Abstract: A supplementary control surface structure for airplanes is installed atop the fuselage of an airplane to enhance the roll rate of the airplane and thereby assists in reducing bending loads on the wings by enabling a smaller aileron deflection for a given roll rate. The supplementary control surface structure desirably includes a moveable vertically oriented roll control surface member desirably installed in a vertically oriented fin or strake that extends atop the fuselage from the flight deck to the vertically oriented tail fin. The supplementary control surface structure is desirably interconnected with the conventional aileron controls of the airplane in order to operate in concert with the ailerons. The supplementary control surface structure is also adaptable to other roll control systems, such as spoilers and wing warping.