Quad unstable to take off

Hi, 

I am new to Quad world. Recently building one new quad it become unstable when i installed propellers and ready to take off. I am not dare to take off with this condition, so i tried to hold my quad in the air and try almost half throttle pretending it is hovering and what i noticed was four motors are running at different speed. I am pretty sure it is level, if it is not only slightly uneven but it wont make such big different. Sometimes one of motors just stop spinning...

I ran out of ideas....could any one help on this?? I have done ESC, motor, radio and Compass calibration. And propellers are balanced. Any idea what might went wrong?

My Setup Below:
Flight Controller: Pixhawk 3.1.1
Frame: Flycat MWC
Motors: Sunnysky x2212 980kv
ESC: Simonk 30A Brushless ESC with 5V 2A BEC from Banggood

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Replies

  • Im not familiar with the pixhawk but are you sure you have set it up correctly, your frame is X type and not + so maybe its that what's making problems?

    • in Mission Planner show X type

  • Moderator

    Check while holding the quad firmly and safely and running at half throttle that when you lower one arm of the quad then the motor on that arm should speed up resisting the downward movement. You should repeat with each arm making sure that the right motor increases rpm. If it doesn't then your setup is wrong.

    • Hi Graham,

       

      Motors 1 and 4 does not resist when i tilt right then i did ESC calibration one by one.  After this all, it resist all direction, but motor 1 seem like spinning different speed as others 3 motors.  When i increase throttle to about 40%, motor 1 become half dead and further throttle input it eventually stopped. 

       

      I have tried to swap esc and motor with other arm it still have the same result only motor 1 not having right rpm.  I have also checked many times prop and cables are correct

      • Hi Andy,

        Sorry to hear you're having problems before launch -- I know how frustrating that is.  Some random thoughts:

        * Do the motors all seem to spin at about the same rate after you arm the copter prior to take off?

        * Have you checked all of your joins/soldering to ensure there's nothing loose and/or shorting against other components?

        * How about swapping an ESC from another arm (leaving the motor as-is).  Does the 'slow' motor change to the other arm or stay on motor 1?

        * Have you tried re-doing your accelerometer calibration and make sure it is perfectly flat on the 'level' step.

        I hope one of the above give you a lead.

        • Hi Matt,

          * Do the motors all seem to spin at about the same rate after you arm the copter prior to take off?

          - all other 3 motors seem having same rate but except motor 1.

          * Have you checked all of your joins/soldering to ensure there's nothing loose and/or shorting against other components?

          - Yes, i did check and swap with others arm motors and esc.  no luck at all....it happened only on Motor 1 arm.

          * How about swapping an ESC from another arm (leaving the motor as-is).  Does the 'slow' motor change to the other arm or stay on motor 1?

          - After swap from other arm esc and motor, Motor 1 still stay slow.  Previous Motor 1 esc and motor work well on other arms.

          * Have you tried re-doing your accelerometer calibration and make sure it is perfectly flat on the 'level' step.

          - Yes, i did it many times. no luck at all....it seem like configuration issue.

          • - After swap from other arm esc and motor, Motor 1 still stay slow. Previous Motor 1 esc and motor work well on other arms.

            How about power distribution.  Are you plugging motor 1's ESC into the same place after swapping?  Can you try a different location?

            If that doesn't work, can you please upload a log to have a look at?

            • I will try that tonight

  • any one have any idea?

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