Airship

Airship: A dirigible balloon, an aircraft floating in air owing to its being filled with gas which is lighter than air. Propelled by motors driving air-screws (propellers). A rigid airship is one in which numerous gasbags are contained in a rigid framework so that if one or more are punctured the machine does not collapse. All Zeppelins are "Rigids." In a non-rigid airship the gas is contained in one big bag, possibly with internal partitions. If punctured all gas leaks away, or whole gasbag (envelope) may tear, and collapse. It can be deflated and transported by sea or land. A semi-rigid airship has a single, or partitioned, envelope, and is liable to sudden deflation, but being supported by long boom below, to which car or "gondola" is suspended, will not fold up and collapse suddenly when merely leaking.