I bumped into a really strange problem yesterday during the preflight check - the rudder was moving in the wrong direction. This happened only when I banked the plane. I had to set the rudder mix to a negative value to get it moving in the right direction.
The rudder moved in the right direction in both manual and FBWA when moving the sticks.
What comes next is even more strange. The rudder was twitchy as hell in flight. It was almost impossible to fly the plane in FBWA. Manual control had to be taken. I tried setting different yaw tuning parameters to zero to see which one was the culprit. It was the yaw damper. During tuning the YAW2SRV_DAMP was set to 14. This seemed like a high value, but the plane flew well with the tuned settings. The plane also performed well on a 2 hour mission after tuning. Anyway, the plane flew the mission just great with yaw2srv_damp set to 0.
Nothing has changed in the construction and servo/linkage-wise. So it’s very strange that a well tuned plane would act up like that.
Also, MP was giving a bad gyro message. That happens from time to time, but there doesn’t seem to be any consequences.
You use the reversing settings on your radio to get the controls moving correctly in manual, then the RCXX_REV parameter values to get auto modes correct. Don’t make the mix weight negative.
To test this, on the ground in FBWA, move the plane around. Ailerons, elevator and rudder should move to counter the direction you tilt or rotate the plane. Ie: If you quickly yaw the plane to the left, the rudder should move to the right and vice versa. If it doesn’t work right, set RC4_REV to -1.
The range of values of YAW2SRV_DAMP is 0-2. So 14 is a silly value and would just mean 2. In the log you have sent the value is 1.4, not 0 as you indicated you had it set.
Your YAW2SRV_INT is 6 and again the range is 0-2.
I don’t know what the log is of. Is it supposed to be the bad flight with the rudder going in the opposite direction or the good flight where it behaves?
Thanks, Grant.
Thank you for replying, gmorph and sorry for my late reply.
In the beginning of the log just after take-off you should see the plane wagging it’s tail wildly. The plane was switched to manual and I started changing the yaw parameters. Changing the damping to 0 fixed the issue. I am certain I set it to 0.
14 seemed like a ridiculously large number, but it worked. I think I should also upload the tuning log.
Maybe there was an issue with data types or with memory corruption.