One minor point here. The reason there is heat is not because of the prop, well, not totally. Heat is a waste, a byproduct of the way a motor is made. Ideally, if the prop turned and there was no heat, then all of the energy would be going into the prop. It would be 100% efficient.

That's just not so.

Part goes to turn the prop, part goes into making the heat. Just like glow fuel engines. Part of the fuel goes to run the engine, part goes to cool it off, and part goes right out the exhaust unused.

CGr.