Rigid airship

Construction of USS Shenandoah (ZR-1), 1923, showing the framework of a rigid airship.

A rigid airship is a type of airship in which the envelope retained its shape by the use of an internal structural framework rather than by being forced into shape by the pressure of the lifting gas within the envelope as used in blimps (also termed pressurized airships) and semi-rigid airships.^[1][2]

Rigid airships were produced and relatively successfully employed from the beginning of the 1900s to the end of the 1930s; their heyday ended when the Hindenburg ignited on May 6, 1937.

Terminology

Although "rigid airship" is the proper formal term, these aircraft are often casually referred to by several other names such as dirigibles (which is incorrect since both semi-rigid airships and non-rigid airships are dirigible, i.e. steerable), zeppelins (after the most successful ships of this type built by the Zeppelin Company), or the big rigids.

Early days

By 1874 several people had conceived of a rigid dirigible (in contrast to non-rigid powered airships which had been flying since 1852). Frenchman Joseph Spiess had published a rigid airship proposal in 1873 but failed to get funding.^[3] Count Zeppelin had outlined his thoughts of a rigid airship in diary entries from 25 March 1874 through to 1890 when he resigned from the military.^[4] David Schwarz had thought about building an airship in the 1880s and had likely started design work in 1891, definitely by 1892 he was starting construction.^[5] It was not until after Schwarz's death in 1897 that his all-aluminium airship, built with help from with Carl Berg and the Prussian Airship Battalion, was test flown. Schwarz and Berg had an exclusive contract and Count Zeppelin was obliged to come to a legal agreement with Schwarz's heirs to obtain aluminium from Carl Berg, although the two men's designs were different and independent from each other.^[6] With Berg's aluminum, Zeppelin was able in 1899 to start building and, in 1900 July, to fly the Zeppelin LZ1.

Great Britain

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Great Britain and the USA lagged behind Germany in rigid airship technology. According to a 2001 PBS documentary, much of Britain's knowledge was based on reverse engineered technology from World War I German zeppelin crashes. After several crashes of experimental airships, the British ceded this field to the Germans^{[citation needed]}.

France

France's only rigid airship was built by Alsatian Joseph Spiess using a wooden framework and it flew on April 13, 1913. It was 146 metres (479 ft) long, with a diameter of 13.5 metres (44.3 ft) and a gas volume of 16,400 cubic metres (579,161 cubic feet). Joseph Spiess is buried in the famous Cimetiere du Pere-Lachaise in Paris. His gravestone celebrates his achievements with a bronze frieze of his rigid airship.

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Germany

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In 1900, Count Ferdinand von Zeppelin began trials with a rigid airship based on the theories of engineer David Schwarz, a Croatian aviation pioneer of Hungarian-Jewish descent. Germany had over twenty very large lighter-than-air rigid airships by the beginning of World War I, seven owned by the company Luftschiffbau Zeppelin. In the five years prior to the outbreak of war, his airline carried 32,722 passengers on over 1,588 flights totalling 172,530 kilometres (107,210 mi). The German war ministry took over two of them in 1909 and one crashed. Commercial airlines ended in Germany at the outbreak of the War, during which Zeppelin’s company built 95 giant military airships. German military airship stations had been established before the War and on September 2–3, 1914, the Zeppelin LZ 17 dropped three 200 lb bombs on Antwerp in Belgium. On January 19, 1915, two further airships dropped bombs on Norfolk, England, killing numerous people; the third ship in the air raid returned to Germany with engine trouble before reaching England. On May 31, 1915, the first bombs fell on London. The night of September 2–3, 1916 was when the first German airship was shot down over English soil; it was done using a small heavier-than-air aircraft. Further bombs were dropped on London during the night of November 27–28, 1916, this time by a winged aircraft. However, the build-up of England’s defences against such aircraft led to the discontinuation of airship raids by Germany. The last casualties occurred on April 12, 1918.^[7]

Italy

Italy was the only country other than Germany to use lighter-than-air craft for bombing purposes, against targets in the Austro-Hungarian Empire. Italian airships were "semi-rigid dirigibles," they were different from the "rigid" Zeppelins in that they typically only had a keel for rigidity, though sometimes they had some further structure at the nose and/or tail, as opposed to the entire frame favoured by the Germans. Their first bombing raid was on 26 May 1915, three days after entering the war, when they crossed the Adriatic to attack Sebenico, which was attacked by a dirigible again the following day. On 8 June 1915, the Città di Ferrara took off from an airfield in Pordenone to bomb the Whitehead torpedo factory and the oil refinery at Fiume (later Rijeka, Croatia), killing one civilian, injuring several other people, but only causing slight damage. After Città di Ferrara turned for home, it was intercepted and shot down by a Lohner L flying boat (pennant number L-48) of the Austro-Hungarian Navy, over Kvarner Gulf, near the island of Lussino. This was the first time that an airship had been destroyed in air combat.^[8]

United States

The United States rigid airship program was mostly based at Lakehurst Naval Air station, New Jersey. The USS Shenandoah (ZR-1) was one of the first of these rigid airships, serving from 1923 to 1925, when it was torn about in severe weather killing 14 of the crew. The ZR-2 was a British airship intended to join the naval fleet, but it crashed on a trial flight 1921 before it could be delivered to the States. Forty-four of those on board died. The USS Los Angeles (ZR-3) was a German airship, sold to the United States in 1924. The ship was grounded in 1931, due to the Depression, but was not dismantled for over 5 years. The sister ships Akron and Macon both crashed after technical failure. The Akron was flown into the sea in bad weather and broke up. Over seventy were killed, including one of the US Navy's proponents of airships - Rear Admiral Moffett. Macon also ended up in the sea when it flew into heavy weather with unrepaired damage from an earlier incident, but the introduction of life-jackets following the loss of the Akron meant only two lives were lost.

These crashes ended the rigid airship program.

Production

As well as the Zeppelin Company, Schütte-Lanz also manufactured rigid airships. Both America and Britain have manufactured rigid airships at some point.

Demise

Following the Hindenburg disaster in 1937, Germany grounded its airship fleet with the intention of replacing their hydrogen gas with non-flammable helium. By this time, however, Europe was well on the path to World War II, and the United States, the only country with substantial helium reserves, refused to sell the necessary gas. International travel was crippled during the war, and commercial aircraft - able to fly much faster than rigid airships - soon became the favored method of international air travel.

Famous rigid airships

• R34, British airship and the first aircraft to traverse the Atlantic Ocean from east to west, in 1919.
• USS Shenandoah, American naval airship which served the U.S. Navy from 1923 until its crash in Ohio in 1925.
• R38 (ZR-2), British airship intended to join the American naval fleet, but crashed during testing in 1921.
• USS Los Angeles, German airship sold to the United States in 1924 as part of German reparations from World War I. The ship served with distinction from 1924 to 1931.
• LZ 127 Graf Zeppelin,^[2] German passenger airship designed and piloted by Hugo Eckener. It circumnavigated the globe in 1929 and had a spotless safety record. It was ultimately dismantled by the Nazis at the outset of World War II.
• R80, British airship that first used Barnes Wallis's geodesic construction approach that was later applied to the Wellington bomber.
• R-100, British airship built by the Airship Guarantee Company, a private company created solely for the construction of this airship, as a subsidiary of the armaments firm, Vickers.
• R-101, British airship designed and built by the British government in a kind of competition with the R-100. The R-101 crashed on its maiden flight in 1930 in France, with considerable loss of life. Its crash effectively ended British participation in rigid airship construction.
• USS Akron,^[2] American naval airship designed and built by the Goodyear Tire and Rubber Company in Ohio in 1931. Deployed as an airborne aircraft carrier, it was lost at sea in a storm off New Jersey in 1933 with considerable loss of life.
• USS Macon, sister ship to the Akron, it was a near carbon-copy of her. Though it suffered only 2 deaths, its crash in 1935 off the coast of California ended American participation in rigid airship development.
• LZ 129 Hindenburg,^[2] German passenger airship also designed and built by Hugo Eckener. The airship was lost in a famous fire in New Jersey in 1937. With its end came the end of the age of the Great Rigid Airships.

Modern rigids

There are no rigid airships flying today. The Zeppelin company refers to their NT ship as a rigid but this is a misnomer. The envelope shape is retained in part by super-pressure of the lifting gas, and so the NT is more correctly classified as a semi-rigid.^[1]

See also

• List of Zeppelins
• List of Schütte-Lanz rigid airships
• List of Parseval semi-rigid and non-rigid airships
• Airship hangar

Notes

References

• Dooley, Sean C., The Development of Material-Adapted Structural Form - Part II: Appendices. THÈSE NO 2986 (2004), École Polytechnique Fédérale de Lausanne
• Hartcup, Guy. The Achievement of the Airship: A History of the Development of Rigid, Semi-Rigid and Non-Rigid Airships. David & Charles : London. 1974.

External links

• Airships.net: The Hindenburg and other Zeppelins
• "Biggest Birds That Ever Flew" Popular Science, May 1962