A swashplate guide for use with a spherical bearing and which connects with an adjacent component includes a hollow cylindrical tube formed from a composite material. An exterior surface of the hollow cylindrical tube provides an engagement surface with the spherical bearing. A flange arranged at an end of the hollow cylindrical tube provides an interface with the adjacent component.

In one embodiment, a rotor hub comprises a yoke for attaching a plurality of rotor blades, a constant velocity joint to drive torque from a mast to the yoke and to enable the yoke to pivot, and a rotor control system configured to adjust an orientation of the plurality of rotor blades. Moreover, the rotor control system comprises: a swashplate, a phase adapter fulcrum, a plurality of actuators controlled based on a flight control input, a plurality of lower pitch links configured to transfer motion between the plurality of actuators and the swashplate, a plurality of phase adjustment levers configured to adjust a control phase associated with motion transferred between the plurality of actuators and the plurality of lower pitch links, and a plurality of upper pitch links configured to adjust a pitch of the plurality of rotor blades, wherein there are more upper pitch links than lower pitch links.

In one embodiment, a rotor hub comprises a yoke for attaching a plurality of rotor blades, a constant velocity joint to drive torque from a mast to the yoke and to enable the yoke to pivot, and a rotor control system configured to adjust an orientation of the plurality of rotor blades. Moreover, the rotor control system comprises: a swashplate, a phase adapter fulcrum, a plurality of actuators controlled based on a flight control input, a plurality of lower pitch links configured to transfer motion between the plurality of actuators and the swashplate, a plurality of phase adjustment levers configured to adjust a control phase associated with motion transferred between the plurality of actuators and the plurality of lower pitch links, and a plurality of upper pitch links configured to adjust a pitch of the plurality of rotor blades, wherein there are more upper pitch links than lower pitch links.

Methods and apparatus to control pitch and twist of blades are disclosed. An example apparatus includes a twist input assembly driven by a drive shaft that drives a rotation of blades of a rotorcraft, the twist input assembly comprising a twist shaft, a first gear set driven by the drive shaft, and a first frequency controller to create a first rotational speed difference between a first gear of the first gear set and the drive shaft, the first rotational speed difference to cause the twist shaft to oscillate. The examples apparatus includes a pitch input assembly driven by the drive shaft, the pitch input assembly comprising a pitch link in communication with a first one of the blades of the rotorcraft, a second gear set driven by the drive shaft, and a second frequency controller to create a second rotational speed difference between a second gear of the second gear set and the drive shaft, the second rotational speed difference to cause the pitch link to oscillate.

Systems and methods of operating a tiltrotor aircraft include providing a control system that includes sensors and/or gauges that provide feedback regarding hub shear forces in rotor systems of the aircraft that produce aeroelastic instability known as whirl flutter. Feedback from the sensors and/or gauges is communicated to a flight control subsystem that includes an algorithm that provides a cascading set of responses to control whirl flutter and a failsafe that adjusts operational characteristics of the aircraft in response to the continuation or excitation of the whirl flutter.

An aircraft rotor assembly has a yoke and a plurality of rotor blade assemblies coupled thereto. Each of the rotor blade assemblies include a rotor blade, a bearing, and a blade grip coupling the rotor blade to the bearing. Each of the rotor blades is rotatable about a lead-lag axis, flap axis, and a pitch change axis, wherein all the axes intersect within the bearing. Adjacent pairs of rotor blade assemblies are coupled together via a damper assembly that is coupled to the pitch change axis of each of the rotor blade assemblies.

In one embodiment, a rotor hub comprises a yoke for attaching a plurality of rotor blades, a constant velocity joint to drive torque from a mast to the yoke and to enable the yoke to pivot, and a rotor control system configured to adjust an orientation of the plurality of rotor blades. Moreover, the rotor control system comprises: a swashplate, a phase adapter fulcrum, a plurality of actuators controlled based on a flight control input, a plurality of lower pitch links configured to transfer motion between the plurality of actuators and the swashplate, a plurality of phase adjustment levers configured to adjust a control phase associated with motion transferred between the plurality of actuators and the plurality of lower pitch links, and a plurality of upper pitch links configured to adjust a pitch of the plurality of rotor blades, wherein there are more upper pitch links than lower pitch links.

A bearing arrangement for use with a structure defining an outer surface which expands and contracts inward and outward relative to the structure includes, a member having at least one inner surface to face the outer surface, and at least one protrusion extending from the inner surface, the at least one protrusion being biased toward and in contact with the outer surface and maintains contact as the structure expands and contracts.

A swashplate guide for use with a spherical bearing and which connects with an adjacent component includes a hollow cylindrical tube formed from a composite material. An exterior surface of the hollow cylindrical tube provides an engagement surface with the spherical bearing. A flange arranged at an end of the hollow cylindrical tube provides an interface with the adjacent component.

A helicopter rotor blade control pitch link for transmitting movement of a rotating swashplate to a rotor blade pitch horn includes a spring module. The spring module includes at least one elastic member configured to generate link compliance when a force is transferred through the pitch link from the rotating swashplate to the rotor blade pitch horn. A plurality of such rotor blade control pitch links is used in a helicopter rotor blade control system having a swashplate assembly operatively connected to each of a rotor shaft and a rotor having a plurality of rotor blades with respective rotor pitch horns. Each rotor blade pitch link is configured to control a pitch of one rotor blade via the corresponding rotor blade pitch horn.