Re: [ATM] sonotube for telescope

[Daniel Fundo <fundo@bellsouth.net>]

<<  I found a concrete company in Sturgis, MI a city nereby that has 24"
diameter by 12'.  My telescope is 20" in diameter (the mirror)  and the
f # is F 5 so it is 100".  I could cut it to 8' which is 96".  This
seams okay.  Do you think that the wall thickness is allright at 3/16"? 
I have a Jeep Cherekee.  Do you think that I could put the 8' section on
top and the 4' section inside?  >>

David,  24" Sonotube is pretty heavy...about 1/2 inch thick, IIRC. 
You're looking at a tube that will weigh 70 pounds or more WITHOUT the
mirror, mirror cell, secondary and focuser.  I'd bet that the entire OTA
would weigh well over 100 pounds.  To properly balance and support such
a weight will require a similarly large, high-profile mounting.  Even as
lightweight as you could design it, the mounting would still be
large.....too large for your current transportation.  From personal
experience, a big heavy telescope discourages observing (unless its in a
permanent location, of course <G>)

The current wisdom is minimalism; get it as light and stiff as
possible.  A truss system could be designed that would require a much
lighter,lower profile mounting.  With a little care, the entire
instrument could come in at less than 100 pounds.  At the very least, no
component would weigh more than 50 pounds (the mirror box).

*****-----
Dan F.
Secretary/MAS
Memphis, TN
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