I, too, thought that the Bridi kit called for too much dihedral. When I was in California on a business trip in the early 80's I had the opportunity to meet Joe Bridi and I asked him about it. He replied that Jim Kimbro (the designer) had made the modification to the dihedral that Joe incorporated into the kit. Nevertheless, if you use the rudder as designed (the movable portion only extends down to the top of the fuselage) I still feel that the kit dihedral is too great. That was how I built my first one. My second had the movable portion extended all the way to the bottom of the fuselage to get more rudder authority and to lower the center of pressure on the rudder. If one were to do this, then there would be less adverse roll induced by the rudder deflection and the amount of dihedral should definitely be reduced. Dihedral will result in a roll in the direction the rudder is deflected. A rudder which has the center of pressure above the fuselage will result in a roll opposite the direction of deflection. Dihedral should be balanced against the adverse roll induced by the rudder. There are other considerations, of course, but this is certainly one. Back then I asked Don Lowe about this situation since he has a background in aerodynamics. His repsonse was that it was simple to take an electric saw and cut through the top of the wing center section, adjust the dihedral, and put an epoxy bandage over the cut. That way you could slice and dice and adjust the dihedral all you wanted. That was how he dialed in the correct amount on some of his designs. But, I never could bring myself to cut the wing on a successfully flying model. Not enough engineer in me, I guess (actually I am a theoretical physicist).

Jeff