Hey all. I am a newb who just had his first non-minor crash.
I would love help on this specific crash but I am also looking for advice on troubleshooting steps to take after my many future, inevitable crashes :)
On to how I broke my baby.
I am flying a 3dr hex that I bought RTL. 850kv motors, 10x4.7 apc SF props, 20amp ESCs, 5000mah 3s turnigy bat, and the most recent versions of APM and mission planner. I am using the 3dr telemetry and a spektrum 8x tx.
I was testing autopilot functions. After 4 successful flights of takeoff - waypoints - land/RTL my hex fell out of the sky. I can't figure out any easy explanation.
I have tried to diagnose the crash on my own. I figure that if there was a specific motor/esc problem that there should be a spike or dip in one of the servo channels. If there was a compass problem then my offsets would be too large. If my earplug vibration dampening system wasn't working then it should not have flown the prior flights. I can't find any of these issues represented in the logs. In fact, there are no outlier spikes or dips that I can see in any of the logs. I have attached them in case that helps.
I got video of the flight. No noise or strange movements are noticeable to my untrained eyes/ears.
I couldn't get the voltage to show up in mission planner so I figured I would keep the airtime at<5 min. After the flight I measured the voltage using my charger and it read >11 volts.
The only strange thing is that, as far as I can see, all the logs cut out before the crash. But in the video the motors don't shut off.
Any thoughts on where should I look next? Did I miss anything?
Thanks for your help in advance.
Replies
Are you using the 3DR Power Module on this aircraft?
Here is your Vcc graph...(over the time of the entire log - didn't mark the actual flight time section)
Vcc is 5VDC for the APM before regulation to 3.3VDC (on the APM).
It looks to me that your Vcc is falling out of spec. It is cleary below 4.7VDC near the end of the flight.
This graph should be as flat as possible..I mean dead flat (in a perfect world).
You are hardly near 5.0VDC for any length of time. A good setup for a brown-out/reset.
Watching the log playback, around 97% the motor state went from DISARMED, to ARMED, to nothing.
I think your APM reset due to Vcc dropping too low.
-=Doug
That is too bad and with the video it looks like the 'drop' side motors lost it.
I will look over the tlog and be right back.
-=Doug
Update: I am testing it post crash. I armed and put the motors at full throttle (without props). Sometimes the motors will lose power, dropping to < 50%. When I power down I am unable to re-arm. This happens ever 3rd or 4th time.