VTOL Plane Crash due to unexpected speed change during mission

Hello,

I have had a crash with a VTOL aircraft. The crash was big, and the battery caught fire, destroying the flight controller. the aircraft had a lot of expensive equipment on it so I am worried about trying again before I figure out the problem.

I know that in the end, the wing ripped off because the aircraft was trying to achieve an airspeed that was much faster that the maximum airspeed. Does anyone know why the aircraft may have changed speed mid-mission and why the maximum speed parameter wouldn’t have prevented it from exceeding this parameter?

I managed to save the .tlog but the original log is destroyed.

https://deepelementjo-my.sharepoint.com/:u:/g/personal/james_bethell_deepelement_net/ET8Mye0t3yxOqx9iYls30dQBPGMNTHl1LCDUMXSH6l_Lrg?e=i3v4w5

Thank you for any advice.

try to recover the SD card. It contains much better information than the tlog.

There were some very wild pitch oscillations that I think triggered q-assist. The quad motors had turned off as expected through the transition but during the climb the motors started up again. I’m not sure why the plane was trying to go so fast, and I’m not sure if it was because of the q-assist or something in the mission. The parameters have the max airspeed speed at 35m/s, and the plane didn’t seem to go significantly faster than that. If 35m/s is correct then I don’t think the speed is so much the issue, as the oscillations.

The other thing I noticed is the plane is commanding an negative pitch while it’s climbing. That might have something to do with why it’s speeding up, while the quad motors are running.

Lots to speculate. CofG shift, did something come loose inside the plane and move around. Some kind of mechanical failure (control surface). My question is why did the quad motors need to come on to try and stabilize the plane?

I checked and the autopilot is configured to not use the airspeed, cruise throttle is set to default.
Neither battery failsafe nor compensation are enabled.

Overall I suspect poor configuration of the craft as a significant contributing factor.

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