An unmanned aerial vehicle (UAV) includes a central body, a plurality of arms extending out from the central body, and a plurality of propulsion units. Each of the plurality of arms includes a stem portion, one or more branch portions, and a joint connecting the stem portion with the one or more branch portions. The joint includes a sleeve configured to lock a position of one of the one or more branch portions relative to the stem portion. Each of the propulsion units is attached to one of the one or more branch portions of one of the plurality of arms.