Abstract: A tiltrotor rotor hub comprises first and second configurations of yokes arranged in two parallel and axially offset planes, each having an equal number of two or more yokes substantially equally spaced about a mast, wherein a portion of each yoke overlaps with a portion of each azimuthally adjacent yoke. Another tiltrotor rotor hub is selectively positionable for operation in helicopter/airplane/transition modes and comprises substantially parallel and axially offset first and second planes, each containing a plurality of blade yokes arranged about a central axis and a portion of each yoke overlaps with a portion of each azimuthally adjacent yoke. Another tiltrotor rotor hub is coupled to a tiltrotor mast and comprises a stacked arrangement of blade yokes wherein a portion of each yoke overlaps with a portion of each azimuthally adjacent yoke, and a plurality of mounting components coupling each yoke to the overlapping azimuthally adjacent yoke.

Abstract: A rotary system including a yoke having an opening forming a bridge for receiving a spoke extending therethrough. A rotor blade couples to the spoke and a pitch horn positioned outside the opening pitches the rotor blade during flight. A bearing assembly attaches the spoke and the pitch horn to the bridge and control blade forces exerted against the hub assembly during flight.

Abstract: A system and method to amplify displacement includes a housing forming a cylindrical chamber having an elastomeric material disposed therein. The chamber being sealed with a first membrane and a second membrane. The first membrane being attached to a first end having and the second membrane being attached to a second end, the first end having a greater diameter than the second end. The method including producing an input displacement with a driver attached to the first membrane, which in turn results in an amplified output displacement at the second end.

Abstract: A rotary system includes a retention member and a flexible yoke having an opening forming a bridge. The rotary system is further provided with two bearing assemblies, a first bearing assembly extending through the opening of the yoke and configured to secure a rotor blade to the retention member and a second bearing assembly extending through the opening of the flexible yoke and configured to secure the rotor blade to the bridge. The second bearing element includes a bearing element having a first surface forming a spherical contouring and an opposing integral second surface forming a conical contouring.

Abstract: A system and method to tilt coaxial counter-rotating rotor hub assemblies relative to a fuselage. The system includes a first rotor hub assembly and a second rotor hub assembly spaced apart from the first hub assembly and carried by the fuselage. The method includes pivotally attaching the first rotor hub assembly and the second rotor hub assembly to a pivot joint and thereafter tilting the first rotor hub assembly and the second rotor hub assembly about the pivot joint with a driver.

Abstract: A tunable vibration isolator with active tuning elements having a housing, fluid chamber, and at least one tuning port. A piston is resiliently disposed within the housing. A vibration isolation fluid is disposed within the fluid chambers and the tuning ports. The tunable vibration isolator may employ either a solid tuning mass approach or a liquid tuning mass approach. The active vibration elements are preferably solid-state actuators.

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: 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: According to one embodiment, a rotor system comprises a yoke, a grip, an elastomeric bearing, and a bearing restraint. The grip is positioned around a portion of the yoke and has both a closed end and an open end. The elastomeric bearing is coupled to the closed end of the grip and located between the closed end and the yoke.

Abstract: 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.

Abstract: A rotary system and method to control feathering and centrifugal forces of a rotor blade during flight. The rotary system having a hub assembly, which includes a hollow yoke arm to receive a spindle section of the rotor blade. A tension-torsion strap extends through the hollow yoke arm and couples the rotor blade and the hub assembly. The method includes allowing the spindle section of the rotor blade to pivot within the hollow yoke arm and controlling rotational and centrifugal movement of the rotor blade with the tension-torsion strap.

Abstract: The present application includes a blade-pitch control system for controlling a pitch angle of each of a plurality of blades on an aircraft rotor. A feedback lever associated with each blade is pivotally mounted to the rotating portion of a swashplate assembly. A pitch link connects an output arm of a lever to a pitch horn of a corresponding blade, and a feedback link connects the input arm of the lever to a yoke. Flapping motion of the yoke causes motion of the feedback link, and this motion causes corresponding rotation of the lever. Rotation of the lever causes motion of the pitch link, which changes the pitch angle of the attached blade. This provides for selected pitch-flap coupling between flapping motion of the yoke and pitch motion of the blades.

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 blade-pitch control system for controlling a pitch angle of blades on a rotor has an input swashplate assembly having non-rotating and rotating portions, the rotating portion being operably connected to blade grips. A feedback swashplate assembly has non-rotating and rotating portions, the rotating portion being connected to the yoke for movement with the yoke during flapping of the yoke. Linear actuators connect the non-rotating portion of the input swashplate assembly to the non-rotating portion of the feedback swashplate assembly. Motion of the yoke during flapping causes a corresponding motion of the feedback swashplate assembly and input swashplate assembly for providing selected pitch-flap coupling between flapping motion of the yoke and pitch motion of the grips.

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: The bearing system is configured for treating and reacting dynamic loading within a rotor hub of rotorcraft. The bearing system includes an outer member having a plurality of alternating outer elastomeric layers and shim layers. The outer member has an inboard surface configured for bonding to an inboard bearing support, and the outer member has an outboard surface configured for bonding to an outboard bearing support. The bearing system has an inner member bonded to an interior surface of the outer member. The inner member can include a rigid inner core, as well as a plurality of elastomeric layers and shim layers configured to react torsional movements of the rotor blade.

Abstract: A vibration isolator includes a housing having an upper fluid chamber, a lower fluid chamber, a piston, a tuning passage, and a linear inductance motor assembly for changing the isolation frequency of the vibration isolator. The piston is resiliently disposed within the housing. A vibration tuning fluid is located in the upper fluid chamber, the lower fluid chamber, and the tuning passage. The linear inductance motor assembly includes a magnet member and an inductance coil at least partially surrounding the magnet member. A control system is configured to selectively actuate the magnet member; wherein selective actuation of the magnet member selectively imparts a pumping force on the tuning fluid, thereby changing the isolation frequency.

Abstract: A rotor hub assembly and method for controlling movement of a rotor blade relative to a swashplate. The hub assembly having an attachment device operably associated with the rotor blade and the swashplate. The attachment device provides pivot and rotational blade movement relative to the swashplate. A dual spring-rate damper is operably associated with the attachment device. The damper switches between a first spring rate and a second spring rate during flight to control movement of the rotor blade. The method includes the process of switching the damper between the first spring rate and the second spring rate during flight.

Abstract: A pylon mounting system with vibration isolation is provided. The system generally includes a housing that defines a first fluid chamber and a second fluid chamber, a fluid disposed within the fluid chambers; a piston assembly at least partially disposed within the housing, and a tuning passage defined by the piston assembly for providing fluid communication between the fluid chambers. The piston assembly has a first arm and a second arm, and each arm has a tubeform bearing for providing pitch and roll stiffness.

Abstract: A system and method for adjusting a rotor blade upon detection of a harmful force exerted on an aircraft wing includes a sensor attached to the wing and a subsystem operably associated with the sensor. The method includes sensing the force exerted on the wing with the sensor and determining whether the sensed force is potentially harmful to the structural integrity of the wing. The method further includes counteracting the harmful force by adjusting the rotor blade movement.