Re: Armadillo 4/18

On Mon, 19 Apr 2004, Alex Fraser wrote:
>     My calculation involve holding a pen up in the air and imagining 
> what it will do. It is not easy to do if you balance it on your finger tip.

Note, that is an unstable system, which is considerably worse than an
neutrally stable system like a rocket VTOL.  The analogy is false; the
rocket has no built-in tendency to amplify a perturbation, departing
faster and faster from the desired attitude once nudged off center. 

And as already noted, it's easier with a broomstick, which moves more
slowly and is a better match to the limited control bandwidth of the
eye-brain-hand system.

                                                          Henry Spencer
                                                       [email protected]