Re: Alternative mirror technologies, WAS ATM Liquid-mirror telescopes

[Chuck Knight <cknight@flash.net>]

J.O. Williams wrote:
> > I've got a question.  I've seen occasional references to mylar
> > film mirrors...pulled into a parabola with a vacuum.  What
> > makes it take on a parabolic shape?

> Take a look at the July 1997 (page 60) Scientific American.  It is
> an article on "Sail Making."  However, the sails are made out of
> kelvar and mylar.  The sails are made on large formable shapes.
> A lot of technology is devulged including vacuum shaping.

I got a response that said flat mylar doesn't form a parabola 
when drawn this way.  While I'm sure that it would be possible 
to tension a *pregenerated parabola* with a vacuum, I don't know 
if just flat mylar would be a reasonable choice.

BUT, it can't hurt to try!  And, it'd provide quick enough results,
so I may have to go ahead and try this.  I gotta' get a few supplies
first, though, like a vacuum pump and some aluminized mylar.

After a while I may try forming parabolas on large forms, much like 
the sails mentioned above...but, step ONE comes first.

In anticipation of step TWO, who has a convex tool left over, that 
I could use for a parabolic form?  (hey, y'gotta start looking for 
supplies *early!*)

     -- Chuck Knight