nI expect the cylindrical surface on the rudder and tail flaps is tangent to the cutout face in the airframe body. This is a bad situation for meshing. nThere are two directions you can go to eliminate this tangent condition.n1) Move the cutout surface forward to create a gap with the cylindrical surfaces.n2) Move the cutout surface backward to create an overlap between the leading edge and the cutout.nI recommend #1 since it avoids creating elements that need a small angle at the new edges created in #2.n