I really liked that old Lou Andrews Airomaster, built 7 of them trying out the different combinations of wing sweep. I did find that all of the flew best with the upper wing at about 1.5 degrees less angle of attack than the lower wing was. Just a slight variation made quite a difference in how well they flew. They all also liked about 2 to 3 degrees right thrust and 3 to 5 degrees downthrust.