... This theory keeps replicating itself without any rigorous scientific substantiation, and sometimes it's re-stated as a quasi-fact. IMO, we need to be...
... Very good point, Rob. There are three main sources of scatter; 1) moisture/ice in the atmosphere, 2) the telescope itself, and 3) your eye. The eye is a...
Brian, In your work have you determined the following: 1) Does a 3 vane spider actually produce a better image over a 4 vane? 2) Do a thin vanes actually...
I rebut. I strongly support my original statement. There is no way in which a structure whose elements are designed to resit to bending/torsion loads may be...
... dysequilibrium. I have been experimenting with "faux" spiders ... thickness. It seems that a well designed wire spider ... design where you have 4...
... at lie > in planes parrallel to the optical axis. Thin piano wire forms the sides = of triangles whoose respective bases are co-axial with the > treaded...
... This sparked the thought that an old guitar may provide the tuning. Using steel guitar or piano wire, one could arrange three upper and three lower points...
... Hi Bryan, Yeh, I got that part right in a later post after I searched around the web. All of the discussion does seem to go back to that original exchange...
User Group, When I completed the 17.5" dobsonian scope with its ServoCAT and Argo- Navis DSCs I thought things couldn't get any better with an Alt/AZ scope --...
... William This is precisely the kind of thing I have had in mind - you saw my hand! If such an arrangement were feasible than1) Tension and "tunning" could...
From: "Bryan Greer" ... Once I tried to see what kind of cooling effect a dark surface would get under a clear sky - I could measue about 1 deg c cooler than a...
Enter your vote today! A new poll has been created for the bigdob group: The importance of aperture. Which feature do you see on Saturn considered you scope ...
bigdob@yahoogroups.com
Jan 1, 2004 8:53 pm
8420
I have been thinking about this whole spider being cooler than ambient air phenomenon and it bothers me. Heres why: Suppose we have a closed system (Imagine a...
The following bigdob poll is now closed. Here are the final results: POLL QUESTION: Are you pleased with your mirror performance? CHOICES AND RESULTS - Yes!...
bigdob@yahoogroups.com
Jan 1, 2004 11:53 pm
8422
... Hi Mauro, But now you're answering a different issue than I was referring to. I was singling in on the statement that a curved support would _always_ have...
... Hi again Mauro, I just re-read your first post, and see that you did add the stipulation "for the same stiffness." Forgive my hasty reading of your first...
Hi Nils Olof, Good to hear from you again. Here are a few more somewhat random things to throw in the soup. ... This is in the ballpark as what Martin Lewis...
Hi Joe, No, the spider vane can't violate the second law. Yes it can get colder than the surrounding air. There are three mechanisms of heat transfer for the...
Bryan, Thanks for a great and informative post. I will see if I can get my hands on the references. If I recall correctly, the old thread on Mel's site...
Compliments. Very clear (and correct) explanation. Now the simple workaround and "bug fix" is puttin a dew cap on top of the tube. This prevents the spider...
... If fact it is not. But setting the target values for stiffness and the design load is a different (and in certain sens preliminary) step of the design...
... requirements. I forgot to say that, before actuaslly carrying out the design (optimisation) one have to select a "concept" tthat is an arrangement, or...
... Myron and Mauro Perhaps I was unclear. I understand the qualitative aspects of the explanation in terms of conduction, convection, and blackbody radiation...
I read a post on talking telescopes (#93515) and had the "ah-ha" experience! You guys are absolutly correct! Again, its not a matter of being right - its only...
... fundamental ... had ... ananlogy, ... conservation ... laws ... hold ... Myron I re-read your post. Your explanation is absolutly clear to me now. Thank...
... Hi joe, THis sounds interesting. Can you scan your drawings into a file folder in the group page? As it happens, i am planning on building a new upper...
if i may add something: getting the frequency higher can be done by reducing the mass of the suspended assembly and combined with dampers made of split foam...
Shortly after starting the business, I built a special platform for a friend who owns a Meade 16". He seems please with the performance. His main use is...
... i want to do this ... I think one could find pretty much any thickness of steel or braided guitar strings that may be suitable. Yet, visions of Pete...
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