Inertia is a property of matter by which it continues in its existing state of rest or uniform motion in a straight line, unless that state is changed by an external force. Celera Motion standard rotors look much like a cylinder. The inertia formula for a cylinder = density*1.57*Length*(Ro^4-Ri^4), where density is the material density, length is the length of the rotor cylinder, Ro is the outer radius of the rotor and Ri is the inner radius. Since our rotors are combined of magnet material and steel, the density of each could be averaged, or the two inertias can be calculated separately, and added together.
