Re: Bubble Sextant
From: Jean-Philippe Planas
Date: 2008 Jul 11, 11:40 -0700

For  overhauled and calibrated instruments you may try Celestaire in the US or Navastro in Europe (both are very nice and trustworthy people). These instruments will most likely be rather expensive but will be perfectly usable  dependable and reliable and will provide the required  precision:
http://celestaire.com/catalog/products/2101.html
http://www.navastro.fr/index.html

If you are reasonably gifted with your hands and ready to spend time to work on the instruments (and also take some risks) you can regularly find specimens on Ebay as currently :

http://cgi.ebay.fr/Aircraft-Sextant-Bubble-type-AN-5854-1-Bausch-Lomb_W0QQitemZ260260797535QQihZ016QQcategoryZ4721QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
http://cgi.ebay.fr/WW-II-Aircraft-Sextant-US-Army-Air-Corps-A-10_W0QQitemZ260260803364QQihZ016QQcategoryZ4721QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
http://cgi.ebay.fr/NAVY-SEXTANT-BUBBLE-TYPE-AN-5851-1-WITH-ORIGINAL-BOX_W0QQitemZ150266316156QQihZ005QQcategoryZ4721QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
http://cgi.ebay.fr/AIRCRAFT-SEXTANT-MARK-V-BUBBLE-TYPE-PIONEER-INSTRUMENT_W0QQitemZ270252774568QQihZ017QQcategoryZ37971QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
http://cgi.ebay.fr/WW2-BRITISH-AIRCRAFT-NAVAL-BUBBLE-SEXTANT-MK-IXA-W-CASE_W0QQitemZ150269277288QQihZ005QQcategoryZ156424QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
http://cgi.ebay.fr/World-War-2-AM-Air-Ministry-Bubble-Sextant_W0QQitemZ220254580692QQihZ012QQcategoryZ4721QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

JPP


--- On Fri, 7/11/08, Hewitt Schlereth <hhew36---.com> wrote:
From: Hewitt Schlereth <hhew36---.com>
Subject: [NavList 5799] Re: Bubble Sextant
To: NavList@fer3.com
Date: Friday, July 11, 2008, 10:38 AM

Are there any sources for these sextants?  HewS

On 7/11/08, engineer <engineer{at}clear.net.nz> wrote:
>
> The British Mk IX is about 200 grams lighter. and is my favourite
> because all the controls come readily to hand, it is easy to use and
> read and you have a reasonable chance of getting one that works. With
> the exception of the averager on the Mk IX A, the works of the Mk IX
> series are accesible and usually easy to fix. The bubble assembly is
> also easy to refill.
>
> My A7 has a vapour pressure bubble chamber which, if empty when you
> get it is very difficult for the non-specialist to refill. Many of the
> WW II US instruments suffered from "complification" and some
used 4
> prisms, heavy and expensive to produce. The AN 5854-1's
> averager(strictly, a median device)is temperamental and hard to fix if
> it has suffered corrosion in storage. The AN 5851(Navy Mk 5)is heavy
> and clunky and initial setting of its averager needs care. The A10-A
> is perhaps the handiest instrument to use, provided the electrical
> marking system is in good order. It is not impossible for
> a reasonably handy person to fix the system, once it has been
> understood. The A10 uses the Mark I finger to operate the marking
> pencil. That leaves rarer instruments, like the A8-A and the Navy Mk
> IV. The latter was plainly not a success and if you find one, the
> averaging system will tax the average person to fix. The A12 is a
> favourite of many people and was designed to be cheap to produce(some
> of the others cost almost the price of a small home to produce). The
> arc and vernier on mine are poorly cut, but if you can get one free
> from corrosion and in working order it would be a good one to start
> with.
>
> The Achilles heel of nearly all the bubble sextants is the bubble
> chamber. For practical purposes, you cannot refill a vapour pressure
> chamber. Happily, most of the later bubble sextant produced used a
> different system with an air reservoir; and these are fairly easy to
> refill. The MA series are, alas, expensive and do not often come on to
> the market.
>
> Bill Morris
>
>
> On Jul 11, 1:54 pm, "Gary J. LaPook"
<glap...---.net> wrote:
> > My fravorite is my MA-1 which isn't a bubble sextant but a
pendulous
> > mirror type and my second favorite is the MA-2 with a bubble. If you
> > want a light, simple sextant get a Bendix A-7, it is the lightest
bubble
> > sextant I have.
> >
> > gl
> >
> >
> >
>
> > glap...---.net wrote:
> > >Here is a link to a site with discriptions of many types of
bubble
> > >sextants:
> >
> > >http://home.earthlink.net/%7Es543t-24dst/airnav/index.html
> >
> > >gl
> >
> > >On Jul 5, 3:19 am, glap...---.net wrote:
> >
> > >>You should also check the files section of the Yahoo sextant
group for
> > >>more information on sextants.
> >
> > >>http://groups.yahoo.com/group/Sextants/files/
> >
> > >>gl
> >
> > >>On Jul 3, 5:14 pm, bubi352
<benjaminriec...---.com> wrote:
> >
> > >>>I am new to this group and new to celestial navigation.
I currently
> > >>>work as an airline pilot and fly extensively over water
at night. I
> > >>>have developed a keen interest in determining my
position the old
> > >>>fashion way.
> >
> > >>>Could someone tell me which bubble sextant I should buy?
> > >>>What should I be looking on a bubble sextant?
> > >>>Where can I buy one?
> >
> > >>>Thank you in advance.
> >
>
> > >>>Bubi- Hide quoted text -
> >
> > - Show quoted text -
> >
>


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