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The ''Akron''-class airships were a class of two rigid airships constructed for the US Navy in the early 1930s. Designed as scouting and reconnaissance platforms, the intention for their use was to act as "eyes for the fleet", extending the range at which the US Navy's Scouting Force could operate to beyond the horizon. This capability was extended further through the use of the airships as airborne aircraft carriers, with each capable of carrying a small squadron of aeroplanes that could be used both to increase the airship's scouting range, and to provide self-defense for the airship against other airborne threats. The two ships were built as a continuation of the US Navy's rigid airship programme that had started just after World War I, and were used to further refine the tactics of the use of such machines in the fleet, predominantly over whether it was the airship that was the scout, with its air group only there for self-defense, or whether the airship was merely the mother ship and the aeroplanes were responsible for carrying out the long-range scouting mission. Both ships had short careers in the US Navy, as each one crashed into the sea during routine flights less than two years after it was commissioned. ==Background== The US Navy had been experimenting with rigid airships since shortly after the end of the First World War. In 1917, a German zeppelin, ''L 49'', was forced down in France following a bombing raid over England, and was captured virtually undamaged. This led to the idea of the United States obtaining a pair of German airships as part of the reparations plan; however, the ones that were earmarked were destroyed by their crews in 1919.〔Swanborough, G. and Bowyers, P. M. ''United States Navy Aircraft since 1912'' (2nd ed.), p. 587. London: Putnam, 1976 ISBN 0-370-10054-9〕 As a substitute plan, it was agreed that Germany would build and pay for an airship to be turned over to the Americans, while the US would build one of its own. In July 1919, the US Navy placed an order with the Naval Aircraft Factory in Philadelphia for the components to build a new rigid airship, which would be assembled at Naval Air Station Lakehurst in New Jersey; initially designated as FA-1 (Fleet Airship Number 1), the ship was soon redesignated as . The plan for the Germans to construct an airship was modified when the Royal Navy cancelled its own order for four rigid airships. The first ship of the class, ''R38'', was already under construction, and so an agreement was reached in October 1919 to sell the incomplete airship to the United States, which gave it the designation ZR-2.〔Robinson 1974, p. 169〕 In 1921, ZR-2 was completed and undertook a number of test flights from its construction site at Cardington, before travelling for further testing over the North Sea, being based at Howden. During a test flight in August, ZR-2 experienced a catastrophic structural failure and crashed into the Humber Estuary, killing all but five aboard.〔(【引用サイトリンク】title=R38/ZR2 )〕 Despite this setback, the US Navy continued with its rigid airship programme, starting construction of ZR-1 in June 1922. As a safety measure, it was decided that rather than use hydrogen as the lifting gas, which had been used on ZR-2, and which caused the fires following its crash, ZR-1 would be filled with helium.〔 The scarcity of helium, and the expense of producing it, meant that the airship utilised most of the world's reserve of the gas.〔Hayward (1978) p.64〕 ZR-1 was commissioned into the US Navy as USS ''Shenandoah'' in October 1923. At this time, another new rigid airship was under construction at the Luftschiffbau Zeppelin works in Germany - intended to compensate for the ships intended for reparations after the war, the ship was also used as a means of keeping zeppelin construction alive in Germany. Known initially by its construction number as LZ 126, it was appropriated by the US Navy as and commissioned as USS ''Los Angeles'' in November 1924. Owing to the scarity of helium, upon its commissioning, ''Los Angeles'' utilised gas obtained from ''Shenandoah''; the intention was to alternate use of the two airships until more of the gas could be procured. The use of ''Shenandoah'' and ''Los Angeles'' as platforms to evolve the tactics of airship use with the fleet led to the US Navy instituting a plan to procure a pair of new, purpose-built airships, which originated in a set of design studies undertaken by the Bureau of Aeronautics in 1924 as ''BuAer Design No. 60'',〔Grossnick (1986), p. 28〕 intended as an improvement over the ''Shenandoah'' design. The loss of ''Shenandoah'' in a crash in Ohio in September 1925 did not interrupt this; indeed, the incident left the US Navy with only one rigid airship that, under the terms of her construction, was not permitted to take part in military operations.〔 As a consequence, a pair of new airships was authorized in June 1926,〔 with the Goodyear-Zeppelin Corporation winning the contract to build them in October 1928. To facilitate construction, the company built a brand new construction and storage hangar, which came to be known as the Goodyear Airdock, at Akron, Ohio, in 1929. Upon completion of the building, work began on building the first of the new airships, which would receive the designations and . 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Akron-class airship」の詳細全文を読む スポンサード リンク
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