3DR Y6 crash, failsafe RTL flip, logfile analysis, AC 3.0.1

Log Analysis -- deprecated Copter Logs -- deprecated
1

Hoping to get some expertise on deciphering my logfile after a crash of my trust 3DR Y6 on flight #106. I interpret a radio signal loss failsafe causing a near inversion of the craft near the ground and a correction to upright attitude before impact but still enough vertical speed to cause damage. I’ve had plenty of failsafes usually causing the desired RTL behavior, which I often interrupt with a loiter command and then resume flying.

The logfile shows a very aggressive roll upon failsafe RTL, causing the momentary inversion near the ground. I can’t quite explain it.

This is a RTF 3DR Y6 using DragonLink UHF contro, with gimbal, GoPro, minimOSD. Using APM Copter 3.0.1. It is my usual flying field at about 1400’ elevation. Range was about 500’. Altitude 10’ AGL. Flight was a mix of loiter and altitude hold, with the failsafe RTL intervening. Battery life was 6 minutes into a 10 minute proven flight duration.

Log attached. Any help is greatly appreciated!

2

I should add that the copter is physically and mechanically sound, no loose props or motors, no failed esc’s or motors, wires tight. I’ve had 105 fairly flawless flights before this.

It’s my first time diagnosing logs but I do notice the roll curve departs sharply from the DRoll and RollIn, which seems suspicious. I also see the XAccel and YAccel seem to be pretty far off from zero at the moment RTL kicked in. My waypoint speed is set to 7m/s and waypoint acceleration to a modest setting. I’d have thought the copter wanted to haul ass back to home when RTL kicked in, but it not only pitched over far enough to point straight at home, but actually slightly inverted. Of note Pitch/roll P is 5.