Most, but not all, of the American Goodyear airships have been blimps. There was a combination of aircraft types which included airships and airplanes. Aerostats include unpowered balloons and powered airships. Aerostats include free balloons, airships, and moored balloons. It features steamboats, trains, airships and inventors. The great zeppelin airships of the twentieth century were rigid types. Allied airships and military aircraft also made some use of radiotelegraphy. Because it is lighter than air, airships and balloons are inflated with helium for lift. I the Zeppelin company built 95 military airships. Konstanz was the birthplace of Count Ferdinand von Zeppelin, constructor of the famous Zeppelin airships. Solar ships can refer to solar powered airships or hybrid airships. These combine the structures of both hot-air balloons and small airships. Hydrogen fires had previously destroyed many other airships. They were originally built for the construction of large airships during WW1. Most, but not all, of the German Zeppelin airships have been of this type.