Potential thrust loss motor 2


How on earth does one start trouble shooting potential thurst loss. Log attached.

I cant see any physicall damage to the ESC or the motor on motor 2

Motor 2 thrust is potentially (probably) too low for the current vehicle configuration.

Possible causes:

  • Motor 2 is defective
  • ESC 2 is defective
  • propeller 2 is defective
  • too much vehicle weight is carried by motor 2, redistribute weight in order to reduce it
  • too much weight or too low battery voltage


  • test the causes above one by one
    Improve your propulsion system.

Propulstion is adequate for the copter weight and there is no visible damage to the motor and propeller.

But Ill try to replace both motor and ESC to troubleshoot.

Could my ESC rampup settings be an issue?

Yes, that could be an issue.

Are you following How to methodically tune (almost) any multicopter using ArduCopter 4.4.x ?

Yes. Quick question. The ramp up power in your settings. Why is that at 80 percent?

@Janno can you answer him?

Increasing the ramp up power may have following effects:

  • quicker motor response through higher peak current during acceleration
    • therefore possible damage to ESC if operating close to its limit
  • possibly higher vibrations
  • possibly higher motor temperature

The default ramp up power in blheli_32 is 50% iirc. With our setup I don’t worry about burning out the ESC, so I set it to 80% to increase responsiveness. So far we have not seen excessive vibrations or excessive motor temperature caused by ramp up power.

Both the flights in the log look identical, Motors 1,2 and 4 are commanded to maximum output for brief periods.
I dont think this is an issue with the ESCs, or it would be staying broken.

Props could be slipping on shafts maybe?? You dont have those collet adapter things do you?

Otherwise it’s probably that tuning is not good enough for the copter to remain stable and the oscillations get out of control.

You’ve got other posts about building a H frame - is this a H or X ?

Try these to get you out of trouble and then jump back into the new tuning guide

INS_HNTCH_ENABLE,1  // write then refresh params to see the rest

That is the Harmonic Notch Filter done and sorted unless you’ve got an awful mess of harmonics or something odd.

Rampup power is not critical - read the BLHELI32 documentation, it just used to go from “not working” to “working” and wont make any difference unless you notice a problem with yaw oscillations when arming, or you have EXTREMELY large props.

This is an Xframe. Props are attached via screw in quick release mounts

Tuning was done on standard default settings that have flown perfectly the previous day and for the last 3 months while i get my build sorted out.

Only physical difference is that I changed motor mounts and moved the motors maybe 4 cm further out.

Why I am asking about rampup power is that after I changed that the problems started. Yesterday the drone could barely get off the ground.

I can not hear any oscilations on the motors. It does seem to do a weak “toilet bowel” but then that is usually when i get the thrust loss warning on my Ground station.

One thing I forogt to mention was that when I used the Motor Test function the day before the flight the motors would stop when I used 100 percent. I would gradully increase the power in 5 percent increments and the moment it went above 90 precent the motors would stop and jitter.

I’ve increased the ramp up power from 40 to 60 so lets see what it does today

OK so changed motor no 2 andnd did some “ground” runs with the props off and again got potential thurst loss on motor 2. Ill change the ESC and see if that makes a difference

Do you have Low RPM Power Protect = OFF in BLHELI32 settings?

No its on as in the photo attached

This could be alot of reasons.

Check your rotor arm, is it firmly holding the motor, is it unhinged or vibrating too wildly. Is the propeller firmly attached. How about the wires to motor. Is it Connected properly. When you fly how does it fall to the ground. Is it swaying to one side or directly falls. When you push your throttle up alittle is the motors turning at the right speed? If not ESC could be a problem etc

When does it happens? During mid air? How long? or just when you take off? If its mid air after some time flying could be you overheat your motor.

OK so no to all the build issues. Arm and everything is very secure.

The thrust loss message i just got today was while applying power with no prop attached.

Yesterday the thrust loss happened at roughly the same amount of time, Almost done changing the esc then ill see if it is that :slight_smile:

OK so would you suggest i keep it at 50 percent for my setup?

Do I need to turn it off or on?

The latest firmware versions have Auto which would be OK too.
It might not be you problem though since the motors were running OK up until problems appeared from nowhere.

This was off. I only changed it on recommendation of the Tuning guide mentioned by @amilcarlucas

FYI, Rampup power mostly only affects starting up a motor and change of direction.
Acceleration would affect speed changes during operation more than Rampup power.

That’s what I get from the documentation.

AND we have success. Test flight went well.

I’ve attached the log file again just in case someone wants to have a look to see if there are any issues I need to resolve before I continue with the tuning process. psc_azz_i and p was set in accordance with mot_ths_hov.

Question. When this has been set do i need to switch hover learn off?