Foldable multi-rotor aerial vehicle

An unmanned aerial vehicle includes a central body, a plurality of arms extendable from the central body, and one or more joints. Each of the plurality of arms is configured to support one or more propulsion units, and is configured to transform between (1) a flight configuration in which the arm is extending away from the central body and (2) a compact configuration in which the arm is folded against the central body. Each joint is configured to couple one arm to the central body. At least one of the one or more joints includes an elastic element configured to cause at least one of the plurality of arms to automatically retract when the at least one of the plurality of arms is reversibly folded to a first predetermined state, and automatically extend when the at least one of the plurality of arms is reversibly extended to a second predetermined state.