information associated with noise generating components operating on the unmanned aerial vehicle (UAV). The filter may be configured to receive the audio signal and noise information from the audio capture module. The filter also may be configured to retrieve a baseline profile from a database based on the noise information. The baseline profile includes noise parameter to filter out audio frequencies from the audio signal corresponding to the noise generating component. The filter may generate a filtered audio signal for output.

Techniques for using an unmanned aerial vehicle (UAV) to deliver a payload while generating an expected sound by the UAV during delivery may be provided. For example, during delivery or while in flight, propellers of different sizes that are associated with the UAV may be instructed to modulate at different rotational speeds to thereby generate an expected sound.

Sounds are generated by an aerial vehicle during operation. For example, the motors and propellers of an aerial vehicle generate sounds during operation. Disclosed are systems, methods, and apparatus for actively adjusting the position of one or more propeller blade treatments of a propeller blade of an aerial vehicle during operation of the aerial vehicle. For example, the propeller blade may have one or more propeller blade treatments that may be adjusted between two or more positions. Based on the position of the propeller blade treatments, the airflow over the propeller is altered, thereby altering the sound generated by the propeller when rotating. By altering the propeller blade treatments on multiple propeller blades of the aerial vehicle, the different sounds generated by the different propeller blades may effectively cancel, reduce, and/or otherwise alter the total sound generated by the aerial vehicle.

Sounds are generated by an aerial vehicle during operation. For example, the motors and propellers of an aerial vehicle generate sounds during operation. Disclosed are systems, methods, and apparatus for actively adjusting the position of one or more propeller blade treatments of a propeller blade of an aerial vehicle during operation of the aerial vehicle. For example, the propeller blade may have one or more propeller blade treatments that may be adjusted between two or more positions. Based on the position of the propeller blade treatments, the airflow over the propeller is altered, thereby altering the sound generated by the propeller when rotating. By altering the propeller blade treatments on multiple propeller blades of the aerial vehicle, the different sounds generated by the different propeller blades may effectively cancel, reduce, and/or otherwise alter the total sound generated by the aerial vehicle.

Disclosed is an unmanned aerial vehicle (UAV) with a pre-defined shape to deploy one or more items. The unmanned aerial vehicle (UAV) includes an upper housing, a lower housing, and a power unit. The upper housing includes plurality of rotors to lift and propel the unmanned aerial vehicle (UAV). Further the unmanned aerial vehicle (UAV) includes various electronic components such as plurality of electronic cards, a processing unit, a Global Positioning System (GPS), a communication unit, an electronic gyroscope, a barometer, engines and flight control system, video camera, a forward looking infrared (FLIR) device, a microphone, and a laser telemeter/designator/range finder. The power unit powers the aforementioned electronic components. The lower housing includes plurality of storage units to stores one or more items. The lower housing is removably attached with the upper housing in a way to deploy the items at a predetermined location through plurality of openings.

An unmanned aerial vehicle (UAV) may emit masking sounds during operation of the UAV to mask other sounds generated by the UAV during operation. The UAV may be used to deliver items to a residence or other location associated with a customer. The UAV may emit sounds that mask the conventional sounds generated by the propellers and/or motors to cause the UAV to emit sounds that are pleasing to bystanders or do not annoy the bystanders. The UAV may emit sounds using speakers or other sound generating devices, such as fins, reeds, whistles, or other devices which may cause sound to be emitted from the UAV. Noise canceling algorithms may be used to cancel at least some of the conventional noise generated by operation of the UAV using inverted sounds, while additional sound may be emitted by the UAV, which may not be subject to noise cancellation.

Noises that are to be emitted by an aerial vehicle during operations may be predicted using one or more machine learning systems, algorithms or techniques. Anti-noises having equal or similar intensities and equal but out-of-phase frequencies may be identified and generated based on the predicted noises, thereby reducing or eliminating the net effect of the noises. The machine learning systems, algorithms or techniques used to predict such noises may be trained using emitted sound pressure levels observed during prior operations of aerial vehicles, as well as environmental conditions, operational characteristics of the aerial vehicles or locations of the aerial vehicles during such prior operations. Anti-noises may be identified and generated based on an overall sound profile of the aerial vehicle, or on individual sounds emitted by the aerial vehicle by discrete sources.

Multiple motors may drive (rotate) a single shaft coupled to a propeller. The motors may be selected such that a first motor is capable of rotating the drive shaft in an event of a failure of a second motor coupled to the drive shaft. A one-way clutch bearing, or similar device, may interface between a motor and the drive shaft to enable free rotation of the drive shaft in an event of the motor becoming inoperable, such as the motor freezing or locking in a position due to failure caused by overheating or caused by other conditions or events. Use of the second motor may secure a position of the drive shaft which may support the propeller in radial eccentric loading.

A thrust producing unit for producing thrust in a predetermined direction, comprising at least two rotor assemblies and a shrouding that accommodates at most one of the at least two rotor assemblies, wherein the shrouding defines a cylindrical air duct that is axially delimited by an air inlet region and an air outlet region, and wherein the air inlet region exhibits in circumferential direction of the cylindrical air duct an undulated geometry.