Quadcopter flies off at 35 degrees on every takeoff

ArduCopter
1

Hello everyone

We did a flight test today on a newly built drone. We have an issue where the drone weers to the same direction on each takeoff, front right (35 degrees maybe). We are flying on stabilise. We have scoured the forums for solution, but nothing seems to work for us so far.
We are using the Mamba Mk3 flightcontroller with a Cinematic f30a 4-1 esc and 4 t-motor 1204 with 2 blade 4 inch props.

We have tried looking at vibrations, is under 30 usually so shouldnt be a problem.
We have checked for trim on controller and calibrated RC.
We have checked framtetype and motor assignment, should be okay.

Please take a look at the videos we filmed and the DataFlash logs:
https://drive.google.com/drive/folders/1OEhHc8f9xztW6WIWaacd_ywSZMrKvBiq?usp=sharing

The video doesn’t correlate to the DataFlash logs but it was from an identical test.

2

Is the center of gravity at the physical center of the Copter? Is other words is the weight equally distributed on all motors?

3

In this case, the center of gravity may be slightly off indeed, or, more probably, the accel calibration is slightly off, but normally this is compensated quickly enough.

I don’t quite like the way the pilot lifts off - the box intercepts your copter when it goes sideways, which makes the copter think that it shall try harder, etc - so when it finally leaves the box, it exerts quite some force acting sideways, and the pilot has to compensate it. Indeed, the Stabilize flight mode cares only about the attitude.

It also seems to me (it can be that I am wrong, but it really looks this way) that the pilot has little total experience in manual modes. The Stabilize mode requires quick reaction to keep the copter close to a fixed point, and the pilot seems to not expect that. Maybe AltHold is slightly easier to begin with, since one cares way less about maintaining throttle in this mode.

In any case, it is too naive to expect a freshly built copter to maintain a steady hover above a point in Stabilize with no stick input at all. None of my copters do, although some come quite close - but one shall always be totally alert when flying in manual modes (and in other modes too, actually).

4

Seemed like it worked. We didnt do AltHold since it had wobling issues making it climb too much. We did stabilize without box and with stick input for adjustment during flight and it stabilized finally. And we did some parameter tuning and it doesn’t wobble anymore, and now althold works. Thanks for your input!