Airship

An airship is a lighter-than-air aircraft that stays aloft because its large envelope contains a gas less dense than the surrounding air. Modern airships generally use helium, an inert gas that does not burn, while many early airships used hydrogen, which is lighter but highly flammable.

Unlike a hot-air balloon, an airship normally has engines and can be steered. Rigid airships, such as Zeppelins, have an internal framework that maintains the envelope’s shape. Non-rigid airships, often called blimps, rely mainly on the pressure of the lifting gas to keep their form.

An airship can remain in the sky for a long time because most of its lift comes from buoyancy rather than wings. Its speed is usually modest, and wind can affect its movement. In the early twentieth century, large rigid airships carried passengers and performed military patrols.

Serious accidents, especially the 1937 Hindenburg disaster, contributed to the decline of hydrogen-filled passenger airships, while airplanes offered faster travel. Today, airships have specialized uses in advertising, aerial observation, scientific research, tourism, and some communication or surveillance applications. Their long endurance is useful when staying in the sky matters more than speed.