Aircraft rotating on the ground phenomenon

[+dtmdragon]

I have noticed the the odd add on aircraft that will slowly rotate left or right in one direction when stationary on the runway before takeoff. It will do this with no throttle applied. When you try and take off there will be an initial pull in that discretion. The pull is more pronounced if you let auto pilot take off. Any ideas why? I have pored over the data.ini to figure out why to no avail.

[+Wrench]

possible mismatch in aerodynamic statements for left/right wing, (flaps, lift numbers, etc)

landing gear not matching (possibly rolling coefficient, shock strokes, rolling radius, etc)

 

possible issue with lod; when mirroring the one side to create the other, sometimes the don't lineup (but I don't think that might be case--that's more of a decal/skin thing

 

any aircraft in particular? -- you can name them, it's alright

[+dtmdragon]

Su-39 and F-35A. Su-39 is the worst and is the one I am trying to fix to make a Su-25T. I have checked the engine thrust co-ordinates but they are symmetrical. All the landing gear statements except the rolling radius I have changed match the SF2 Su-25. I will now check the wing data etc.

[+Fubar512]

Make sure that all the component mass fraction statements add up to a total of 1.0

[+Cliff7600]

I have a suggestion :

 

For the F-35A

 

[RightWing]

...

Ymac=1.76 instead of Ymac=-1.76 ( - is for the left side of the model)

 

[RightOuterWing]

...

Ymac=3.14 instead of Ymac=-3.14

 

Can't tell if it's really the issue...

[+Fubar512]

YMAC = Mean Area Chord on the "Y" axis.  If the lifting surface statements are reversed (as opposed to merely being duplicated) it would have no discernible effect on the model, until it receives damage to that surface while in flight.