Re: [ATM] Celestron 20" R-C telescope

["Stuart Hutchins" <stuart452@earthlink.net>]

Art,

Serrurier truss?  Linear deflection at the cage equals linear deflection of
the mirror.  Pointing angle then does not change as the structure sags.
http://astro.umsystem.edu/atm/ARCHIVES/JUL95/0114.html
http://astro.umsystem.edu/atm/ARCHIVES/SEP03/msg00804.html

Stuart

----- Original Message ----- 
From: <artbianconi@blast.net>
To: <Atm@atmlist.net>
Sent: Tuesday, May 04, 2004 7:06 AM
Subject: [ATM] Celestron 20" R-C telescope


> Why Two Truss Sections?
>
> Of all the telescopes at the recent NEAF show, the one that was most
> memorable for me was the 18" prototype of Celestrons 20" R-C style
> telescope. It's not the conical mirror or size so much that intrigues
> me as was their choice to make the OTA out of two seperate truss
> systems.
>
> Most every open truss telescope I've seen utilizes one set of tubes
> to secure the two mirror assemblies. For some reason, Celestron has a
> seperate, short lower cage for the primary and a seperate upper cage
> that is about 2-1/2 times longer than the primary one. Then joined
> them together.
>
> While two cages break down the truss tubes into something more
> compact and thus more transportable, that does not explain it for me.
> Two sets of truss tubes of the same length would be shorter and
> easier to move about than the tubes resulting from the cage ratio
> chosen.
>
> I can see no manufacturing advantage either. In fact the design
> requires two additional machined rings of considerable size and twice
> as many tube attach points. It's also heavier because of the added
> components and fasteners.
>
> With so many additional fasteners and components, ease of assembly
> seems hardly likely although I suspect that machines with this degree
> of sophistication do not get packed up and moved very often.
>
> Superior mount rigidity could explain it but there are simpler ways
> of accomplishing that.
>
> Could they be trying to place a mounting point closer to the CG?
>
> Can any one tell me what might have been the reasoning?
>
> Thanks
>
> Art Bianconi
>
> _______________________________________________
> ATM mailing list http://www.atmlist.net/
>


_______________________________________________
ATM mailing list http://www.atmlist.net/