QF 4.7英寸Mk IX與Mk XII速射艦砲（英語：4.7 inch QF Mark IX and Mark XII）[note 1]是第二次世界大戰期間為大多數英國皇家海軍和大英國協海軍驅逐艦所搭載的45倍徑4.7英寸（120公釐）艦載主砲，[1]並且在第二次世界大戰以後、隨著搭載著它倆的驅逐艦被出售而出口到眾多國家，包括巴西、阿根廷與荷蘭，發射4.7英寸（120公釐）分裝式砲彈。
Quick Facts QF 4.7英寸Mk IX與Mk XII速射艦砲QF 4.7 inch Mark IX & Mark XII, 類型 ...
QF 4.7英寸Mk IX與Mk XII速射艦砲 QF 4.7 inch Mark IX & Mark XII
S級驅逐艦（英語：S and T-class destroyer）為QF Mark XII 4.7英寸艦砲導入了CP（Central Pivot；中央樞軸）Mk XXII單裝砲架。這款新型砲架所裝有的砲盾（英語：Gun mantlet）的前部傾斜度很高，可將艦砲的仰角從40度增加至55度，[9][10]與以前的CP Mk XVIII的垂直正面形成鮮明對比，並且可輕鬆地將S級與先前的前型們區分開來。在這方面，野蠻人號（英語：HMS Savage (G20)）卻是例外，配備4.5英寸口徑速射艦砲；一座前舷的雙聯砲架與後舷的兩座單裝砲架。
最終在1943年，4.7英寸口徑艦砲被Z級驅逐艦（英語：W and Z-class destroyer）以上的4.5英寸口徑速射艦砲所取代。所有新型4.5英寸砲的砲架是英國皇家海軍第一款真正的雙用砲架，都具有仰角達到55度的砲架，而實際發射的砲彈亦比4.7英寸的Mk IX與XII艦砲稍重，雖然比4.7英寸Mk XI艦砲（英語：QF 4.7-inch Mk XI naval gun）所發射的砲彈稍輕。
3月，英國驅逐艦，P358，金伯利號（英語：HMS Kimberley (F50)），在納爾維克（March, British Destroyers, P358, Kimberley at Narvik）：「總共齊射了180次…火砲訓練非常好，很大一部分的裝填動作實現了間隔僅約5秒…」（Salvos fired about 180 in all...drill to guns very good, great part of the action a loading interval of about 5 seconds was achieved...）
原文：It became clear at once that in an attack from the air in narrow waters flanked by mountains, the cards were held by the aircraft. There was too little sea-room for full freedom of manoeuvre, and the aircraft's approach was screened by the rock walls. As often as not, when they did come into view it was at such an angle that our 4.7-inch guns, whose maximum elevation was only forty degrees, could not reach them... Aandalsnes is approached through the Romsdal Fiord, and lies forty miles from the entrance, off which we arrived on the 24th April. The daylight passage of the convoy and escort through this waterway, speed five knots, on a steady course and with mountains rising steeply either side, presented an alluring invitation to enemy aircraft. Junkers attacks persisted to the end, but the fire of the destroyers, although limited to an elevation of forty degrees, was enough to keep the enemy just too high for their standard of marksmanship. Not a ship received a direct hit, though some were damaged by the splinters from near misses.
霍奇斯，部族級驅逐艦，p32：圖解高空轟炸機的攻勢（Hodges, Tribal Class Destroyers, p32: Diagram of High Level Bomber Attack）：從進入引信保存測定的有效射程之時起，直到它飛至4.7英寸艦砲抬升至仰角55度的最小射程之內以前，高度為12,000英尺、時速為240英里／小時的目標可能會在約58秒以內受到火力打擊。相對地，一艘部族級驅逐艦只能使用4.7英寸的Mk XII艦砲抬升至仰角40度，與相同目標交戰約37秒。（A 240 mph target, at 12 thousand feet altitude could expect to be under fire for about 58 seconds, from the time it enters the effective range of the FKC until it flies to within the minimum range of a 4.7-inch gun elevated to 55 degrees. A Tribal class destroyer would be able to engage the same target for about 37 seconds with a 4.7-inch Mk XII gun elevated to 40 degrees.）
Campbell, John. Naval Weapons of World War II. Annapolis, Maryland: Naval Institute Press. 1985. ISBN 0-87021-459-4.
Hodges, Peter; Friedman, Norman. Destroyer Weapons of World War 2. London: Conway Maritime Press. 1979. ISBN 0-87021-929-4.
March, Edgar J. British Destroyers: A History of Development, 1892–1953; Drawn by Admiralty Permission From Official Records & Returns, Ships' Covers & Building Plans. London: Seeley Service. 1966. OCLC 164893555.
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