A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Paul Dolkas
Date: 2018 Jun 4, 16:51 -0700
I’m curious why a pendulous reference is considered easier to use than a bubble. The reason that I’m asking is because I had a design class once where my project was a sextant for land/aviation use. Not knowing anything about sextant design at the time I essentially re-invented the wheel and came up with a pendulum-based reference. But I subsequently realized that almost every aircraft sextant out there is based on a bubble, so I figured I goofed.
Was I right after all?
If thinking of buying a Kollsman Periscopic Sextant you need to know that there are bubble models and pendulous reference ones. The latter are generally considered easier to use and are recognisable by a device resembling a circular tobacco tin or enlarged ice hockey puck on the bottom. Kollsman Periscopic Sextants also come with 24V lighting for most users and 3V lighting for the RAF and Bundeswehr. 24V lighting will need more thought over power supplies. If you wish to make full use of any periscopic sextant, Kollsman or Smiths, Kelvin-Hughes, you really need a mounting for it. Unfortunately these are a lot harder to find on eBay than the sextants, because they stop with the aircraft although they do come up occasionally. DaveP