Aart M. Olsen (aart@uiuc.edu) writes:
>Has anyone made a real Serrurier design, where there is a bottom truss >that
is designed to sag as much as the top so there is no angular shift >of the
secondary and focuser from the optical axis? Most ATM designs >have only the
top set of poles set in a solid and more rigid bottom >box. Is this just half
of a Serrurier? Once you get to decent poles, >say 1.25 aluminum, is the
nonsymmetrical sag small enough not to >matter?
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At last, someone else out there realizes what a Serrurier truss design
really is!
My own 17.5" has truss tubes above and below the center section but is not
a balanced design like the Hale (200") telescope. I have not found any
differential sagging but then on a small scope like mine, it wouldn't be
practically measurable. I did it only for the most compact design
(disassembled) to fit in the trunk of my car.
-- Tom Lum (tom_lum@risc.sps.mot.com)