An unmanned air vehicle includes a generator that generates a flying force and also generates an air flow, a structural component, a microphone that outputs a first signal, a speaker, and a processor. The processor generates a second signal according to the first signal. The structural component surrounds a noise source of the generator, and includes a through-hole extending in a direction of the air flow. The through-hole is in a direction opposite to the direction of the air flow. An end, in the opposite direction, of the structural component corresponds to an end, in the opposite direction, of the noise source of the generator. An end, in the direction of the air flow, of the structural component extends, in the direction of the air flow, beyond an end, in the direction of the air flow, of the noise source of the generator.

The present disclosure provides various embodiments of a multicopter-assisted launch and retrieval system generally including: (1) a multi-rotor modular multicopter attachable to (and detachable from) a fixed-wing aircraft to facilitate launch of the fixed-wing aircraft into wing-borne flight; (2) a storage and launch system usable to store the modular multicopter and to facilitate launch of the fixed-wing aircraft into wing-borne flight; and (3) an anchor system usable (along with the multicopter and a flexible capture member) to retrieve the fixed-wing aircraft from wing-borne flight.

Systems and methods relate to a vertical takeoff and landing (VTOL) platform that can include a stator and a rotor magnetically levitated by the stator. The rotor and stator can be annular, such that the rotor rotates about a rotational axis. The stator can include magnets that provide guidance, levitation, and drive forces to drive the rotor, as well as to control operation of rotor blades of the rotor that can be independently rotated to specific pitch angles to control at least one of lift, pitch, roll, or yaw of the VTOL platform. Various controllers can be used to enable independent and redundant control of components of the VTOL platform.

Systems and methods relate to a vertical takeoff and landing (VTOL) platform that can include a stator and a rotor magnetically levitated by the stator. The rotor and stator can be annular, such that the rotor rotates about a rotational axis. The stator can include magnets that provide guidance, levitation, and drive forces to drive the rotor, as well as to control operation of rotor blades of the rotor that can be independently rotated to specific pitch angles to control at least one of lift, pitch, roll, or yaw of the VTOL platform. Various controllers can be used to enable independent and redundant control of components of the VTOL platform.

A method and system to isolate vibrations, including a first pair of fluid chambers disposed to isolate first vibrations between a first body and a second body, wherein the first vibrations are parallel to a first axis, wherein the first body is a propeller hub, a rotor hub, a pylon attachment, or an engine, and wherein the second body is a propeller shaft, a rotor mast, or a body attachment; a second pair of fluid chambers disposed to isolate second vibrations between the first and second bodies, wherein the second vibrations are parallel to a second axis perpendicular to the first axis; first and second inertia tracks disposed to place the first and second pairs of chambers in fluid communication, respectively; and a plurality of elastic energy storage devices coupled to the first body and the second body and disposed to isolate vibrations between the first and second bodies.

Systems and methods relate to a vertical takeoff and landing (VTOL) platform that can include a stator and a rotor magnetically levitated by the stator. The rotor and stator can be annular, such that the rotor rotates about a rotational axis. The stator can include magnets that provide guidance, levitation, and drive forces to drive the rotor, as well as to control operation of rotor blades of the rotor that can be independently rotated to specific pitch angles to control at least one of lift, pitch, roll, or yaw of the VTOL platform. Various controllers can be used to enable independent and redundant control of components of the VTOL platform.

Systems and methods relate to a vertical takeoff and landing (VTOL) platform that can include a stator and a rotor magnetically levitated by the stator. The rotor and stator can be annular, such that the rotor rotates about a rotational axis. The stator can include magnets that provide guidance, levitation, and drive forces to drive the rotor, as well as to control operation of rotor blades of the rotor that can be independently rotated to specific pitch angles to control at least one of lift, pitch, roll, or yaw of the VTOL platform. Various controllers can be used to enable independent and redundant control of components of the VTOL platform.

A vibration control system for a rotor hub provides vibration attenuation in an aircraft by reducing the magnitude of rotor induced vibratory. The system can include a force generating device attached to a rotor hub which rotates along with the rotor at the rotational speed of the rotor. Vibratory shear force is generated by rotating unbalanced weights each about an axis non-concentric with the rotor hub axis at high speed to create large centrifugal forces. The rotational speed of the weights can be a multiple of the rotor rotational speed to create shear forces for canceling rotor induced vibrations. The amplitude of the generated shear force is controlled by indexing the positions of the unbalanced weights relative to each other, while the phase of the shear force is adjusted by equally phasing each weight relative to the rotor.

A damping device is described that is designed to counter the transmission of vibrations to a further element and comprises: a beam element, which extends mainly parallel to an axis, is constrained to the further element and is designed to flexurally oscillate, in use, in a plane parallel to the axis to counter the transmission of vibrations to the further element; an actuator, which comprises a transmission element operatively connected to the beam element and extending mainly along the axis; the actuator being controllable to apply a direct tensile or compressive load along the axis on the transmission element that is variable according to the frequency of the vibrations to be dampened.

The present disclosure provides various embodiments of a multicopter-assisted launch and retrieval system generally including: (1) a multi-rotor modular multicopter attachable to (and detachable from) a fixed-wing aircraft to facilitate launch of the fixed-wing aircraft into wing-borne flight; (2) a storage and launch system usable to store the modular multicopter and to facilitate launch of the fixed-wing aircraft into wing-borne flight; and (3) an anchor system usable (along with the multicopter and a flexible capture member) to retrieve the fixed-wing aircraft from wing-borne flight.