After a few very successful flights where my confidence grew, today I tried to tune the PID's.
I guess I were hit by a bug in Flight Planner. Having the PC's locale set to swedish it was impossible to enter numbers with a decimal point (or decimal comma as we use here). (trying to enter 0.16 became 16.0)
So I switched windows's Locale to En-US and things seemed to be normal. I raised the Roll+Pitch "P" by 10 percent, double-checked all other PID parameters and went outside to check the result.
Arming as usual, and gave just a nudge of throttle as I always do to see if there's any huge inbalance. But instead of just spinning the props slowly the tricopter took off like crazy, flipped in the air, stabbed me in the arms and forehead before totally obliterating itself when it hit ground!
Complete disaster. Arms broken, two motors destroyed, one prop broken in halves, and of course the yaw mechanism completley smashed to pieces. But atleast I got my prop scars!
Can anyone have a look at my dataflash log to see what happened.