Abstract: An airfoil member can have a root end, a tip end, a leading edge, and a trailing edge. The airfoil member can include an upper skin, a lower skin, and a composite core member having a plurality of cells, an upper surface network of the cells can be bonded to the upper skin, a lower surface network of the cells can be bonded to the lower skin. The composite core can have a septum layer embedded in the cells that form the composite core, the septum layer being configured to provide tailored characteristics of the airfoil member.

Abstract: A rotor assembly for a rotary-wing aircraft, the rotor having a central hub assembly with a flexure-type, twist-shank yoke with multiple arms, each arm being adapted for a rotor blade to be mounted thereto. The arms provide for pitch changes of blades attached to the yoke through twisting of portions of the arms about a corresponding pitch axis. An inboard pitch bearing associated with each arm is attached to the hub assembly and allows for rotation of the attached blade about the pitch axis, the inboard pitch bearing also allowing for out-of-plane motion of the arm relative to the hub assembly about a flapping axis. An outboard pitch bearing associated with each arm is attached to the associated arm a selected distance from the inboard pitch bearing and allows for rotation of the attached blade about the pitch axis.

Abstract: An aircraft rotor assembly has upper and lower hub plates adapted to be mounted to a central rotor mast for rotation therewith. A plurality of radial arms is connected to at least two flap bearings mounted between the hub plates and forming a discrete flap hinge, each flap hinge defining a flap axis and allowing rotation of the associated arm relative to the hub plates and about the corresponding flap axis. Each of a plurality of blade grips is rotatably connected to one of the arms for rotation about a pitch axis and adapted for mounting of a blade to each blade grip, such that each blade is capable of rotation with the grip about the pitch axis and capable of rotation together with the corresponding arm relative to the hub plates and about the corresponding flap axis.

Abstract: According to one embodiment, a method comprises calendering an elastomeric material into an elastomeric layer having a thickness that is more uniform than the elastomeric material prior to the calendaring. After calendaring, the elastomeric layer is vulcanized to a composite shim comprising at least one reinforcement layer and at least one layer of adhesive.

Abstract: A rotor assembly for a rotary-wing aircraft, the rotor having a central hub assembly with a flexure-type, twist-shank yoke with multiple arms, each arm being adapted for a rotor blade to be mounted thereto. The arms provide for pitch changes of blades attached to the yoke through twisting of portions of the arms about a corresponding pitch axis. An inboard pitch bearing associated with each arm is attached to the hub assembly and allows for rotation of the attached blade about the pitch axis, the inboard pitch bearing also allowing for out-of-plane motion of the arm relative to the hub assembly about a flapping axis. An outboard pitch bearing associated with each arm is attached to the associated arm a selected distance from the inboard pitch bearing and allows for rotation of the attached blade about the pitch axis.

Abstract: The present application includes a main rotor assembly for an aircraft. The rotor assembly has a main rotor mast configured for rotation about a mast axis and two yokes pivotally connected to the mast for rotation therewith about the mast axis. Each yoke is independently pivotable relative to the mast about at least one flap axis that is generally perpendicular to the mast axis. In at least one embodiment, a torque splitter connects the yokes and allows for limited rotation of the yokes relative to each other about the mast axis. Each yoke is configured for the attachment of rotor blades extending generally radially relative to the mast axis.

Abstract: A rotor assembly for a rotary-wing aircraft, the rotor having a central hub assembly with a flexure-type, twist-shank yoke with multiple arms, each arm being adapted for a rotor blade to be mounted thereto. The arms provide for pitch changes of blades attached to the yoke through twisting of portions of the arms about a corresponding pitch axis. An inboard pitch bearing associated with each arm is attached to the hub assembly and allows for rotation of the attached blade about the pitch axis, the inboard pitch bearing also allowing for out-of-plane motion of the arm relative to the hub assembly about a flapping axis. An outboard pitch bearing associated with each arm is attached to the associated arm a selected distance from the inboard pitch bearing and allows for rotation of the attached blade about the pitch axis.

Abstract: An airfoil member can have a root end, a tip end, a leading edge, and a trailing edge. The airfoil member can include an upper skin, a lower skin, and a composite core member having a plurality of cells, an upper surface network of the cells can be bonded to the upper skin, a lower surface network of the cells can be bonded to the lower skin. The composite core can have a septum layer embedded in the cells that form the composite core, the septum layer being configured to provide tailored characteristics of the airfoil member.

Abstract: An aircraft rotor assembly has upper and lower hub plates adapted to be mounted to a central rotor mast for rotation therewith. A plurality of radial arms is connected to at least two flap bearings mounted between the hub plates and forming a discrete flap hinge, each flap hinge defining a flap axis and allowing rotation of the associated arm relative to the hub plates and about the corresponding flap axis. Each of a plurality of blade grips is rotatably connected to one of the arms for rotation about a pitch axis and adapted for mounting of a blade to each blade grip, such that each blade is capable of rotation with the grip about the pitch axis and capable of rotation together with the corresponding arm relative to the hub plates and about the corresponding flap axis.

Abstract: According to one embodiment, a method comprises calendering an elastomeric material into an elastomeric layer having a thickness that is more uniform than the elastomeric material prior to the calendaring. After calendaring, the elastomeric layer is vulcanized to a composite shim comprising at least one reinforcement layer and at least one layer of adhesive.

Abstract: The present application includes a main rotor assembly for an aircraft. The rotor assembly has a main rotor mast configured for rotation about a mast axis and two yokes pivotally connected to the mast for rotation therewith about the mast axis. Each yoke is independently pivotable relative to the mast about at least one flap axis that is generally perpendicular to the mast axis. In at least one embodiment, a torque splitter connects the yokes and allows for limited rotation of the yokes relative to each other about the mast axis. Each yoke is configured for the attachment of rotor blades extending generally radially relative to the mast axis.

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 constant-velocity drive system for an aircraft rotor has a gimbal mechanism and a differential torque-combining mechanism. The gimbal mechanism has gimbals driven in rotation by a rotor mast about a mast axis, the gimbals providing for gimballing relative to the mast about gimbal axes generally perpendicular to the mast axis. The differential torque-combining mechanism is connected to the gimbal mechanism and configured to be driven in rotation about the mast axis by the gimbal mechanism. The differential mechanism is capable of gimballing relative to the mast about the gimbal axes, the differential torque-combining mechanism having an output component attached to a yoke of the rotor for driving the yoke in rotation with the differential torque-combining mechanism.

Abstract: A yoke and bearing fitting assembly for a multi-blade aircraft rotor is disclosed. The assembly has a yoke having arms extending generally radially from a central portion of the yoke, the arms each having opposing surfaces. An aperture is formed in each arm and extends between the surfaces. A bearing fitting has a body configured for insertion into the aperture of the yoke and has two rims protruding from a periphery of the body, the body also having a bearing mount adapted for mounting a pitch change bearing assembly to the yoke. Each rim abuts one of the surfaces of the associated yoke arm when the bearing fitting is installed within the aperture, so as to create clamping forces between the rims and the arm and the arm. The bearing fitting transmits forces from the pitch bearing assembly into the yoke.

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 pitch control system for blades on a rotor of an aircraft has a gimballing rotor hub (31) and a plurality of step-over arms (61) connected to the hub and capable of pivoting relative to the hub about a pivot axis. Each of a plurality of pitch links (55) connects one of the step-over arms (61) to a flight control system for pivoting the connected step-over arm (61) about the pivot axis and relative to the hub in response to inputs from the control system. Each of a plurality of step-over links (69) connects one of the step-over arms (61) to one of the blades for rotating the associated blade about the pitch axis in response to pivoting of the associated step-over arm.

Abstract: A constant-velocity drive system for an aircraft rotor has a gimbal mechanism and a differential torque-combining mechanism. The gimbal mechanism has gimbals driven in rotation by a rotor mast about a mast axis, the gimbals providing for gimballing relative to the mast about gimbal axes generally perpendicular to the mast axis. The differential torque-combining mechanism is connected to the gimbal mechanism and configured to be driven in rotation about the mast axis by the gimbal mechanism. The differential mechanism is capable of gimballing relative to the mast about the gimbal axes, the differential torque-combining mechanism having an output component attached to a yoke of the rotor for driving the yoke in rotation with the differential torque-combining mechanism.

Abstract: A yoke and bearing fitting assembly for a multi-blade aircraft rotor is disclosed. The assembly has a yoke having arms extending generally radially from a central portion of the yoke, the arms each having opposing surfaces. An aperture is formed in each arm and extends between the surfaces. A bearing fitting has a body configured for insertion into the aperture of the yoke and has two rims protruding from a periphery of the body, the body also having a bearing mount adapted for mounting a pitch change bearing assembly to the yoke. Each rim abuts one of the surfaces of the associated yoke arm when the bearing fitting is installed within the aperture, so as to create clamping forces between the rims and the arm and the arm. The bearing fitting transmits forces from the pitch bearing assembly into the yoke.

Abstract: A rotor assembly for a rotary-wing aircraft, the rotor having a central hub assembly with a flexure-type, twist-shank yoke with multiple arms, each arm being adapted for a rotor blade to be mounted thereto. The arms provide for pitch changes of blades attached to the yoke through twisting of portions of the arms about a corresponding pitch axis. An inboard pitch bearing associated with each arm is attached to the hub assembly and allows for rotation of the attached blade about the pitch axis, the inboard pitch bearing also allowing for out-of-plane motion of the arm relative to the hub assembly about a flapping axis. An outboard pitch bearing associated with each arm is attached to the associated arm a selected distance from the inboard pitch bearing and allows for rotation of the attached blade about the pitch axis.

Abstract: A yoke for a rotary wing aircraft rotor system has a plurality of arms, each arm having a root. Each root has a notched portion configured to allow passage of a portion of a blade-pitch control system through the notched portion.