From: "CSC" 
To: "Atm" 
Reply-To: "CSC" 


Changes from design to design.  By throwing the scope out of focus, it's
easy to see various currents.  Most currents are convection from the
primary mirror being warmer than the ambient, a slow flamelike effect.  On
tubed scopes, there's tube cooling effect and the funneling of mirror heat.
Rarely have I seen currents off the secondary.

Colin
-----Original Message-----
From: owner-atm{at}shore.net [mailto:owner-atm{at}shore.net]On Behalf Of Emery
Greg
Sent: Thursday, June 19, 2003 8:29 AM To: atm{at}shore.net; tkrajci{at}san.osd.mil
Subject: ATM Heat Transfer



Hi All:

What is the preliminary mode of heat transfer in telescopes?  Is there a
dominant mode or does it change from design to design?.  Tom Krajci
mentioned radiation in the wire spider thread.  Tube currents suggest
convection.  Blowing air with a fan through the cell onto the back of the
primary is convection and conduction.

I am probably naive, I just don't see radiation being large in a spider or
secondary setup, I would ( and have ) assumed that for spiders all three
modes are operating with convection/conduction being dominant.  As
optimizing heat transfer requires identification of the modes, I am
interested in this before I start constructing my bino scope ( actually I
have started building already :) ).

ttfn
greg

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