Problems with fwd flight

I've managed to get my ac together and in nice trim. It is very smooth to hover, but i have two weird issues with flight.

First one is with forward flight; in stabilize, simple and alt hold modes when i start to accelerate forward, the copter suddenly turns 90-180 degrees to either side around z-axis after short flight.

You can see the issue in video i posted (vid is compilation, about 6 min, this problem is seen in about 4:30, and hey, nice Finnish views too!).

Another issue is with loiter. The loiter radius is about 10-20 meters, gradually increasing, the copter seems to fly rectangular pattern which expands after every turn. Eventually the copter shoots really fast out of control.

Any help is appreciated.

 

fw is 2.0.42

 

https://www.youtube.com/watch?v=COPywDrpKck

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  • Moderator

    You do have a magnetometer installed, yes?

  • Hello,

    just my two cents:

     

    1. I had motors just like yours once. Even the prop holders looked like yours.

     

    Problem: This setup makes the motor shaft very long. So if the shaft is even a tiny bit unbalanced this will have a huge impact on vibrations. I had exactly this problem. My copter (about one year ago it was a Mikrokopter) wouldn't fly in a streight line.

    Different motors with a differnt prop holding system: problem solved

     

    2. In your video I hear a really loud, strange sound as soon as you try to fly forward. Maybe there is just something wrong with your front-left motor.

    ...just a guess

     

    I hope you can solve the problem.

    Kai

  • I have seen this before in one of my quads and posted about it. I was playing with PID's trying to get rid of the 'springy' yaw i still see today.. When i had the yaw stabilize P down to low all i had to do was a bit of forward flight in any direction and the yaw would spin 90-180 degrees or more. I reverted P to higher value and it went away, wierd. I cant explain it and have not sen it sense (but never lowered my P since).

  • Developer

    I've never had this problem before, but I've heard about it from others. I think it's an uncalibrated compass.

    Fly around a bit and then disarm the copter. Disarming will save the compass calibrations.

    If you want to verify it's the compass, disable it in the CLI Setup menu. "Compass off"

    Jason

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