For all the reasons already discussed on this list my advice would be to go for an A12, which design is very simple to understand, easy to use, maintain, renovate and recalibrate but nevertheless very accurate for backyard practice.
JPP
--- On Fri, 7/11/08, Hewitt Schlereth <hhew36@gmail.com> wrote:
From: Hewitt Schlereth <hhew36@gmail.com>
Subject: [NavList 5803] Re: Bubble Sextant
To: NavList@fer3.com
Date: Friday, July 11, 2008, 1:50 PM
Thank you Jean-Philippe. I knew about Celestaire; will check out Europe. HewS
On 7/11/08, jean-philippe planas <jeanphilippeplanas@yahoo.com> wrote:
> 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_W0QQitemZ220254580692QQihZ012QQcategoryZ4721QQssPageNameZWD
VWQQrdZ1QQcmdZViewItem
>
> JPP
>
>
> --- On Fri, 7/11/08, Hewitt Schlereth <hhew36@gmail.com> wrote:
> From: Hewitt Schlereth <hhew36@gmail.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@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...@pacbell.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...@pacbell.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...@pacbell.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...@hotmail.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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