Catastrophic chrash with 4.5 kg Quadcopter X

Hello guys, Bruno from Brazil here.

We were flying a big 4.5kg Quadcopter X with 4 Turnigy G60 500kV and 18x6.5 props for the first time. Something went really bad. All normal calibration and setup was done, nothing changed from PID gains, just the original values that come with ArduCopter.
Some guess on how this turned into a big chrash?
It took off roughly in Loiter mode, started to drift a little but we managed to bring it back. When trying to land we couldan’t.

Do you have any ideas and advice on what to do with our next flight?

log_9_2019-8-15-10-31-38.bin (885.6 KB)



A lot of vibrations, with large props…

Have a look at the motor-bearing quality and propellers balance.

When we look at the Attitude screen (des roll and pitch compared to roll and pict, Delta is increasing…


Have a look at the Arducopter tuning section.

Some defaults parameters relative to propellers size are to be set before first flight.

Nice place, is there a chicken factory in the south-west of the city?

Hi mlebret,

Thanks a lot for replying!

Is there anyway we could check vibrations before accelerating the motors? We saw a little vibration when we armed the vehicle, but we didn’t know it could lead to a crash.

I didn’t understand the chicken factory…

Victor Hugo Turcato
First things first. Remove propellers, get the calibration correct.
Assuming you have done Accelerometer, Compass, Radio calibration and set failsafe,
1.Put the throttle stick to maximum
2. Connect battery (you’ll notice red and blue lights blinking rapidly)
3. Disconnect battery and connect again keeping the throttle stick at maximum
4. Now you’ll here CubePilot boot and motor arming sound. Wait for initial beeps on ESCs and pull the stick down.
5. ESCs should make the sound of boot completion. Increase throttle to check whether all motor start-up and spool equally. At this point, all motor pwm values are directly sent to ESC.
6. Disconnect and reconnect. ESCs are calibrated.
Set BRD_SAFETYENABLE back to 1 after calibration.

Coming to the flying part,

  1. Make sure your props are balanced.
  2. Set MOT_HOVER_LEARN=2 (learn and save)
  3. Set MOT_THST_HOVER= 0.2 to 0.25
  4. Your MOT_SPIN_MIN looks ok.
  5. Switch to STABILIZE mode. Try to fly. Check for gains. While your flying in stabilize mode, the controller learns the hover throttle.
  6. If you feel it flies good, try switching to altitude hold.

Look like a chicken farm.

hahahaha it is an old chicken farm far away from the town, it is no longer active.

By the way, did you find this place thru the Mission Planner log? Which tool do you use for log analysis?

I’ve never managed to see the flight path in Mission Planner logs.

We checked here and the ESCs were not really calibrated at all. The ‘beeps’ pattern emitted during this ESC calibration is a little bit different from what is described in Arducopter guide, and lead us to an incorrect calibration procedure.

@mlebret @Mallikarjun_SE It is not the first time that when we try to land a quadcopter X in Loiter mode, the landing is not recognized by the autopilot system, leading to an unstable behavior, which already damaged some props. We had this problem with a smaller model twice.

The other post about this problem is in Problems landing a quadcopter X

Any guess on how to achieve a more stable and smooth landing?

As a starting point with 18inch props set these:

And for landings check these:
WP_NAVALT_MIN {2 or 3}

Hey @xfacta
Did you try flying in STABILIZE and ALTHold mode?
You don’t need ground effect parameters unless you really have problem with landing. Send a screenshot of your gains.
I would suggest to keep MOT_THST_EXPO as default. Try flying in STABILIZE mode let me know the results.