All my quadcopter tilt above ~80% throttle

[Blacksmith]

Hi guys,

in the last few month, i built three quadcopter with kk2 boards.

1 x V-tail (30,5 cm arm length, like simplecopter.com) with sunnysky 2212-980kv @ SF 10x4.5
1 x Spider with motorspan 36cm with Turnigy D2830/11 1000kv @ SF 10x4.5
1 x Quad x with motorspan 24cm with Turnigy DD2822/14 1450kv @ SF 8x4.5

All of these copters tilt above a specific throttle position. The first two copters tilt above a throttle position of ~85-90%. The small one ist slightly overpowerd and tilts earlier.

I tried to switch the props, the motors, the esc´s. I don´t get it.....It happens with and without selflevel.

When i built my first one, I though one motor has more power than the others. But switching the above named parts didnt help and could not locate the mistake. Now, the other two have the same problem.

Vtail and Spider tilt front and left or right, always the same side, but dont know which atm.
Quad X tilt backwards

Any ideas?

Btw. I do have a Speedmeter for the Props, but I did not dare to give full throttle while its straped on the ground.

Thanks for your help.

 

[Craftydan]

Where's your control board in relation to the CG?

 

[epic.engineering]

Also in the v tail flite test build video.. David explains settings to compensate when the copter tilts front or back by adjusting settings on the kk2 board

 

[Gremlo]

If its a KK2.0 board, go into the settings and turn down the max throttle of the motor that is makeing the copter tilt. I had the same issue with my tricopter and it fixed it first try. do slow adjustments so you can go through your full throttle range from take off to full throttle without having the copter tilt.

 

[xuzme720]

Here's the video:

He talks about the KK2 board setup starting around 9:00.

 

[patechoc]

Hi Blacksmith,
I got exactly the problem you described with my quadcopter. I tried both X and + configuration of the motors, and in both cases, the quad is tilting.
I also thought of different motor power, but I didn't check it by exchanging them as you did since I found your post before.
I haven't seen where to change the "max, Throttle". I found the "min Throttle" though, but I don't understand how that will cure the problem.
But I am really puzzled still, have you found how to correct for this strange behavior?
Thanks in advance for your help

 

[Cyberdactyl]

If you start messing with the 'mixer editor' settings, make sure you write down the original settings. If you really screw-up the settings, you can go back to the original.

 

[Blacksmith]

I tried different things.

First of all. 2 Points are very important. the CoG (as mentioned above) and the Center of Thrust. It is NOT always the same (e.g. V-tail). The Control board has to be placed on the CoG. That is the center of a imaginary straight line between the front motors and the rear motors. The Center of Thrust is a imaginary diagonal line between all motors.

click here

I placed the board on the CoG and balanced the copter on the CoT.
Another aspect is the position of the GoPro. Above the copter is more unstable than hanging under the copter. But it is not gone yet :/

That´s my experience with the balancing thing.

 

[patechoc]

Thanks Cyberdactyl, I don't think my small modifications affected anything actually. I also tested already to reset all parameters on the KK2 board, and the problem remains, unfortunately! It could be some default setting then, but I have no clue which one(s) to modify.

 

[patechoc]

Thanks too Blacksmith,
I thought of the balance when reading different forums with similar issues, but I have a simple quadcopter: a symmetric "plus" shape. So for me the Center of mass/gravity or the center of thrust should be the same. I just have my battery below the quad, along the axis front/back of the quad which could affect the balance, but the quad is clearly rolling , so the battery weight should not be the issue.
Anyway thanks again for your replies, and if you are other ideas, I would love to hear more from you ;-)
Happy new year!