ORIGINAL: Stickbuilder
Okay, let's say that you have a biplane with both top and bottom wings (Clark-Y) set at zero (to the datum line). If built per instructions the tail will have 3 degrees positive incidence.
Bill, AMA 4720
WACO Brotherhood #1
If that airplane flies around with it's tail say 5degrees down, then moving both wings' AOI up 5 degrees would be one of the very first things to consider.