In case anybody is even slower than me, I have three spreadsheets that solve the “direct problem” (given a Lat/Lon and range and distance, what’s the next Lat/Lon) for a flat earth, using the haversine equations, and for using Vincenty’s equations. I use LibreOffice Calc which is a little bit handicapped for xlsx files, so producing a KML file for a phone app requires a manual “run macro” rather than pushing a button. The Vincenty code is modified from Github and therefore includes the “inverse problem” functions. The other two are my work, although it’s just moving from formulae to excel cells. My implementations are for running a metes & bounds traverse of 15 legs, although that can be contracted or extended by just copying cells.
I won’t further pollute the forum with words unless someone expresses an interest.
