Cooling newtonian

[markse68]

 

Really interesting indeed.  It basically says nobody will ever fully benefits its newton without a very active cooling?   Wow and almost 2 decades later we still think about solutions😬

Yes I saw his site before- worth clicking through the links to his other pages if you didn’t- he’s done some pretty cool stuff with sealed peltier cooling 

http://www.acquerra.com.au/astro/cooling/version3/

[Robindonne]

1 hour ago, bottletopburly said:

Came across this this week interesting read 4parts http://www.acquerra.com.au/astro/cooling/ don’t think anyone posted this link .

And this was all back in 2004/2005.  Imagine the small costs you can build an peltier (€2,-) temp-predicting small pc (€10,-)  Silent fans (€ 2,-) TempSensors (€1,5) and some alu/3d parts (€15,-).  Or buy a complete peltier cooler kit for €35,- from the east, maybe they can ship it on the same ship our scopes are shipped😬. But serious, my idea of that ring is **** compared to the Solution used in the 2004 test from your link.  
it needs to be much more then just improve airflow directions 

[Robindonne]

4 minutes ago, markse68 said:

Yes I saw his site before- worth clicking through the links to his other pages if you didn’t- he’s done some pretty cool stuff with sealed peltier cooling 

http://www.acquerra.com.au/astro/cooling/version3/

I did.  Ended with part 4.   Maybe there is more but couldn’t see it on my phone. But his message was basically: cool more then you think.  Maybe we need M.Pyott for this?😎

[callisto]

When I was getting some info for Lacerta Apo frac's (Austria) I came across these-  https://teleskop-austria.at/LaCool283#m 

[Robindonne]

56 minutes ago, callisto said:

When I was getting some info for Lacerta Apo frac's (Austria) I came across these-  https://teleskop-austria.at/LaCool283#m 

Also not bad at all.  Nice sealed so a lot of suction in the tube.  

[bottletopburly]

The article I posted basically states three things need to cool to an equilibrium, mirrors ,  ota and ambient air temperature so once all three are close to the same temperature then you should get better results , would encasing the tube in the foil bubble wrap stuff you get from diy stores work in keeping the tube  temperature more stable ? , and adding a fan purely for cool down prior to imaging on to the scope cover end cap  .

[Ricochet]

20 minutes ago, bottletopburly said:

The article I posted basically states three things need to cool to an equilibrium, mirrors ,  ota and ambient air temperature so once all three are close to the same temperature then you should get better results , would encasing the tube in the foil bubble wrap stuff you get from diy stores work in keeping the tube  temperature more stable ? , and adding a fan purely for cool down prior to imaging on to the scope cover end cap  .

Wrapping the tube to keep the inside temperature stable works with Maks/SCTs because they are closed systems and there is no/little air movement if the air is stable. With a Newtonian the fact that it is open at both ends means you are still going to get convective currents rising up the tube if the air inside the scope is warmer than that outside. Where you might see an improvement is in the situation detailed at the linked website where dew formation causes cools the metal tube and this cools the air inside below the ambient temperature. I have flocked the inside of my OTA, which is a plastic sheet with a fibre surface, and I suspect that this might actually insulate the air inside the tube from the tube itself in a manner like you are suggesting. Dew formation on my scope seems to be limited to the outside of the OTA, whilst the inside remains dry and relatively warm to the touch (not that I have made a habit of touching the inside of my OTA).

[Ricochet]

On 18/06/2020 at 20:59, Robindonne said:

Maybe If you can find the time someday to make a picture from the inside of your tube Pls.

I don't know if this has come out enough for you to be able to make out properly. 

Also, my method of mounting the fan to the rear of the tube 

[Robindonne]

Yes thanks.  And i know how hard to take a good picture from the mirror.  Tried it myself last week with a bad result!   So thx.  From what i can see is the tube much bigger than mine.  I have to admit that most of the reactions here, from you all, gave me a much better idea of what a newtoniar should try to reach.  I think the ring will probably help a bit, cooling from both sides should go faster then from the back Only.   And the main goal is of course the surface side first.  
I cant really see the solution you tried with the flat alu ring, but it seems i have them also in my tube.  Forgotten it is deliverd with “baffles?” And the lowest one will probably be replaced or combined with my curved ring plan.   It wont be enough to get the best out of it im afraid.   Trying to find a nicely fit for peltier cooling.  And one of the links above shows a nice looking newton-jacket where most of the stuff can be installed out of sight. Not the most important of course but why not.

[Ricochet]

This is an old picture of the first test ring, that was the width of the tube. The current one is the same width as the mirror clips. It shows better the set up that I have. As it is a standard Newtonian I have no other baffles within the tube. 

[jetstream]

22 hours ago, John said:

Making the best of the imperfect is what we are about I think

 

 

I think you and I get very good views with basic cooling - my VX10 got Mars at 400x years ago and gave a view thats still burned in my brain. Not sure about others but if basic cooling is done the sky is normally the limiting factor.

[Robindonne]

Oke its being printed and delivered in a couple of weeks.  It will fit and glued right below the lowest baffle en will cover the mirror 3 mm.  Hope its enough to spread the cool air both over the back and surface Of the mirror at the same time.  It should keep up a bit better with the lowering temperature During the night i hope.  Although its maybe a strange design and never used before, if something occurs to you regarding any details i’m not aware of then help me out please.