Thanks for the bug report and log. That one looks like it might be interesting
Here’s the first pass at QACRO mode. It’s currently a PR against the previous branch in my repo: https://github.com/kd0aij/ardupilot/pull/7
The new mode number is 23 (the GCSs won’t know about it) and only tested in SITL at present.
Roll, pitch and yaw are body-frame rates hard-wired to a max of only +/-90 deg/sec, and there is no transition logic involved. Also, there is no throttle curve yet, so there will probably be some adjustment needed qoing to/from QSTABILIZE and QHOVER. I’ve had no problems switching back and forth between qhover and qacro in SITL. But it’s easy to get going too fast and get large control oscillations. It flies exaclty like a helicopter in heading-lock mode (you need to use rudder to turn), and roll/pitch behave as expected, although things will get wild if you stall the wing at low throttle. QHOVER should make for a quick recovery, I hope.
Update: parameters ACRO_PITCH_RATE and ACRO_ROLL_RATE now set the max roll and pitch rates in QACRO. Default is 180 deg/sec for both.