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 cyclic stick for transmitting control commands to blades of a rotorcraft via at least one transmission member, including a grip configured for engagement with a pilot's hand, a control arm and at least one locking mechanism. The control arm has a bottom end configured for connection to the transmission member(s) and for rotational connection to a base support structure, and a top end pivotally connected to the grip. The control arm includes first and second arm portions pivotally connected to each other, the first arm portion defining the bottom end, the second arm portion defining the top end. The locking mechanism(s) selectively prevent a relative pivoting motion between the first and second arm portions and a relative pivoting motion between the second arm portion and the grip. A method of adjusting a position of a grip of a cyclic stick in a rotorcraft cabin is also discussed.

Abstract: A vibration attenuator for a rotor is rotatable about a mast axis and has a frame configured for rotation about the mast axis relative to the rotor. A first mass is axially translatable in a first direction relative to the frame parallel to a first axis, and a first biasing force urges the first mass toward a first-mass rest position in which the first mass is symmetric about the mast axis. A second mass is axially translatable in a second direction relative to the frame parallel to a second axis, and a second biasing force urges the second mass toward a second-mass rest position in which the second mass is symmetric about the mast axis. A selected first or second mass moves radially outward from the rest position to oppose vibrations in the rotor.

Abstract: An aircraft has a vertical takeoff and landing fight mode and a forward flight mode. The aircraft includes an airframe with first and second M-wings having first and second pylons extending therebetween, each M-wing forming a pair of leading apexes with swept forward and swept back portions extending therefrom at a swept angle. A propulsion system includes a plurality of propulsion assemblies each attached to the airframe proximate one of the leading apexes. Each of the propulsion assemblies includes a rotor assembly having a tilting degree of freedom. A flight control system is operable to control the propulsion assemblies including tilting the rotor assemblies to generate variable thrust vectors. In the vertical takeoff and landing fight mode, the aircraft operates responsive to thrust-borne lift from the propulsion system. In the forward flight mode, the aircraft operates responsive to wing-borne lift in a biplane orientation.

Abstract: An inlet barrier filter system for a tiltrotor aircraft comprising a filter duct extending from a filter to a filter outlet, a ram air duct extending from a ram air inlet to an engine where the filter duct connects to the ram air duct at the filter outlet, and a closure member movable between a first position blocking the ram air duct and a second position blocking the filter outlet. In use, the inlet barrier filter system provides for two mutually exclusive air flow paths, one for introducing ram air to the engine while closing off the filter and another air flow path for introducing filtered air to the engine while closing off the ram air duct.

Abstract: An aircraft system includes a wing member and a plurality of unmanned aircraft systems selectively connectable to the wing member. The wing member has a generally airfoil cross-section, a leading edge and a trailing edge. The unmanned aircraft systems have a connected flight mode while coupled to the wing member and an independent flight mode when detached from the wing member. In the connected flight mode, the unmanned aircraft systems are operable to provide propulsion to the wing member to enable flight. The unmanned aircraft systems are operable to be launched from the wing member to perform aerial missions in the independent flight mode and are operable to be recovered by the wing member and returned to the connected flight mode. Thereafter, in the connected flight mode, the unmanned aircraft systems are operable to be resupplied by the wing member.

Abstract: A high stiffness hub assembly for a rotor system operable to rotate with a mast of a rotorcraft. The hub assembly includes a yoke and a constant velocity joint assembly. The yoke has a plurality of blade arms each configured to hold a rotor blade. The constant velocity joint assembly provides a torque path from the mast to the yoke that includes a trunnion assembly, a plurality of drive links and a plurality of pillow blocks. The trunnion assembly is coupled to the mast and has a plurality of outwardly extending trunnions. Each drive link has a leading bearing coupled to one of the trunnions and a trailing bearing coupled to one of the pillow blocks. Each pillow block is independently mounted between an upper surface of the yoke and a hub plate.

Abstract: A method of assisting in rotor speed control in a rotorcraft can include measuring a rotor speed with a sensor; detecting a droop in the rotor speed beyond a lower droop limit; and commanding a decrease in collective in response to the rotor speed drooping beyond the lower droop limit. A system of assisting in rotor speed control in a rotorcraft, the system can include: a computer having a control law, the control law operable to generate a decrease collective command to an actuator in response to a rotor speed decreasing below a lower droop limit; wherein the lower droop limit is below a normal lower rotor speed range.

Abstract: Systems and methods include providing an aircraft with a fuselage and a wing assembly rotatable relative to the fuselage about a stow axis between a flight position and a stowed position. The aircraft includes a drive component having a retractable driveshaft that selectively engages the mid-wing gearbox via axially translatable motion along a rotation axis when the wing assembly is in the flight position. The mid-wing gearbox is misaligned with the retractable driveshaft when the wing assembly is in the stowed position. A seal is coupled to the drive component at a first end and the mid-wing gearbox at a second end and deploys in order to maintain a sealed connection between the drive component and the mid-wing gearbox when the wing assembly is transitioned between the flight position and the stowed position.

Abstract: Systems and methods include providing an aircraft with a fuselage and a wing assembly rotatable relative to the fuselage about a stow axis between a flight position and a stowed position. The aircraft includes a gearbox having a retractable driveshaft that selectively engages the mid-wing gearbox via axially translatable motion along a rotation axis when the wing assembly is in the flight position. The retractable driveshaft also selectively disengages the mid-wing gearbox in the flight position to allow selectively rotation of the wing assembly about the stow axis from the flight position to the stowed position resulting in the mid-wing gearbox being misaligned with the retractable driveshaft when the wing assembly is in the stowed position.

Abstract: An inboard bearing attachment for carrying centrifugal force (“CF”) loads in a rotor blade assembly of a rotorcraft includes a CF fitting having a curved surface and a shear bearing retainer aligned with the curved surface. A mounting flange connected to either the CF fitting or the shear bearing retainer is used to mount the inboard bearing attachment to a yoke.

Abstract: A method of operating an automated fiber placement machine including determining an effective length and a steering radius of a localized curved portion of a path and obtaining data including combinations of effective length and steering radius reference values each associated with a corresponding one of maximum speed values. A predetermined defect is avoided when the tape is laid along a curved path characterized by any of the combinations of effective length and steering radius reference values and laid at the corresponding maximum speed value. The method further includes determining a maximum speed based on the maximum speed values of the data in function of a correspondence between the effective length and the steering radius of the curved path and the combinations of effective length and steering radius reference values, selecting a speed for laying the tape being at most the maximum speed, and laying the tape on the surface.

Abstract: An engine mount assembly for coupling an engine to an airframe includes a torsion bar, a lateral movement control assembly and a vertical movement control assembly. The torsion bar has a torsional stiffness and is coupled between the engine and the airframe such that torsional movement of the engine causes torsion in the torsion bar. The lateral movement control assembly has a lateral stiffness and is coupled between the torsion bar and the airframe such that lateral movement of the engine causes rotation of the torsion bar which reacts on lateral movement control assembly. The vertical movement control assembly has a vertical stiffness and is coupled between the engine and the airframe such that vertical movement of the engine reacts on the vertical movement control assembly. The engine mount assembly, thereby enables torsional, lateral and vertical movement of the engine to be independently controlled.

Abstract: A rotor hub comprises a gimbal assembly and an elastomeric centrifugal force bearing. The gimbal assembly is configured to transfer rotational movement of a mast to the rotor hub and to enable the rotor hub to flap relative to the mast. The elastomeric centrifugal force bearing is configured to withstand centrifugal force of a rotor blade when the mast is rotated and is configured to accommodate pitch changes of the rotor blade. A method comprises designing a gimbal assembly that enables a tail rotor hub to flap relative to a tail rotor mast. A centrifugal force bearing is selected that enables tail rotor blades to withstand centrifugal force and that allows for tail rotor blade pitch change articulation. Then, instructions are provided to use the gimbal assembly and the centrifugal force bearing in an in-plane tail rotor assembly.

Abstract: In accordance with an embodiment, a method of operating a rotorcraft includes operating the rotorcraft in a position hold mode by determining whether GPS position data is usable, receiving a position of the rotorcraft from a GPS sensor, determining a position error based on received GPS position data and a held position when the GPS position data is usable, determining the position error based on a rotorcraft velocity when the GPS position data is not usable, and transmitting an actuator command based on the determined position error.

Abstract: A tiltrotor aircraft has a fuselage and a wing having upper and lower surfaces with a plurality of channels extending therebetween, each with a cycloidal rotor mounted therein. At least two pylon assemblies are rotatably coupled to the wing to selectively operate the tiltrotor aircraft between helicopter and airplane flight modes. Each pylon assembly includes a mast and a proprotor assembly operable to rotate with the mast to generate thrust. At least one engine provides torque and rotational energy to the proprotor assemblies and the propulsion assemblies. Each of the cycloidal rotors has a plurality of blades that travels in a generally circular path and has a plurality of pitch angle configurations such that each cycloidal rotor is operable to generate a variable thrust and a variable thrust vector, thereby providing vertical lift augmentation, roll control, yaw control and/or pitch control in the helicopter flight mode.

Abstract: An interconnect drive system for an aircraft has a driveline and clutch control system. The driveline comprises a shaft for each propulsion assembly, each shaft for transferring torque to and from the associated propulsion assembly, and a clutch operably coupling the shafts and configured for selective engagement. The clutch is capable of transferring a first amount of torque between the shafts while engaged and a second amount of torque between the shafts while disengaged. The system also has a clutch control system, comprising a computer operably connected to the clutch for controlling operation of the clutch and sensors for sensing torque applied to the driveline, output from the sensors being communicated to the computer. The computer commands operation of the clutch in response to the output from the sensors, the clutch being commanded to disengage to relieve a transient torque imbalance in the driveline.

Abstract: In accordance with an embodiment of the present invention, a method of operating a rotorcraft includes receiving a measured yaw rate from a yaw rate sensor or a measured lateral acceleration from a lateral acceleration sensor of the rotorcraft, filtering the measured yaw rate or the measured lateral acceleration using a filter to form a filtered measured yaw rate or a filtered measured lateral acceleration, and regulating a yaw rate or a lateral acceleration of the rotorcraft based on the measured yaw rate or the measured lateral acceleration. The filter includes a bandpass characteristic or a notch characteristic, and the filtering is configured to reduce lateral vibrations caused by airflow in a tail section of the rotorcraft.

Abstract: A ring gear includes a ring having one or more sets of inwardly facing teeth, a circumferential flange extending outward from the ring, and the flange is mounted between a first housing and a second housing. In addition, the flange protrudes into an ambient air outside the first housing and second housing.