A convertible ducted fan engine and mounting system. The convertible ducted fan engine has a shroud encircling a mechanical fan. The convertible ducted fan engine includes a fluid-propulsion configuration in which the mechanical fan rotates freely with respect to the shroud to produce thrust through fluid flow, and a drive-wheel configuration in which the shroud rotates about the rotational axis. The mounting system includes at least one gimbal ring and may include a circular track system thereby enabling the convertible engine to be oriented in any direction.