motot constant found this at km rating ''km'' is the ''motor constant'' sometimes ''motor size constant'' defined as frac tau sqrt p where scriptstyle tau is the motor torque si units n m scriptstyle p is the resistive power loss si units w the motor constant is winding independent as long as the same conductive material used for wires e g winding a motor with turns with parallel wires instead of turns single wire will double the velocity constant kv but km remains unchanged km can be used for selecting the size of a motor to use in an application kv can be used for selecting the winding to use in the motor it look to me as if the scope is well beyond the original article and if put anywhere it should be herer