Airship is a self-propelled and lighter than air craft equip with directional control surfaces which allows steering through the air. They are also called dirigible from
the French word "dirigeable", meaning steerable.

During the early days most French, German, and British airships were primary lifted by hydrogen gas because it offered greater lift and was relatively cheaper to use. As hydrogen is highly inflammable when mixed with the air and only provides 10% greater additional resilience compare to helium, in 1920 due to ones safety opposed to cost, airship fueled by hydrogen were replaced by helium. Till this day only a small amount of experimental airship still use hydrogen.

There are various types of rigid airships. These include:

  • Rigid airships – these use a rigid frame enclosing multiple non-pressurized gas cells or balloons to offer the lift. They do not rely on internal pressure to maintain their shape.
  • Non-rigid airships or blimps – they use an internal pressure level in excess of the surrounding air pressure in order to keep its shape.
  • Semi-rigid airships – these too require internal pressure to maintain its shape but also have an extensive usually articulated keel frames that runs along the lower part of the envelope to disperse suspension loads into the envelope and to allow lower envelope pressures.
  • Metal-clad airships – these have all the characteristics of both rigid and non-rigid airship, but they use a very thin airtight metal envelope rather than the rubber coated fabric envelope.
  • Hybrid airships – this is a term use for aircraft that has combinations of characteristics of heavier than air and lighter than other air technology.

Ever since the development of airship, there have been many improvements to safety, but these has not allow it to overcome its downfall which included many accidents involved lost of lives. The public lost faith in the airship and it soon abandoned
carrying passengers. Today, airships continued to be used for other purposes such as commercial (e.g. adverting and as TV camera
platforms at major sporting events), and security measures (e.g. during the Athens 2004 Summer Olympics as part of security anti-terrorism measures).

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