MK Hexa XL unstable

Hello everyone

I am a new member of the forum and I have a problem.

I've got a MK hexa xl kit that I've just finished putting together, and it tries to flip on takeoff. I'm running + config with Arducopter 2.1 firmware.

I checked out the motors with the CLI command, calibrated ESC and radio. In APM Planner setup inputs from the radio are correct.

The hand test gives a first problem: the pitch is reversed (pitch stick forward and hexa points back with motor 1 faster) so I set to reverse on the radio. (but the motors command in CLI give me all ok...)

At take-off throttle gently tilts the hexa, with strong throttle gets going right and then almost stabilized in flight with a tendency to always go to the right. Each time, not to miss the exa, I have come down with a crash.

The motors are MK3638 with propellers 13x4.5 CF with payload a GoPro . Lipo 3S
The propellers are too powerful and create instability? For a total weight of about 2.5 kg such propellers are recommended?

In bench tests, in APM Planner status I see with minimal throttle trigger all channels 1-2-3-4-7-8 in 1189 but with more throttle only increase the channels 1-3-8. Is it OK that arducopter run a hexa take off as a tri?

I am a little frustrated because after 4 attempts at flights I broke about a dozen propellers and an arm of the frame.

Thanks in advance to anyone who can help me

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  • Hi to all

    these are the video of two first flights; in the first probably i dosed wrong the throttle but on the second the hexa go independently to the right

    To see the video use passwd  volo

  • I rate batteries to how much drained with current over time at a given voltage.

    Work is HP.

    If your batteries need more power recharge over time maybe they are failing or need to be replaced.

  • Thanks to all

    the battery is a 3s lipo with 50C discarge rate (nanotech 6000mAh)

    I think it's a software problem because all the engines running and there is not brown out on esc.
    Takeoff (simulated without propellers) all engines running with outputs 1189; more throttle,
    only the engines 1, 3 and 8 increased speed. But if I change manually the tilt, all engines are controlled by apm.

    Then I can not explain why the test engine is correct and in flight the pitch is reversed

  • Developer

    In your setup you must use "APC SlowFly 12x3.8" and 4s lipo for better performance.

  • I run a similar setup in Y6 config. I found flying it on 3s was super difficult, try switching to 4s and re-doing the entire assembly regarding the APM. Another thing, if your comfortable try loading the firmware from Arduino rather than the mission planner. I almost exclusively do it this way since the mission planner always gives me problems.

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