Dihedral Wing

[SanderB]

I'm trying to use the dihedral effect on my airplanes but no matter in which way I try to make planes with dihedral wings, they will always roll out of control starting from a SAS-off level flight using trim that keeps altitude and heading but can not maintain roll at 0 because for some reason the dihedral setup doesn't have the desired effect of neutralizing roll.

In the video my plane after take off starts rolling right away. It is symmetrical, the trim is neutral to start, but it still rolls and will continue to roll in spite of extreme dihedral configuration. I try to adjust the roll-trim but nevertheless it will remain unstable. The same things happen on less than 10° dihedral wing configuration. What am I doing wrong?

Edited August 31, 2015 by SanderB

[Coyote27]

Do you have this same issue with SAS turned on? I notice that it seems to be off in your screenshot.

[GDJ]

Just from looking at the video posted:

1) Your SAS isn't on. Are you flying with a pilot?

2) Your front canards appear to be a bit aggressive. They might be causing issues due to their proximity to the main wings. I would check the COM / COL balance and reduce your dihedral to 5 degrees. You shouldn't need that much to keep it stable.

If all else fails, post the file for others to chime it.

[Val]

My guess, is that it is because of yaw instability. Try mounting a vertical stabilizer further back.

Normally a yaw stable craft, with dihedral, will roll and "auto-correct" side-slip, but if my theory is correct, your yaw instable craft will just yaw further and therefore roll even more.

[TrainEngie]

That plane looks like it has too much dihedral. Maybe lower the dihedral so that the dihedral is only 5 degrees up from having horizontal iwngs.

[Exploro]

I could be mistaken but what you are experiencing is what is called "dutch" rolling. The first three paragraphs of the wiki regarding dutch rolling should give you an idea of what the phenomena is. Of particular interest is that the effect is amplified by swept wings and dihedral. In your case I might suggest drastically reducing the amount of diherdal you have your wings set to. Also if my recollection of flight dynamics is correct a larger vertical tail surface should also help.

[sal_vager]

Moved to modded support as Gameplay doesn't have a modded section.

As you're using an addon for aerodynamics I suggest you try asking in this thread.

[SanderB]

I'm trying to make the plane fly straight at a constant heading on trim alone without me at the keyboard for hrs on end.

Craft file:
http://www.filedropper.com/01dihedraltest

SAS doesn't allow a stable AFK flight. even with moderate dihedral angle it doesn't stay upright. I'm not sure I can put a vertical stabilizer any further back.

[Val]

You can try shoulder mounted wings. That will give roll stability, without dihedral.