Posts Made By: Floyd Blue

Hi Herb,
I accidently deleted a message on the Equipment Forum, Message #284135! Is it possible to have it restored?
I would retype it, but quite frankly it was a bit long and I do not have a copy of it.
Floyd

Tough choice! The Ultima might be the better, GPS is not badly needed and the 8i is a one arm fork mount.
Floyd

Just bought the Suiter book on Star Testing. Been meaning to buy it but have not been quick enough on the draw to get a copy. I am very interested in get to review this book in it's entirety. I have not gotten to look at it thoroughly before.
Floyd

A friend wrote with results from his experimenting with the cooling fans direction of flow.
"1) After I changed to blowing on the back, I noticed
> two things immediately:
> a) My collimation had to be tweaked sometimes
> drastically every 15 minutes. The scope just would not
> hold collimation. I even tried using a very large floor fan and all I
> achieved was a lot more dust on my primary as well as
> my secondary. The amount of dust on my mirrors from
> very little usage was unacceptable.
> 2) On the night of my excellent seeing conditions, I
> had switched my fans back to sucking and again I
> noticed two changes:
> b) My collimation held tight. I check it every
> hour and only had to do a very slight tweak. I did a
> star test each time like you showed me and had
> perfectly even diffraction rings. Even though I was
> still seven degrees above ambient temperature. The
> scope started out ten degrees above ambient
> temperature. The temperature dropped steadily through
> the night so it was impossible to achieve ambient
> temperature. And off course, I have much less dust on
> my mirrors. I do have a fan installed blowing across
> my mirror. I am considering installing a second fan.
> Don't know if it will make any more difference."
I decided to go down and do some flow tests on the mirror box and cell with the fan mounted in both conditions.
Interestingly, when the fan is sucking air out of the box, away from the mirror, the face of the mirror is swept by violent vortices and the box itself is also extremely turbulent. I tested this with smoke using incense. The results were showing that the air flow from a fan sucking air away from the mirror was quite effective in stripping away the boundary layer from the face of the mirror. The speed of the fan and the flow rate directly effect the amount of turbulence seen above and around the mirror.
So, in conclusion, I would have to say that running the fan with it blowing away from the mirror appears as effective as blowing toward the mirror. Based upon his findings that the dust accumulated less on the primary in this configuration, I am going to try it this way for a while and see what develops.
This is interesting, because I have found that the mirror blowing on the back of the mirror produced the most rapid drop in temperature of the mirror. However it may be that the rapid cooling may effect collimation more than slower cooling but not improve the image more than slower cooling with good air turbulence. Also, if the dirt problem is lessened by reversing the fan direction, then it is worth the slower cooling I guess. Either way, I feel that this requires looking into as there is disagreement as to which is the best method of cooling with a fan.
I have always thought the more rapid cooling with the fan blowing on the mirror was best, but I am willing to learn that I was wrong, if indeed, this is the case.
I hope to put it to the test tomorrow night. I will mount the dual thermometer to the mirror and observe the drop in temperature as well.
Floyd

Here we are, ready for action. Christmas eve at the Carrizo.
Floyd

Here it is ready to rock, sitting in my secret spot on Christmas Eve.
Great weather and the sun felt good. More on this trip later.
Floyd

http://www.astromart.com/classifieds/details.asp?classified_id=319620
Wow, look at these prices on Hardin scopes!
Floyd

I just made a light baffle for a friend that owns a Night Sky 14.5" f/4.3 scope. Here is a picture of the finished product.
Floyd

I would like to put a finder to aid the Telran on my Starmaster 14.5" Dob. I would like to keep it lightwieght as the 80mm I have now is just too heavy for this scope. I would like your opinions on right angle finders that are around 50mm and are lightweight. I have access to a couple to try out, an Orion and one from another scope. I think the Orion weighs in at 1lb 8oz.
Thanks all,
Floyd

When you take a look at a newt with an aperture mask installed, it sure seems that what is being simulated here is an Off-Axis Newt. Is this not true? The portion of the mirror being used is about the same as used in an off-axis design and the opening is not obstructed in any way. This certainly seems likely to me. What about it experts?
Floyd