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 retains 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 are often casually referred to by several other names such as dirigibles, zeppelins, or the big rigids^{[citation needed]}.

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 caught fire on May 6, 1937.

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

The British R34 in Long Island during the first ever return crossing of the Atlantic in July 1919

The British Royal Navy took an early interest in rigid airships and ordered His Majesty's Airship No. 1 in 1909 from Vickers Limited at Barrow-in-Furness, based on Zeppelin principles. It was 512 feet long with two Wolseley engines. It was completed in 1911 but broke in two before its first flight and was scrapped.^[7] Attention switched to non-rigid types but in 1913 an order was placed for HMA No. 9r which was not completed until April 1917. By then, the war against U-Boats was at its height and No. 9 was quickly followed by 4 airships of the 23 Class, two R23X Class and two R31 Class,^[8] the last being based on the Schütte-Lanz principle of wooden construction, and remain the largest mobile wooden structures ever built.^[9] The only significant combat success of these airships, aside from their deterrent effect, was assistance in the destruction of SM UB-115 by R29 in September 1918.^[10]

The end of the war saw two new airships of the R33 Class nearing completion. R33 became a civilian airship, finishing her career doing experimental work. The R34 became the first aircraft to complete a return Atlantic crossing in July 1919 but was lost in January 1921 in bad weather over the North Sea.^[11] R36 was the only airship of the R35 class to be completed; it entered civilian service but was damaged three months after its first flight and was never repaired.^[12] Only the name ship of the R38 Class was completed; it was sold to the US Navy and renamed ZR-2. In June 1921, it broke up in the air over Kingston-upon-Hull before it could be delivered, killing 44 of its Anglo-American crew. The last airship that had been ordered in World War I was the R80; it completed in 1920 but was tested to destruction in the following year after it was found to have no commercial use.^[13]

In 1924, the British Government launched research that resulted in the Imperial Airship Scheme, which in turn led directly to the construction of R100 and R101. The R100 was privately built by Vickers-Armstrongs with a design team led by Barnes Wallace who had co-designed the R80. After her first flight in December 1929, R100 made a successful round trip to Quebec in Canada in July and August the following year. The competing R101 was designed and built by the Air Ministry. After a series of problems during early trials, it was decided to extend the airship's envelope. R101's maiden flight was to British India in October 1930, but it crashed in France killing 48 of the 54 people on board. Following this disaster, the R100 was grounded and finally scrapped in November 1931, marking the end of British interest in the rigid airship.^[14]

France

The extended Spiess airship in 1913.

France's only rigid airship was designed by Alsatian engineer Joseph Spiess (1838 - 1917), using the principles set out in his patent of 27 September 1873. It was constructed by Société Zodiac at the Aérodrome de Saint-Cyr-l'École.^[15] It had a framework of hollow wooden spars braced with wire, and was given the name Zodiac XII but had the name SPIESS painted along the side of the envelope.^[16] It was 113 metres long, with a diameter of 13.5 metres, powered by a single Chenu 200 horse power engine that drove two propellers. It first flew on April 13, 1913, but it became clear that it was underpowered and required more lift, so the envelope was extended to 140 metres to accommodate three more gas cells and a second engine was added. Spiess then presented the airship to the French government as a gift.^[17] After further trials it was not accepted by the French military, because their view was that smaller non-rigid types would be more effective.^[18] The Spiess airship seems to have been broken-up in 1914. Joseph Spiess is buried in the Cimetiere du Pere-Lachaise in Paris; his gravestone has a bronze frieze depicting his airship.^[19]

Germany

In 1900, Count Ferdinand von Zeppelin began trials of his first airship, the LZ 1. 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). Commercial airlines ended in Germany at the outbreak of the War, during which Zeppelin’s company built 95 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, 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. On the night of September 2–3, 1916 the first German airship was shot down over English soil by Lt. Leefe Robinson flying a BE 2c. 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.^[20]

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.^[21]

United States

USS Akron passes over Lower Manhattan

The United States rigid airship program was mostly based at Lakehurst Naval Air station, New Jersey. 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. 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. 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, The Zeppelin company vowed that their future passenger airships would be inflated with nonflammable 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, so development of new airships was halted. Following new advances in aviation from World War II, fixed-wing heavier-than-air 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 1939.
• LZ 127 Graf Zeppelin,^[2] German passenger Zeppelin. 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, 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 Zeppelin. The airship was lost after catching fire and exploding in New Jersey in 1937. With its end came the end of the age of the Great Rigid Airships.

Modern rigids

• 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]
• Aeroscraft has recently been certified airworthy by the FAA and has begun flight testing.^[22]

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.
• * Price Bradshaw: The role of technology in the failure of the rigid airship as an invention. Dissertation, University of Florida 1975. Online via Archive.org

External links

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