NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: New compact backup CELNAV system
From: Gary LaPook
Date: 2009 Feb 28, 17:22 -0800
From: Gary LaPook
Date: 2009 Feb 28, 17:22 -0800
Your version looks very nice, much nicer than mine but I have an excuse. The basis for mine were the scales printed out by use of the program kindly provided to me by Zvi Doran so that I could build a working Bygrave. I modified this original scale by adding a few tick marks at some five minute points and added more labels for the scale where the original labels were far apart. Since I am not a whiz at this computer stuff I used a brute force method to add these marks. I added the tick marks by hand on a printout of the cotangent scale. I then used a Dymo labeler to print out the labels and then stuck them onto the scale. I scanned this in, printed out two copies and taped them together and then scanned the double wide scale back in. It was a "proof of concept" model and it works quite well. The one you made looks like you had the help of a computer and it looks real professional. I worked a couple of problems with yours and got the right answers so it looks like you got the scales right. I would like to make two suggestions. First, you used the double quote symbol ( " ) for minutes and it is usual to use the single quote ( ' ) for minutes and the double quote for seconds so it would look nicer if you changed these marks to single quotes. At some points on the scales the ten minute tick marks are too far apart making visual interpolation inaccurate.To deal with this problem on the one I made, I made the axiliary vernier scale to aid in the interpolation since it would have been a lot of work adding more tick marks by hand. This complicates the computation whenever you are working with values less than ten degrees or more than eighty degrees because you have to maneuver this third sheet on top of the other two scales. So my second suggestion, if it is not too difficult to get your computer program to do this, would be to add tick marks every one minute in the areas of the scales above eighty degrees on both scales and also below ten degrees on the cotangent scale. This would simplify the computation, no need for the auxiliary scale, and would increase accuracy. gl waldendand@YAHOO.COM wrote: > Since I'm of the "do it yourself to understand it" school, here are my versions of the Lapook flat Bygrave. They seem correct, but please check. Still some clean up on labels and tickmarks for large and small angles needed. > > > > > > --~--~---------~--~----~------------~-------~--~----~ Navigation List archive: www.fer3.com/arc To post, email NavList@fer3.com To , email NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---