[ATM] Gymbal mounted mirror and stress

[Ken Hunter <atm_ken_hunter@yahoo.com>]

--- Jerry Reddell <jerry.p.reddell63@sbcglobal.net>
wrote:
> I am sorry. I just don't see it. 

Jerry,

For a DOB mounted mirror a sling has been customary
and can work well. It's all in the implementation of
the sling.

For an equatorial mounted mirror where DOWN can come
from many different angles (relative to the mirror
mounting) because of rotation, a way needs to be found
to adequately support the glass without introducing
excessive stress. 

In my idea the mirror is basically mounted on the PLOP
or other cell as usual. When pointed straight up there
is no stress imparted to the mirror that is not
figured into the PLOP equation. However, when the
mirror attitude approaches horizontal, stresses are
imparted to the mirror due to the offset of the mirror
support points from the mirror's COG. 

The advantage of my idea is that these forces can be
compensated by virtue of an active weight applying an
opposing force to the mirror AT THE COG OF THE MIRROR
which is hidden behind the Secondary (not at one point
on the edge), and independant of the mirrors pointing
attitude. 

The PLOP designed cell works to support the mirrors
weight while pointing vertical, the idea I propose
supports the weight when pointing horizontal by
applying (anti-gravational) force (in the UP direction
regardless of the mirrors rotation). Intermediate
pointing positions are supported by both.

Hope this makes more sense.

Ken Hunter



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