Interesting discussion. I thought mck was talking about a pattern aircraft and most that I have flown tend to yaw with rudder application and make a very, very slow wings level heading change in the direction of the rudder application although some I flown yaw to the right but actually made a very slow heading change to the left. At slow speed the rudder tends to have a larger impact on the yaw and the ability to change the heading with wings level. Inverted they yaw the opposite direction than when upright in relationship to the pilot on the ground. I wouldn’t want a pattern aircraft that causes much roll with the application of rudder. True, rudder roll coupling was used on the old rudder only aircraft with a lot of dihedral to turn but that would really mess up a pattern or sport aircraft when doing stall turns, knife edge using rudder on landing, take off, etc. Maybe my aircraft are unusual and I have a great thing going. My main point was recommending to mck that he should make sure his vertical stab and rudder are perfectly aligned and his engine thrust angle is OK before he started messing with the aileron trim.