A modular fuselage for an unmanned aerial vehicle (UAV) includes a battery module, an avionics module, and a mission payload module. The battery module houses a battery to power the UAV. The avionics module houses flight control circuitry of the UAV. The mission payload module houses equipment associated with a mission of the UAV. The battery module, the avionics module, and the mission payload module are detachable from each other and mechanically securable to each other to contiguously form at least a portion of the modular fuselage of the UAV.