X 8 Setup How to run 8 motors on APM 2.5?

Hello everybody,I want to ask about the oktokopter.I built a coaxial model with config X8 motors and I use a APM 2.5.The problem I have is this,only lower motors runing and I am now in a dead end.I could use some advices and sugestions.Thank you and have a great day.

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  • You have to set up the code via arduino ide not mission planner. updates however can be done via mission planner.

    Do not do as suggested before which is basically a hacked quad. Yes it will fly by not as stable and smooth as what is called the co-axial octocopter by many. I have one and I love it. Plus it will have no yaw authority if you run the motor pairs counter to each other

    Make sure you've examined the motor order and direction very closely, I.e. upper and lower motors spin opposite directions and the upper motors count ccw while the lower motors count cw.
    Another thing I got wrong is that the writing on the props should always face up.

    If possible use a slightly higher pitch prop on the lower motors. Eg 10x4.5 upper and 10x4.7 lower
  • MR60

    I'm no expert on this, so if someone else answers, trust their answer over mine.

    Each motor pair should be controlled together.  Hence both are controlled by the same APM output through your BEC command wire.  You treat the copter like a quad and then reverse wire the lower motors so when commanded to lift that side of the X to lift more, the top motor lifts and the bottom motor lifts.

    That would mean only four BECs going to the APM 2.5.  Each BEC is split to go to two motors.

    Again, I have no experience with this so it's only what I'd try from a logic point of view.  You might wait a little to see if someone else can reply first to see if this guess is correct.  I'd also test it with only one motor pair.

  • I can't help with your problem. I would imagine that the zip file is in the google code wiki downloads section. That is an awesome frame, could give some more details on it (how did you do 2 props on the top with one motor going through the other?)?

    Good luck


  • Developer

    Is it possible that you loaded the quad firmware instead of the Octa firmware? 

    I'm a little confused when you say X8 and lower motors.  Maybe you mean an octa-quad?  I.e. looks like an X quad in that it has 4 arms but there are 2 motors on each arm, 1 on the top, 1 on the bottom.  To be honest, although we have a library for that, I'm not sure you can load it through the mission planner.  You might only be able to do it by uploading from the .zip file and if you do it that way you'd need to add a line like this to the APM_Config.h file:


    ..and because you're uploading to an APM 2.5 you'd want to uncomment line 5 from APM_Config.h so it looks like this:


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