From: "Russell Jocoy" 
To: milnecd{at}yahoo.com, atm{at}shore.net
Reply-To: "Russell Jocoy" 


>From: Clive Milne 
>Reply-To: Clive Milne 
>To: atm{at}shore.net
>Subject: Re: ATM Truss design thoughts.
>Date: Wed, 23 Jul 2003 10:14:26 -0700 (PDT)
>
>
>
>"John Sherman"  wrote:
>    Thus I think
> > that the upper and lower trusses can be made out of
> > much smaller diameter tubing saving a lot of weight.
> > Anybody have any thought about reducing the left and
> > right truss diameters?
>
>    Tom K has done some interesting research on various different
>truss configurations and has posted real performance data on his
>web page (absolutely worth reading).  One comment I will pass though,
>and this is not to be implied as criticism of Tom's work, is that
>asside from any conclusions that you might draw from the _RELATIVE_
>performance of any given truss, be mindful of the _ABSOLUTE_
>deflection values given (even in the worst case).
>From this data and the experimental work of myself and others, we
>can conclude that a (properly designed) truss made from tubes of a
>diameter sufficient to resist buckling, will be plenty strong enough
>to make a supremely rigid telescope.   ie) For a 20" telescope,
>anything larger than 3/4" (19mm) is just a waste of materials.
>    So to answer your question. Yes, by all means reduce the
>diameter of ALL the truss tubes. (3/4" will be fine) If your scope
>still vibrates, I'd wager it's not the truss tubes at fault.
>It might be time to take a good hard analytical look at the whole
>design from the ground up.  Just because everyone has built them
>basically the same way for for the last 15 years doesn't make it right.
>It's high time we moved on.
>    ~Clive.
>



("atm{at}shore.net")

           Here, here.... I agree, How can you blame vibration on supports
when you are using
primative secondary cages made of wood and rocker boxes of thick Plywood.
But at what cost are
you willing to go to more exotic materials?  Most ATMers are on a budget
and are ready to deal
with these inperfections of design. Hey we all want the best but sometimes
the wallet (or wife) makes
us settle for a little less than our dream.  Just a thought.. I would love
to have a Jaguar automoble but
I own a Dodge Caravan.. dratt.....
                            Russ J.

("atm{at}shore.net")
       Russ J.
("atm{at}shore.net")
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