 Complete the following phrase:  Hans Jacobs 30 April 1907 in Hamburg - 24 October 1994 was a German sailplane designer and pioneer. He had been taught sailplane design by Alexander Lippisch, designer of many gliders during the 1920s and the 1930s. As the head of the Deutsche Forschungsanstalt für Segelflug DFS - German Research Institute for Sailplane Flight at Darmstadt in the years before World War II, he was responsible for a number of highly successful designs, including the DFS Rhönsperber, DFS Rhönadler, DFS Habicht, DFS Weihe, DFS Kranich, and the DFS 230 assault glider. Hans also designed a glider-seaplane, the Sea Eagle, test flown by Hanna Reitsch. In 1936, Hans developed self-operating dive brakes, on the upper and lower surface of each wing, for gliders. He designed the DFS 230 used in the 