A vibration damping device equipped with a resonator mechanism comprising at least one resonator, the at least one resonator having a first beater extending from an embedded end to a free beating end. The resonator consists of an elastically deformable base equipped with a first branch and a second branch connected by a central section, the embedded end being embedded at the first branch, the first branch extending from a first end to a second end each rigidly fastened to a mount, the second branch extending from a first end section to a second end section each rigidly fastened to a vibration source.

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.

A dual axis bifilar vibration absorber system including a first bifilar vibration absorber having a first support provided with a first cantilevered end including a first opening and a second cantilevered end including a second opening. The first opening is spaced from the second opening along a first axis. A first mass is operatively connected to the first support. A second bifilar vibration absorber is collocated with the first bifilar vibration absorber. The second bifilar vibration absorber includes a support member having a first opening element and a second opening element. The second opening element is spaced from the first opening element along a second axis that is substantially perpendicular to the first axis. A second mass is operatively connected to the support member. The first mass is selectively pivotable about the second axis, and the second mass is selectively pivotable about the first axis.

Systems and methods include providing a coaxial helicopter with a main rotor system having an upper rotor system, a coaxial counter-rotating lower rotor system, and a rotor mast assembly having an upper rotor mast and a coaxial counter-rotating lower rotor mast. The upper rotor system and an associated upper vibration reduction system are coupled to the upper rotor mast. The upper vibration reduction system provides in-plane vibration control and reduction to the upper rotor system. The lower rotor system and an associated lower vibration reduction system are coupled to the lower rotor mast. The lower vibration reduction system provides in-plane vibration control and reduction to the lower rotor system. A third vibration reduction system is coupled to the rotor mast assembly and cooperates with the upper and lower vibration reduction systems to provide total in-plane vibration control and reduction to the main rotor system.

A vibration attenuator for an aircraft has at least one weight mounted in a rotating system of a rotor hub of the aircraft, each weight being rotatable about an axis of rotation of the hub relative to the hub and to each other weight. Drive means are provided for rotating each weight about the axis of rotation at a selected speed for creating oscillatory shear forces that oppose and attenuate rotor-induced vibrations having a selected frequency. A vertically oriented vibration attenuator is configured to oppose and attenuate vertical rotor induced oscillatory forces that would otherwise travel vertical down the rotor mast and into the airframe. A vibration attenuator having weights rotating about separate axes offset from each other.

A rotorcraft tail rotor comprising at least two blade elements, each blade element being suitable for pivoting about a collective pitch variation axis Z in order to vary the collective pitch of each blade element of the tail rotor, each blade element including at least one compensation weight comprising a projection emerging substantially perpendicularly to a main inertia axis of the blade element, the main inertia axis being parallel to a longitudinal direction of the blade element. In the invention, the tail rotor is wherein the compensation weight includes a deformable portion that is movable relative to the projection in a plane P that is parallel to the main inertia axis of the blade element.

An engine mount assembly for mounting an engine which produces a torque to a body having a persistent troublesome frequency vibration is disclosed. The engine mount assembly includes two fluid elastomeric chambers groundable to the body, an intermediate cradle link disposed between the two fluid chambers, a lateral link grounded to the body and the intermediate cradle, and a fluid conduit connecting the two fluid chambers. When subjected to torque a positive fluid pressure is generated within the fluid chambers and fluid conduit with the two fluid chambers share a plurality of loads while a transfer of the persistent troublesome frequency vibration from the body to the engine is inhibited.

A rotor damping system includes a rotor blade defining opposed leading and trailing edges, wherein the rotor blade has flexibility in an edgewise direction defined between the leading and trailing edges. A spar is mounted within the rotor blade, wherein the spar is stiff against flexure in the edgewise direction. A damper is operatively connected to the spar for damping relative motion of the spar and blade.

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 vibration attenuator for a rotor is rotatable about a mast axis and has a frame configured for rotation about the mast axis relative to the rotor. A first mass is axially translatable in a first direction relative to the frame parallel to a first axis, and a first biasing force urges the first mass toward a first-mass rest position in which the first mass is symmetric about the mast axis. A second mass is axially translatable in a second direction relative to the frame parallel to a second axis, and a second biasing force urges the second mass toward a second-mass rest position in which the second mass is symmetric about the mast axis. A selected first or second mass moves radially outward from the rest position to oppose vibrations in the rotor.