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 suspension device provided with at least one suspension means. The suspension means comprise a tuned mass damper, the damper comprising an inertial mass carried by a mass support. The suspension means include at least a first actuator generating a dynamic force for acting on the swinging motion of the damper. The inertial mass being movable longitudinally in translation relative to the mass support, the suspension device including a second actuator connected to the inertial mass to move the inertial mass longitudinally relative to the mass support.

A kit is described that comprises a device adapted to dampen the vibrations transmitted by the rotor to the fuselage; the device comprises two first elements movable along a first axis; two second elements rotatable about the first axis; a first inerter with a first female screw, a first screw, and first rollers rotatable about respective second axes and around the first axis with respect to the first female screw and first screw; a second inerter with a second female screw, a second screw operatively connected to the second female screw; and a plurality of second rollers rotatable about second axes and around the first axis with respect to the second female screw and second screw; the first and second female screws defining the first threaded elements, and the first and second screws defining the second threaded elements; or the first and second screws defining the first threaded elements and the first and second female screws defining the second threaded elements.

A rotor for a hover-capable aircraft includes an attenuating device to attenuate the transmission of vibrations from a mast to the aircraft. The attenuating device includes a first mass free to oscillate parallel to a hub rotation axis with respect to a casing of the attenuating device and elastically connected to the casing. The attenuating device further includes a second mass free to oscillate parallel to the hub rotation axis, connection means adapted to make the first and second masses integrally movable along the hub rotation 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.

In one embodiment, a rotor blade may comprise a blade body, a spar structure, and a blade nose. The blade body may comprise a skin, wherein the skin is configured to form an airfoil shape, and wherein the airfoil shape comprises an inboard end, an outboard end, a leading edge, and a trailing edge. The spar structure may comprise a first spar cap and a second spar cap, wherein the first spar cap is coupled to an upper portion of the skin, and wherein the second spar cap is coupled to a lower portion of the skin. The blade nose may comprise a cavity, wherein the cavity is configured to house a plurality of modular weights at a plurality of radial blade locations, wherein the plurality of radial blade locations comprises a range of locations between the inboard end and the outboard end.

In some examples, an oscillatory pumping system comprises: one or more active piston, a fluid, and two motors. The one or more active piston is disposed in a channel fluidically coupling two fluid chambers. The passive piston has a frequency response operable to counteract a vibratory displacement. The fluid is disposed in the channel and the two fluid chambers. The two motors couple to the one or more active piston. The two motors are operable to selectively change the frequency response of the passive piston based on oscillating the one or more active piston.

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.

A vibration attenuator for a rotor of an aircraft has a housing adapted for rotation with the rotor about an axis. A first ring is rotatably carried within the housing on a first bearing, a first weight being coupled to the first ring for rotation therewith relative to the housing about the axis. A second ring is rotatably carried by the first ring on a second bearing, a second weight being coupled to the second ring for rotation therewith relative to the housing and to the first ring. A first motor is configured for rotating the first ring relative to the housing, and a second motor is configured for rotating the second ring relative to the housing and to the first ring. The first and second motors are operated to rotate the weights within the housing and position the weights relative to each other for attenuating vibrations.

A rotor for an aircraft is described that comprises: a hub rotatable about an axis and, in turn, comprising a plurality of blades; a mast connectable to a drive member of the aircraft and connected to the hub to drive the hub in rotation about the axis; and damping means to dampen the transmission of vibrations to the mast in a plane orthogonal to the axis; the damping means comprising at least a first mass and a second mass that can eccentrically rotate about the axis with a first and a second speed of rotation, respectively; the first mass and second mass are operatively connected to the mast to generate, respectively, a first and a second damping force on the mast having a main component in a direction radial to the axis; the rotor comprises a transmission unit, which is interposed between the mast and the first and second masses so as to drive the first and second masses in rotation.

A vibration attenuator for an aircraft has first and second coaxial spinners configured for rotation about a mast axis and relative to a rotor. Upper and lower weights of each spinner are spaced radially from the axis and positioned 180 degrees from each other about the axis. The weights of each spinner are spaced from each other a distance parallel to the mast axis, each weight rotating about the mast axis in a different plane. The spinners rotate together relative to the rotor at a selected angular rate and are selectively rotatable relative to each other between a minimum-moment configuration, in which the upper weight of each spinner is angularly aligned with the lower weight of the other spinner, and a maximum-moment configuration, in which the upper weights are angularly aligned and the lower weights are angularly aligned, producing a whirling moment about the mast axis as the spinners rotate.