Mcdonnell Douglas Helicopter Company

The Boeing Company

Friedrich K Straub

Ahmed A Hassan

Dennis K Kennedy

David B Domzalski

Terrence S Birchette

Thomas A Zientek

Robert J Murrill

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.

Apparatus, system, and method for pitching and twisting a blade of a rotorcraft

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. When placed on the trailing edges of a tip jet-exhaust driven rotor blade, the porous surfaces of the present invention can supplement the tip jet momentum of the exhaust to thereby reduce an amount of exhaust needed to drive the rotor blade.

Oscillating air jets for implementing blade variable twist, enhancing engine and blade efficiency, and reducing drag, vibration, download and ir signature

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. An electrical locking device is included which is operable when de-energized to lock the trim tab against deflection, and operable when energized to unlock to permit the trim tab to be deflected. A trim actuation control system in communication with the rotor track and balance analyzer and the locking device is arranged to energize the locking device and to supply electrical power to the actuator so as to deflect the trim tab to the new tab position predetermined in the rotor track and balance analyzer, and to then de-energize the locking device and cut off the electrical power to the actuator. Thus, electrical power is supplied to the actuator only while the trim tab is being deflected, and is then discontinued once the tab has reached the desired position and the locking device has been de-energized to lock the tab against further movement.

Helicopter in-flight rotor tracking system, method, and smart actuator therefor

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. Spherical joints are disposed between the column actuators and the actuator tube to prevent transmission of substantial bending loads to the column actuators and a mid-point support is also provided for each of the column actuators to limit the magnitude of acceleration induced bending loads, which would otherwise lead to tensile failure of the ceramic actuator elements.

Helicopter rotor blade flap actuator government interest

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. The device for changing a lift generated by the rotor blade can include at least one aperture on the rotor blade and a diaphragm in the interior of the rotor blade. The diaphragm can be activated and moved between a first position and a second position at a frequency. Movement of the diaphragm from the first position to the second position pushes air out of the at least one aperture, and movement of the diaphragm from the second position to the first position draws air into the at least one aperture.

Oscillating air jets for helicopter rotor aerodynamic control and BVI

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. This targeting can be achieved through use of negatively pressurized air (suction) blowing in a direction normal to the blade surface to reduce the rotor blade's effective thickness resulting in a smaller leading edge radius as perceived by the vortex wake, and positively pressurized air (blowing) to increase the effective thickness resulting in an increase in the leading edge radius of the blade.

Growing community of inventors

Mesa, AZ, United States of America

Friedrich K Straub