RC-FIEND....I think your intention was good but you gave a wrong analogy. Maybe a better one would have been a helicopter rotor because that's an extreme example of a very large diameter prop. It turns slow but gives huge thrust.
I am glad you admit you don't understand so lets take it step by step.
A prop, lets say that folds up and down like on a glider, will A rotate much faster while the prop is reaching it's peak extension and will spin slower when the prop is full extended . How much slower I am not going to prove, but its obvious the longer the prop is, means more resistance while it is in motion and thus for it spins slower
A heli prop is no different from an airplane prop , it is only mounted differently and because of the size of it , more thrust is created allowing it to lift the heli straight into the air. OH that would be the same as an airplane doing 3D hovering ! [X(] .
So although I may not explain every thing to a tee I hope this clears things up a little.