Hi Everyone,

I've recently installed a pixhawk running Plane 3.4 into a 2015 Skywalker 1830. The plane flies pretty nicely in Manual and FBWA modes but there seems to be an imbalance in the aggressiveness of left and right turns in AUTO mode.  When turning left, the plane seems to under steer and take a long time to get back on track. The opposite happens when turning right however, with the aircraft over steering a lot, which often results in tip stalling. 

If one or the the other action happened for both directions I would usually be able to tune it out, but if I tune for one circumstance it makes the other worse in this case. 

The plane is balanced about the longitudinal axis, and there doesn't seem to be any uneven twisting in the wings. The propeller is spinning in a clockwise direction when viewing it from the aft of the plane, which I'd assume would aid the aircraft to turn left with torque roll,  if there is enough torque roll to make a noticeable difference.

Has anybody else experienced a similar issue? Am I missing something obvious? Any help would be really appreciated!

I've attached param and tlog files of the plane doing a survey grid. Here is a dropbox link to the .bin file.

Thanks,

Luke

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Rudder?

Hi Bruce,

Rudder is a possibility, but would I expect to see some form of adverse effects in FBW-A if that was the case?

Could be a rudder mix thing?
Tried flying with the rudder unplugged?

Is the torque of the motor prop combo too high?

Really I'm just going through a series of fault finding procedures here cause I dont know the answer.

I will try these out next time I fly.

Thanks for the suggestions. :)

Check and see that you have the same amount of throw on your airalons and rudder. Adjust the max and min of your servos and re calabrate the rc in mission planner.
Also make sure that you dont have any trim set on your radio side.

You could also try more up aileron than down aileron movement. I had this recently on a Radian, changed the up aileron movement to 120% and down movement to 40% with 30% aileron/rudder mix, now it turns both ways very well. Always do radio calibration after changing any servo throws/end points

Does the plane always track to the right of the course when flying the grid? If do, this is s common Skywalker issue. The fix is tuning the yaw controller, and tons of rudder trim.

Are there shims on the engine mount?

I believe the issue is spiraling slipstream on the tail, so I don't think shims will help much.
I have a new aero-m that is always tracking to the right and flying at about 10-15deg roll. Havnt had time to check it out properly yet but everything looks good on the ground. Its on the default tuning it come with as this works well on our other aeros.

What prop are you using? 12x12 and 12x10 exacerbate the spiral slipstream issue iskess mentioned. A simple fix is to get a prop with smaller advance ratio and add some mechanical offset to your rudder to the left. Also turn down throttle slew, the quick motor spin-up while turning right is a big part of it. the E384 uses 45% throttle slew.

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