Plane wants to go left

[SnappingTurtle]

My space planes always want to go left on the runway which makes them impossible to launch. Even without thrust they go left just rolling down the runway. The whole thing was built with symmetry mode.

Edited June 21, 2013 by SnappingTurtle

[Johnno]

Are your landing gear all horizontal and aligned forward?

[SnappingTurtle]

Here's some footage of my more recent attempts.

Since it was done in symmetry mode I don't know why the plane would prefer to go either left or right, no matter the orientation of any of the parts.

[Superfish57]

Sometimes if the wheels are not vertical or just at the wrong angle it can lead to weird affects like that, happened to me once.

[SnappingTurtle]

I'm certain all the wheels are vertical and pointing straight forward. On a side note, can anyone tell me why the center of lift of my plane seems to be angled forward?

Is it veering because I'm using a delta deluxe winglet as a my rudder?

Edited June 20, 2013 by SnappingTurtle

[Superfish57]

I know what you are talking about but I have no idea why that is. I just ignore that and things still tend to go right. Just try placing the wheels in a different area.

[zanzibar196]

Known issue. Been reported as a bug with symmetry.

I think it's because you are using 3 wheels, and one of those wheels is under the command pod. Here is another video of this happening:

[SnappingTurtle]

So it's because the landing gear part itself isn't symmetrical?

[CaptainKipard]

I've always found that as long as your center of mass, center of lift, and rear gear are in line then you wont have any veering off like that.

[SnappingTurtle]

I've always found that as long as your center of mass, center of lift, and rear gear are in line then you wont have any veering off like that.

How could they not be in line using symmetry mode?

[CaptainKipard]

I mean if you look at it from the side, they should all be in the same place. Not too far forward and not too far back. Basically if your center of lift is behind your center of mass then your plane wont pitch up as easily during takeoff. The same is true if your rear gear is too far behind your center of mass. AFAIK this causes the plane to veer off to one side because rounding errors in the physics engine accumulate to a degree where they create phantom forces. IIRC taking pressure off of your nose gear, will take care of that problem.

Edit: ....rear gear is too far behind your center of mass.... not lift sorry.

Edited June 21, 2013 by Cpt. Kipard

[SnappingTurtle]

I think I see what you're saying. Thanks.

[Razor235]

It's because of the single tailfin. The lift vector is just slightly angled to the left with only one tail (for some reason). Put two vertical stabilizers with symmetry.

[SnappingTurtle]

Is it because the delta deluxe winglet causes more lift on one side than the other? Is there a part that works better as a rudder?

[Razor235]

No, it happens with every canard/fin in the menu. The best way to fix it on a single-fuselage plane is to put two fins in a V-shape on the rear of the body.

[CaptainKipard]

I should say keep your rear gear just a little bit behind your center of mass but not too much. If it's too close, your plane might tip over backwards

[SnappingTurtle]

I thought that the best method would be to have the centers of mass, lift and thrust aligned as best as possible to keep it stable in level flight, but to have the rear gear higher up than the front gear so that it would have an initial attitude. This is going off the specific topic but I'm finding it difficult to build a plane that is controllable in flight. Pitch authority is always terrible, often the only way to control pitch is to adjust thrust.

Edited June 21, 2013 by SnappingTurtle

[CaptainKipard]

Yes, a raised angle of attack will help you take off, but on the other hand will make landing a little more difficult.

[Razor235]

If you want I can PM you an example plane that I made, which flies very well.

[SnappingTurtle]

I think maybe I'm having a problem that I heard mentioned somewhere, that the plane wants to go backwards because of the aerodynamics but I don't know what causes this.

[CaptainKipard]

I've never heard that before, with relation to this problem. Try the suggestions in this thread and if something works then tell us what it was.

[SnappingTurtle]

The veering problem is more or less solved, I've stopped using a single rudder or tail guide wheel. I'm getting off topic with this thread. Maybe it would be better to let it die, if I have a more specific problem then I'll make a new thread. At the moment though the plane is definitely trying to go backwards.

[zanzibar196]

No, it happens with every canard/fin in the menu. The best way to fix it on a single-fuselage plane is to put two fins in a V-shape on the rear of the body.

My video shows a craft that does this, and it still veers off when ASAS is turned off...