Dale, not sure if this helps but i just finished a quadplane build around the ranger ex… Overall it is flying well but i too had a very bad right yaw… worse at higher throttle. I to am using a tractor prop with the motor turning counter clockwise viewed from the front. After lots of testing and reading every forum on thrust angles for pusher plane i decided the problem is related to the rotation of the prop but that’s not the whole problem. It still pulled right even while using a pusher prop. The prop that volantex sends is a tractor prop and the built in down and right thrust is not good. Long story short i ended up continuing to use tractor props but rebuilt the motor mount with additional down and instead of right thrust left… much better than it was…
So after a lot of testing, the PID values below work well for me. Smooth, human-like responses, with no ridiculous oscillations. This is on a 2m piper cub with max control surface deflection.
roll and pitch:
P: 0.1000
I: 0.0200
D: 0.0001 (min limit)
The AUTOTUNE values for roll ant pitch were:
P: 0.340
I: 0.258
D: 0.035
tried it with a pusher prop today - completely solved my problems. no need to offset my motor mount. don’t want to take this thread off topic, but I’ll just say I think the Volantex Ranger EX has had a few revisions and perhaps my version has an appropriate offset on the motor mount to give a good thrust line, given a pusher prop.
I’ve had a small victory adjusting PTCH_RATE_SMAX down to remove oscillations from high P and D values. I don’t know if it will work for you here, but it’s worth a shot if you’re stuck. I used the PID values from the autotune.
@Allister Graph your servo output values for roll and pitch. I bet you will see oscillations (which wear out the servos and waste battery) even though the plane seems to fly ok. (You can also see them by just tilting the plane while it is on the ground, in stabilize mode.) I had to go to really low PID values to get rid of them. Still responds fine, so I don’t know why autotune sets them so high.
I like your suggestion. I may play with this some more.
Here is an example the oscillations that I was focused on during take off:
After adjusting rate_smax I can’t find any evidence of that. However…
I wouldn’t call that oscillations, but it is jittery. But to be fair, what’s normal here? Even in manual mode that little wing get’s bounced around the there’s a lot of movement on those servo channels. So how much of that is just the FC doing its best to keep a 900mm wing on the straight and level?
And to be clear, I see no jitter or twitch in the elevons when the plane is on the ground (and I have seen it in the past on other settings and on other planes)
Your thoughts?
@Allister No, that second graph isn’t too bad. One good way to look at is to scroll to a section of the graph where there is no stick input, and see if you see a sinusoidal pattern in RCOU. It is not as easy to detect when it is also following stick inputs.
There’s another issue where the oscillations magnify as speed decreases. Does PTCH_RATE_SMAX/RLL_RATE_SMAX affect that?
These oscillations have been a long standing problem for me on this plane so I’ve been crawling over all the logs looking for that sinusoidal pattern. So far between Autotune in 4.1 beta 3, and now PTCH_RATE_SMAX it’s like a new plane and I’m not seeing any signs of oscillation anymore. Flight mode, speed, and conditions (that I’ve had a chance to try so far) don’t seem to make a difference. Compared to when I first tuned it in 4.0.7 the oscillations got so bad that at one point I thought the elevons were going to come off and I had to use manual to get the plane back under control.
I don’t know how much SMAX will effect the overall tuning. My adjustment was a total guess. I’m hoping that somebody who knows more about the code can share more about the impact and any potential issues/benefits.
Make sure SERVO_AUTO_TRIM is set to 1.
Hello, i’m having the same issue after the autotune.
The arwing pro after the tune is very nervous on the ground, prior to the tune the adjustment were gentle.
It is flying ok in all the automatic mode.
May i post here the log?