Abstract: A method and apparatus for moving a blade of a rotorcraft. The method comprises operating the rotorcraft and applying a torque to an elongate member connected to a tip portion of the blade during operation of the rotorcraft using a tip actuation mechanism that is external to the blade and associated with the elongate member such that the tip portion of the blade rotates about an axis through the blade.

Abstract: A porous surface on an aircraft structure driven with oscillating positive and negative pressures is used as an active control device for attenuating negative aerodynamic interactions. The porous surfaces can be driven with positive and negative pressures either continuously or when predetermined flight conditions are present. The porous surfaces can be used on rotor blades to reduce BVI noise in descent flight conditions. The porous surfaces can be configured on rotor blades for affecting blade variable twist in accordance with various flight conditions, and can further be incorporated for reducing rotor hub vibrations as well. Porous surfaces placed on aerodynamic surfaces below the rotor blades of a tiltrotor aircraft can attenuate or eliminate download and fountain flow conditions.

Abstract: A system for quasi-statically correcting tracking of rotor blades of a helicopter rotor during operation includes a trim tab mounted on each rotor blade and deflectable relative to the rotor blade so as to change a tracking path of the rotor blade, and a rotor track and balance analyzer that includes sensors for acquiring rotor tracking and balance information and is operable to process the rotor tracking and balance information so as to predetermine a new tab position to which the trim tab should be deflected for bringing the tracking path of a mistracking rotor blade into alignment with a reference path. The trim tab is deflected by an actuator mounted to the rotor blade, the actuator having an actuating element coupled with the trim tab and formed of a smart material such that the actuating element deforms proportional to a stimulus applied to the actuating element.

Abstract: A system for quasi-statically correcting tracking of rotor blades of a helicopter rotor during operation includes a trim tab mounted on each rotor blade and deflectable relative to the rotor blade so as to change a tracking path of the rotor blade, and a rotor track and balance analyzer that includes sensors for acquiring rotor tracking and balance information and is operable to process the rotor tracking and balance information so as to predetermine a new tab position to which the trim tab should be deflected for bringing the tracking path of a mistracking rotor blade into alignment with a reference path. The trim tab is deflected by an actuator mounted to the rotor blade, the actuator having an actuating element coupled with the trim tab and formed of a smart material such that the actuating element deforms proportional to a stimulus applied to the actuating element.

Abstract: A system for quasi-statically correcting tracking of rotor blades of a helicopter rotor during operation includes a trim tab mounted on each rotor blade and deflectable relative to the rotor blade so as to change a tracking path of the rotor blade, and a rotor track and balance analyzer that includes sensors for acquiring rotor tracking and balance information and is operable to process the rotor tracking and balance information so as to predetermine a new tab position to which the trim tab should be deflected for bringing the tracking path of a mistracking rotor blade into alignment with a reference path. The trim tab is deflected by an actuator mounted to the rotor blade, the actuator having an actuating element coupled with the trim tab and formed of a smart material such that the actuating element deforms proportional to a stimulus applied to the actuating element.

Abstract: An actively controlled helicopter rotor blade includes a trailing edge flap actuated by a fast-acting actuator. A lightweight, rugged, fast-acting actuator suitable for use as the flap actuator comprises a pair of column actuators composed of a smart material such as piezoelectric, magnetostrictive, shape memory alloy or other material that exhibits a shape change when subjected to an external stimulus. Each of the column actuators is composed of multiple piezoelectric ceramic actuator elements bonded together to form the individual columns. Each of the column actuators engages the base of an actuator tube that, in turn, is urged against the column actuators by a tension member. Differential voltage applied to the columns causes a differential elongation of the column actuators, which causes the actuator tube to pivot about an axis proximal the tips of the column actuators. The movement of the actuator tube is coupled by a linkage to the rotor blade flap.

Abstract: An active control system for reducing blade-vortex-interaction (BVI) noise generated by a rotor blade. The active control system includes a pressure sensor assembly, a device for changing a lift generated by the rotor blade, and a controller for activating the device upon a detected change in air pressure by the sensor assembly. The sensor assembly is disposed in close proximity to the rotor blade, and is adapted to detect a change in air pressure on a surface of the rotor blade near a leading edge of the rotor blade. The device is adapted to be activated by the controller, to thereby change a lift of the rotor blade. The controller activates the device to change a lift of the rotor blade in order to introduce a compensating pressure onto the surface of the rotor blade. This compensating pressure attenuates the magnitude of the change of air pressure.

Abstract: A pressurized porous surface near the leading edge of a rotorcraft blade, is designed to be used as an active control device which alleviates the aerodynamics of blade vortex interactions (BVI) and thus the impulsive BVI noise levels and signature. The pressurized porous surface can be actuated on an azimuth-dependent deployment schedule or actuated continuously. The pressurized porous surface is supplied with either positively pressurized air, negatively pressurized air, or a combination of both, when actuated. The pressurized porous surface targets the local blade aerodynamics, rather than the vortex strength or blade/vortex separation distance.