Primary Mirror Fan

[justindereuck]

Hi Guys

Just wondering for a newtonian telescope, is it best to have the fan behind the primary mirror extracting air out of the OTA or pushing air in?

Thanks

Justin

[NGC 1502]

Hi Justin, there are lots of theories about cooling fans for Newts, but the most common is a single fan, placed behind the primary, blowing air towards the back of the mirror.

My club's 16" Dob has an extra fan above the primary, blowing air across it.

Regards, Ed.

[Bart]

I have fans on my 10" and 16", but rarely use them, maybe I should!

[justindereuck]

Thanks Sub Dwarf...kinda what I figured as well.

[swamp thing]

I have fans on my 10" and 16", but rarely use them, maybe I should!

Barry

The LB fan isn't all that is it ?

It can kinda help, but as you say, not really worth buying the batteries for.

[umadog]

Even a moderate air flow rate will significantly decrease cooling time: http://www.fpi-protostar.com/bgreer/fanselect.htm Rear fan blowing at the back is the best way of getting effective cooling without too much effort. Fans blowing at the front will break up the boundary layer and speed up cooling yet more. They are more of a problem to install, though.