Lu said, "Since most of you are pilots why can’t you reference the gyros that are spinning at great speed just a foot or two in front of your nose. Or, why can’t you reference a gimbaled gyroscope that most of us have seen in science class or flight or mechanics school."
Reread my post, where you see "hockey puck" insert the words "gimballed gyroscope".
The point is that attitude indicators, toy gyroscopes, science class gyroscopes, suspended hockey pucks, etc. all fit into the constraints that I identified. Most rotor systems do not.
Matthew.