JLN Labs is currently developing a “a machine that can demonstrate the ability to ‘hover close to its control-ground station, providing a surveillance capability for convoys, security force bases and other roles.'” Continue reading for a video.
Basically, the Coanda Effect is the tendency of a fluid (air included) to stick to a curved surface, so that a small propeller can be mounted above a larger body, with the lift created by the propeller flowing around the body and thrusting down to provide lift
[via OhGizmo!]