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Protostar air-spaced tube

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8 replies to this topic

#1 Bob Trabucco

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Posted 08 July 2014 - 12:02 PM

Hi all. After getting a fan on the mirror and the little ETX-70 mounted as a "super finder" on the XT10i the "it's summer in Florida so you can't use the telescope so might as well mod it" bug is still with me.

So thinking about flocking the tube.

Anyone with experience using the Protostar air-spaced tube liner? Looks like a good relatively easy solution but was hoping someone had first hand experience.

Protostar air-spaced tube

Thanks in advance!

#2 KerryR



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Posted 08 July 2014 - 12:20 PM

I think it's a great idea for thermal stabilization. Haven't tried it yet. Protostar is somewhat notorious for being uncommunicative and particularly slow to ship, but this usually pertains only to spiders, which require time for them to make, during which buyers have been unsure of the transaction. I've bought flockboard from them with no issues whatsoever. Eventually, I'm going to do the tube-insert mod on my 8" steel-tubed econodob (with replaced optics).

#3 Billytk


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Posted 08 July 2014 - 05:09 PM

I did not use the air spaced stuff but I did install their other flocking board and love it.

#4 shams42



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Posted 08 July 2014 - 05:37 PM

They have discontinued the air spaced liners.

#5 yowser


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Posted 08 July 2014 - 07:01 PM

I hear ya! I live in west-central Florida and summers here are terrible for viewing -- clouds, hot, humid, wet. At the time, Protostar didn't have air-spaced tubes to fit my scopes so I made my own with the flockboard. I placed "ribs" of foam insulation from Home Depot inside the tube, one at each end and another in the middle to create the air gap and then inserted the flockboard. On the 8" reflector I did have to cut a hole in the flockboard at the focuser position.

#6 davidmcgo


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Posted 08 July 2014 - 11:02 PM

The air spaced liners for the Hastings tubes are fantastic. On my 8" f6 newt and 10.25" Dall Kirkham cool quickly and perfectly with small rear fans and after 30 to 45 minutes the intra and extra focal patterns are dead still with no swirls and look like the pics in Suiter's book. What a lot of us think is seeing is actually heat transfer at the tube wall and creating turbulence in the tube.

It was very interesting on my 8" rebuild to go from bare aluminum tube, perfect thermally, to powder coated without the liner which showed turbulence all night, to then adding the flocked liner and all being calm and still.


#7 stratocaster



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Posted 09 July 2014 - 12:53 AM

They have discontinued the air spaced liners.

I still see them advertised on their web page.

To answer the OP's original question, I purchased the air spaced tube for my 10" import dob probably close to two years ago. It works as advertised. I also decided to go with the air spaced tube because of the simplicity of installation over attaching material to the inside of the tube.

Now, I'm not 100% sure I can see a difference between what I remember of the views before the use of the tube liner compared to the current views. But my philosophy is that it's not going to hurt, it very likely helps, and the cost is nominal.

As to minimizing tube currents as the ambient air cools...again, hard to tell short of comparing with and without side-by-side. But refer to my philosphy above.

#8 dvb


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Posted 09 July 2014 - 01:20 AM

I used the Protostar air-spaced tube in my 12" Hastings Tube, and am very pleased with the result.

I did find installation into the Protostar end rings a pain. I disagree with their recommendation against rolled ends on the Hastings tube - I think they make installation of the tube easier, cuz you don't have to crimp the ends in their end rings.

I hope the are still available. Protostar advertises a lot of really good products; they just make them really hard to buy!

#9 Bob Trabucco

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Posted 09 July 2014 - 12:08 PM

I think Shams42 may be correct. They are still listed on the website but if you try to order you get "out of stock".

Emailed them - hopefully they will respond...

Hope they do - I was ready to snag one. :(

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