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.

In accordance with one embodiment of the present disclosure, a system includes a first housing, a second housing, a seal, and a spring system. The first housing includes a first volume of fluid. The first housing is capable of connecting to a first element and to a second element, and is also capable of reducing an amount of movement transferred from the first element to the second element. The second housing is connected to the first housing. The second housing includes a second volume of fluid and a volume of gas. The first volume of fluid is in fluid communication with the second volume of fluid. The seal is capable of separating the second volume of fluid from the volume of gas. The spring system is capable of applying pressure to the first volume of fluid and the second volume of fluid.

A vibration attenuation system for attenuating vibrations in a mast of an aircraft includes a weight attached to the mast but free to orbit about the mast. The weight can be comprised of one or more weight assemblies. Embodiments can include a single weight, or plural weight assemblies wherein each weight assembly can include a mechanical interconnecting mechanism so that each weight assembly receives feedback regarding the position and movement of one or more other weight assemblies. Each weight can be associated with a spring that urges the weight towards a neutral position. Rotation of the mast can cause the weight to orbit about the mast and self-excite such that the weight acts against the urging of the spring towards an attenuating position.

A vibration suppression unit for an aircraft comprising a mass assembly having a center of mass and a frequency rotor having a frequency center axis offset from a central axis of rotation and driven to rotate about the central axis, a vibration control amplitude rotor rotationally coupled to the mass assembly and having an amplitude center axis offset from the central axis driven independently of the frequency rotor to rotate about the central axis, the amplitude center axis and the frequency center axis having a selectively variable displacement angle defined by an inclusive angle between a line extending between the central axis and the amplitude center axis and a line extending between the central axis and the frequency center axis, wherein the amplitude rotor and the frequency rotor are controllable to produce a vibration control force vector having a controllable magnitude and frequency about the central axis of rotation.

Embodiments are directed to systems and methods for providing a control link for an aircraft in which the control link comprises an impact-resistant structure with a redundant load path. The control link has an inner structure that is sized to carry the anticipated load of the flight control system and to meet all safety factors. The control link also has an outer structure that is sacrificial and configured to absorb impact damage during operation, thereby protecting the inner structure. The outer structure is also designed to carry the anticipated load of the flight control system on its own, independent of the inner structure, and to meet all safety factors. If the outer structure fails, the inner structure allows for continued safe operation of the flight control system. The space or cavity between the inner and outer structures may be filled with a material, such as a closed-cell foam, to improve the impact resistance of the outer structure.

An aircraft (100) with a rotary wing (40) is equipped with a propulsion system (10). The aircraft (100) includes a rotating mast (50) that rotates the rotor wing (40). The propulsion system (10) includes a pole (20) mechanically connected to the rotating mast (50) of the aircraft (100), where at least one end of the pole (20) is equipped with a motor (30) configured to rotate the pole (20) around the axis of the rotating mast (50) in such a way that the rotation of the pole (20) can be used to rotate the rotating wing (40). At each end of the pole (20) is placed a motor group (30), where each motor group (30) includes a pair of counter-rotating propellers (32,32), said pair of counter-rotating propellers (32,32′) being arranged in such a way as to generate a rotational torque to rotate the pole (20).

The technology described herein relates to autonomous aerial vehicle rotor configurations. In some embodiments, the aerial vehicle includes a central body that extends along a longitudinal axis from a forward end to an aft end including a port side opposite a starboard side. Multiple rotor arms each have a proximal end coupled to the central body and a rotor assembly arranged at a distal end to provide propulsion for the aerial vehicle. The rotor assemblies include a first set of rotor assemblies and a second set of rotor assemblies. The first set of rotor assemblies are arranged in a non-inverted configuration on a top side of the aerial vehicle such that each rotor assembly includes an upward-facing rotor. The second set of rotor assemblies are arranged in an inverted configuration on a bottom side of the aerial vehicle such that each rotor assembly includes a downward-facing rotor.

A compound helicopter includes a fuselage including a fuselage airframe, a translational thrust system coupled to the fuselage airframe and a pylon assembly subject to vibration. The pylon assembly includes a transmission and a rotor system having a main rotor assembly. The compound helicopter also includes a main rotor vibration isolation system including a plurality of augmented liquid inertia vibration eliminator units each having an isolation frequency and each coupled between the fuselage airframe and the pylon assembly to reduce transmission of the pylon assembly vibration to the fuselage airframe at the isolation frequency. Each augmented liquid inertia vibration eliminator unit includes at least one active tuning element movable to tune the isolation frequency thereof.

In some embodiments, a rotorcraft may include a yoke, a blade, a spindle associated with the yoke, and an elastomeric bearing assembly. The center length of the spindle may define a center axis that passes through a center of the elastomeric bearing assembly. The elastomeric bearing assembly may contain a housing coupled to the blade and disposed around the center axis that is configured to rotate in relation to the center axis. The elastomeric bearing assembly may contain an elastomeric shear bearing that has an interior portion coupled to the spindle and an exterior portion coupled to the housing. The elastomeric bearing assembly may contain an elastomeric centrifugal force bearing pressed against the housing. The shear bearing may be configured to counteract a torsional force, and the centrifugal force bearing may be configured to counteract a compression force.

A rotorcraft having an antivibration system, the antivibration system being arranged at the interface between a fuselage of the rotorcraft and a casing of a main power transmission gearbox, or “MGB”, in order to transmit rotary motion generated by an engine of the rotorcraft to a main rotor providing the rotorcraft at least with lift, and possibly also propulsion, the antivibration system including calculation means for analyzing as a function of time the dynamic excitation and the resulting vibration transmitted to the fuselage of the rotorcraft.