NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Artificial horizon glass selection
From: Bruce Hamilton
Date: 2009 Sep 25, 10:29 -0700
From: Bruce Hamilton
Date: 2009 Sep 25, 10:29 -0700
The most recent Edmund optics catalog just got delivered to me, and I started looking at the first surface mirrors. Depending on the grade, they can be quite reasonable. A 75mm diameter� with a surface accuracy of 4-6 lambda per inch is $24.00 USD.� The Freiberger seems to use about a 70 or 80 mm diameter mirror, but i am just guessing by looking at the pictures. If anyone knows the actual diameter , please let me know. Would round or square be better? What would be the lowest surface accuracy one could use to have the necessary accuracy while keeping things cheap? I am guessing that first surface mirrors are best, but let me know if anything else would be better. If you can think of an optical item, the Edmund catalog has it. I remember someone was looking for a penta-prism, and they have these, and the prices are quite good. They have a web page with a sales area so it looks like you can buy direct. BTW Thank you for the discussion on GPS time. I was unaware of the difference between GPS time and UCT, and the single occasion this summer when I thought I would use it as my time source, I had a frustrating night where all my sights from my A 12 were off by 25 miles no matter how many times I tried. I took a lot of sights this summer while camping and learned things like never trust a sight that is taken through too many leaves or too close to the top of a hill. All sorts of odd refraction takes place. Cheers Bruce Thanks --~--~---------~--~----~------------~-------~--~----~ NavList message boards: www.fer3.com/arc Or post by email to: NavList@fer3.com To , email NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---