ORIGINAL: Rotaryphile

The old story about additional incidence on the upper wing making the stall gentler was proven false in the early 1930s in wind tunnel tests. The reverse may actually be closer to the truth, since as the upper wing stalls, its drag increases far more than its lift decreases, and the extra drag, well above the center of gravity, tends to cause pitch up. I rig all my bipes with between zero incidence difference, and a maximum of one degree less incidence on the upper wing. A little negative incidence on the upper wing seems to slightly help aerobatic line holding, at least, if the airplane has positive stagger.