> Al W wrote:>
>  
> > Here's an excellent example. I've seen people describe their
> > reasoning
> > for going rotary. Often I would hear: "It only has three moving
> > parts,
> > therefore it's safer". I suspect that 80% of you believed that. That
> > is a
> > gross error in perspective. No maybe, it's a huge distortion. It's
> > a
> > wonderful theory, it has a component of truth in it, but totally
> > fails
> > the tests for significance.

   I can't agree with you on this one, Al.  Partly, it's not
the whole story.  In fact, your characterization of the
premise is, itself, a distortion.  

   Low parts count DOES, indeed, mean fewer things to fail,
but the simplicity means little if the parts are fragile.
Most renditions mention not only how *few* moving parts
there are, but also how _robust_ they are.  Compare the
eccentric shaft with a typical crankshaft: it is massive;
there are no rod journals to flex.  The rotors are heavier
than a whole set of pistons, but there are no true reversing
loads, just a continuous gentle change of vector.  

   It's the *combination* of low parts count AND robust
parts that made the sale.

Dale R.