Do i need a compass?

[BobTurner]

why cant you taxi on a specific gps heading, accounting for magnetic deviation, and swing your compass like that? really seems more accurate than trying to lign up your airframe up on a compass rose.

It’s just not the official way. There is a small issue that you do need to taxi some distance in a straight line to give the gps a chance to figure out the ground track. And then be able to stop and park for a bit while you twiddle the adjustment screws. IMHO this should work okay.

 

[RV7A Flyer]

It’s just not the official way. There is a small issue that you do need to taxi some distance in a straight line to give the gps a chance to figure out the ground track. And then be able to stop and park for a bit while you twiddle the adjustment screws. IMHO this should work okay.

And when stopped, you need the GPS course to stay steady, but there's no guarantee it will...it depends on the Kalman filter used. The computed GPS position, which is all that GPS "knows" (well, that and time), moves around (everything else is computed from that...velocity, heading, etc.). But without knowing the details of the Kalman filter, you don't know how heading is computed and estimated.