Airship facts for kids

Kids Encyclopedia Facts
Luftschiff small
a modern airship

Airships are kind of aircraft. Airships stay in the sky by floating. This is different from aeroplanes that stay in the sky by moving. An airship floats like a balloon. But an airship is different from a balloon. An airship has an engine for power and a way to control its direction of movement. A balloon does not have an engine or a way to control its direction of movement.

Some people may use the word "airship" to mean any kind of aircraft. This is not exactly correct. Technical people use the word "airship" only to mean an aircraft that floats and has both an engine and a way to control its direction of movement.

Airships are also known as dirigibles from the French dirigeable, meaning "steerable". The term airship is sometimes informally used to mean a machine capable of atmospheric flight. The term zeppelin is a genericized trademark that originally referred to airships manufactured by the Zeppelin Company. In modern common usage, the terms zeppelin, dirigible and airship are used interchangeably for any type of rigid airship, with the terms blimp or airship alone used to describe non-rigid airships.

In the early days of airships, the primary lifting gas was hydrogen. Until the 1940s, most French, German, and British airships continued to use hydrogen because it offered greater lift and was cheaper than helium. However, hydrogen is flammable when mixed with air. The buoyancy provided by hydrogen is actually only about 10% greater than that of helium. So the issue became one of safety versus cost. American airships have been filled with helium since the 1920s and modern passenger-carrying airships are, by law, now prohibited from being filled with hydrogen. Some small experimental ships still use hydrogen. Other small experimental airships are filled with hot air in a fashion similar to a hot air balloon. They are sometimes called hotships.

Types

Usn-airships
Several different kinds of US Navy airships and balloons, circa 1930
  • Rigid airships (for example, Zeppelins) have rigid frames containing multiple, non-pressurized gas cells or balloons to provide lift. Rigid airships do not depend on internal pressure to maintain their shape.
  • Non-rigid airships (blimps) use a pressure level in excess of the surrounding air pressure in order to retain their shape.
  • Semi-rigid airships, like blimps, require 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.
  • Metal-clad airships have characteristics of both rigid and non-rigid airships, utilizing a very thin, airtight metal envelope, rather than the usual rubber-coated fabric envelope. Only two ships of this type, Schwarz's aluminium ship of 1897 and the ZMC-2, have been built to date.
  • Hybrid airship is a general term for an aircraft that combines characteristics 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. It should be noted that most airships, when fully loaded with cargo and fuel, are typically heavier than air, and thus must use their propulsion system and shape to generate airodynamic lift, necessary to stay aloft; technically making them hybrid airships. However, the term "hybrid airship" refers to craft that obtain a significant portion of their lift from aerodynamic lift and often require substantial take-off rolls before becoming airborne.

History

The development of airships was necessarily preceded by the development of balloons. See balloon (aircraft) for details.

Beginnings

DupuyLomeDirigeable
The navigable balloon developed by Henri Dupuy de Lôme in 1872.

Airships were among the first aircraft to fly, with various designs flying throughout the 19th century. They were largely attempts to make relatively small balloons more steerable, and often contained features found on later airships. These early airships set many of the earliest aviation records.

In 1784 Jean-Pierre Blanchard fitted a hand-powered propeller to a balloon, the first recorded means of propulsion carried aloft. The first person to make an engine-powered flight was Henri Giffard who, in 1852, flew 27 km (17 miles) in a steam-powered airship. Charles F. Ritchel made a public demonstration flight in 1878 of his hand-powered one-man rigid airship and went on to build and sell five of his aircraft. Paul Haenlein flew an airship with an internal combustion engine on a tether in Vienna, the first use of such an engine to power an aircraft. In 1880, Karl Wölfert and Ernst Baumgarten attempted to fly a powered airship in free flight, but crashed. In the 1880's a Serb named Ogneslav Kostovic Stepanovic also designed and built an airship. However the craft was destroyed by fire before it flew.

In 1883, the first electric-powered flight was made by Gaston Tissandier who fitted a Siemens electric motor to an airship. The first fully controllable free-flight was made in a French Army airship, La France, by Charles Renard and Arthur Krebs in 1884. The electric-powered flight covered 8 km (5 miles) in 23 minutes. In 1888, Wölfert flew a Daimler-built petrol engine powered airship at Seelburg. In 1896, a rigid airship created by Croatian engineer David Schwarz made its first flight at Tempelhof field in Berlin. After Schwarz's death, his wife, Melanie Schwarz, was paid 15,000 Marks by Zeppelin for information about the airship. In 1901, Santos Dumont, in his airship "Number 6", a small blimp, won the Deutsch de la Meurthe prize of 100,000 francs for flying from the Parc Saint Cloud to the Eiffel Tower and back in under thirty minutes.

The Golden Age

First Zeppelin ascent
LZ1, Count Zeppelin's first airship

The beginning of the "Golden Age of Airships" was marked with the launch of the LZ1 Luftschiff Zeppelin in July of 1900 which would lead to the most successful airships of all time, the Zeppelins. These ships were named after the pioneer Count Ferdinand von Zeppelin. Von Zeppelin began experimenting with rigid airship designs in the 1890's leading to some patents and the LZ1 (1900) and the LZ2 (1906). He had, by the time WW1 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 streamlined engine and crew pods hung beneath the hull.

The prospect of using airships as bomb carriers had been recognised in Europe well before the 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 declared in print that the airship had altered the face of world affairs forever. On 5 March 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 visible) amounted to a few hundred at most. The zeppelins also proved to be vulnerable to attack by aircraft and antiaircraft guns, especially those armed with tracer bullets. Several were shot down in flames by British defenders, and others crashed 'en route'.

1918 view from French dirigible
View from a French dirigible approaching a ship in 1918.
Uss-akron-manhattan
The USS Akron over Manhattan circa 1932

Airplanes had essentially replaced airships as bombers by the end of the war, and Germany's remaining zeppelins were scrapped or handed over to the Allied powers as spoils of war. The British rigid airship program, meanwhile, had been largely a reaction to the potential threat of the German one, and was largely though not entirely based on imitations of the German ships.

Airships using the Zeppelin construction method are sometimes referred to as zeppelins even if they had no connection to the Zeppelin business. Several airships of this kind were built in the USA, Britain, Italy, and the Soviet Union in the 1920s and 1930s, mostly imitating original Zeppelin design derived from crashed or captured German World War I airships.

After the war, modifications to the German designs began to be made. The L-33, was the British R-34. It landed in New York on July 6, 1919, completing the first crossing of the Atlantic by an airship and the first non-stop crossing, un-damaged, by any aircraft. Impressed, British leaders began to contemplate a fleet of airships that would link Britain to its far-flung colonies.

Another example was the first American-built rigid dirigible ZR-1 "USS Shenandoah" ("daughter of the stars", with ZR standing for "Zeppelin Rigid"), which flew in 1923, while the Los Angeles was under construction. The ship was christened on August 20 in Lakehurst, New Jersey and was the first to be inflated with the noble gas helium, which was still so rare at the time that the Shenandoah contained most of the world's reserves. So, when the Los Angeles was delivered, it was at first filled with the helium borrowed from ZR-1.

The Zeppelin works were saved by the purchase of what became called the USS Los Angeles by the United States Navy, paid for with "war reparations" money, owed according to the Versailles Treaty. The success of the Los Angeles encouraged the United States Navy to invest in larger 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. Interestingly, the Graf Zeppelin burned un-pressurised blau gas, similar to propane, as fuel. Since its density was similar to that of air, it avoided the weight change when fuel was used.

Downfall

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. In fact, with the exception of the Graf Zeppelin, most of the world's most famous airships eventually crashed.

R-38-rescue
Rescuers scramble across the wreckage of British R-38/USN ZR-2, August 24th, 1921

Although USS Los Angeles flew successfully for 8 years, the U.S. Navy eventually lost all three of its American built rigid airships to accidents. USS Shenandoah flew into a thunderstorm over Ohio in 1925 and broke into pieces. USS Akron was caught by a microburst and driven down into the surface of the sea off the shore of New Jersey in 1933. Both storm-related losses led to great loss of life. USS Macon broke up after suffering a structural failure in its upper fin off the shore of Point Sur in California in 1935. All but 2 of the 83 people aboard Macon survived the crash.

Britain suffered its own airship tragedy in 1930 when R 101, a ship far advanced for its time but rushed to completion and sent on a trip to India before she was ready, crashed in France with the loss of 48 out of 54 aboard. Because of the bad publicity surrounding the crash, the Air ministry grounded the competing R 100 in 1930 and sold it for scrap in 1931.

Zeppelin Postkarte 1936 a
The Hindenburg, on a postcard from 1936

The most spectacular and widely remembered airship accident, however, is the burning of the Hindenburg on 6 May 1937, which caused public faith in airships to evaporate in favour of faster, more cost-efficient (albeit less energy-efficient) airplanes. What is generally not remembered is that of the 97 people on board, 62 got out alive. There were 36 dead: 13 passengers, 22 aircrew, and one American groundcrewman.

Most probably, the airplane became the transport of choice also because it is less sensitive to wind. Aside from the problem of manoeuvring and docking in high winds, the trip times for an upwind versus a downwind trip of an airship can differ greatly, and even crabbing at an angle to a crosswind eats up ground speed. Those differences make scheduling difficult.

Airships in the Second World War

The greatest number of airships in use during the Second World War were blimps used to form anti-aircraft defences. Thousands were put up tethered to the ground by steel cables to form obstacles to German aircraft flying on bombing missions over England.

American construction of airships for civilian purposes was halted in the 1930s by a series of fatal crashes. However, military development of airships was continued in the US.

While Germany determined that airships were obsolete for military purposes in the coming war and concentrated on the development of airplanes, the United States pursued a program of military airship construction even though it had not developed a clear military doctrine for airship use.

Continued use

Although airships abandoned carrying passengers, they continued to be used for other purposes. In particular, the US Navy as above.

In recent years, the Zeppelin company has reentered the airship business. Their new model, designated the Zeppelin NT made its maiden flight on September 18, 1997. There are currently three NT aircraft flying. One has been sold to a Japanese company, and was planned to be flown to Japan in the summer of 2004. However, due to delays getting permission from the Russian government, the company decided to transport the airship to Japan by ship. An airship was flown over Athens during the 2004 Summer Olympics as part of security anti-terrorism measures.

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

Present-day research

Recently, several companies have begun 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.

In February 2005, the US Department of Defense announced a research program named WALRUS to explore the development of very large airships. The primary goal of the research program is determine the feasibility of building an airship capable of carrying 500 short tons (450 metric tons) of payload a distance of 12,000 miles (20,000 km) and land on an unimproved location without the use of external ballast or ground equipment (e.g. masts.)

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Airship Facts for Kids. Kiddle Encyclopedia.