NavList:

Gary LaPook writes:

Don't just restrict yourself to A-12s as there are plenty of other aviation sextants available. I have attached links to current ebay sextants. Look at the A-10 (Ansco, Fairchild) which is a light hand held sextant and you can use the natural horizon by looking around the left edge of the index prism.

The Kollsman periscopic sextants (used in B-52, KC- 135s, etc.) was the culmination and perfection of aviation sextants and are very accurate, plus or minus one or two minutes. You can't use this type with a natural horizon. It look s awkward at first sight but becomes very easy to use with a little practice. If you do not plan to take sights in flight you can remove the averager mechanism (the rectangular box like structure on the back of the instrument, just remove four screws) and it then becomes much lighter and even easier to use.

Another very light and easy to use sextant is the A-7 and is the lightest of all of the aviation sextants, and can be used with a natural horizon.

I have used all of these in flight and all are accurate instruments. I am particularly partial to the A-10 since that is the type I used when ferrying small planes across the ocean.





The  Kollsman periscopic sextant  extends through the top of the fuselage in B-52s, C-130s, other military planes and also in Boeing 707s, and DC-8s. Airline Flight Navigators used celestial for oceanic flight up until the early '70s and the military used celestial routinely through the  '90s ( they figured the Soviets would turn off their radio navigational aids in the event of war.) It is still in the current Air Force navigation manual,  AFPAM 11-216.


Here is a link to more information about aviation sextants:


http://home.earthlink.net/%7Es543t-24dst/airnav/index.html


Here is a link where you can download the current (2001) Air Force Navigation manual.

http://www.e-publishing.af.mil/shared/media/epubs/AFPAM11-216.pdf



http://cgi.ebay.com/Vintage-Fairchild-Aviation-Sextant-Air-Force-US-Army_W0QQitemZ250241094048QQihZ015QQcategoryZ37971QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
http://cgi.ebay.com/US-Army-Airforce-Bubble-Sextant-in-Original-Case_W0QQitemZ190217401830QQihZ009QQcategoryZ66528QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

http://cgi.ebay.com/vintage-ansco-air-force-u-s-army-aviators-sextant_W0QQitemZ140228089165QQihZ004QQcategoryZ66528QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

http://cgi.ebay.com/ARMY-AIR-FORCE-SEXTANT-BUBBLE_W0QQitemZ250241982466QQihZ015QQcategoryZ4721QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

http://cgi.ebay.com/vintage-ansco-air-force-u-s-army-aviators-sextant_W0QQitemZ140228089165QQihZ004QQcategoryZ66528QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

http://cgi.ebay.com/US-Army-Airforce-Bubble-Sextant-in-Original-Case_W0QQitemZ190217401830QQihZ009QQcategoryZ66528QQssPageNameZWDVWQQrdZ1QQcmdZViewItem


http://cgi.ebay.com/A-10-Sextant-Manual_W0QQitemZ250243064536QQihZ015QQcategoryZ37971QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

gl
Michael Dorl wrote:

Bruce wrote:

3) I have looked, and bid on, several a-12 air sextants on e-bay. Has
anyone ever had a good result with an e-bay A-12?  Are they fairly
rugged? I hate buying a pig in a poke, but celestaire is not cheap (like
me).
  

A few years ago, I was able to buy a an5851 aircraft sextant for about $150 on ebay.  Mine is in pretty much mint condition and has the averaging mechanism and original Bakelite case.  This is a fairly heavy instrument  but does have a ring for suspending it in your aircraft  navigation dome. This sextant can both be used with the bubble or the horizon and is equipped with various filters and an stigmatizer. Don't expect more than a minute or so of precision though.



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