Pitch control surface inversion (1.0.5)

[chawleysnow]

KSP Version: Version 1.0.5 Windows 32-bit

What happens: Some pitch control surfaces are inverted (react the wrong way) on certain wing configuration

Mods: Stock + Asteroid Day

Created the following craft. Notice that wing roots attach forward of CoM, but control surfaces are aft of CoM.

When I get it out on the runway, the tailplane pitch responds correctly, but the elevon pitch reacts in the opposite direction; in this case I am commanding nose-down pitch:

Roll responses work correctly:

This control inversion ends up with the craft unable to attain positive rate of climb and crashing at the end of the runway, often without ever lifting off. To be fair, the craft needs some work in the stability department, but conflicting control surfaces isn't helping any

[sal_vager]

Hi chawleysnow, thanks for the report, it is unfortunately an old issue which catches a lot of people out.

The control surfaces use their x axis to determine which way they should pitch relative to the vessels center of mass, here's some pics to help explain.

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The only stock "fix" is to move the wings and/or the CoM so the control surfaces are the other side of it.

Hi T-Bouw and Wink

Edited November 10, 2015 by sal_vager

[T-Bouw]

This is one bug that made the transition from 1.0.4. and is known.

It doesn't make a difference to KSP that the control surfaces are located aft the COM. Your wing onto which they are attached is forward.

Weird bug indeed.

Edit: Ninja'd by Sal (Hi Sal!).

[WinkAllKerb'']

Hi chawleysnow, thanks for the report, it is unfortunately an old issue which catches a lot of people out.

The control surfaces use their x axis to determine which way they should pitch relative to the vessels center of mass, here's some pics to help explain.

http://imgur.com/a/DFrxJ

The only stock "fix" is to move the wings and/or the CoM so the control surfaces are the other side of it.

thks a lot for the explains Sal.