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.

An aircraft turbomachine comprising a fan conduit with a wall, a flow of air passing through the turbomachine via the fan conduit. An air passage comprising an air opening is arranged in the wall, the air passage configured to receive a portion of the flow of the air through the fan conduit. A deflector is fixed to the wall upstream of the air opening, the deflector comprising at least one cross-section extending in the fan conduit to capture the flow of air. The at least one cross-section is porous. The deflector protects the air passage structure and is easy to produce and to fix to the wall of the fan conduit when it is screwed or riveted directly thereto. The deflector, as a result of its location in the fan conduit, is easy to access and thus allows rapid maintenance operations without having to disassemble the air passage.

A method of manufacturing a portion of an aerofoil, the portion having an outer surface, the outer surface comprising a porous region, the method comprising using an additive manufacturing technique to manufacture the portion.

Propulsion assembly for an aircraft comprising a turbomachine having at least one rotating part rotating about an axis of rotation, an attachment strut, and a structural element carrying the turbomachine via the attachment strut, the rotating part being disposed upstream of the structural element and of the attachment strut such that an air jet emerging from the rotating part, in the wake of thereof, impacts the structural element and the attachment strut, a leading edge of the structural element and/or of said attachment strut locally comprising at least one acoustic attenuation device disposed at least partly in the wake of the rotating part, the acoustic attenuation device being a local modification of the structure and/or of the profile of the leading edge.

An aircraft wing (1) provided with a trailing edge region (2) which is provided with a noise attenuation structure, which at least comprises in combination, looking in an upwards direction: a first micro perforated plate (2.1) with micro perforations, a structure (2.2) with open channels, a second micro perforated plate (2.3) with micro perforations, and a third micro perforated plate (2.4) with micro perforations, wherein the open channels of the structure (2.2) connect micro perforations of the first micro perforated plate (2.1) with micro perforations of the second micro perforated plate (2.3), and that at least one of the second micro perforated plate (2.3) and the third micro perforated plate (2.4) is slidable with respect to the other for aligning and/or misaligning the micro perforations of the second micro perforated plate (2.3) and the third micro perforated plate (2.4) with respect to each other, wherein the trailing edge region (2) is delimited by a trailing edge, wherein a density of the micro perforations in the respective micro perforated plates (2.1, 2.3, 2.4) increases towards the trailing edge.

Sound absorbers and airframe components comprising such sound absorbers are disclosed. In one embodiment, an airframe component comprises an aerodynamic surface (48) and a sound absorber (38). The sound absorber (38) comprises a perforated panel (40) having a front side exposed to an ambient environment outside of the airframe component and an opposite back side. The panel (40) comprises perforations extending through a thickness of the panel for permitting passage of sound waves therethrough. The sound absorber (38) also comprises a boundary surface spaced apart from the perforated panel. The boundary surface and the back side of the perforated panel (40) at least partially define a cavity in the airframe component for attenuating some of the sound waves entering the cavity via the perforations in the perforated panel (40).

A structure ensuring acoustic attenuation of a flow of a first fluid and heat exchange between a first fluid and a second fluid. The structure includes a first wall which is perforated, a second wall, and a plurality of intermediate walls extending between the first wall and the second wall. For each intermediate wall, there is a pipe intended to receive the second fluid and inscribed within the intermediate wall. Such a structure makes it possible to optimally integrate the acoustic wave attenuation function and the heat exchange function.

The present disclosure is directed to controlling, reducing, and/or altering sound generated by an aerial vehicle, such as an unmanned aerial vehicle (UAV), while the aerial vehicle is airborne. For example, one or more transducers, such as piezoelectric thin-film transducers, or carbon nanotube transducers may be applied or incorporated into or on the surface of propeller blades that are used to aerially navigate the aerial vehicle. As the propeller blade rotates and generates sound, the transducers may be activated to generate one or more anti-sounds that cancel, reduce, or otherwise modify the sound generated by the rotation of the propeller blade. The anti-sound combines with the sound and causes interference such that the combined, or net-effect, is an overall cancellation, reduction, or other modification of the sound.

A dispenser for storing and launching countermeasures from an aircraft, comprising an elongate body provided with at least one launch opening adapted for storing the countermeasures in cartridges, where the dispenser comprises a manoeuvrable spoiler arranged in front of the launch opening, where the spoiler is adapted to be fully retracted before a countermeasure has been launched, and that the spoiler is adapted to extend outwards in a predefined manner when a countermeasure has been launched. The advantage of the invention is that a spoiler will reduce induced noise from the open cartridges by extending a spoiler outwards depending on the number of launched countermeasures. This allows for a simple, reliable and cost-effective solution.

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.