Within a motor are two annular relatively fixed members, and a rotor mounted for rotation in closely fitting relation therewith between the outer annular member and the inner annular member. Both the inner and outer annular members are adapted to circulate air in each of opposite radial directions through the rotor, such circulation being through circumferentially spaced passageways in the rotor having outlet ports terminating in coacting passageways of the inner and outer annular members respectively to develop thrusts which effect rotation of the rotor. The passageways in the rotor communicate with coacting passageways in the inner and outer annular radial members so that when compressed air or other fluid exits from the rotor either radially outwardly or radially inwardly it will develop a thrust on the rotor. The passageways are serially connected so that the propelling fluid can be recirculated to produce successive thrusts on the rotor whenever the fluid exits from the rotor in either a radially outward direction or a radially inward direction. Furthermore, the passageways in the rotor are specially constructed so as to develop thrust on the rotor regardless of the angular position of the rotor and at ideal angles of thrust on the rotor.