Dear APM users, I need your valuable inputs to resolve this issue.

My Quad tends to either roll to the left or pitch to the rear while raising the throttle alone. I'm flying it in stabilize mode and am continuously required to adjust the pitch and roll stick for a take off. I've read about the probable cause in the forums and solutions posted but without much improvement in my case.
Once in flight, it tries to drift and doesn't stay in one position as well.

I've checked the motor rotation with CLI -> test -> motors and they are proper. I'm using 10x4.7 APF SF props with Turnigy 3525 850KV motors in X config with APM 2.6 [firmware 3.1.5] and External GPS+Compass.

I'm getting a 3d GPS lock along with gpshdop < 2 and satcount 9+ at the time of take off. The compass orientation is proper too. Checked with the phone compass, both match.

Here's the gyro calibration values for my quad:
G_off: 0.01, -0.01, -0.01
A_off: -0.01, 0.03, 0.50
A_scale: 1.01, 1.00, 0.98

During Hand test, I can feel the quad resisting my movements and trying to stabilize itself.

Here are the Roll, Pitch and Yaw values when the quad is disarmed and lying flat on a level surface. The snap was taken indoors, so no GPS lock.



Are these defaults normal?

Also, I've read that the pwm outputs from the APM to the motors should be nearly the same. In my case, when disarmed the ch1out, ch2out, ch3out and, ch4out is set at 1007.



Once armed and as I raise the throttle a little bit, the ch1out, ch2out, ch3out and, ch4out values are as shown:



 Can anyone suggest something to highlight what might be wrong?

Are you able to hover the quad in stabilize mode? If so try to perform auto trim.

Yes I can. But then it is continuously drifting even with a 3D GPS lock. Won't remain still. I just re-assembled everything again, changed the ESC outputs to the motors to test. The problem remains - raising the throttle causes the quad to roll to its left. I didn't flash the APM again except I went for the ESC calibration. I noticed that while doing the All in one calibration, only two motors will start spinning. Once armed all 4 motors spins.

Try calibrating your Radio in MP & 4 ESCs individually. So your quad drifts even in Loiter/Position Hold mode?

Yes, drifts in Loiter and Position hold as well. Will redo the Radio Calibrations and the individual ESC  calibration once again.

As stated earlier, Only two motors spins after doing the all at once ESC calibration, Is that whats causing the flip over?

Which APM firmware are you using and what Tx? Did you check Trims before doing Radio calibration?

APM firmware version 3.1.5 (3c57e771) with FLYSKY FS-T6 6 Channel TX-RX.

The trims are centred and its visible as so in the display on TX.

In your Tx, which model type is selected for the quad? Acro? Heli? or any other?

Can you set your model as Acro in your Tx and try to fly once again?

Selected the only other option for model type.




Rolls to the left at 50% throttle.

I still haven't performed the individual ESC calibrations.

Ok.Erase eeprom and recalibrate everything.How did you mount your APM on the quad? Pls post some pics of that.

Process:

• After re-assembling everything from scratch, I flashed the APM's memory & did the initial setup again
• With the Quad placed on a level surface, the MP output is as shown:
  Arducopter flips during takeoff
• Re-did the all at once ESC calibrations once again, now all the 4 motors spins. The ESC was not getting properly calibrated as I was keeping the throttle in the max position for a longer duration during which this ESC went into programming mode.
• I also changed the motor connections on the ESC just to be sure.
• Replaced the old props with 11x4.7 APC SF ones and balanced them.
• Mixed the transmitter auxiliary channels to obtain four flight modes - Stabilize, RTL, Loiter & Alt Hold.

Top View:


APM View:





During Take off, there's no flipping now

P.S. There used to be an Air Module in place, now its lying buried somewhere.

 

Thanks for your inputs, again!

Your setup is very nice and clean

Thanks & Much appreciated!!

Also, the appreciation in part goes to Mr. Chintal from RCMumbai.com as his advice and help proved invaluable!!