Yes – I’ve done auto-tune twice: first at 6 level, then at 7. I did many more than the min 20 turns/pitches each time. I got back reasonable results, but the plane was more sluggish than when using the default 3DR-Aero params (provided with mission planner) and reducing the P’s a bit (I was getting some oscillations). I’ll post my values back to the DIYDrones thread where I saw your requested.
An update: The airplane (Skywalker 2013) is now tracking the flight lines and the main cure seems to be a LOT of left rudder trim (almost the max on RC controller). I had tried this earlier, but far too little to have an effect I suppose. I also removed most all the right alieron trim that I’d added in an effort to remove the constant left bank I was observing in the HUD.
Here’s my theory: I think the slipstream off the 12" prop was impacting the rudder on the right side, yawing the plane significantly to the right. The autopilot was correcting with left aileron (why?) causing the plane to fly sideslipped but still being pulled off the flight lines. I suppose when trying to use right aileron trim, I was fighting the autopilot.
It flies right down the lines now (no bank in the HUD), resulting in evenly spaced lines. However, in manual mode the left rudder trim seems too much – plane wants to turn left. I’ll see if I can decrease a little, and see if it still tracks the flight lines. Maybe that will be the case, as even in auto, the plane is more efficient at making left turns, than right.
@iskess – I had enabled the side slip controller at the same time I made the big trim changes. I’ve since turned it back off and I’m still right on the flight lines. I think it wasn’t an issue.
I just built a new Skywalker and this issue is much more pronounced than with my first Skywalker, although its the same model. Mapper905, now I really feel your pain. I had to add so much left rudder to stay on centerline, that the plane is very difficult to fly in Manual mode. I had to back off some of the left rudder just for safety. My last survey mission worked out because it was up a steep incline. Flying the up lines at high throttle settings the plane tracked a few meters right of centerline. On the down lines at very low throttle the plane tracked a little left of centerline. This actually worked out fine because it just shifted the flight lines over a bit and didn’t affect the sidelap. However on flat terrain this is still really an issue.
I think as a work around I might try programming my RC so it removes the excess trim in Manual Mode.
Although we have determined that the cause of the issue is sideslip produced by propeller torque/slipstream/p-factor, and the remedy is lots of rudder, it doesn’t seem right that the autopilot can’t track the centerline, even if the plane is in a sideslip. It also doesn’t seem right that the sideslip controller doesn’t remove this sideslip automatically.
Perhaps we can reopen this issue rather than calling it Solved. Maybe Tridge and Paul could take another look?
I know there are others still struggling with this problem. Here is one: diydrones.com/forum/topics/plane … e=activity
Here is another: viewtopic.php?f=44&t=10046
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