Mini Talon Quadplane yaw oscillations

Hi Guys,

I tried to maiden my mini talon quadplane, but run into a strange issue.
After takeoff in QLOITER , it seems quite ok, but after some yaw input, it goes into some kind of YAW oscillation, it increases until it hardly manage altitude.
According to the log the desired yaw starts to oscillate and the plane follows…

The plane setup is quite similar Greg’s, but front motors moved ahead about 5cm and back motors facing down (Below wing level). It is a H setup. Before starting to rewire it to X, or poking around parameters I really would be happy if somebody with more knowledge take a look at the logs…

Any ideas ?

Logs are here :

Hi Andras,

How does it behave in QSTABILIZE mode?

The yaw issue you describe sounds similar to the problem I have on the Ranger EX QuadPlane after using v3.8.0 firmware and converting to H-frame. I never got time to determine a fix as I am happy with the performance as an APM Plane. It became a large and awkward QuadPlane.

On your mini Talon, have you cleared the parameters fully when downloading the firmware? There is sometimes an issue when just updating from a previous release. You could then upload my .param file I posted in my thread and then make changes specific to your setup.

If your quad motor Kv is similar to mine on 4s with 10x5 (2-blade) or 9x5 (3-blade) props then you can use the same PIDs.

Hopefully, Tridge will look at the logs for you…

Good luck!

Just another idea, if QSTABILZE/QHOVER performs well:
A kind of toilet bowl effect due to bad calibrated compass ?

Good luck!

Thanks for your input. I’ll definitely will check your params. Perhaps i’ll install arducopter and test the plane in copter mode… to make sure that the hardware is working well… The controller come from a 3.5 copter, and never had AP before, so parameter update should not be an issue…
I have a couple suspects, will go though all of them…

but I’ll check in Qstabilize first…

In theory, toilet bowling should not cause unwanted yaw… (Or it’s working differently on Quadplane ?)

The log shows an oscillation driven by the yaw P term. The usual rule is to keep halving the PID parameter until the oscillation goes away, so by that rule you would halve Q_A_RAT_YAW_P.
I’d be also looking for a physical reason for the oscillation, such as frame flex. A frame that can flex too much will need much lower gains to be stable.

1 Like

An overhead picture of the airframe would be good. The mini talon does not have very good yaw control, particularly with smaller propellers, and depending on the layout and constructions of the arms, if they can flex it can result in little to no yaw control. In our version using the HQuad PXH setup and short arms across the fuselage, improved yaw authority because the arms bent in the right direction. Are the quad arms across the fuselage or across the wings?