Fan on Dob

Hey Folks,

I'm thinking again of trying a new fan arrangement. I'm wondering if anyone has tried the "fan over the center of the primary blowing down" configuration?

I've tried everything else short of the dreaded 'cut holes in my scope' approach. Yikes!

BTW, it's a 10 inch F5.6 Discovery Dob. I have an idea on a way to mount a fan like this, and still be able to collimate with my laser ;-) But I thought before I went through the trouble, I'd ask and see if anyone else has tried it. My veiws have been awesome with this scope, I finally see all those goodies on Jupiter that my 6 inch F5 wouldn' show me, but I read others have improved their views even more, going up to 500 even on the planets with XT's and such. I wanna do that ;-)

Thanks for any input!
Ron

(Hey Michael, I see your missing your Tak, is it the veiws or just that those are so cool?)

Ron

Anybody remember the S&T article on fans and cooling. What was the general idea of that study? (not all the gory detials, but just the basic idea)? A single fan blowing ACROSS the primary or two fans in some other configuration?

Ron,

This may be a better solution:

http://www.tomhole.com/Active%20Cooling.htm

Clear skies,

Tom

In all of these discussions of tube currents and boundary layers, I haven't seen (maybe I missed) any mention of a way to tell if the fan is helping, other than the subjective quality of the image. Thermal distortion of the mirror figure would, I guess, have to be evaluated with a star test which, I understand, takes some study and skill to use correctly, but tube currents and boundary layer motion should be visible by looking for motion in a deliberatly defocused image at moderate power as described in the recent S&T article. Have you looked for this? Do the fans improve it?