Airship

Airships are also known as dirigibles from the French dirigeable, means "steerable". The term airship is sometimes informally used more generally, to mean a machine capable of atmospheric flight. Likewise, the term dirigible is sometimes used informally to refer only to rigid airships (see below.)

In contrast to airships, balloons move through the sky by being carried along with the wind.

Airships are typically filled with either helium or hydrogen. Some airships are filled with hot air in a fashion similar to a hot air balloon.

Types of Airships

• Rigid airships which have rigid frames containing multiple, non-pressurized gas cells or balloons to provide lift. Rigid airships are not dependent on internal pressure to hold their shape.
• Non-rigid airships (a.k.a blimp) use a pressure level in excess of the surrounding air pressure in order retain their shape.
• Semi-rigid airships, which resemble blimps in requiring internal pressure to maintain their shape, but have extended, usually articulated keel frames running along the bottom of the envelope to distribute suspension loads into the envelope and allow lower envelope pressures.
• Hybrid airships, a very general term for any combination of heavier-than-air (airplane or helicopter) and lighter than air technology. Examples include helicopter/airship hybrids intended for heavy lift applications and dynamic lift airships intended for long-range cruise.

History

Although some balloons with limited mobility were flown in the 1800s, the first successful airships were built by Alberto Santos-Dumont in Paris around 1900.

On March 5, 1912 Italian forces became the first to use dirigibles for a military purpose by using them for reconnaissance west of Tripoli behind Turkish lines.

The British dirigible R-34 landed in New York on July 6, 1919, completing the first crossing of the Atlantic by an airship.

The most successful airships were the rigid Zeppelin type, so named because they were pioneered by Count Ferdinand von Zeppelin (B Kostantz, Baden, Germany April 8, 1838 - D March 8, 1917)

Initially airships were very successful and compiled an impressive safety record. Most notably, the Graf Zeppelin flew over 1 million miles (including the first circumnavigation of the globe by air) without a single passenger injury.

However these initial successes, were followed by a series of tragic rigid airship accidents. The most spectacular and widely remembered is the explosion of the Hindenburg [see: Hindenburg disaster ], which caused public faith in airships to evaporate in favour of faster, more cost efficient (albeit less energy efficient) airplanes.

Although airships were no longer for passenger service, they continued to be used for other purposes. In particular, the US Navy built hundreds of blimps for use in World War II. The most successful application of these airships was for convoy escort near the US coastline. During the war, some 532 ships were sunk near the coast by submarines. In contrast, none of the 89,000 or so ships escorted by blimps was lost to enemy fire.

Blimps continue to be used for advertising and as TV camera platforms at major sporting events.

Recently, several companies are again exploring the possibilities of airships with their potentially huge lifting capacities, near-VTOL capabilities, and potentially lower freight costs, though none has demonstrated the economic viability yet.

External links

General

• Airship Home Page (http://spot.colorado.edu/~dziadeck/airship) - the most comprehensive list of airship related websites. Also contains information on the most widely read airship mailing list.
• Airship and Blimp Resources (http://www.hotairship.com/) - This site focuses more on how to build your own airship with a particular focus on hot air airships (a.k.a "hotships")
• The Airship Association (http://www.airship-association.org/) - A Brithish based association for people solely interested in powered lighter-than-air aviation.
• The Association of Balloon and Airship Constructors (http://www89.pair.com/techinfo/ABAC/abac.htm) - Maintains an extensive technical library on airship technology old and new.

Manufacturers

• Cargolifter (http://www.cargolifter.com/) a company developing a huge semi-rigid. The company ran into serious financial trouble in 2002. Its future is uncertain.
• Advanced Technologies Group (http://www.airship.com) a company developing a range of products such as UAV's - Unmanned Aerial Vehicles, heavier-than-air airships and HAPS' - High Altitude Platform Stations for telecommunication
• SkyStation (http://www.skystation.com/sts) a company focusing on the development of HAPS'