I have heard of incidences being set like that on a biplane where the top wing is slightly negative to the bottom wing. I set up a scratch built Fokker triplane in that manner and it flew perfectly The unrelaible reasoning for this that I was told was the top wing would stall after the bottom wing and the stall would be more stable...kind of makes sense....maybe? In looking through my plans for the TF Se5 it would seem impossible to get the engine thrust line off. Here is a photo of that Triplane that flies so well and it really does or did fly very very well. I sold it to a hobby shop owner in atlanta so I don't know if it is still with us or not.