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The 13 pounder 9 cwt anti-aircraft gun〔In the name, 13 pounder referred to the approximate weight of the standard shell, and 9 cwt referred to the weight of the barrel and breech (9 × 112 lb = 1008 lb), to differentiate it from other varieties of "13 pounder".〕 became the standard mobile British anti-aircraft gun of the World War I era, especially in theatres outside Britain. ==History== Earlier anti-aircraft guns based on 13 pounder and 18 pounder guns proved unsatisfactory, primarily due to their low muzzle velocities. On 18 February 1915 Sir John French, commander of the British Expeditionary Force in France, asked for an anti-aircraft gun with a muzzle velocity of .〔History of the Ministry of Munitions, page 26〕 On 19 August 1915 the Army Council proposed adapting existing 18-pounder guns (3.3-inch bore) to use 13-pounder (3-inch) shells, thus meeting the requirement for higher velocity.〔History of the Ministry of Munitions, page 27〕 This weapon combined an 18 pounder breech and barrel with a liner (sleeve) inserted to reduce the bore from to so that it could fire the slightly smaller 13 pounder shell but still use the larger cartridge and propellant charge of the 18 pounder resulting in a much higher velocity. A slight neck was introduced in the 18 pounder cartridge to hold the slightly narrower 13 pounder shell in place. The initial Mk III mounting was based on the 13 pounder Mk II anti-aircraft mounting, but proved to be not strong enough for the extra power of the 18 pounder cartridge. The Mk IV mounting which followed raised the height by and increased recoil from 24 to and hence relieved the strain on the mounting.〔Hogg & Thurston 1972, page 64〕 Several guns are known to have been mounted on 2-wheeled high-angle field carriages and deployed on the Italian front. Hogg & Thurston state that they could theoretically be used as anti-aircraft guns, field guns or howitzers, but they were not officially introduced and may have been of an experimental nature.〔Hogg & Thurston 1972, page 66-67〕 Routledge states that the carriage was improvised because some of 4th AA Group's guns had arrived in Italy without mountings.〔Routledge 1994, page 33〕 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「QF 13-pounder 9 cwt」の詳細全文を読む スポンサード リンク
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