NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Bubble Sextant
From: Steven Grobler
Date: 2003 Feb 13, 21:59 +0800
From: Steven Grobler
Date: 2003 Feb 13, 21:59 +0800
Hi Jim Thanks for your comments and kind words. I still need to put some more time into my star sights - I seem to be getting better result from sun sights. This may be because one of my lamps is not working, so I struggle to get the time noted quickly. Also, the mosquitos are a bit distracting! In terms of the Delta between my actual position and the lines of position, I usually get sun sights with Delta's of between -3NM and +3NM. They are not well separated in azimuth terms and the fix is about 5 NM from the > actual position. I'd be interested in seeing any photos of your instrument you may have. Regards Steve G > ----- Original Message ----- > From: "Jim Dullea"> To: > Sent: Tuesday, February 11, 2003 9:05 PM > Subject: Re: Bubble Sextant > > > > Steve, > > > > Very nice site with great pictures. Your learning curve on position > > accuracy seems at least comparable to mine using the Bendix Navy Mk V with > > about the same level of practice. I agree with you assessment that in > > aircraft at several hundred Knots this accuracy is probably > sufficient....I > > don't expect to get much better than the 2-3 nm > > > > Since I know my AP using GPS very accurately and not needing to use a > moving > > fix I used multiple sites throughout the day trying out stars, planets, > moon > > and sun. I achieved the following > > > > Day 1: Sun lower limb, Rigel, Betelgeuse --- 4.45 nm > > Day 2: Sun lower limb, moon lower limb, Rigel 3.86 nm > > Day 3: Sun and moon lower limb and Polaris 4.91 nm > > Day 4: Sun and moon lower limb and Jupiter 8.61 nm (poorly dispersed > in > > azimuth for a good position, all within 90 degrees) > > > > Use all 12 LOP's 2.84 nm > > > > From the plot it appears I have better plots using stars and planet than > > with the moon and sun which makes me want to consider how > > > > Jim Dullea > >