A vibration attenuator is configured for use on an aircraft rotor rotatable about a mast axis and has upper and lower weight assemblies, each comprising a weight with a center of gravity being a radial distance from the mast axis. The weight assemblies are configured for rotation together relative to the rotor at a selected angular rate about the mast axis, the weights being located on opposing sides of the mast axis. A first motor is configured for selective translation of one of the weight assemblies relative to the other weight assembly along the mast axis between a minimum-moment configuration, in which the centers of gravity of the weights revolve about the mast axis in the same plane, and a maximum-moment configuration, in which the centers of gravity of the weights revolve about the mast axis in different planes for producing a whirling moment about the mast axis.

A rotor for a hover-capable aircraft is described that comprises: a hub rotating about an axis and, in turn, comprising a plurality of blades, a mast connectable to a power unit of the aircraft and operatively connected to the hub to drive the hub in rotation about said axis, and an attenuating device to attenuate the transmission of vibrations from the mast to the aircraft parallel to said; the attenuating device, in turn, comprising a casing, a first mass free to oscillate parallel to said axis with respect to the casing and elastically connected to the casing, a second mass free to oscillate parallel to said axis, connection means adapted to make the first and second masses integrally movable along said axis when the angular speed of the mast assumes a first value, and actuator means activatable to decouple the first and second masses when the angular speed of the mast assumes a second value, different from the first value.

A rotor for an aircraft is described that has a mast, an attenuating device to attenuate the transmission of vibrations from the mast in a plane orthogonal to the first axis, and a transmission device interposed between the mast and the attenuating device; the attenuating device comprises a first and a second mass unit with a first and a second mass rotatable about the first axis with a first and a second rotational speed, two control units operable to cause an additional rotation of at least one of the first and second masses, and a first and a second support assembly carrying the first and second masses; each control unit controls the angle between the first and second masses and comprises a set of drive gear teeth integral with the first support assembly, a cogwheel with a set of control gear teeth meshing with the drive gear teeth, and an actuator to cause the rotation of the cogwheel about a second axis and of the first mass about said first axis.

A dual-frequency vibration-reduction apparatus includes a beam having a longitudinal axis and a transverse axis perpendicular to the longitudinal axis. An attachment mechanism mechanically couples a portion of the beam to a structure. One or more masses are attached to the beam such that the apparatus vibrates bi-modally at a primary frequency and a secondary frequency for reducing vibrations of the structure at the primary frequency and the secondary frequency. A first mode may be a bending mode of the apparatus, while a second mode is a torsion mode. The vibration reduction apparatus may be tuned such that the primary frequency substantially matches a blade-pass frequency of a propeller-driven aircraft and the secondary frequency substantially matches a harmonic of the blade-pass frequency. The vibration reduction apparatus includes a mounting mechanism for mounting to any structure requiring low-frequency vibration attenuation.

A rotor for an aircraft is described that has a mast, an attenuating device to attenuate the transmission of vibrations from the mast in a plane orthogonal to the first axis; and a transmission device interposed between the mast and the attenuating device; the attenuating device comprises a first and a second mass unit with a first and a second mass rotatable about the first axis with a first and a second rotational speed, two control units operable to cause an additional rotation of at least one of the first and second masses and a first and a second support assembly carrying the first and second masses; each control unit controls the angle between the first and second masses and each control unit comprises: a belt coupled to the support assembly and a drive unit coupled to the first belt, to cause the rotation of the first support assembly with respect to said transmission device.

Embodiments disclosed herein present a spring system for use in a torque dependent rotor assembly designed to operate in resonance, where changes in applied torque controls the blade pitch angle and ultimately the movements of a rotary wing aircraft. More specifically, the present invention relates to a spring system used in such a rotor assembly where the stiffness of an associated spring member is allowed to vary in response to the torque applied from a motor to the assembly.

In some examples, an aircraft comprises an airframe, a rotor system coupled to the airframe, and a vibration attenuation system. The rotor system is operable to exert a vibratory force on the airframe. The vibration attenuation system comprises two or more batteries and elastic devices. The two or more batteries are operable to supply power to the rotor system. The elastic devices coupled to the two or more batteries and the airframe. The elastic devices are configured to attenuate the vibratory force based on facilitating oscillation of the two or more batteries. In other examples, a method comprises coupling elastic devices to two or more batteries and an airframe of an aircraft. The elastic devices receiving a vibratory force via the airframe and attenuate the vibratory force based on facilitating oscillation of the two or more batteries.

An anti-tail buffet device leverages existing rotorcraft components to attenuate a tailboom's lateral ringing from air buffeting. Anti-buffet masses are tuned to the tailboom's lateral-bending or torsional natural frequency such that when lateral motion occurs, the response at this frequency is cancelled by the anti-buffet system, preventing this vibration from entering into the tailboom structure. Motion stops prevent over-travel. The mass of the tail rotor actuator is soft-mounted, such that its natural frequency is equal to the tailboom's lateral-bending or torsional natural frequency. When lateral loading occurs on the tail rotor disk, the lateral response at this frequency is attenuated by the soft-mounted tail rotor actuator, thereby preventing the vibration in the tailboom structure.

The present embodiments disclose a torque dependent and resonant operating thrust-generating rotor assembly including a cyclic pitch control system for controlling tilting moments about a longitudinal rotor blade axis of one or more rotor blades, in order to control the pitch angle of the rotor blades and thereby also the horizontal movements of a helicopter vehicle or a rotary wing aircraft. A rotor torque assembly of the rotor assembly is further configured to operate in resonance, thereby providing a resonant gain effecting a rotational offset in relation to changes in torque generated by the motor.

A main body of an unmanned vehicle is provided. The main body comprises a propulsion-receiving module having a mount point for removably mounting a propulsion source, a payload-receiving module having a mount point for removably mounting a payload, and a damper interposed between the payload-receiving module and the propulsion-receiving module to inhibit transmission of vibrations from the propulsion-receiving module to the payload-receiving module when the payload-receiving module and the propulsion-receiving module are in mechanical communication.