An unmanned air module includes one or more rotors, engines, a transmission and avionics. Any of several different ground modules may be attached to the air module. The air module may fly with and without the ground module attached. The ground module may be a vehicle ground module and may be manned. The vehicle ground module may transport the attached air module across the ground. The air module may have two rotors, which may be ducted fans, and three different configurations: a tandem rotor configuration, a side-by-side configuration, and a tilted-rotor configuration.