Blimp

A blimp is a nonrigid lighter-than-air aircraft whose shape is maintained by the pressure of its lifting gas. Unlike a rigid airship, it has no internal structural frame.

Aerostatics: The study of fluids at rest and the forces they exert on immersed or floating bodies. Buoyancy from displaced air supports a blimp against gravity.
Lighter-than-air aircraft: Aircraft supported chiefly by buoyancy rather than aerodynamic lift from forward motion. A blimp belongs to this broader family of buoyant flying machines.
Aerial advertising: The use of aircraft to display promotional messages from the air. Blimps provide conspicuous, slow-moving platforms for displaying signs above events and cities.
Hot-air balloon: A balloon that rises because heated air inside it is less dense than the surrounding air. It uses heated air for lift, whereas a blimp relies on lifting gas and has propulsion.
Lifting gas: A gas less dense than surrounding air, used to produce lift in balloons and airships. Its pressure fills the envelope while its lower density provides buoyant lift.
Airship: A powered, steerable lighter-than-air aircraft. Blimp names the nonrigid structural type within the wider airship category.
Airborne early warning and control: The detection and management of airborne threats from an elevated sensor platform. Persistent blimp platforms can carry radar above a region for surveillance.
Gas balloon: An unpowered balloon lifted by gas less dense than the surrounding atmosphere. A gas balloon shares a blimp’s source of buoyancy but lacks its powered, steerable flight.
Airship envelope: The gas-retaining outer covering of an airship. This flexible enclosure takes its shape from the pressure of the lifting gas.
Nonrigid airship: An airship whose form is maintained by internal gas pressure rather than a rigid frame. This is the structural class that defines a blimp.

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