A system to maintain a phase difference is disclosed. Two or more aircraft fly in a continuous periodic trajectory. The system maintains a phase difference between the two or more aircraft. Telemetry information for a reference aircraft moving in a first periodic trajectory is received. A phase difference between a primary aircraft and the reference aircraft with respect to the first periodic trajectory is determined. A variance in the phase difference between the primary aircraft and the reference aircraft from the target phase difference is determined. A new trajectory for the primary aircraft that decreases the variance in the phase difference with respect to the new periodic trajectory is determined, and the primary aircraft is maneuvered to follow the new trajectory.

An unmanned aerial vehicle (UAV) can deliver a package to a delivery destination. Packages delivered by a UAV may be lowered towards the ground while the UAV continues to fly rather than the UAV landing on the ground and releasing the package. Packages may sway during lowering as a result of wind or movement of the UAV. By modulating a rate of descent of a package, a package sway may mitigated. The lowering mechanism includes wrapping a tether in various directions around the package such that the package rotates in a first and second direction as the package descends. Additionally, a rip-strip lowering mechanism that separates under tension to lower the package and a rappel mechanism that slides the package down a tether may be used. Accordingly, the tether can control a descent of the package assembly.

Embodiments relate to a client-facing application for interacting with a transport service that transports items via unmanned aerial vehicles (UAVs). An example graphic interface may allow a user to order items to specific delivery areas associated with their larger delivery location, and may dynamically provide status updates and other functionality during the process of fulfilling a UAV transport request.

The present disclosure provides various embodiments of a multicopter-assisted launch and retrieval system generally including: (1) a multi-rotor modular multicopter attachable to (and detachable from) a fixed-wing aircraft to facilitate launch of the fixed-wing aircraft into wing-borne flight; (2) a storage and launch system usable to store the modular multicopter and to facilitate launch of the fixed-wing aircraft into wing-borne flight; and (3) an anchor system usable (along with the multicopter and a flexible capture member) to retrieve the fixed-wing aircraft from wing-borne flight.

A method for unmanned delivery of an item to a desired delivery location includes receiving, at an unmanned vehicle, first data representative of an approximate geographic location of the desired delivery location, receiving, at the unmanned vehicle, second data representative of a fiducial expected to be detectable at the desired delivery location, using the first data to operate the unmanned vehicle to travel to the approximate geographic location of the desired delivery location, upon arriving at the approximate geographic location of the desired delivery location, using the second data to operate the unmanned vehicle to detect the fiducial; and upon detecting the fiducial, using the fiducial to operate the unmanned vehicle to travel to the delivery location and deliver the item.

A method for loading an Unmanned Aerial Vehicle with one or more items is disclosed. The method includes positioning one or more items in specific positions within one of the Unmanned Aerial Vehicle and a container configured to be carried by the Unmanned Aerial Vehicle based on a Center of Gravity of each of the one or more items. The method also includes securing the one or more items in the specific positions within the one of the Unmanned Aerial Vehicle and the container to prevent the one or more items from shifting and changing a combined Center of Gravity of the one or more items combined with the one of the Unmanned Aerial Vehicle and the container during a flight of the Unmanned Aerial Vehicle.

A method for loading an Unmanned Aerial Vehicle with one or more items is disclosed. The method includes determining a Center of Gravity of each of the one or more items. The method also includes matching a combined Center of Gravity of the one or more items with a Center of Gravity of the Unmanned Aerial Vehicle.

A method for loading one of an Unmanned Aerial Vehicle (UAV) and a container for the Unmanned Aerial Vehicle with one or more items is disclosed. The method includes determining a Center of Gravity (COG) of the one or more items. The method also includes loading the one of the UAV and the container for the UAV with the one or more items based on the COG of the one or more items. The method further includes positioning one or more weights relative to the one or more items and relative to the one of the UAV and the container for the UAV such that a combined COG of the one or more items, the one of the UAV and the container for the UAV, and the one or more weights is positioned within a predetermined region relative to the one of the UAV and the container for the UAV.

A method for loading an Unmanned Aerial Vehicle with multiple items is disclosed. The method includes determining a weight, size, and Center of Gravity of each of the multiple items. The method also includes positioning the multiple items relative to one another such that a combined Center of Gravity of the multiple items will be positioned within a predetermined region. The method further includes loading the multiple items onto the Unmanned Aerial Vehicle with the combined Center of Gravity of the multiple items positioned within the predetermined region.

A method for loading an Unmanned Aerial Vehicle with one or more items is disclosed. The method includes determining a weight and a Center of Gravity of each of a plurality of objects. The plurality of objects includes one or more of the Unmanned Aerial Vehicle, a container, one or more items to be delivered, and packaging for securing the one or more items to be delivered within one of the Unmanned Aerial Vehicle and the container. The method also includes optimizing a combined Center of Gravity of the plurality of objects for performing delivery by the Unmanned Aerial Vehicle.