Abstract: A rotor blade system includes a hub assembly pivotally attached to a rotor blade, a mast attached to the hub assembly, and a swashplate engaged with the mast, the swashplate includes a non-rotating ring and a rotating ring. The method to raise the swashplate includes using an anti-drive link system pivotally engaged with a transmission top case and pivotally engaged with the non-rotating ring.

Abstract: A drive coupling has first and second coaxial end adapters. A first set of at least two coaxial helical elements has a first end of each element attached to the first end adapter, and a second end of each element is coupled to the second end adapter. At least one biasing device biases the end adapters relative to each other. Torque applied to one of the end adapters is transferred through the first set of helical elements to the other end adapter, the helical elements allowing for misalignment of the end adapters during operation.

Abstract: 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.

Abstract: In one embodiment, an apparatus comprises a shaft, a rotor, and a cam surface. The shaft comprises a spiral spline along a length of the shaft. The rotor comprises a blade extending from the rotor and a tubular hole extending into the rotor. The tubular hole comprises a spiral groove configured to mate with the spiral spline on the shaft. Relative rotation between the spiral spline and the spiral groove causes the rotor to linearly move along the shaft. The cam surface comprising a recession. The blade nesting in the recession to constrains rotation of the rotor about the shaft and allows linear movement of the rotor along the shaft.

Abstract: A rotor yoke manufactured by a process comprising preparing a molded rotor yoke in a closed cavity tool and possibly machining at least one portion of the molded rotor yoke to form the rotor yoke. In the preferred embodiment, the preparing of the molded rotor yoke is accomplished by applying layers of uncured low-flow composite material and a layer of uncured high-flow adhesive; substantially enclosing the uncured molded rotor yoke in the closed cavity tool; and applying pressure so as to compress the uncured molded rotor yoke; and curing the uncured molded rotor yoke. During the curing process, the high-flow adhesive bleeds out of the molded rotor yoke, thereby preventing marcels from forming through movement of the low-flow composite material.

Abstract: In one embodiment, a tiltrotor aircraft may comprise a fuselage; a biplane wing coupled to the fuselage, wherein the biplane wing comprises an upper wing structure and a lower wing structure; a plurality of tiltrotors coupled to the biplane wing; and at least one engine to power the plurality of tiltrotors.

Abstract: A multirotor aircraft comprises at least three proprotors. Each proprotor has a plurality of rotor blades pivotably attached to a mast assembly. When a rotor blade pitch angle is changed for a proprotor, all rotor blades on the proprotor change to a same pitch angle. The proprotors are configured to spin freely when a power source is disengaged or fails. In various embodiments, one or more engines provides power to each proprotor, or at least one engine provides power to two or more proprotors. A rotor blade control system is configured to control a collective rotor blade pitch angle on each proprotor independently of the rotor blade pitch on the other proprotors. The rotor blade control system is configured to set a negative collective rotor blade pitch angle on an unpowered proprotor, such as in response to manual inputs by a pilot or in response to current engine conditions.

Abstract: There is provided a rotorcraft, including a body, including a front portion and a tail portion; a main rotor system coupled to the front portion of the body, the main rotor system operable to provide a lifting force on the body; and an anti-torque system coupled to the tail portion of the body, the anti-torque system including a primary tail rotor system and a secondary tail rotor system; wherein the primary tail rotor system and the secondary tail rotor system are operable to provide a first anti-torque force and a second anti-torque force. In other aspects, there are methods of providing anti-torque force in a rotorcraft.

Abstract: In one embodiment, a rotor hub comprises a hub plate, a yoke for attaching a plurality of rotor blades, a plurality of yoke support bearings, and a plurality of cushioned damper bearings for attaching a plurality of dampers.

Abstract: 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, an adapter ring, a plurality of actuators controlled based on a flight control input, a plurality of lower pitch links configured to transfer motion between the swashplate and the adapter ring, a plurality of phase adjustment levers configured to adjust a control phase associated with motion transferred between the swashplate and the adapter ring, 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.

Abstract: In one embodiment, a rotor hub comprises a hub body, and a plurality of blade grips configured for attaching a plurality of rotor blades. The rotor hub further comprises a plurality of centrifugal force bearings coupled to the plurality of blade grips, wherein a focus of the plurality of centrifugal force bearings is aligned with a centerline of a rotor mast. The rotor hub further comprises a plurality of drive links configured to transfer torque to the plurality of rotor blades, wherein the plurality of drive links is positioned to correspond with a leading edge side of the plurality of rotor blades. The rotor hub further comprises a plurality of pitch horns configured to adjust a pitch of the plurality of rotor blades.

Abstract: An aircraft rotor assembly has a central yoke and a plurality of rotor blades coupled to the yoke for rotation with the yoke about an axis, each blade having a Lock number of approximately 5 or greater. A lead-lag pivot for each blade is a radial distance from the axis and allows for in-plane lead-lag motion of the associated blade relative to the yoke, each pivot allowing for in-plane motion from a neutral position of at least 1 degree in each of the lead and lag directions. Lead and lag motion of each blade is opposed by a biasing force that biases the associated blade toward the neutral position, and the biasing force is selected to achieve a first in-plane frequency of greater than 1/rev for each blade.

Abstract: 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.

Abstract: A rotor system includes a hub assembly, a first, second, and third rotor blade rotatably attached to the hub assembly, a first, second, and third damper pivotally attached to the hub assembly and pivotally attached to the first, second, and third rotor blade, respectively, and a control system operably associated with the first, second, and third damper. A method to control vibratory forces exerted on the hub assembly via the first and second rotor blade includes separately controlling a dynamic spring rate of each of the first and second dampers with the control system.

Abstract: In one embodiment, a method may comprise coupling a plurality of reinforcement fibers to a plurality of spherical components; inserting the plurality of spherical components into an enclosure; and heating the enclosure to cause the plurality of spherical components to expand, wherein the plurality of spherical components expands to form a geodesic structure, wherein the geodesic structure comprises a plurality of polyhedron components configured in a geodesic arrangement.

Abstract: A noise control system for a ducted rotor assembly, the ducted rotor assembly including a hub, a duct, and two or more blades coupled to the hub and supported by the duct. The noise control system including a microphone configured to receive a sound input generated by the ducted rotor assembly, the microphone configured for association with the hub; a speaker unit configured to generate a cancellation noise, the speaker configured for association with the hub; and a controller operably connected to the microphone and the speaker unit, the controller configured to selectively adjust harmonics of the cancellation noise to reduce an acoustic signature of the ducted rotor assembly. In another aspect, there is provided a rotorcraft with a ducted rotor assembly in a tail portion including a noise control system. In a third aspect, there is a method of reducing an acoustic signature of a ducted rotor assembly.

Abstract: A rotor blade including a root portion adapted to be connected to a helicopter rotor hub for rotation therewith, the root portion having a first edge surface; a first movable member having a first movable surface adjacent to the first edge surface; a first elastomeric joint disposed between the root portion and the first movable member, the first elastomeric joint having an inner surface facing the first edge surface of the root portion and an outer surface facing the movable surface of the first movable member; and an actuating system mounted within the root portion and the first movable member for moving the first movable member. The first elastomeric joint deforms to adjust for shear from actuation of the first movable member to a first position during helicopter mode; and to a second position during airplane mode.

Abstract: A vibration control system for a rotor hub provides vibration attenuation in an aircraft by reducing the magnitude of rotor induced vibratory. The system can include a force generating device attached to a rotor hub which rotates along with the rotor at the rotational speed of the rotor. Vibratory shear force is generated by rotating unbalanced weights each about an axis non-concentric with the rotor hub axis at high speed to create large centrifugal forces. The rotational speed of the weights can be a multiple of the rotor rotational speed to create shear forces for canceling rotor induced vibrations. The amplitude of the generated shear force is controlled by indexing the positions of the unbalanced weights relative to each other, while the phase of the shear force is adjusted by equally phasing each weight relative to the rotor.

Abstract: In one embodiment, an apparatus comprises a shaft, a rotor, and a cam surface. The shaft comprises a spiral spline along a length of the shaft. The rotor comprises a blade extending from the rotor and a tubular hole extending into the rotor. The tubular hole comprises a spiral groove configured to mate with the spiral spline on the shaft. Relative rotation between the spiral spline and the spiral groove causes the rotor to linearly move along the shaft. The cam surface comprising a recession. The blade nesting in the recession to constrains rotation of the rotor about the shaft and allows linear movement of the rotor along the shaft.

Abstract: A rotor system includes a hub assembly, a first, second, and third rotor blade rotatably attached to the hub assembly, a first, second, and third damper pivotally attached to the hub assembly and pivotally attached to the first, second, and third rotor blade, respectively, and a control system operably associated with the first, second, and third damper. A method to control vibratory forces exerted on the hub assembly via the first and second rotor blade includes separately controlling a dynamic spring rate of each of the first and second dampers with the control system.