A helicopter autopilot system includes an inner loop for attitude hold for the flight of the helicopter including a given level of redundancy applied to the inner loop. An outer loop is configured for providing a navigation function with respect to the flight of the helicopter including a different level of redundancy than the inner loop. An actuator provides a braking force on a linkage that serves to stabilize the flight of the helicopter during a power failure. The actuator is electromechanical and receives electrical drive signals to provide automatic flight control of the helicopter without requiring a hydraulic assistance system in the helicopter. The autopilot can operate the helicopter in a failed mode of the hydraulic assistance system. A number of flight modes are described with associated sensor inputs including rate based and true attitude modes.

An anti-torque rotor of a helicopter, having: a supporting body; a drive shaft which rotates about a first axis with respect to the supporting body; a hub connected operatively to drive shaft and angularly fixed with respect to first axis; at least one blade which is connected operatively to hub, is angularly fixed with respect to first axis, and is angularly movable with respect to a second axis to adjust the pitch angle of blade; and an actuator which can be operated to rotate blade about second axis to adjust the pitch angle of blade; actuator has an electric motor which generates torque along the first axis; and a mechanical stage interposed between the electric motor and blade, and designed to convert the torque into rotation of blade about the respective second axes; electric motor is fixed to supporting body.

A method of controlling an electric aircraft that has a plurality of actuators that includes a plurality of electric propulsion units includes: receiving force and moment commands for the electric aircraft; determining control commands for the plurality of actuators based on the desired force and moment commands by solving an optimization problem that comprises a noise minimization term for minimizing noise generated by the electric propulsion units; and controlling the plurality of actuators according to the determined control commands to meet the force and moment commands for the electric aircraft.

A method of controlling an electric aircraft that has a plurality of actuators that includes a plurality of electric propulsion units includes: receiving force and moment commands for the electric aircraft; determining control commands for the plurality of actuators based on the desired force and moment commands by solving an optimization problem that comprises a noise minimization term for minimizing noise generated by the electric propulsion units; and controlling the plurality of actuators according to the determined control commands to meet the force and moment commands for the electric aircraft.

Embodiments are directed to systems and methods for providing a control link for an aircraft in which the control link comprises an impact-resistant structure with a redundant load path. The control link has an inner structure that is sized to carry the anticipated load of the flight control system and to meet all safety factors. The control link also has an outer structure that is sacrificial and configured to absorb impact damage during operation, thereby protecting the inner structure. The outer structure is also designed to carry the anticipated load of the flight control system on its own, independent of the inner structure, and to meet all safety factors. If the outer structure fails, the inner structure allows for continued safe operation of the flight control system. The space or cavity between the inner and outer structures may be filled with a material, such as a closed-cell foam, to improve the impact resistance of the outer structure.

Embodiments are directed to systems and methods for providing a control link for an aircraft in which the control link comprises an impact-resistant structure with a redundant load path. The control link has an inner structure that is sized to carry the anticipated load of the flight control system and to meet all safety factors. The control link also has an outer structure that is sacrificial and configured to absorb impact damage during operation, thereby protecting the inner structure. The outer structure is also designed to carry the anticipated load of the flight control system on its own, independent of the inner structure, and to meet all safety factors. If the outer structure fails, the inner structure allows for continued safe operation of the flight control system. The space or cavity between the inner and outer structures may be filled with a material, such as a closed-cell foam, to improve the impact resistance of the outer structure.

Actuators are components of machines, which move and/or control a mechanism or system. During operation, actuators can experience regeneration events, with the actuator actually generating excess energy (e.g., regenerative energy) which must be stored or dissipated to avoid damaging the power supply. An actuator motor controller is configured to implement field oriented voltage control and flux weakening voltage control without current sensors. Dissipating regenerative energy includes providing a motor controller to command a motor drive to modify an input voltage, or to dissipate regenerative energy in a dump circuit. This command can cause motor windings to dissipate regenerative energy. Systems having a plurality of actuators distribute regenerative energy from one actuator to another. A central controller provides centralized regeneration dissipation control for the plurality of actuators. A power distribution unit includes a dump resistor to dissipate regenerative energy in addition to or instead of in the actuators.

A proprotor system for a ducted aircraft includes a duct and proprotor blades surrounded by the duct. Each proprotor blade is rotatable about a respective pitch change axis. The proprotor blades are configured to change collective pitch about the pitch change axes. The proprotor blades are extendable along the pitch change axes into various positions including a retracted position and an extended position. The proprotor blades change between the retracted position and the extended position based on the collective pitch of the proprotor blades, thereby controlling a tip gap between the proprotor blades and the duct.

A proprotor system for a ducted aircraft includes a duct and proprotor blades surrounded by the duct. Each proprotor blade is rotatable about a respective pitch change axis. The proprotor blades are configured to change collective pitch about the pitch change axes. The proprotor blades are extendable along the pitch change axes into various positions including a retracted position and an extended position. The proprotor blades change between the retracted position and the extended position based on the collective pitch of the proprotor blades, thereby controlling a tip gap between the proprotor blades and the duct.

A cycloidal rotor is provided having a flexible by actuators or self-flexing blade-positioning tack, which can be brought into shape corresponding to currently desired blade orbit. This rotor can also be provided with frontal shielding or partial enclosure to assure that rotor operates at any speed as if in hovering flight; rotor track can be inclined to produce forward thrust or external thrusters can be used. Optionally in other embodiments blade orbit shape is determined by a variable cam mechanism or the inclination of blade positioning track of fixed shape to produce a change of its projected shape onto blades' plane of operation thus changing blades elliptic orbit. Blade centrifugal force countervailing mechanism is also proposed.