Flight path offset


I’m having problem with flight path accuracy. During the last mission the plane only between the planned flight tracks seldom following the planned flight path. The same behavior was observed during a mission where the plane was supposed to fly above a road, but instead always stayed to the right of the road.
Any advice?
Here is the log --> dropbox.com/s/kxgx8pp3wy45fu1/49.BIN?dl=0

This is primarily caused by not having enough rudder trim in to account for a large prop. What type of plane? This is a common issue for the New Skywalker. Activating the yaw damper may also help. See this thread:

It’s a 3 meter glider type plane. It has a 23" prop.
Hmm, not enough rudder trim. The plane is well trimmed in manual and can be flown hands off. Will have to check this theory.
Thank you for your input, iskess.

Take all aileron trim out and center the ailerons. Then fly and use rudder to trim while under cruise power. See if the side step goes away.
I thought I had a trimmed airplane too, but it was flying in a slight slip, this was masked by the aileron trim. Check the logs or graph real time to check the lateral acceleration.

I graphed accY and it’s pretty close to zero. I’m not really sure what I should be looking at.
iskess, maybe you could post a picture of a graph that shows your lateral acceleration problem?

I solved this issue a while back so I’d have to really dig to see if I could find a graph.
Is your plane flying in a slight bank? Like 5 degrees or so? That is another symptom of the Sideslip issue.
Did you activate the Sideslip controller YAW2SRV_SLIP and _RLL?

I was using the live graph plotting which uses a different scale, and is called “ay”. My notes say I was flying in a 6 degree left bank, slipping to the left, with yaw to the right, requiring left rudder trim to resolve. I was at about 28 units of lateral acceleration (ay). A left slip will give you + values, and a right slip will give - values.

I looked at the roll graph and the airplane seems to be banking right about 7 degrees during the entire mission.
I have not activated the sideslip controller because I was thinking that my plane probably does not have enough fuselage area.

Sounds very familiar. Try a bunch of left rudder trim, and right aileron trim to counter. I bet that will resolve your issue.

Thank you for the advice, iskess.
I’ll check it out when the weather gets better here.

[quote=“martig”]Thank you for the advice, iskess.
I’ll check it out when the weather gets better here.[/quote]

Have you resolved your side-slip issue? My latest build has is really bad. If I use enough rudder trim to get on center line, I can barely fly it in manual mode.
I don’t know why the autopilot logic won’t track the centerline, even if it were in a sideslip.

Here is a post I recently made on the subject: viewtopic.php?f=98&t=7913&start=20

Sorry, I haven’t been able to resolve the issue. I crashed the plane a few days ago and I’m not sure I’ll rebuild it in the same configuration.