Airships were originally called "dirigible balloons" and are still sometimes called dirigibles today. So, in 1911, the construction of dirigibles known as the Astra-Torres airships was begun. Ships, boats, submarines, dirigibles and aeroplanes usually have a rudder for steering. The requirements for gliders, balloons, gyroplanes, and dirigibles vary slightly. Todd first started studying dirigibles before she moved onto designing airplanes. I brought bombing raids by dirigibles and airplanes, with thousands of injuries and deaths. The military was interested in helium for balloons and dirigibles. Reconnaissance dirigibles, an airplane, troops and Coast Guard personnel were stationed at Montauk. During the 1930s, the Navy briefly used the air base for helium dirigibles. He designed 18 balloons and dirigibles before turning his attention to fixed-winged aircraft. This helium was intended for use in British dirigibles for World War I. Non-rigid dirigibles are characterized by a moderately aerodynamic gasbag with stabilizing fins at the back. The Brazilian Alberto Santos-Dumont became famous by designing, building, and flying dirigibles. Baldwin wanted improved propeller designs for dirigibles. Rather than traditional landings, it would send crews into the upper atmosphere, using dirigibles.