Hello,
I’m running a new 3DR ardupilot 2.6 with Ublox and have the following results while running the latest Arduplane firmware. This issue does not exist while running Arducopter firmware on the same device setup.
Compass calibration is not a problem, nor are any setup issues. However, I note that when I power up the plane and attach to Mission planner the on-screen compass rose shows the plain is aiming North and properly follows rotation around the compass no matter what heading the plane is in when powered up. I.e., the system thinks that it’s aiming North no matter what direction the plane is aiming when booted up. I hope this is clear…I’m having a bit of trouble trying to describe this anomaly.
Any help will be VERY appreciated. 
It may be a setting I’ve missed, but I’ve tried anything and everything that I think may affect this. Maybe it’s not an issue if I carry a compass with me and ensure the plane is facing North before powering and flying but this doesn’t appear to be a good way to deal with it (said tongue-in-cheek). To date I’ve refrained from flying it until this is solved.
I should also mention that I’ve disconnected the video Tx, camera, and telemetry radio with no effect.
Current equipment:
3DR 2.6 Ardupilot/uBlox/power module
3DR Telemetry radio
RVJet airframe
Jeti Duplex 9 channel Rx
1280 mhz Video
TIA, and have a great weekend!
Bob