RCOUT always fluctuates before totally taking-off


I am facing this symptom, I hope someone could point out if this is an error/problem to the system (how can we fix it) or it is hamrless.

My RCOUT(s) are always up and down like the photo below when arming. If it is lifted off, this is not (or can not be seen) observable anymore. Please have some time to check an your advices are invaluable.


Log files: https://drive.google.com/file/d/1EZyQ5v9cEqkqIHP2bC6DEtnMpyyMQBQk/view?usp=sharing

Set these

What size props have you got? Some of these parameters don’t make complete sense. Some filter values seem too low, and Harmonic Notch filter looks like a very low frequency, maybe too low.

I would connect to MissionPlanner and go to the Setup, Mandatory…, Initial Parameters section and enter your prop size and accept all the gyro and filter values offered.

You’ve got PWM min and max setting as if you have T-Motor Flame ESCs, but you’ve got MOT_THST_EXPO,0.75
If you do have the Flame ESCs you could be better off with 0.4 or maybe 0.2

Three important things I notice:

  1. physical yaw bias caused by a twisted motor mount
  2. motor outputs going to near maximum just to get airborne = wrong motors and props, or too much payload
  3. Motor 2 actually stopped functioning or desynced near the end = thrust loss message, causing descent even though motors are close to maximum.

I feel a redesign coming on

Thank you so much for the help.

Low gyro/accel filter because I have very high noise in the frame. I tried with 10Hz, 12Hz… and 8Hz works for me

This is an optimal phase, not the first drone I have tune so I totally understand about the Tunning guide written in the wiki.

No, I have the Alpha ESC. Already tried with 0.65 but never went lower. Lower value should be more linear. More on this: Quadcopter crash in Autotune - #5 by dkemxr

About 1. I agree and this problem is observable. We are working on in
About 3. Yes this flight the drone crashed because out of battery, it caused potential thrust lost
About 2. I am using P80 III, 3218 props size for maximum load of 42Kg. Do you have some time to take a look on this spec:

To sum up, do these things relate to the question I mentioned above?

Thanks in advance,

Forget to mention about this. I do not think it is necessary at the moment because it is right in front of my face, being ready for land on the bushed or motor emergency stop. We are tuning it, not using as normal.

What happens is people forget to set these when tuning reaches some acceptable level, and test flights get longer and longer…
There’s no detriment to setting them before first flights. It might just flag some battery or configuration issue.
I always set the Fence parameters first too - then you always have a Home position to return to.

I see and get your point clearly. I am totally aware of these initial parameters and this is not the first drone I have ever tuned.
I am coming back from some flight tests and keep you posted.
If this issue is fully analysed and solved, someone in the furture may found it helps.