I have not seen anyone declare a "best" OTA position for quickest and best cooling down (or warming up) of a newt. Knowing that warm air rises and cool air sinks, I would think keeping the tube horizontally (front end open and no wind present) would be best since warm air inside the tube can rise and exit out the top edge of the tube while cooler air will migrate into the tube to replace the warmer air that has escaped. This is of course, for newts that have no ventilation openings at the primary mirror end. But even with them, is a horizontal position the best? This also does not include fans for cooling.

Mr Q

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What goes around, comes around, eventually.

Meade DS-10 (10" newt)
10x50, 10x70 binos

Hmmm...interesting issue. I've always left my tube vertical on the assumption that the warm air will rise out of the tube more efficiently. My tube does have openings at the primary mirror end though, and I also use a fan.

Redshifter - I found that keeping the primary end of the tube closed up (taped), It keeps a lot of dust from getting on the mirror during storage along with a cap for the open end. When it's brought outside, I keep the tube horizontal, which seems to cool down the scope the fastest. Using this method, I only have to clean the mirror every couple of years or so.

Just wondering what position other people use for cooling dowm. Mr Q

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What goes around, comes around, eventually.

Meade DS-10 (10" newt)
10x50, 10x70 binos

I also have vents at the back of my scope. In fact, I created more than it came with originally to speed cooling.

I store the scope vertically, with a cover over the open end, and have no problem with dust on the mirror -- even when I use the table saw in the garage.

I'm not sure the angle of the scope makes a big difference in cool down time, although I have not done tests to be sure. I do know that even my little fan blowing on the back of the mirror makes a difference.

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"I'm as accurate as any psychic. And I'm a cartoon!" -- Squidward

"Arrrgh, the laws of physics be a harsh mistress!" -- Bender

I assumed this discussion was about cooling our scopes down prior to observing as opposed to how we keep them stored. I store mine vertically as well simple for space considerations, but keep both ends of the tube covered when storing. I clean my mirrors roughly every two years as well.

I'd love to see data regaring cool down time; horizontal vs. vertical.

I'm beginning to believe that cooling it down by keeping the secondary end vertical or horizontal does not matter, especially with venting next to the primary. In my case, the vents are closed and the front end caped to keep dust out. So with the no-vented primary end, this is why I was asking, assuming the scope was not left outside a few hours before observing starts. In other words, what position (with primary mirror end vents closed) produces the quickest cool down time? Or are there too many variables to determine this to a rough degree?
Mr Q

__________________
What goes around, comes around, eventually.

Meade DS-10 (10" newt)
10x50, 10x70 binos