A linear actuator is provided. The linear actuator comprises: a body; a shaft adapted to move linearly relative to the body; a driver adapted to drive the linear movement of the shaft; and a shape memory alloy component configured to compensate for thermal expansion or contraction of the linear actuator due to a change in temperature thereof.

A linear actuator is provided. The linear actuator comprises: a body; a shaft adapted to move linearly relative to the body; a driver adapted to drive the linear movement of the shaft; and a shape memory alloy component configured to compensate for thermal expansion or contraction of the linear actuator due to a change in temperature thereof.

A rotor blade system having a plurality of rotor blades, wherein at least one of the rotor blades includes an outer surface having generally opposing first and second surfaces, the rotor blade including a fluid flow altering surface positioned relative to one of the first or second surfaces which is moveable between first and second positions, wherein movement of the fluid flow altering surface is effected by an expandable member.

A rotor blade system having a plurality of rotor blades, wherein at least one of the rotor blades includes an outer surface having generally opposing first and second surfaces, the rotor blade including a fluid flow altering surface positioned relative to one of the first or second surfaces which is moveable between first and second positions, wherein movement of the fluid flow altering surface is effected by an expandable member.

An aircraft uses trajectory-based control algorithms for blade pitch (or twist). This approach greatly enhances the ability of the actuator to accurately achieve the desired blade pitch and to track the commanded pitch position. An actuator includes an electronic rotor blade controller that converts communicated or desired changes in pitch (or similar parameter) to actual physical effects that match the desired changes as closely as possible. The controller preferably includes a motor drive circuit, such as an h-bridge, a communication circuit for connection to external commands, and a processor with associated enabling circuitry (e.g. memory, I/O) to coordinate and implement the control.

An aircraft uses trajectory-based control algorithms for blade pitch (or twist). This approach greatly enhances the ability of the actuator to accurately achieve the desired blade pitch and to track the commanded pitch position. An actuator includes an electronic rotor blade controller that converts communicated or desired changes in pitch (or similar parameter) to actual physical effects that match the desired changes as closely as possible. The controller preferably includes a motor drive circuit, such as an h-bridge, a communication circuit for connection to external commands, and a processor with associated enabling circuitry (e.g. memory, I/O) to coordinate and implement the control.

A main rotor trim tab retention system includes, a blade housing having flanges separated by a cavity defined between the flanges, and a trim tab assembly. The trim tab assembly includes, a trim tab having an aerodynamic surface, at least one arm extending from the trim tab positionable within the cavity while the trim tab extends outward from the cavity, and a spherical bearing connecting the trim tab and the at least one arm, the spherical bearing having a first axis which is substantially perpendicular to the aerodynamic surface of the trim tab. The at least one arm is pivotable about the spherical bearing about a second axis substantially perpendicular to the first axis to rotate the trim tab relative to the blade housing.

A main rotor trim tab retention system includes, a blade housing having flanges separated by a cavity defined between the flanges, and a trim tab assembly. The trim tab assembly includes, a trim tab having an aerodynamic surface, at least one arm extending from the trim tab positionable within the cavity while the trim tab extends outward from the cavity, and a spherical bearing connecting the trim tab and the at least one arm, the spherical bearing having a first axis which is substantially perpendicular to the aerodynamic surface of the trim tab. The at least one arm is pivotable about the spherical bearing about a second axis substantially perpendicular to the first axis to rotate the trim tab relative to the blade housing.

While an aircraft is mid-flight, a braking start point associated with a stoppable rotor is calculated where the stoppable rotor includes a first and second blade and the stoppable rotor is configured to rotate about a substantially vertical axis. A process to stop the stoppable rotor is started, while the aircraft is mid-flight, when the stoppable rotor reaches the braking start point, where the stoppable rotor is stopped with the first blade pointing forward and the second blade pointing backward.

According to one aspect, a lubricant level sensing system for an actuator is provided. The lubricant level sensing system includes a pressure port in an outer housing of the actuator, a pressure sensor, and a pathway from the pressure port to the pressure sensor. The pathway establishes fluid communication between the pressure sensor and a free volume of an internal cavity of the outer housing relative to a lubricant level in the internal cavity such that the pressure sensor detects a pressure of the free volume used to derive the lubricant level.