Kerbal Space Program

Hi Vycma, please explain how the authority control is not affecting roll.

On testing your vessel I can see that roll is being inverted with pitch, and that control surfaces are determining their direction from the CoM, as expected.

The control surfaces on your wings all have their pivot axis in front of the CoM, this causes them all to move the same way unless their control authority is inverted you can see this by adding some mass tot he front of the vessel, which will cause the pitch and roll of the elevons to invert.

Inverting the input inverts the input to the elevon, not individual axis.

Having added some mass in front of the plane, shifting the CoM far in front of the elevons, I still have to invert the authority limits on the inner control surfaces to get identical behaviour with the outer ones. So there also might be an issue related to those large elevons.

Digging deeper, I noticed that this is a long standing issue. I knew for a fact that this craft here worked properly in pre-1.0.

Now, although the inner elevons have not a significantly different longitudinal position with regard to the CoM than the outer ones, they essentially cancel each other out.

To sum it up:

The authority limiters work as expected.

The CoM dependency of elevons does work as expected.

However the CoM dependency of elevons does not work as is desirable.

A certain not insignificant set of designs runs into issues where elevons counteract eachother. They seem to be characterized by a flying wing property, meaning that the root of a wing seems to be in front of the CoM, whereas the elevons are behind it; or where a wing is split into subwings.

Here comes the connection to authority limiters: They are a potential workaround for the underlying issue, yet a limited one. Should the initial CoM change significantly during flight, a tweaked authority setting will swap from being a fix to being the issue.

IF an additional option would exist that allowed the player to disable the CoM dependency of elevons, CoM shifts could be accounted for by design.

Yet, I still would consider this sub-optimal. Imho the CoM dependency of control surfaces has to be reworked to close the gap between the players design intuition and the actual flight performance.

Potential related issue:

http://bugs.kerbalspaceprogram.com/issues/5172
Even after detaching affected elevons, rotating them by 180° around the z-axis and reattaching them, as well as substituting them for both crafts with new ones in up and down orientation they still rotate in wrong directions.

It's working as designed, but as it's not desirable to you this is really feedback, sorry.

What you want is the behaviour of KSP changed at a fundamental level, the dependency on the CoM cannot simply be disabled, there's no hidden feature to make that possible, this would require an extensive rewrite of a large part of the game that would effect all craft, not just your flying wing.

A workaround would be to not use combined ailerons and elevators, and to separate these controls, ensuring that they are not so close to the CoM to be affected.