I created an aircraft where the horizontal stabilizer acted as aileron. The main wings only had flaps. In this configuration the flaps provided lift, as expected. The aircraft was easily controllable. However, due to roll performance issues, I decided to move the ailerons to the main wings and activated the "ailerons with flaps".
The control surface parameters (chord ratios, deflection...) remained exactly the same, so full flap deflection with flaps only was considered equal as with "ailerons with flaps"). But in simulation, the latter situation would cause te aircraft to pitch down heavily (in an uncontrollable way). I know there are settings (flap Cm) that controll the pitch with flap deflection, but these don't seem to solve very much.
It just seems strange to me that identical control surface with identical parameters and deflection act differently in another configuration.
Is there any logical explanation for this? Or is it a bug? Any idea how this can be solved?
Thanks in advance!