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Orion
19-05-2005, 08:05 PM
Hi all, Just came across this site some of you might be interested. It's about the thermal equilibrium of telescope mirrors. (you might have seen it before)

http://www.acquerra.com.au/personal/bird/astronomy/cooling/
slice of heaven
19-05-2005, 08:49 PM
Yeah, its by Bird
I like the way he approached the problem.
Orion
19-05-2005, 09:08 PM
Well done Bird :thumbsup:
Enjoyed reading it.
Starkler
19-05-2005, 11:17 PM
Its hard to argue with the man considering the images he gets.

There was a fascinating thread lately on the CN forums re forced fan cooling of newtonians also. Quite a tutorial with a lot of work and research put in.
mch62
20-05-2005, 09:25 AM
You can try getting around the problem by getting a conical mirror put it in an open Truss tube and reach equilibrium with in 1/2hr without forced cooling.
When I made mine I was going to add forced cooling but R.Royce said it would not be needed , but I had to see for myself.

Needless to say i never did fit the fans on.

But I know what he's saying .

I have seen full thickness standrd mirrors never reach equilibrium even with forced cooling.
Hence thin mirrors , but then that has it's own design paremeters to contend with in proper plop mounting of the mirror.

Mark
asimov
27-05-2005, 07:23 PM
Could you be refering to Alan Adlers published work on "thermal management in newtonian reflectors" ?

Asimov
Starkler
27-05-2005, 11:41 PM
OK I found the thread , theres maybe 2 hours of reading in it :)

http://www.cloudynights.com/ubbthreads/showthreaded.php/Cat/0/Number/360923/page/1/view/collapsed/sb/5/o/all/fpart/1
slice of heaven
28-05-2005, 11:21 AM
I enjoyed that thread too.Understanding what problems youve got built into the scope and chasing the answers is the key.Theres a wide variety of styles and setups to check over in that thread.
To me theres nothing worse than a hot mirror, though the kids like looking for caterpillars and whirlwinds in the scope while it cools. Kids seem to find the best in anything.
Bird shows that he has to contend with a continual drop in ambient temp at his location, that was his major concern and I think he attacked it well.
gaa_ian
28-05-2005, 02:40 PM
Glad i live in the tropics :D
We dont get those sudden temp drops, but perhaps fitting a cooling fan to rear of the scope could still be a good Idea considering we are coming into the dry season :astron: