Airship

An airship is a lighter-than-air aircraft that can be steered and propelled through the air.

Airships are also known as dirigibles from the French dirigeable, meaning "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.

Table of contents

1 Types of Airships 2 History 3 External links 3.1 General 3.2 Manufacturers

Types of Airships

• Rigid airships have rigid frames containing multiple, non-pressurized gas cells or balloons to provide lift. Rigid airships do not depend on internal pressure to hold their shape.
• Non-rigid airships (a.k.a blimps) use a pressure level in excess of the surrounding air pressure in order to retain their shape.
• Semi-rigid airships 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 cruising.

  Picture of a blimp provided by Classroom Clipart

History

Although some balloons with limited mobility flew in the 19th century, the first successful airships were built by Alberto Santos-Dumont in Paris around 1900. Santos-Dumont's machines typically consisted of a long, non-rigid gas envelope beneath which was hung a truss to which the engine and pilot's seat were attached.

The most successful airships were the rigid Zeppelin type, so named after the pioneer Count Ferdinand von Zeppelin (born in Konstanz, Baden, Germany April 8, 1838 - died March 8, 1917). Von Zeppelin began experimenting with rigid airships before World War I. He had, by the time war broke out, given them a standard and highly efficient layout: an essentially cylindrical metal-framed and fabric-covered hull, large tail fins for stability, and streamlned engine and crew pods hung beneath the hull.

The prospect of using airships as bomb carriers had been recognized in Europe well before airships themselves were up to the task. H. G. Wells described the obliteration of entire fleets and cities by airship attack in The War in the Air (1908), and scores of less famous British writers declaed in print that the airhsip had altered the face of world affairs forever. On March 5, 1912 Italian forces became the first to use dirigibles for a military purpose during reconnaissance west of Tripoli behind Turkish lines. It was World War I, however, that marked the airship's real debut as a weapon.

Germany believed it had found, in the zeppelin, the ideal weapon with which to bypass the British Navy and strike at Britain itself. Raids began by the end of 1914, reached a first peak in 1915, and then were discontinued until 1917. Zeppelins proved to be terrifying but inaccurate weapons. Navigation, target selection and bomb-aiming proved to be difficult under the best of conditions, and the darkness and clouds that frequently accompanied zeppelin missions reduced accuracy even further. The physical damage done by the zeppelins over the course of the war was trivial, and the deaths that they caused (though tragic) amounted to a few hundred at most. The zeppelins also proved to be vulnerable to attack by aircraft and antiaircraft guns. Several were shot down in flames by British defenders, and others crashed 'en route'.

Airplanes had essentially replaced airships as bombers by the end of the war,and Germany's remaining zeppelins had been scrapped or handed over to the Allied powers as spoils of war. One such prize, the British dirigible R-34, landed in New York on July 6, 1919, completing the first crossing of the Atlantic by an airship and the first nonstop crossing by any aircraft. Impressed, British leaders began to contemplate a fleet of airships that would link Britain to its far-flung colonies. The success of another prize, the Los Angeles, encouraged the United States Navy to invest in airships of its own. Germany, meanwhile, was building the Graf Zeppelin, the first of what was intended to be a new class of passenger airships.

Initially airships met with great success and compiled an impressive safety record. The Graf Zeppelin, for example, flew over 1 million miles (including the first circumnavigation of the globe by air) without a single passenger injury. The expansion of airship fleets and the growing (sometimes excessive) self-confidence of airship pilots gradually made the limits of the type clear, however, and initial successes gave way to a series of tragic rigid airship accidents.

The U.S. Navy eventually lost all three of its American built rigid airships: Shenandoah in 1925 and Akron and Macon in the early 1930s. All three ships crashed--two with great loss of life--when their structural elements failed in severe storm-related turbulence. Britain suffered its own airship tragedy in the 1930s when the R-101, a fatally flawed machine barely able to lift its own weight, crashed in France with the loss of all aboard.

The most spectacular and widely remembered airship accidence, however, is the explosion of the Hindenburg [see: Hindenburg disaster ] on 6 May 1937, which caused public faith in airships to evaporate in favour of faster, more cost-efficient (albeit less energy-efficient) airplanes.

Although airships abandoned carrying passengers, 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.

Photographs, illustrations and clipart at Classroom ClipArt.com

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