Abstract: A rotor assembly includes a yoke operably associated with a rotor blade. The yoke includes a first device and a second device that attach the rotor blade to the yoke. The first device is configured to allow transverse movement of the rotor blade about a chord axis and rotational movement about a pitch-change axis. The second device is configured to allow rotational movement of the rotor blade solely about the pitch-change axis. The method includes rotating rotor assembly about a first plane of rotation, while retaining a relatively stiff out-of-plane rotation and a relatively soft in-plane rotation during flight.

Abstract: An aircraft includes a rotor blade and a rotor hub system. The rotor hub system includes a lead-lag damper having a rod end and being operably associated with the rotor blade; a blade adapter having a first arm and an opposing second arm; a pin carried by the blade adapter and configured to secure in position via the first arm and the second arm; and an actuator secured to the pin and configured to adjust the position of the lead-lag rod end relative to the first arm and the second arm.

Abstract: A rotor assembly includes a yoke operably associated with a rotor blade. The yoke includes a first device and a second device that attach the rotor blade to the yoke. The first device is configured to allow transverse movement of the rotor blade about a chord axis and rotational movement about a pitch-change axis. The second device is configured to allow rotational movement of the rotor blade solely about the pitch-change axis. The method includes rotating rotor assembly about a first plane of rotation, while retaining a relatively stiff out-of-plane rotation and a relatively soft in-plane rotation during flight.

Abstract: An aircraft includes a rotor blade and a rotor hub system. The rotor hub system includes a lead-lag damper having a rod end and being operably associated with the rotor blade; a blade adapter having a first arm and an opposing second arm; a pin carried by the blade adapter and configured to secure in position via the first arm and the second arm; and an actuator secured to the pin and configured to adjust the position of the lead-lag rod end relative to the first arm and the second arm.

Abstract: A rotor assembly includes a yoke operably associated with a rotor blade. The yoke includes a first device and a second device that attach the rotor blade to the yoke. The first device is configured to allow transverse movement of the rotor blade about a chord axis and rotational movement about a pitch-change axis. The second device is configured to allow rotational movement of the rotor blade solely about the pitch-change axis. The method includes rotating rotor assembly about a first plane of rotation, while retaining a relatively stiff out-of-plane rotation and a relatively soft in-plane rotation during flight.

Abstract: An aircraft includes a rotor blade and a rotor hub system. The rotor hub system includes a lead-lag damper having a rod end and being operably associated with the rotor blade; a blade adapter having a first arm and an opposing second arm; a pin carried by the blade adapter and configured to secure in position via the first arm and the second arm; and an actuator secured to the pin and configured to adjust the position of the lead-lag rod end relative to the first arm and the second arm.

Abstract: A dual series damper includes a fluid damper portion and a elastomeric damper portion. The fluid damper portion includes a first housing, a first connection member, and a piston coupled to the first connection member. The piston divides an interior of the first housing into a first fluid chamber and a second fluid chamber. The piston has a fluid passage in the piston, the fluid passage being configured to provide fluid communication between the first fluid chamber and the second fluid chamber. The elastomeric damper portion includes a second housing, a second connection member coupled to the second housing, and an elastomer between the first housing and the second housing. When a lead/lag force is introduced to the dual series damper, the fluid damper portion behaves rigidly so that the elastomeric damper portion dampens the lead/lag oscillation.

Abstract: The system and method of the present application relate to a lead/lag damper for a rotorcraft. The lead/lag damper is configured to harvest power from the lead/lag oscillatory motions of rotor blades with an electromagnetic linear motor/generator. Further, the lead/lag damper is configured to treat the lead/lag motions with the electromagnetic linear motor/generator. The system and method is well suited for use in the field of aircraft, in particular, helicopters and other rotary wing aircraft.

Abstract: An aircraft includes a rotor blade and a rotor hub system. The rotor hub system includes a lead-lag damper having a rod end and being operably associated with the rotor blade; a blade adapter having a first arm and an opposing second arm; a pin carried by the blade adapter and configured to secure in position via the first arm and the second arm; and an actuator secured to the pin and configured to adjust the position of the lead-lag rod end relative to the first arm and the second arm.

Abstract: A rotor assembly includes a yoke operably associated with a rotor blade. The yoke includes a first device and a second device that attach the rotor blade to the yoke. The first device is configured to allow transverse movement of the rotor blade about a chord axis and rotational movement about a pitch-change axis. The second device is configured to allow rotational movement of the rotor blade solely about the pitch-change axis. The method includes rotating rotor assembly about a first plane of rotation, while retaining a relatively stiff out-of-plane rotation and a relatively soft in-plane rotation during flight.

Abstract: A lead-lag damper for a rotor assembly has a body mounted to either an inboard portion of a blade assembly or a fixed portion of the rotor assembly. A piston carried within the body is configured to allow for relative motion between the body and the piston. The piston defines opposing chambers within the body, the chambers being in fluid communication through a fluid passage. A link connects the piston to the other of the inboard portion of the blade assembly and the fixed portion of the rotor assembly, and the link engages a central portion of the piston. The piston acts on fluid in the chambers during relative motion between the piston and the body and causes fluid flow between the chambers through the fluid passage. Flow through the passage acts to damp lead-lag motion of the blade assembly relative to the fixed portion of the rotor assembly.

Abstract: A dual frequency damper includes a liquid inertia vibration eliminator (LIVE) portion and a fluid damper portion. LIVE portion and fluid damper portion operate in series and function so that dual frequency damper is optimized in both stiffness and damping at multiple frequencies. LIVE portion acts as a frequency dependent switch to selectively cause low frequency oscillatory forces to be treated primarily by the high spring rate and high damping rate characteristics of the fluid damper portion, and also to select high frequency oscillatory forces to be primarily treated by the low spring rate and low damping rate characteristics of the LIVE unit portion.

Abstract: A dual frequency damper includes a liquid inertia vibration eliminator (LIVE) portion and a fluid damper portion. LIVE portion and fluid damper portion operate in series and function so that dual frequency damper is optimized in both stiffness and damping at multiple frequencies. LIVE portion acts as a frequency dependent switch to selectively cause low frequency oscillatory forces to be treated primarily by the high spring rate and high damping rate characteristics of the fluid damper portion, and also to select high frequency oscillatory forces to be primarily treated by the low spring rate and low damping rate characteristics of the LIVE unit portion.

Abstract: The system and method of the present application relate to a lead/lag damper for a rotorcraft. The lead/lag damper is configured to harvest power from the lead/lag oscillatory motions of rotor blades with an electromagnetic linear motor/generator. Further, the lead/lag damper is configured to treat the lead/lag motions with the electromagnetic linear motor/generator. The system and method is well suited for use in the field of aircraft, in particular, helicopters and other rotary wing aircraft.

Abstract: A rotor hub has a yoke with radial arms allowing flapping of connected blades about a flap axis. A grip is rigidly attached to each blade, and a lead-lag bearing connects each grip to one of the arms, the bearing defining a lead-lag axis outboard of the flap axis. Each arm has a pair of straps located on opposite sides of the rotor plane for transferring centrifugal force from the blades to the central portion of the yoke. A pair of lead-lag dampers is provided for each grip, the dampers of each pair being located on opposite sides of the rotor plane and connecting an inboard end portion of the grip to the adjacent strap. In-plane motion of a blade causes rotation of the attached grip about the lead-lag axis, causing opposite motion of an inboard end portion of the grip. The dampers act to oppose rotation of the grip.

Abstract: A dual series damper includes a fluid damper portion and a elastomeric damper portion. The fluid damper portion includes a first housing, a first connection member, and a piston coupled to the first connection member. The piston divides an interior of the first housing into a first fluid chamber and a second fluid chamber. The piston has a fluid passage in the piston, the fluid passage being configured to provide fluid communication between the first fluid chamber and the second fluid chamber. The elastomeric damper portion includes a second housing, a second connection member coupled to the second housing, and an elastomer between the first housing and the second housing. When a lead/lag force is introduced to the dual series damper, the fluid damper portion behaves rigidly so that the elastomeric damper portion dampens the lead/lag oscillation.

Abstract: A rotor hub has a yoke with radial arms allowing flapping of connected blades about a flap axis. A grip is rigidly attached to each blade, and a lead-lag bearing connects each grip to one of the arms, the bearing defining a lead-lag axis outboard of the flap axis. Each arm has a pair of straps located on opposite sides of the rotor plane for transferring centrifugal force from the blades to the central portion of the yoke. A pair of lead-lag dampers is provided for each grip, the dampers of each pair being located on opposite sides of the rotor plane and connecting an inboard end portion of the grip to the adjacent strap. In-plane motion of a blade causes rotation of the attached grip about the lead-lag axis, causing opposite motion of an inboard end portion of the grip. The dampers act to oppose rotation of the grip.

Abstract: A lead-lag damper for a rotor assembly has a body mounted to either an inboard portion of a blade assembly or a fixed portion of the rotor assembly. A piston carried within the body is configured to allow for relative motion between the body and the piston. The piston defines opposing chambers within the body, the chambers being in fluid communication through a fluid passage. A link connects the piston to the other of the inboard portion of the blade assembly and the fixed portion of the rotor assembly, and the link engages a central portion of the piston. The piston acts on fluid in the chambers during relative motion between the piston and the body and causes fluid flow between the chambers through the fluid passage. Flow through the passage acts to damp lead-lag motion of the blade assembly relative to the fixed portion of the rotor assembly.

Abstract: A vibration absorber having a mass member which when static is supported by in-plane springs spaced apart from a base plate, top plate and spring retaining structures. The mass member has a bumper surface for contacting a motion limiter in the base plate. The mass member, base plate and top plate can have a passageway through the axis. The vibration absorber can be tuned by proper selection of the springs, degree of precompression and the variation of the amount of mass by the addition or removal of mass tuning weights.