rigid

1. (aviation) An airship whose shape is maintained solely by an internal and/or external rigid structural framework, without using internal gas pressure to stiffen the vehicle (the lifting gas is at atmospheric pressure); typically also equipped with multiple redundant gasbags, unlike other types of airship.Examples: "The rigid could reach the greatest sizes and speeds of any airship, but was expensive to build and bulky to store. Rigids fell out of favor after the R101 and Hindenburg disasters made the type seem unsafe to the travelling public."