[thaianh.imex]

Hello everyone. I am building a f450 drone with cc3d and 4x 30A Hobyking Esc, 4x 2212 1000kv. After finished setup cc3d with LibrePilot, i found the 4th motor dont work . When i am armed form 0 to 50%, both 1,2,3th motor run except 4th. From 50% to 100% , the 4th motor begin run but very slow. I am calibed all 4 motor and test OK, but when I use TX to control, the 4th motor still dont work .
Thank you for your listening.

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[TheOtherCliff]

When you set drone on the ground it is not perfectly level.  Some motors are lower than others.  The highest motor will spin slower or not at all, until the lower motors have lifted up the low part of the drone.  For a test you can put something under the foot of the drone to make the bad motor the lowest to see if this is the problem.

If that doesn't show the problem, then I suggest that you redo the ESC calibration and motor neutral settings.  While you are doing it, make sure each motor can achieve full RPM.

Follow these instructions:
https://librepilot.atlassian.net/wiki/spaces/LPDOC/pages/12058743/ESC+Calibration

Please don't post the same question in two places.  I deleted your other post.  I have also moved this post off to a separate thread since it is not about the yaw channel.  Thanks. 

[thaianh.imex]

Thank you very much, you are so kind. I will do the right things at next time .

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[thaianh.imex]

When you set drone on the ground it is not perfectly level.  Some motors are lower than others.  The highest motor will spin slower or not at all, until the lower motors have lifted up the low part of the drone.  For a test you can put something under the foot of the drone to make the bad motor the lowest to see if this is the problem.

If that doesn't show the problem, then I suggest that you redo the ESC calibration and motor neutral settings.  While you are doing it, make sure each motor can achieve full RPM.

Follow these instructions:
https://librepilot.atlassian.net/wiki/spaces/LPDOC/pages/12058743/ESC+Calibration

Please don't post the same question in two places.  I deleted your other post.  I have also moved this post off to a separate thread since it is not about the yaw channel.  Thanks. 

Hello TheOtherCliff. I level many times and calib the esc many time but it still not fixed . Always have 1 motor dont work .

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[TheOtherCliff]

same motor each time?  but all motors work during esc calibration?  making that motor very low when sitting on ground doesnt fix it?

[thaianh.imex]

same motor each time?  but all motors work during esc calibration?  making that motor very low when sitting on ground doesnt fix it?

Yes, its always the 4th motor. When calibration all 4motors, its very smooth from slow to high. But after finish all the calibrarion and level   its begin not working. When I place it lower then the anotherside, its begin run normally, but the other will be stop. Always have 3 motors work on the same time , not four.

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[TheOtherCliff]

Try setting it on the ground at different angles to find what angle seems to make it think it is level.  If that angle is not level, you should understand that it will fly off in that direction.  Slowly for tiny angles.  Pretty badly for any angle that is easy to see.

It sounds like your leveling calibration may be a bit off if one arm consistently acts like it is too high.  I would carefully redo Configuration->Attitude->Calibration->Level.

Another thing to check is Configuration->Stabilization->Integral->ZeroTheIntegralWhenThrottleIsLow must be checked, not unchecked.

Also be aware that this is somewhat normal.  The highest motor will not run at full speed until the lower motors have risen to the same level.  This isn't a problem when actually flying unless the drone is actually at an angle when the motors are all running the same.

PIDs affect this too.  I would start from default PIDs, not PIDs that you try to match from a similar model.

Here is a page that may help you avoid flipping on takeoff.
https://forum.librepilot.org/index.php?topic=4408.0

[thaianh.imex]

Dear Sir. I am so happy when solved the problem .
"Another thing to check is Configuration->Stabilization->Integral->ZeroTheIntegralWhenThrottleIsLow must be checked, not unchecked."
Its unchecked already and I am just umchecked it .
Now everything is goood. And I will takeoff soon .
Thank you alot .


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