Ok so tonight I have just finished connecting my new gps module to my tbs discovery running 3.1 and an apm 2.5. I have 2 hours flight time on this drone with only stabilise and alt hold and 0 problems at all.

I got a UBLOX NEO-6M from unmanned tech and set about mounting it etc before test flying tonight. 

Here is the sequence of what happened:

-Wind 8mph

-Took off in STABILISE

-flew around a little no problems

-switched to ALT HOLD no issues

-switched to LOITER and took hands off the sticks, severe drift in one direction with a steady climb in  altitude but responding vaguely to throttle and cyclic input.

-switch to STABILISE no effect the drone appeared to remain in LOITER

-slowly managed to reduce height and bring in for a landing 

-wobbly landing as very minimal cyclic control, while on ground the drone would not DISARM and took off  again while throttle at 0%.

-as it took off it caught a blade loosening it which in turn caused it to flip

-I powered off by unplugging battery (props still trying hard to spin)

Flight 2:

-GPS unplugged

-took off in STABILISE did not feel normal, severe drift in one direction

-switched to ALT HOLD, same problem again that I had with LOITER mode

-managed to land quickly

-would not DISARM

-had to hold it down with 1 hand and slide my left hand under the spinning rotors and slide battery plug  out. 

Below is a screenshot of the autopilot before heading out (no fix as in my house)

Any help or suggestions welcomed, I am about to recalibrate the accelerometers and compass and will try again tomorrow with no GPS unit attached.


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For the motors spinning, check and see if it went into land mode.  Might have been caused by a low battery failsafe.  If it did, check the min throttle it is set to.  mine was high enough to keep my quad a few inches in the air.  it would also keep the motors spinning and not let it disarm.

Posting your dataflash logs would be better if you want some suggestions...

I wasnt connected to my ground station, so im guessing I will have no logs?

Thanks for that I will check the fail safes and throttle. The battery was full but I will look at that anyway, one thing I did notice was the 3 position switch on my transmitter had somehow assigned loiter to the position where stabilise had been previously. I think this could of been a major factor that and I am unsure if I had a good GPS lock as I hadn't looked for the blue light on the apm. I t is not possible to see the lights on my GPS unit unfortunately as I have beefed it up a bit to stop it being damaged by the elements. (see pic's attached)


Thanks for that! ill get them up as soon as I can.


ok here are the logs for the 2 problem flights. 


Need the .log files

The TLOG files are attached, there was also RLOG?


Really, its just the .log file we need that you got from Mission Planner when you downloaded the logs.

Same here.

Motors working at about 30% throtte and lost connect with fc. No disarm, no

telemetry not tx. Spinning rotors and I was lucky to plug out battery.



@Xian06: sounds like you were in another mode. Again, logs or its just guesswork...

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