Shaded poles in unusual electric motors

Modern machine theory has been developed to deal with motors and generators of cylindrical shape in which the conductors of both rotor and stator are contained in slots, and in which the airgap is an extremely small part of the magnetic circuit. As a result, the prediction of the performance of devices in which a large part of the magnetic path is through air is extremely difficult, but an imaginative use of the shaded-pole principle can be used to indicate, at least qualitatively, what will happen.