[jtrout19]

So this issue started all of the sudden. 2 motors got real hot one day. So i switched to back to 10inch props. Now I am having an issue where it takes about 65-70 percent throttle to raise off the ground. Once off the ground it is really hard to keep it in the air. I can leave throttle at 80 percent and it will rise and fall. Sometimes even at 100 percent throttle it starts falling. I checked motors I have one that has a clicky bearing. The others feel good and have no play. In this video I am controlling throttle through the transmitter. If I go into the GCS and use that to speed up one motor at a time there is no bad sound coming from any but the one with a bad bearing. I am using oneshot but have also tried pwm to see if it would get rid of the noise.

what do you guys think?

https://www.dropbox.com/s/uyfcdn3fgg8fdl6/20161125_143220%5B1%5D.mp4?dl=0

[TheOtherCliff]

If your PIDs are too high, you can experience an invisible high speed oscillation.  This drives the throttle toward 50% whether the stick is higher than that or lower than that.

If the motors seem to suddenly (not just a slow I term windup) rev up at very low throttle settings that is an indication that this is your problem.

If you are using AutoTune and have a SmoothQuick slider, adjust it to a lower (smoother) value.  Or you can simply manually adjust your PIDs to lower values.

[jtrout19]

I am at work currently took that video on my lunch I cant plug my quad in and check right now. But I will tell you that I have not changed default values. I selected generic quad X in the vehicle setup wizard. Today was going to be tuning day but...... yeah.

[TheOtherCliff]

Hot motors are also an indication of this invisible oscillation.  Default PIDs may be too high for some, especially for small fast quads.

[jtrout19]

Alrighty cliff my pids right now are. And My quad is a 550 size. so not small. I remember before I did the reset and re-setup Autotune put my PIDs really high higher than defaults but I will try lowering them and see what happens.

      Inner Loop
Roll         pitch          yaw
.00300    .00300      .00620
.00650    .00650      .01000
.000033  .000033    .000050

     Outer Loop
Roll        Pitch
2.500     2.500
0.000     0.000

[jtrout19]

I cut the values in half and got rid of the issue. Quad just needs tuned now.

[TheOtherCliff]

I had this problem on a 500 quad also.  I fixed it by removing the anti-vibration FC mount and bolting it to a solid mount that was attached with several layers of double sided tape.

[jtrout19]

My fc Is bolted directly to my frame. I do have some double sided tape under it. But it is bolted nice and sturdy!

[FPVghost]

If I may add two my two cents here. Keep an Eye on those motors and your ESCs because once the motors have gotten really hot the magnets have been computerized! Heat kills magnets!