Servers by jDrones

Flight path offset

(martig) #1


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 -->

(Iam) #2

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:

(martig) #3

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.

(Iam) #4

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.

(martig) #5

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?

(Iam) #6

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.

(martig) #7

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.

(Iam) #8

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

(martig) #9

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

(Iam) #10

[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

(martig) #11

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.