Quad drifts and crash in RTL,flips on takeoff + GPS question

Log Analysis -- deprecated Copter Logs -- deprecated
1

As you can see I am new to this forum. Bought a 2014 quad-kit from 3dr and telemetry radio, followed the manual on build and done wiki step by step.

I have two issues that I seems to fail to understand why is happening.

  1. If i slowly raise the throttle, the quad eventually flips, for me I looks like two motors on one side spins faster than the other two. I have tried ESC-calibration several times. If I raise the throttle fast it will take off crocked to that side it tends to flip but corrects itself when in air. Not sure if that is the way it supposed to be?

  2. Although flying on a open field I’m having trouble getting more than 10 satellites and hdop belov 2.00. GPS + Compass is mounted on mast so it should not be any interference.

  3. When changing mode to any other than Stabilize (only tried Alt Hold and Loiter) it drifts to the right so I have only been flying in Stabilize mode. This has worked fine after tuned Thottle mid and turned down sensitivity on RC Feel and Roll/Pitch to a more comforting levels in Basic Settings.
    The real problem occurred when Battery failsafe kicked in (as my understanding by the log) and it changed to RTL, I loose control over it and it started to drift to the right and a littlebit tilted backwards before it crashes to the ground. I tried to bring it back to Stabilize and save it in last minute but failed, that may be the reason why the last change is AltHold and Drift.

I have attached both tlog and df-log (not sure if rlog is needed but it seems that it is disallowed)

Any help is deeply appreciated.

[attachment=0]2014-08-15 19-18-40.tlog[/attachment]
[attachment=1]3.BIN[/attachment]

2

No suggestions anyone?

3

Maybe you should repeat the accelerometer calibration. Make sure the copter shows to be leveled in the flight data in MP when it is leveled on the ground.

10 satellites and an hdop around 2 should be fine.

Don’t configure the battery failsafe as long as the GPS controlled modes (i.e. loiter) do not work as expected. Anyways, you should not rely on the battery failsafe to kick in. Use telemetry or a timer on your transmitter to know when it’s time to land.

Best Regards,
Claus

4

I did recalibrate both compass and accelerometer before the flight whitch ended in crash, I have also plotted in magnetic declination based on my position from this website: magnetic-declination.com/

Quad reporting level when placed on floor and and showing correct movement when moving it in my hand.

But a thought, what happens if I calibrate the compass direction wrong, may this be a explination to the drift in the wrong direction? As informed i first post, I have pixhawk and u-blox mounted on external mast. I see under Manual in “Initial Setup => Mandatory Hardware => Compass” that it had “ROTATION_ROLL_180” listed, but isn’t “ROTATION_NONE” correct?

5

COMPASS_ORIENT is set incorrectly. Set it to zero, assuming you’re using the GPS+MAG unit mounted in the indicated orientation. Re-do compass calibration after this.