NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Mileage of rhumb line compared to mileage of great circle
From: UNK
Date: 2011 Jun 04, 14:08 +0000
From: UNK
Date: 2011 Jun 04, 14:08 +0000
On 2011-06-04 07:04, Andres Ruiz wrote: > Hello Andrew, > > > but the rhumb line formula is more complex > > >What do you mean "more complex"? It is > dist=60*(lat2-lat1)/cos(true_course) > > This is an approximation to RL, is mid-latitude sailing. > It is rigorous rhumb line sailing, too. Not an approximation. Since I stay on a constant angle c with the meridian, for every tiny bit dL I go towards north, I go dL * sec(c) towards the destination, no? > Rhumb line or loxodrome in an WGS84, or other Earth model, is based in > differential calculus, see the paper at my Web page: > http://sites.google.com/site/navigationalalgorithms/papersnavigation/Sailings.pdf > To throw in WGS84 confuses the issue. This is not what Gary had in mind when he said GCD was easy. (It isn't in WGS84.) His response that the real trick is to find the angle is right on spot. Herbert Prinz
