Abstract: Retention washers include a washer body having a first side and a second side opposite the first side. The washer body has a perimeter having one or more lobes, and the retention washer further includes a multi-point star-shaped hole extending through the washer body from the first side to the second side. The retention washer is configured to maintain an installation torque of an installed nut when the retention washer is positioned such that the hole circumscribes the nut. Systems for retaining a propeller assembly on a shaft may include a nut installed on a bolt, and a retention washer positioned such that the hole of the retention washer circumscribes the nut, thereby limiting rotation of the nut with respect to the bolt and retaining the nut on the bolt. The system may include a circular array of nuts and bolts, each nut having a respective retention washer positioned thereon.

Abstract: Delivery systems for aerial vehicles may provide a passive automatic delivery system that is automatically triggered during landing of the aerial vehicle. One or more arm assemblies of the delivery system may include a respective landing arm, resilient member, and package guide. The landing arm is configured to rotate in response to an applied external force, with the resilient member being operatively coupled to the landing arm and configured to bias the landing arm towards a resting position. The package delivery system automatically releases the package when a delivery condition is met, such as the landing arms of the delivery system being rotated past a threshold position. Delivery systems can thus passively and automatically ensure that all landing arms are on a landing surface before the package is released. Related methods include approaching and contacting a landing surface, and releasing the package at the landing surface of the delivery location.

Abstract: Aerial vehicles may be selectively transitioned between a fixed wing flight configuration and a vertical takeoff and landing (VTOL) configuration. In the fixed wing flight configuration, a forward propeller may rotate in a first forward plane, whereas in the VTOL configuration, the forward propeller may be tilted to rotate in a second forward plane. A forward landing arm may extend downward in the VTOL configuration and be configured to be tilted to a stowed position when the aerial vehicle is in the fixed wing flight configuration. The forward landing arm may be coupled to the forward propeller such that tilting of the forward propeller causes corresponding tilting of the forward landing arm. In some examples, a plurality of such landing arms and propellers are tilted during transitioning of the aerial vehicle, such as one or more forward propellers and landing arms and/or one or more aft propellers and landing arms.

Abstract: Methods and apparatus to guide an unmanned aerial vehicle for recovery thereof are disclosed. A disclosed example apparatus to recover an aircraft or a payload thereof includes a tether line, and markers supported by the tether line at different positions of the tether line, the markers to be detected by the aircraft, the aircraft to be guided to engage the tether line by determining positions of the markers and calculating a position of at least a portion of the tether line based on the determined position of the markers.

Abstract: A jet valve includes a valve body, a juncture operatively coupled to the valve body. The juncture having a first fluid connection fluidly coupled to a header tank and a second connection fluidly coupled to a storage tank. A spool is movably disposed within the valve body. A jet pump is fluidly coupled to a fuel pump of the header tank via a bleed line. Operation of the fuel pump pressurizes the bleed line and moves the spool to a first position to (i) close a first fluid path between the header tank and the storage tank and (ii) provide a second fluid path between the header tank and the storage tank, the second fluid path through the aperture. Depressurization of the bleed line enables the spring to move the spool to a second position to close the second fluid path and open the first fluid path.

Abstract: Methods, apparatus, systems and articles of manufacture are disclosed. A disclosed example apparatus to recover an aircraft includes a mast extending from a base, a boom extending from the mast at a first end of the boom to a second end of the boom opposite the first end, a tether line extending between the mast to the base and guided by the boom, a portion of the tether line extending between the second end of the boom and the base, and a mount to operatively coupled the a kite to the tether line, the kite to support the tether line as the aircraft contacts the portion for recovery thereof.

Abstract: Apparatus and methods for controlling unmanned systems (UMSs), such as unmanned aircraft, are provided. A UMS can be provided that includes a physical computer, one or more auxiliary systems for the UMS, and a payload. The physical computer can execute software to cause the physical computer at least to instantiate a plurality of virtual computers that include a mission virtual computer and a payload virtual computer for: controlling the one or more auxiliary systems for the UMS using the mission virtual computer, communicating with the payload using the payload virtual computer, determining whether a software fault has occurred on one virtual computer of the plurality of virtual computers, and after determining that a software fault has occurred on one virtual computer of the plurality of virtual computers, preventing the software fault from causing a fault on a different virtual computer of the plurality of virtual computers.

Abstract: A method for detecting change in a pair of sequential images. The method includes training a feature descriptor based on a generated training set of matching and non-matching image pairs. An imaging subsystem captures a pair of substantially sequential images of a field of view. The pair of captured images is aligned and then transformed into corresponding arrays of patches. A matching and non-matching probability is determined for each pair of adjacent patches based on the feature descriptor. Each pair of patches is classified as matching or non-matching based on a comparison of the matching and non-matching probability. A mask is generated identifying the pairs of patches that indicate change and then displayed overlaid on at least one of the sequential images to indicate change on a user interface.

Abstract: Methods and apparatus to recover rotorcraft are disclosed. A disclosed example apparatus includes a rotor of a vehicle, a rotatable hub to support the rotor, and a rotor hook disposed on the rotor. The rotor hook has a groove to receive a recovery line. The rotor is to contact the recovery line when the vehicle is flown toward the recovery line.

Abstract: Apparatus and methods for controlling unmanned systems (UMSs), such as unmanned aircraft, are provided. A UMS can be provided that includes a network, auxiliary systems, and a payload, where the network can connect the auxiliary systems and the payload. A network switch of the network can logically separate the network into at least a second tier of communications and a third tier of communications. The network can be used to control the UMS by at least: controlling the auxiliary systems using messages communicated by the second tier of communications, and communicating with the payload using messages communicated by the third tier of communications.

Abstract: Apparatus and methods for controlling an aircraft and/or a vehicle are described. A vehicle speed and direction are received. A wind-over-vehicle speed and direction of wind at the vehicle are measured. An aircraft ground speed and direction are received. An aircraft-relative-to-vehicle speed and an aircraft-relative-to-vehicle direction are calculated based on the aircraft ground speed and direction and the wind-over-vehicle speed and direction. A wind-over-vehicle envelope is calculated based on system design limits for retrieving the aircraft at the vehicle. The wind-over-vehicle envelope maps limits of wind-over-vehicle speeds over a range of directions that enable retrieval of the aircraft at the vehicle. The aircraft and/or the vehicle are controlled using the wind-over-vehicle envelope, the aircraft-relative-to-vehicle speed, and/or the aircraft-relative-to-vehicle direction.

Abstract: A method for detecting change in a pair of sequential images. The method includes training a feature descriptor based on a generated training set of matching and non-matching image pairs. An imaging subsystem captures a pair of substantially sequential images of a field of view. The pair of captured images is aligned and then transformed into corresponding arrays of patches. A matching and non-matching probability is determined for each pair of adjacent patches based on the feature descriptor. Each pair of patches is classified as matching or non-matching based on a comparison of the matching and non-matching probability. A mask is generated identifying the pairs of patches that indicate change and then displayed overlaid on at least one of the sequential images to indicate change on a user interface.