 The most famous airships today are the passenger-carrying rigid airships made by the German Zeppelin company, especially the "Graf Zeppelin" of 1928 and the "Hindenburg" of 1936.The "Graf Zeppelin" was intended to stimulate interest in passenger airships, and was the largest airship that could be built in the company's existing shed.Its engines ran on "blau gas", similar to propane, which was stored in large gas bags below the hydrogen cells.