airship
airship an aircraft that consists of a cigar-shaped gas bag, or envelope, filled with a lighter-than-air gas to provide lift, a propulsion system, a steering mechanism, and a gondola accommodating passengers, crew, and cargo. All extensions, like the fins and the gondola/control car, are attached to the envelope; the propellers are attached to the gondola/control car.
Soon after the hot-air balloon was invented in 1783, attempts began to control the balloon's flight. Although sails, paddles, and flapping wings were tried, propellers proved to be the most suitable form of propulsion. The French inventor Henri Giffard built a steam-power-driven airship as early as 1852. However, it was not until the invention of the gasoline engine in 1896 that airships became practical. The Brazilian Alberto Santos-Dumont was the first to construct and fly (1898) a gasoline-powered airship.
For more than a century the principal lighter-than-air gas for both balloons and airships was hydrogen, the lightest of the elements, despite its being highly dangerous because of its extreme flammability. Helium (which although somewhat inferior to hydrogen in lifting strength will not burn or explode) began to be used in the United States in 1917, when a means of extracting it cheaply in large quantities from the natural gas in which it is found was developed. Helium was subsequently adopted as the preferred gas worldwide.
There are three types of airships. In a nonrigid airship, also known as a blimp, the shape of the gas bag is maintained by the internal pressure of the enclosed gas. In a semirigid airship, also known as a keel-airship, internal gas pressure acts in conjunction with a longitudinal keel to maintain the form of the gas bag. In a rigid airship, the form of the gas bag is determined by a rigid framework, usually made of aluminum or a special aluminum alloy called Duraluminium; the framework is formed of longitudinal girders and cross-rings, also made of girders. The whole structure is covered with fabric for aerodynamic purposes. The rigid airship is often called a zeppelin in honor of its inventor, Count Ferdinand von Zeppelin . It is also often referred to as a dirigible, a shortening of dirigible balloon, from the French ballon dirigeable, meaning steerable lighter-than-air craft.
In 1910 the rigid Deutschland became the world's first commercial airship. Between 1910 and the beginning of World War I in 1914, German zeppelins flew 107,208 miles and carried 34,028 passengers and crew entirely without injury. During World War I, the Germans used rigid airships on both the Eastern and Western Fronts as bombers although airships never became effective offensive weapons. Airships did excel as defensive weapons, and the British used nonrigid airships to patrol their coasts and rigid airships for convoy protection. The U.S. navy operated nonrigid aircraft during the war, as did the French and Italian armies and navies. The U.S. navy continued operating nonrigid airships during and after World War II, the only service in the world to do so. In addition to convoy protection, the airships conducted search-and-rescue, photographic, and mine-clearing missions.
Rigid airships rose to the peak of their commercial success between World War I and World War II. The best-known rigid airships were the Graf Zeppelin, which traveled 20,000 mi (32,000 km) around the world in 1929; England's R34, which crossed the Atlantic in 1919; and the Hindenburg, which burst into flames while preparing to dock at Lakehurst, N.J., in 1937, killing 36 people. No fully rigid airship has been built since the 1930s.
In 1997 the Zeppelin NT, which uses modern technologies and design innovations to realize a more maneuverable and efficient semirigid airship, made its maiden flight and testing began in the hope of putting airships into commercial service once again. Several have been built; they are usually flown in a slightly heavier-than-air condition and use engine power to attain lift. The airships began tourist flights over Lake Constance in 2001. All of the other airships flying today are of the nonrigid variety. No nonrigid airships are used to carry passengers or cargo; they serve a number of utilitarian functions such as military surveillance, flashing advertising messages, and providing "bird's eye" television images of sporting events.
Bibliography: See L. Gerken, Airships, History and Technology (1990); H. G. Dick and D. H. Robinson, The Golden Age of the Great Passenger Airships (1992); D. H. Robinson, The Zeppelin in Combat: A History of the German Naval Airship Division, 1912-1918 (1993); W. A. Althoff, Sky Ships: A History of the Airship in the United States Navy (1998); G. H. Khoury and J. G. Gillette, ed., Airship Technology (1999).
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