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.

An unmanned aerial vehicle (UAV) includes a central body and a plurality of landing gears that are extendable from and movable relative to the central body. The plurality of landing gears are configured to transform between a flight configuration and a surface configuration. In the flight configuration, the landing gears are extending laterally away from the central body and not in contact with a surface below the central body. In the surface configuration, the landing gears are extending towards the surface below the central body. When the landing gears are in the surface configuration, the landing gears are configured to support a weight of the central body on the surface and transport the UAV over the surface by moving one or more of the landing gears relative to the surface.

Systems and methods for enabling aircraft shock strut shrink are provided. The system may comprise a shock strut comprising a shrink piston, an accumulator comprising a gas piston and a hydraulic chamber, wherein the gas piston is configured to apply gas pressure to the hydraulic chamber, and a first valve in fluid communication with the accumulator. The system may further comprise a second valve, wherein the second valve is in fluid communication with a vent, the pneumatic cylinder, and the gas piston, wherein the first valve is in fluid communication with the hydraulic chamber and the shrink piston.

A shrink mechanism for use with a landing gear of an aircraft. The landing gear includes an outer cylinder rotatably coupled to a frame of an aircraft about a trunnion axis of rotation and a shock strut assembly movably coupled to the outer cylinder so as to reciprocate along a longitudinal axis of the outer cylinder. The shrink mechanism incudes a first shrink link member pivotally coupled to the outer cylinder, a second shrink link member coupling the first shrink link member to the shock strut assembly, a crank member pivotally coupled to the outer cylinder, a drive member coupling the crank member to a walking beam of a landing gear retract mechanism, and a driven member coupling the crank member to the first shrink link member.

An aircraft landing gear includes a shock strut with a rod slidably received within a cylinder. A beam is rotatably mounted to the rod, and wheels are mounted to the beam. The landing gear further includes a link assembly with an upper link and a lower link. The upper link has a first end rotatably connected to the cylinder, and the lower link has a first end rotatably connected to the beam. The second ends of the upper and lower links are rotatably coupled to each other by a limiter joint. The limiter joint includes a first stop associated with the upper link and a second stop associated with the lower link. The stops are configured such that the first stop engages the second stop to limit rotation of the upper link relative to the lower link.

Methods and systems are provided that facilitate the maintenance of levered landing gears by monitoring the condition of the stop pads of such landing gears. One embodiment provides for calibrating a sensor for measuring a condition of a stop joint formed by a first stop pad and a second stop pad of a levered landing gear against a nominal condition of at least one of the first stop pad and the second stop pad; monitoring, by the sensor, a current condition of the at least one of the first stop pad and the second stop pad from the nominal condition; determining whether a non-conformance from the nominal condition of the at least one of the first stop pad and the second stop pad has been detected by the sensor for the current condition; and in response to determining that the non-conformance has been detected, generating an alert.

A vehicle includes a fuselage having a longitudinal axis and a propulsion system that is coupled to the fuselage. The vehicle also includes a pair of articulated appendages that is coupled to the fuselage. Each one of the articulated appendages includes a plurality of airfoil segments and is moveable between a ground configuration, in which each one of the pair of articulated appendages supports the vehicle during takeoff or landing of the vehicle, and a flight configuration, in which each one of the pair of articulated appendages produces lift during flight of the vehicle.

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.

A system for shrinking landing gear includes a shock strut having a cylinder and a piston to be received by the cylinder. The system further includes an upper cam fastened to the piston and a lower cam fastened to the cylinder. The system further includes a brace configured to be coupled to the shock strut to lock the landing gear in a deployed position, and to fold towards the shock strut during retraction of the landing gear. The system further includes a collar coupled to the brace and the piston and configured to rotate relative to the cylinder in response to folding of the brace such that rotation of the collar rotates the piston and the upper cam relative to the lower cam, the rotation of the upper cam relative to the lower cam forcing the piston towards the aircraft attachment within the cylinder.

A latch assembly for a shock strut may comprise a first linkage coupled to a strut cylinder and a shrink piston of the shock strut. A second linkage may be coupled to the strut cylinder. The second linkage may be configured to rotate the first linkage in response to the shock strut translating between a landing gear up position and a landing gear down position.