Hi Spad , Where did you read about ail; being parallel with stab? I always put ail; so that when i look at the wing from the tip it looks like a continuation of the airfoil section . Some WW1 planes have a 2-3 degree positive on the stab so that would look weird if ail; set the same . Why not put ail; as i suggest & try flying it again . 2 degrees down sounds right & i usually have 2 degrees right also .