problems getting off the ground


ok so we bought the thing, we followed the instructions and double-triple checked, it still doesn't work.

the problem is: it is very unstable, it can't stabilize itself. We try to get off the  ground , and within one second of take off, it goes insane, makes a sudden move/ flip... without touching anything but the throttle stick.

We tried to hold it in our hands while running, and it gave us a vague impression that it acts as it is in "+" config, although it is in "x". Also, it seems to try to stabilize in the wrong way: instead of compensating, it reacts exactly opposite, and increases errors.

one other issue: when throttle goes to 0, two motors stop fast, the other 2 take about 2 or 3 more seconds to... could that mean anything? Also, when it is almost taking off, but keeps contact barely, it spins... is that just vibrations, or does it mean anything?

I actually wanted to take a video of it but we ran out of propellers and also a motor mount broke. So a video will be coming shortly (if it helps any). We also have some logs, just say if it can help.

(we are begginers to quadcopters and RC in general, but say we know our way around mechanics and electronics and Arduino...we are students!)

thank you very much,

any help is welcome,


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  • Check my response to other query.  Basically, the 4-wire connector came connected wrong from DIY.  The white wire shoutld be outboard on the upper board connection.  I found that switching the connector around so that the white is on the outside, and the inner two wires switched with each other works.  Be careful taking it out of the plastic connector.  Get someone who knows how to do it!!!

  • a video so you can better see what happens (this doesn't show instability, only motors stopping at different times)

    also a log, if someone can make use of it: (don't remember exactly what the log contains, what we did then. If you want something specific, please say so)

    2012-05-02 19-37-03.rlog

    2012-05-02 19-37-03.tlog

  • ... It also sounds like your Rate_P and/or Stabilize_P is too high. I had the same effect when I chose a Rate_P roll and pitch which was above the value which I am flying now. Maybe that helps..
  • Developer

    "one other issue: when throttle goes to 0, two motors stop fast, the other 2 take about 2 or 3 more seconds to... could that mean anything?"

    Yes, I believe this indicates at least one issue: The ESCs are not calibrated, or not calibrated *equally*. 

    Calibration means that your ESC "learns" the extreme positions of your RC controller throttle stick. Let's say your RC controller puts out a PWM pulse with a min of 1050 and a max of 1850. All the ESCs need to know this, so that they all start (and stop) at 1050 pulse and go to max at 1850.

    This may only be one of the problems you are facing, but you will not be able to resolve the others until you fix this.

    See here:

    Success equals: All ESCs start at the exact same time, seem to spin at the same speed and stop at the same time.

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