Abstract: In an exemplary variable area nozzle, a fixed duct section has an inlet and an outlet oriented approximately perpendicular to the inlet. A controllable nozzle member is disposed adjacent the outlet of the fixed duct section. The controllable nozzle member has an area that is adjustable to maintain a substantially constant nozzle pressure ratio. The controllable nozzle member may include first and second flap doors hinged and pivotable in opposite directions between an open position and a closed position and that also may be hinged and pivotable in a same direction so thrust from gas exiting the nozzle is vectorable. When disposed in rotor tips of an aircraft capable of rotary wing flight and fixed wing flight, the variable area nozzle may maintain a substantially constant nozzle pressure ratio near an optimized nozzle pressure ratio as the aircraft transitions from rotary wing flight to fixed wing flight.

Abstract: Composite structural members are provided including a fitting and a tubular shaft. The fitting has a coupling region defining at least one recessed portion bounded by one or more non-recessed portions. The recessed portion may extend circumferentially around the fitting to form a neck. The tubular shaft has a mating region and defines a lumen in which the fitting is disposed. The mating region of the shaft mates with the coupling region of the fitting to create interference between the shaft and fitting. Adhesive may be disposed between the mating region of the fitting and the coupling region of the shaft. The mating region of the shaft may be partially and proximately surrounded by a reinforcing member, and a sleeve may be coupled substantially concentrically to the shaft for discouraging separation of the reinforcing member and the mating region of the shaft. In some cases, adhesive is disposed between the reinforcing member and sleeve.

Abstract: A composite structural member is provided. The structural member includes a tubular shaft having a mating region of stiffness, and possibly thickness, greater than another region of said shaft. The shaft defines a lumen, and a fitting is disposed in the lumen. The fitting has a coupling region that defines at least one recessed portion bounded by one or more non-recessed portions, and the mating region mates with the coupling region of said fitting. As such, the shaft and fitting are mechanically restrained from at least some relative movement due to interference of the shaft and the fitting. A sleeve may be coupled to said shaft, for example, by including a tubular inner surface that proximately surrounds at least part of said shaft and mating region, for discouraging expansion of the mating region of said shaft.

Abstract: Composite structural members are provided including a fitting and a tubular shaft. The fitting has a coupling region defining at least one recessed portion bounded by one or more non-recessed portions. The recessed portion may extend circumferentially around the fitting to form a neck. The tubular shaft has a mating region and defines a lumen in which the fitting is disposed. The mating region of the shaft mates with the coupling region of the fitting to create interference between the shaft and fitting. Adhesive may be disposed between the mating region of the fitting and the coupling region of the shaft. The mating region of the shaft may be partially and proximately surrounded by a reinforcing member, and a sleeve may be coupled substantially concentrically to the shaft for discouraging separation of the reinforcing member and the mating region of the shaft. In some cases, adhesive is disposed between the reinforcing member and sleeve.

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 device for use on an aerodynamic structure is provided. The aerodynamic structure includes an outer aerodynamic skin and an interior volume, wherein the outer aerodynamic skin surrounds the interior volume. The active control device includes at least one aperture disposed on the outer aerodynamic skin and a diaphragm disposed in the interior volume of the aerodynamic structure. The at least one aperture connects the outer aerodynamic skin to the interior volume, and the diaphragm in the interior volume is movable between a first position and a second position. Movement of the diaphragm from the first position to the second position pushes air through the at least one aperture and out of the interior volume. Movement of the diaphragm from the second position to the first position draws air through the at least one aperture and into the interior volume. The diaphragm may be circular, or may be oval-shaped.

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.