Accel calibration - necessary after upgrade?

Hi, I was just having flights with my Skywalker (1,68m, T-tail) to get it mechanically trimmed and determining the horizontal flight attitude. Before installing the F765-WSE board in the plane I had done 3D calibration successfully.
When I returned home there was the 4.2.3 FW available, and I upgraded.

For some reason, as far as I could tell, after upgrading it seemed that the FC had returned to default parameter settings. Luckily I had a backup of the parameter list and installed that.

Now, when I try to arm the FC, Mission Planner requires me to do a 3D calibration.

This is a bit awkward with the FC and other equipment already installed in the plane, so I wonder if 3D re-calibration is really necessary. However arming is now an issue.

Is accel calibration really necessary now?

Thanks, Helge.

I hit something similar after flashing a 4.3 dev load.

According to Accelerometer Calibration — Plane documentation, other than the initial level, the other positions only have to be within 20 degrees of exact but they should be still as you press the key.

Alternately you could do a “simple calibration” which just needs the plane to be level.

I found that the best option would be to do a new 3D calibration. So, with the help of some support material (mostly books), and some careful measuring with a spirit level, the calibration was performed successfully with the Flight Controller still in the plane.

Still not sure why I lost the calibration after upgrade though, but ok now.

Did you update to 4.2.3 via Mission Planner? How exactly, with which file?


When I connected to the plane (Matek F765-WSE board) with Mission Planner 1.3.77, on September 8, a popup alerted me of a new upgrade to Arduplane. I followed the instructions and installed the upgrade.

The top line of the MP screen now says ArduPlane V4.2.3 (55685c43).

Initially, when I first installed firmware on the board back in January, I downloaded the file MatekF765-SE from the Ardupilot firmware site. This is the target file listed for Arduplane by MatekSys.

After I did a new accel calibration today, things seem to work ok. I could, however, not understand why a re-calibration was necessary to get the FC armed. And also why the RC setup seemed to revert to defaults when I upgraded. After I corrected the necessary parameters, things seem ok so far.


I have made several updates from 4.2.2 to 4.2.3 without having to recalibrate. In the MP I select “Install Firmware” and “All Options”. There I take the appropriate .apj file.

There were no problems with this.

Thank you.

I will check the options you mention next time I upgrade. Regretfully I do not have a clear memory of exactly which options I saw when I did the upgrade to 4.2.3.