Dirigible

An airship or dirigible is a type of aerostat or lighter-than-air aircraft that is propelled through the air by engine power. An aerostat stays aloft by having a large "envelope" filled with a lifting gas that is less dense than the surrounding air. In early dirigibles, the lifting gas used was hydrogen, due to its high lifting capacity. Helium gas has almost the same lifting capacity and is also nonflammable, but is rare and relatively expensive. Significant amounts were first discovered in the United States and, for a while, helium was rarely used for airships outside the United States. Most airships built since the 1960s have used helium, though some have used hot air. Besides the main envelope, an airship also has engines and crew accommodation, typically in a gondola hung beneath the envelope. [Airship. Wikipedia]