Tricopter and yaw if servo link is not perfect

[hkubota]

Hi,

Maybe a basic question, but I cannot understand why this would be happening what happens:

I got a tricopter. Fun to fly in general. Once the servo holder for the tail was slightly off so that the tail motor was tilting way more left than it should be.
As a result it was turning clock-wise until I actively counter-acted it. The fix was to put the servo back where it belonged to.

Another time I changed props and the different mass if the tail prop (the front 2 are counter-rotating), was different. As a result the tri yawed clock-wise. This time the servo link needed to be shortened to make the tail motor lean less right.

Both times I wondered why this was needed at all. Should the FC (Naze32 in this case, but as there is nothing specific about this, this is more a general MWC question) not automatically adjust what is needed to make it not yaw unless there is user input?


I'd equally expect if I use a 10x3.8 prop in the back and 10x4.5 props in the front, that the tail motor automatically will spin faster when I add throttle.
Just like when I manually try to push the tail down, it'll counteract to keep its desired position and attitude.
That might fail when I suddenly add large amounts of throttle, so it's obvious that this is not a good way to set up your tricopter.
But it should work for slow flying resp. hovering.

The problem I see is when I change the tail propeller, I have to change the link length for the tail motor or adjust the "neutral" position of the tail servo.
Isn't the FC supposed to automatically handle this as part of its PID loop?

On a heli with heading hold, if the linkage for the tail is off, the HH gyro will handle this. Again, not perfect, but it works.
Why does MWC not do the same?

Harald

[hkubota]

Well, for those who are having the same problem: adjust the Yaw I parameter. In my case moving from 0.070 (default on Baseflight) to 0.090 and the tail no longer drifts.

In hindsight it's relatively obvious.