Rotary wing aircraft with electric pitch control. According to the invention, each blade (5.i) of the wing comprises a plurality of flaps (6.i) which are able to control the pitch of said blade and are aligned along the span of the latter, said flaps being individually controlled in orientation from a flight control device (17). Elimination of mechanical and hydromechanical members for controlling the rotor of such an aircraft, without loss of reliability.

A technique for providing a signal representative of blade vortex interaction (BVI) noise for a multi-blade rotorcraft. The fluid (air) pressure at one, two, or more predetermined locations on a rotor blade is measured during at least one predetermined azimuthal segment of blade rotation during operation to provide respective pressure measurements. The pressure measurements are processed to provide a signal for use as a control variable in a control system for the active control of BVI noise. The pressure measurements are made within 10% blade chord length of the blade leading edge and preferably two or more are made between 65% and 95% of blade radial-length. The pressure measurements are filtered and the band of retained frequencies is between 20 and 48 times the rotor rotation frequency. An algorithm operative over a determined blade frequency range optimizes the signal for control use.

A hub mounted actuation system for providing control of a portion of a rotor blade, such as a flap, on a rotorcraft. The rotor blade is attached to a rotor shaft that rotates with respect to an airframe. The hub mounted actuation system includes a stationary support mounted to the airframe and a rotary support attached to the rotor shaft for concomitant rotation therewith. At least one hub actuator rotates in combination with the rotor blade and includes a piston which is slidable within a housing. The piston and housing define a pressure chamber within the actuator which contains a fluid to be pressurized. A displacement control device is disposed between the stationary support and the rotary support for controlling movement of the piston within the housing. A linkage connects the hub actuator to the portion of the blade to be controlled. The linkage is adapted to displace the blade portion as a function of the movement of the piston within the housing.

A flap actuation system for a helicopter rotor blade. The rotor blade includes a root end, a tip end, a trailing edge and a flap hinged to at least a portion of the trailing edge about a pivot axis. The flap actuation system includes at least one supply line mounted within the rotor blade and extending outward from the root end. The supply line is adapted to channel pressurized fluid. At least one actuator fluidly connected to the supply line. The actuator includes a displacement member and a head member. The head member is engaged with the flap and is adapted to pivot the flap about its pivot axis when pressurized fluid is conveyed through the supply line. In one embodiment of the invention there are two supply lines, each extending outward from the root end and is adapted to channel pressurized fluid. There is at least one actuator fluidly connected to each supply line. The actuator on one of the supply lines is adapted to pivot the flap upward when pressurized, and the actuator on the other supply line is adapted to pivot the flap downward when pressurized.

An actuation system for pivoting a flap on a helicopter rotor blade to reduce the interaction of the blade with the preceding blade vortex. The actuation system includes a fluid supply which is connected to first and second fluid supply lines. The fluid supply lines convey flows of pressurized fluid from the fluid supply to an actuator. The actuator includes a housing mounted within the rotor blade and having a channel formed in it. A butterfly shaft is pivotally mounted within the channel and has laterally extending arms which separate the channel into four lobes. A first port connects the first fluid supply line with two diametrically opposed lobes in the channel. A second port connects the second fluid supply line with the other two diametrically opposed lobes in the channel. A torque coupling is attached to the butterfly shaft and engaged with the flap such that rotation of the torque coupling produces concomitant rotation of the flap. The pressurization of the first fluid supply line causes the torque coupling to rotate in a first direction. The pressurization of the second supply fluid line causes the torque coupling to rotate in the opposite direction.