Definition
A lighter-than-air aircraft, commonly called a blimp, whose shape is maintained entirely by the internal pressure of the lifting gas inside its envelope. It has no internal structural framework. The control car, engines, and tail surfaces are attached directly to the fabric envelope, and if the gas pressure is lost, the envelope collapses.
Plain English
An airship that holds its shape only because the gas inside it is under slight pressure. There are no internal beams or framework — just a fabric envelope full of gas. If the gas escapes, the whole thing goes limp.
Context Anchor
Seen in aircraft classification, lighter-than-air aircraft discussions, and descriptions of blimps used for observation, advertising, or patrol work.
Derivation
From Latin 'rigidus' meaning stiff or hard, with the prefix 'non-' meaning not. So nonrigid literally means 'not stiff' — the envelope is flexible and depends on gas pressure to hold its form.
Why Pilots Care
The structure affects how the aircraft is handled, moored, inspected, and protected from damage, because the shape depends on gas pressure and the condition of the envelope.
Analogy
Think of an inflated balloon. It holds its shape only while there's pressure inside. Let the air out and it goes limp. A nonrigid airship works the same way, just on a much larger scale.
Intuition Check
Nonrigid does not mean uncontrolled or shapeless. It means the airship has no rigid internal frame; its shape is held by internal gas pressure.
Example Sentence 1
The Goodyear blimp is a well-known example of a nonrigid airship.
Example Sentence 2
Nonrigid airships can be deflated after flight and stored in smaller spaces than rigid designs.