I've done many tests on many bipes and ALL model bipes I tested flew best with the upper wing at about 1 to 2 degrees LESS angle of attack than the lower wing. This was on 6 Aeromasters (60 size), one super Aeromaster, two 1/4 scale Moths, 2 large Lazy Aces, 2 Phaeton 90's and two Phaeton 40's. Play with lowering the incidence on your upper wing, there will be a point where the plane starts to grove and do what you tell it to do.