A rotary electromagnetic actuator comprising: two stators of a high permeability ferromagnetic structure, with one of those stators being an active stator adapted to receive excitation coil windings to produce a magnetic flux and the other stator being a passive stator, the active stator having a U-shaped cross section in a plane extending along an axis of the actuator and 2 stator poles and the passive stator being formed of a high permeability ferromagnetic plate, the two stators being axially spaced apart a predetermined distance defining an airgap dimension E, wherein the two stator poles of said active stator are spaced apart a radial distance D such that a ratio of D to E (D/E) is in a range of 2 to 5; an inertia assembly comprising: a shaft defining the axis of the actuator; a disc magnet rotor absent a yoke of high permeability magnetic material mounted on the shaft for rotating the shaft, the rotor magnet being axially magnetized with 2 pole pairs of alternating polarity; the rotor being in the air gap and spaced from each stator by a predetermined distance; whereby a magnetic flux circuit flows between the two stators through one pole of the active stator, then through the first pole pair of the rotor, then through the plate, then through the second pole pair of the rotor, then through the other pole of the active stator, and the interaction between the rotor's magnetic field and the stators' magnetic field will result in the generation of a torque delivered to the shaft. two stators of a high permeability ferromagnetic structure, with one of those stators being an active stator adapted to receive excitation coil windings to produce a magnetic flux and the other stator being a passive stator, the active stator having a U-shaped cross section in a plane extending along an axis of the actuator and 2 stator poles and the passive stator being formed of a high permeability ferromagnetic plate, the two stators being axially spaced apart a predetermined distance defining an airgap dimension E, wherein the two stator poles of said active stator are spaced apart a radial distance D such that a ratio of D to E (D/E) is in a range of 2 to 5; an inertia assembly comprising: a shaft defining the axis of the actuator; a disc magnet rotor absent a yoke of high permeability magnetic material mounted on the shaft for rotating the shaft, the rotor magnet being axially magnetized with 2 pole pairs of alternating polarity; the rotor being in the air gap and spaced from each stator by a predetermined distance; whereby a magnetic flux circuit flows between the two stators through one pole of the active stator, then through the first pole pair of the rotor, then through the plate, then through the second pole pair of the rotor, then through the other pole of the active stator, and the interaction between the rotor's magnetic field and the stators' magnetic field will result in the generation of a torque delivered to the shaft. an inertia assembly comprising: a shaft defining the axis of the actuator; a disc magnet rotor absent a yoke of high permeability magnetic material mounted on the shaft for rotating the shaft, the rotor magnet being axially magnetized with 2 pole pairs of alternating polarity; a shaft defining the axis of the actuator; a disc magnet rotor absent a yoke of high permeability magnetic material mounted on the shaft for rotating the shaft, the rotor magnet being axially magnetized with 2 pole pairs of alternating polarity; the rotor being in the air gap and spaced from each stator by a predetermined distance; whereby a magnetic flux circuit flows between the two stators through one pole of the active stator, then through the first pole pair of the rotor, then through the plate, then through the second pole pair of the rotor, then through the other pole of the active stator, and the interaction between the rotor's magnetic field and the stators' magnetic field will result in the generation of a torque delivered to the shaft.