Alasdair Campbell writes: > Thanks, you do a mean tutorial. I forgot all my solid geometry > about 35 years ago, but I get the picture. Am I right in imagining > that all points on the great circle joining the current magnetic > north "spot" and the north pole (earth rotation wise) will have > zero magnetic deviation?
That would be my naive guess, but I'm neither a cartographer nor a geometrician. Irregularities in the earth's spheroid could have some effect; magnetic variations can also be caused by mineral deposits and other geological phenomena. > Also, when selecting a bearing on a VOR, does the needle centre > when I am on that bearing WRT true north or mag north from the > station? It depends on the station. Every station has a published variation, usually a few years old, and adjusts according to that -- I imagine that all US VOR stations outside Alaska have a variation close to the magvar, but that VOR stations in northern Alaska, like stations in the Canadian far north, use true north. In FlightGear, we have the published variations for many stations (especially in the US), and where we don't, we use the current magvar as a close guess. > I think this is the wrong forum, but what I really want to do > depart a very northerly airport, overfly the true north pole and > drop some supplies to some starving explorers up there at lat 0.00, > lon *.**? How would I go about it? Without a GPS or any kind of radio navigation? If you have a clear night sky, stellar navigation can get you pretty close (and FlightGear goes to pains to get the stars in the right places) -- if the North Star's directly above you, you'll be fairly close to the pole, though not bang-on it. > I would appreciate a URL on the subject, if anyone knows of one. A few months ago, Norm posted a URL to a classic navigation textbook that's now available online. Perhaps he could repost it. On an unrelated note, we now have the scenery data necessary to make sure that the Arctic Ocean is covered with ice and snow in the right places; once we generate with that data, your explorers won't need rubber rafts while they're waiting for their supplies. The northernmost airport in North America is Alert (CYLT), near 82N 62W. If you flew from there, you could probably make it to the pole in a C172, but you'd need to refuel somehow to return. Unfortunately, CYLT isn't in Robin Peel's database yet -- I have a few hundred additional Canadian airports ready for him, but he hasn't gotten back to me about adding them. All the best, David -- David Megginson [EMAIL PROTECTED] _______________________________________________ Flightgear-users mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/flightgear-users
