Abstract: Retraction of a landing gear assembly on an aircraft is actuated by a hydraulic actuator. The actuator includes a piston that travels within a cylinder along a stroke length between a first position corresponding to the landing gear assembly when extended and a second position corresponding to the landing gear assembly when retracted. The movement of the piston along its stroke length is snubbed at one end by a different amount according to the direction of travel, for example by use of an orifice plate that has a discharge coefficient that is greater in one direction than in the opposite direction. Asymmetric snubbing is thus provided, which enables the landing gear to retract faster.

Abstract: Processes for optimizing the geometry of a blade for use in a propeller are disclosed. In one exemplary process, an optimization routine that generates new blade geometries based on structural parameters and calculates performance parameters of each blade geometry, including aerodynamic performance parameters, farfield acoustic parameters, and/or electrical power requirements to operate a propeller having the blade geometry, is performed. The optimization routine receives design parameters and weightings from a user and can use one or more surrogate algorithms to map a design space of the weighted values of the design parameters to find their local minima. The optimization routine then determines an optimized blade geometry using a gradient-based algorithm to generate new blade geometries to explore the minima until the weighted values of the design parameters converge at an optimized blade geometry representing the global minima of the design space.

Abstract: A center biased actuator having an outer cylinder, a slave cylinder linearly transposed within the outer cylinder, a rod assembly with a piston linearly transposed within the slave cylinder and a rod extending from the outer cylinder, one or more first dynamic seals arranged to act on a sidewall of the rod to inhibit hydraulic fluid leaking from the outer cylinder, one or more second dynamic seals arranged to act on a sidewall of the slave cylinder or an inner surface of the outer cylinder to inhibit hydraulic fluid leaking from the outer cylinder, and a gas chamber comprising a sealed expandable chamber containing gas. The expandable chamber is arranged to act on hydraulic fluid within the center biased actuator to bias the center biased actuator to assume an intermediate condition which lies between a compressed condition and an extended condition.

Abstract: Retraction of a landing gear assembly on an aircraft is actuated by a hydraulic actuator. The actuator includes a piston that travels within a cylinder along a stroke length between a first position corresponding to the landing gear assembly when extended and a second position corresponding to the landing gear assembly when retracted. The movement of the piston along its stroke length is snubbed at one end by a different amount according to the direction of travel, for example by use of an orifice plate that has a discharge coefficient that is greater in one direction than in the opposite direction. Asymmetric snubbing is thus provided, which enables the landing gear to retract faster.

Abstract: A center biased actuator having an outer cylinder, a slave cylinder linearly transposed within the outer cylinder, a rod assembly with a piston linearly transposed within the slave cylinder and a rod extending from the outer cylinder, one or more first dynamic seals arranged to act on a sidewall of the rod to inhibit hydraulic fluid leaking from the outer cylinder, one or more second dynamic seals arranged to act on a sidewall of the slave cylinder or an inner surface of the outer cylinder to inhibit hydraulic fluid leaking from the outer cylinder, and a gas chamber comprising a sealed expandable chamber containing gas. The expandable chamber is arranged to act on hydraulic fluid within the center biased actuator to bias the center biased actuator to assume an intermediate condition which lies between a compressed condition and an extended condition.

Abstract: A center biased actuator having an outer cylinder, a slave cylinder linearly transposed within the outer cylinder, a rod assembly with a piston linearly transposed within the slave cylinder and a rod extending from the outer cylinder, one or more first dynamic seals arranged to act on a sidewall of the rod to inhibit hydraulic fluid leaking from the outer cylinder, one or more second dynamic seals arranged to act on a sidewall of the slave cylinder or an inner surface of the outer cylinder to inhibit hydraulic fluid leaking from the outer cylinder, and a gas chamber comprising a sealed expandable chamber containing gas. The expandable chamber is arranged to act on hydraulic fluid within the center biased actuator to bias the center biased actuator to assume an intermediate condition which lies between a compressed condition and an extended condition.

Abstract: Processes for optimizing the geometry of a blade for use in a propeller are disclosed. In one exemplary process, an optimization routine that generates new blade geometries based on structural parameters and calculates performance parameters of each blade geometry, including aerodynamic performance parameters, farfield acoustic parameters, and/or electrical power requirements to operate a propeller having the blade geometry, is performed. The optimization routine receives design parameters and weightings from a user and can use one or more surrogate algorithms to map a design space of the weighted values of the design parameters to find their local minima. The optimization routine then determines an optimized blade geometry using a gradient-based algorithm to generate new blade geometries to explore the minima until the weighted values of the design parameters converge at an optimized blade geometry representing the global minima of the design space.

Abstract: A center biased actuator having an outer cylinder, a slave cylinder linearly transposed within the outer cylinder, a rod assembly with a piston linearly transposed within the slave cylinder and a rod extending from the outer cylinder, one or more first dynamic seals arranged to act on a sidewall of the rod to inhibit hydraulic fluid leaking from the outer cylinder, one or more second dynamic seals arranged to act on a sidewall of the slave cylinder or an inner surface of the outer cylinder to inhibit hydraulic fluid leaking from the outer cylinder, and a gas chamber comprising a sealed expandable chamber containing gas. The expandable chamber is arranged to act on hydraulic fluid within the center biased actuator to bias the center biased actuator to assume an intermediate condition which lies between a compressed condition and an extended condition.

Abstract: An assembly useful for providing structural reinforcement and/or sound/vibration damping to a hollow member of a motor vehicle is provided which contains an injection-molded carrier made of a heat resistant thermoplastic composition, at least one of the first side and the second side of the carrier has at least one receptacle adapted to receive and retain an insert comprised of a heat-expandable resin composition. The carrier may have a plurality of openings in at least one of the first side or the second side forming a grid or lattice and the assembly may include a mounting member adapted to fasten the carrier to an interior wall of a hollow member.

Abstract: An aircraft drive system having a fully electric speed-proportional control and drive system for the nose wheel of an aircraft in which variable steering authority is accomplished by monitoring of the signal from a tiller and rudder pedals by a nose wheel controller in conjunction with the speed of the aircraft, in order to command and power an electromechanical steering, actuator to achieve speed-proportional variable steering authority. This provides a system with a quicker response time than current hydraulic-based systems which can help reduce nose wheel shimmy, eliminate certain nose wheel steering failure modes associated with hydraulic systems, and reduce weight when used in small-to-medium sized aircraft.

Abstract: An assembly useful for providing structural reinforcement and/or sound/vibration damping to a hollow member of a motor vehicle is provided which contains an injection-molded carrier made of a heat resistant thermoplastic composition, at least one of the first side and the second side of the carrier has at least one receptacle adapted to receive and retain an insert comprised of a heat-expandable resin composition. The carrier may have a plurality of openings in at least one of the first side or the second side forming a grid or lattice and the assembly may include a mounting member adapted to fasten the carrier to an interior wall of a hollow member.