A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Francis Upchurch
Date: 2016 Feb 25, 05:44 -0000
By the way, your great book on commonsense CN first awakened my passion for CN and using slide rules for same, back in early 1980s! Thanks , or as my wife might say, Thanks a lot Hewitt! (meaning the other thing!)
The basic build technique is described in the attached word document, which you should have received, dealing with my 2 favourites, the Bygrave and the first Fuller 2. The present modified Fuller 3 CN (Aha) is basically the original Fuller 2 ,but with the log scale replaced by tans, a cos/sin scale replacing the original sine only scale, and a second, identical cos/sine scale on the previously naked and unemployed inmost tube. This moves under the middle tube cos/sin scale to allow direct multiplication and division without having to go via the outermost C/D type scale.(not sure of its name on the Fuller?).
There is only one Tan scale, no “Aha” here, so this has to go via the C/D as before, but I haven’t used that yet. Plan to soon, trying the LaPook version of the Bygrave formulae.
So far have done several LOPs and lunars using the cosine formulae and the direct “Aha” multiplication and division. For LOPs, there is only the single addition/or subtraction needing to be written down, otherwise easier than Bygrave, with no need to find strange intermediate things like W or Y. Works perfectly, and eliminates a few moves required for the old C/D method.
It still does everything the old Fuller does, except give logs, which I never used anyway on a slide rule. (Anyone suggest a use in CN other than multiplication or division, which I can do easier the ordinary slide rule way?)
This Fuller 3CN Aha is now my favourite CN rule with the Bygrave a close second. They both look good ,feel good and do you good!
Let me know any extra details you need and I will try to oblige.