A rotor or propeller may have rotor blades and a passive pitch angle adjustment apparatus. The passive pitch angle adjustment apparatus may include levers, rods, and central rod. Levers may be connected to rotor blades and rotate them around a respective pitch axis. Rods may be connected to levers and mechanically link levers with each other via central point that is located outside rotor plane. Central rod may connect central point with base point that is located in a longitudinal direction of rotor axis. The passive pitch angle adjustment apparatus may enable a cyclic pitch adjustment of the rotor blades and block a collective pitch adjustment of the rotor blades.

An unmanned aerial vehicle (UAV) includes a central part, a frame assembly, and a propulsion assembly mounted to the frame assembly. The UAV also includes a servo mounted to the central part. The servo includes a driving apparatus, a control apparatus operably coupled with the driving apparatus, and a sensor configured to obtain operating parameters of the driving apparatus. The operating parameters include operating positions of the driving apparatus. The control apparatus is configured to control the driving apparatus to rotate to a predetermined position and stay at the predetermined position based on the operating positions of the driving apparatus obtained by the sensor.

Embodiments are directed to obtaining data from at least one sensor, processing, by a processor, the data to determine an independent rotor phase lag for each of a plurality of axes associated with a rotorcraft, and issuing, by the processor, at least one command to provide for on-axis moments in accordance with the independent rotor phase lag for each of the axes.

A rotor system including a rotor hub, and a plurality of rotor blades. Each of the plurality of rotor blades includes a hub end. A plurality of rotor blade actuators is operatively connected to the hub end of a corresponding one of the plurality of rotor blades. A fairing is mounted to the rotor hub. The fairing includes an external surface and an internal surface defining an interior portion. The hub end and rotor blade actuator of each of the plurality of rotor blades is arranged in the interior portion. A cooling system is arranged in the interior portion. The cooling system includes a first heat exchanger thermally connected to each of the plurality of rotor blade actuators, a second heat exchanger mounted to the fairing, and at least one fluid conduit extending therebetween.

A rotor blade pitch actuator has a first and second motor configured to control the rotor blade pitch. An actuator control system is configured to drive the first and second motor such that backlash is either eliminated from the system or minimized to an acceptable level.

A rotor system including a rotor hub, and a plurality of rotor blades. Each of the plurality of rotor blades includes a hub end. A plurality of rotor blade actuators is operatively connected to the hub end of a corresponding one of the plurality of rotor blades. A fairing is mounted to the rotor hub. The fairing includes an external surface and an internal surface defining an interior portion. The hub end and rotor blade actuator of each of the plurality of rotor blades is arranged in the interior portion. A cooling system is arranged in the interior portion. The cooling system includes a first heat exchanger thermally connected to each of the plurality of rotor blade actuators, a second heat exchanger mounted to the fairing, and at least one fluid conduit extending therebetween.

Systems and methods are contemplated for favorably improving flight dynamics of aircraft, including enhanced aerodynamic braking and improved flight maneuverability. Air braking systems selectively position a first set of blades at a negative thrust pitch to product a net negative thrust across first and second sets of blades, while balancing torque of the drive shafts to zero. First and second sets of IBC blades can be driven by the same shaft or torque-linked shafts. Flight maneuver systems operate a powerplant at a high power mode, and dissipate the energy from the high power output by positioning a first set of IBC blades at a low efficiency pitch while maintaining constant thrust. As increased or rapid flight maneuverability is required, the first set of blades is positioned toward a high efficiency pitch to instantly increase thrust to the aircraft without requiring a related increase in energy output from the powerplant.

In one aspect, a rotor assembly includes a hub and a plurality of rotor blades; at least one blade root actuator configured to adjust at least one of the plurality of rotor blades independently of the other rotor blades to accommodate forces on the aircraft; and at least one controller couplable to the at least one blade root actuator and configured to send signals to the at least one blade root actuator to enable adjustment of the at least one of the plurality of rotor blades. In another embodiment, at least one blade flap is associated with a rotor blade can be actuated to adjust the shape of the rotor blade. In some embodiments, there are methods and systems incorporating at least one of the root blade actuator and the blade flap for stabilizing a tiltrotor aircraft by counteracting destabilizing forces on at least one rotor blade.

Disclosed is a system for controlling acoustic radiation from an aircraft. The system comprising a plurality of rotor systems (one or more) and a noise controller configured to regulate acoustic radiation from the plurality of rotor systems. The noise controller can be configured to regulate a commanded flight setting from the flight control system and to output a regulated flight setting to the plurality of rotor systems. Based on the regulated flight setting, the plurality of rotor systems are configured to generate, individually and in aggregate, acoustic radiation having a target acoustic behavior. The target acoustic behavior may be achieved using beamforming techniques to, for example, change the directionality of acoustic radiation from the plurality of rotor systems, or otherwise tune the acoustic radiation to reduce detectability and/or annoyance.

Embodiments are directed to obtaining data from at least one sensor, processing, by a processor, the data to determine an independent rotor phase lag for each of a plurality of axes associated with a rotorcraft, and issuing, by the processor, at least one command to provide for on-axis moments in accordance with the independent rotor phase lag for each of the axes.