"Jeremy Lew" wrote:
Well, the fake altimiter and fake "airspeed" indicator are not concerned
with the course delta, but your point is (I think) that everything is
derived from the 2D or 3D position data over time.

Yes, obviously. My apologies for being sloppy.

It seems like someone should be combine a GPS
with a cheap accelerometer and come up with a servicable backup panel.

Given that I can buy a Garmin eTrex for $100, I have to assume the basic
GPS sensor engine is pretty cheap. The obvious next step would be a GPS
in each wingtip and one in the tail and trying to derive pitch, bank,
and heading from those three 3D data points.

Some day, we'll all be flying GPS/INS/FMS/FADEC computer planes. I
suppose by that time all the fun will be gone :-)