Mxsmanic wrote:
writes:
A sensor to find true north in an airplane in flight doesn't exist.
GPS finds true north.
Nope, GPS finds a 3-d position based on the relative distances between
sets of satellites in geosynchronous orbit. It knows no more about
true north than magnetic without elaborate conversion between where
the satellites are at any given instant and where the earth is.
And, just incidentally, you can find true north by
looking at the sky. ANS will do that, and people can do it, too.
Funny, I'm looking at the sky today and all I see are clouds.
My compass still works.
The isogonic lines on a chart take care of all the problems of where
the actual north/south magnetic poles are.
Documenting them doesn't really eliminate them.
It gives you the tool, just like your beloved GPS knows how to find
the real north pole between the combination of the downloaded data
on where the satellites are and a substantial amount of information
on the shape of the earth inside it's internal database.
Unless the airplane is a glider, you have power.
You are clueless aren't you. The engine in just about every airplane
out there runs just freaking fine without any electrical power consumed
nor delivered to the rest of the aircraft.
One third correct: it requires power, but engines provide power. It doesn't
have to be set up against anything else to find true north. It doesn't need
to be constantly updated; the whole idea is to be fairly autonomous.
You are clueless. Your GPS is constantly updated or it won't work.
You put the thing in a box for a week or so or power it up in an
undisclosed location and it will DO NOTHING for you until it downloads
enough information to continue.