In 1936, Hans Jacobs, who headed Nazi Germany's Deutsche Forschungsanstalt für Segelflug (DFS) glider research organization before World War II, developed blade-style self-operating dive brakes, on the upper and lower surface of each wing, for gliders.[4] Most early gliders were equipped with spoilers on the wings in order to adjust their angle of descent during approach to landing. More modern gliders use air brakes which may spoil lift as well as increase drag, dependent on where they are positioned.