My original theoretical consideration was using the electric motor's rotor as drive shaft in a car. It led me to this question: "What will happen if we place a couple of separate, small stators around a long rotor instead of 1 large stator around a short rotor?"
I am a biology teacher. A motor design like this seems useful to me when I consider the structure of skeletal muscles. A skeletal muscle is constituted of a lot of long cells/fibers. Our body controls the force produced by the muscle by controlling the number of contracting fibers at a time. When we want to pick up a pen on the table, a few fibers are recruited; but when we want to pick up the table all fibers are recruited to generate enough force.
I guess that via changing the number of the active stators, a motor like this can be more efficient.
Is there any electric motor design like this? Or, is it possible and if it is, does it make sense from the points of efficiency and weight?