I've built a APM 2.5+ based quadcopter running AC 2.9.1 firmware. I got a gps lock before I took flight, flew around a bit quite successfully (landing several times).
I then switched it into RTL mode to test it out - it increased altitude, rotated towards and flew what seemed to be home, but once it reached there it veered off right. Unfortunately I didn't have enough room to let it continue to see what it was up to, so I switched it back to stabilised (and failed to control it and hit a tree!) No major damage though, battery survived the fall, one prop chipped.
I'm trying to figure out what went wrong, can anyone help?. It's set to loiter for 5 seconds once it reaches before descending to 2m and at first I thought maybe it tried to start circling (the circle radius is set to 10 metres, pretty big for a qc) but arducopter shouldn't circle in loiter mode, only arduplane should do that i think. arducopter loiter should just stay in place as I understand.
I've got a shakey video of the flight (my cameraman understandably panicked a bit as my flying blender suddenly changed course :)
have attached the trace. You can see the RTL kick in when the altitude increases. Any thoughts? Thanks in advance!