Any idea what causes this behavior?

[SteevyT]

Below some RPM, this motor stutters. I don't know what RPM it is, but with a load it stutters bad enough that it is unusable.

This is the exact motor. I was using it on the tail of my tricopter and it started stuttering after a landing with a little too much horizontal velocity. The tri ended up balanced on its side, but no visible damage. There are about 8 flights on this motor.


Here's a video of what I'm talking about (ignore my ESC mention, I did this before I checked whether it was actually the ESC)

https://youtu.be/q2an8FEOYTs

 

[mesolost]

That sounds exactly like the sounds i heard from small brushed motors when the bearings went out. Try some WD-40 or vegetable oil on the bearings, see if that stops the squeal. If it does stop it (will be temporary) then your gonna either need to get new bearings or a new motor.

 

[RAM]

My standard answer is bad parenting but I think mesolost is correct in this case.

 

[Pity_the_fool]

Sounds like a bad electrical connection. If a bullet connector is loose or you have a bad solder joint you can get stuttering like that.

 

[SteevyT]

I had entirely forgotten about this post. It turns out I had the motors over propped and probably damaged something in the motor. Whether a winding was bad, or something had disconnected, I'm not sure still, but it did it either at low throttle or if it had any sort of load.

The size motors I meant to order will arrive tomorrow.