4.7 inch QF Mark XII
Encyclopedia
The 4.7 inch QF Mark IX and Mark XII were 120-mm 45-calibre
naval guns which armed the majority of Royal Navy
and Commonwealth
destroyer
s in World War II
, and were exported to many countries after World War II as the destroyers they were mounted on were sold off.
, changing the cartridges from BL silk bags to separate QF in brass cases and a new horizontal sliding block breech mechanism.
Mark IX was deployed in single mountings CP Mk XIV on the A class destroyer
s of 1930 and on most subsequent destroyer classes up to and including the R class
of 1942.
The almost-identical Mk XII gun was deployed in twin mountings CP Mk XIX on the Tribal class
destroyers of 1936 and J, K and N classes of 1938. This mounting limited the maximum elevation to 40 degrees, but all twin CP Mk XIX were dual-purpose mountings and were equipped with Fuze Setting Pedestals or Mk V Fuze Setting Trays, to allow the mountings to be fired against aircraft while being controlled by the Fuze Keeping Clock
fire control computer. Typical maximum rate of fire was twelve rounds per gun, per minute.During gunnery trials in 1930, HMS Basilisk'
' was able to fire "...five rounds in 17 seconds." The Mk XII gun fired a 50lb shell and used a separate cartridge, with both shell and cartridge being loaded via a loading tray, with power ramming, elevation, and traverse. The maximum range at 40 degrees elevation was 16,970 yards (15520m) fired at the new gun muzzle velocity of 2650fps (808m/s). The 40 degree elevation was justified on the grounds that destroyers would be screening the battle-fleet during aerial attack, and 40 degrees elevation was adequate to engage aircraft that were concentrating their attack on other ships.
Admiral Sir Philip Vian describes the use of Tribal Class destroyer mounted Mk XII guns against aircraft during the campaign in Norwegian waters, April through June 1940:
The S class
, introduced the CP (central pivot) single Mark XXII mounting for the QF Mark XII 4.7 in gun. This new mounting had a shield with a sharply raked front, to allow increased elevation (to 55 degrees), contrasting noticeably with the vertical front of the previous CP Mark XVIII, and easily differentiated the S class onwards from their immediate predecessors. The Savage was the exception in this respect, being fitted with 4.5 inch calibre; a twin mounting forward and two singles aft.
The 4.7 inch calibre was finally superseded by the 4.5 inch calibre on the Z class destroyers in 1943. The new 4.5 inch guns all had 55 degree elevation mounts and actually fired a shell slightly heavier than that of 4.7-inch Mk IX and XII guns, although slightly lighter than that fired by the 4.7 inch Mk XI gun.
Caliber (artillery)
In artillery, caliber or calibredifference in British English and American English spelling is the internal diameter of a gun barrel, or by extension a relative measure of the length....
naval guns which armed the majority of Royal Navy
Royal Navy
The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...
and Commonwealth
Commonwealth of Nations
The Commonwealth of Nations, normally referred to as the Commonwealth and formerly known as the British Commonwealth, is an intergovernmental organisation of fifty-four independent member states...
destroyer
Destroyer
In naval terminology, a destroyer is a fast and maneuverable yet long-endurance warship intended to escort larger vessels in a fleet, convoy or battle group and defend them against smaller, powerful, short-range attackers. Destroyers, originally called torpedo-boat destroyers in 1892, evolved from...
s in World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
, and were exported to many countries after World War II as the destroyers they were mounted on were sold off.
Description and history
These guns succeeded the similar World War I-era BL 4.7 inch gunBL 4.7 inch /45 naval gun
The BL 4.7 inch 45 calibres gun was a British medium-velocity naval gun introduced in 1918 for destroyers, to counter a new generation of heavily-armed destroyers Germany was believed to be developing....
, changing the cartridges from BL silk bags to separate QF in brass cases and a new horizontal sliding block breech mechanism.
Mark IX was deployed in single mountings CP Mk XIV on the A class destroyer
A class destroyer
The A class was a flotilla of eight destroyers built for the Royal Navy as part of the 1927 naval programme. A ninth ship, Codrington, was built to an enlarged design to act as the flotilla leader...
s of 1930 and on most subsequent destroyer classes up to and including the R class
Q and R class destroyer
The Q and R class was a class of sixteen War Emergency Programme destroyers ordered for the British Royal Navy in 1940 as the 3rd and 4th Emergency Flotilla. They served as convoy escorts during World War II. Three Q class ships were transferred to the Royal Australian Navy upon completion, with...
of 1942.
The almost-identical Mk XII gun was deployed in twin mountings CP Mk XIX on the Tribal class
Tribal class destroyer (1936)
The Tribal class, or Afridi class, were a class of destroyers built for the Royal Navy, Royal Canadian Navy and Royal Australian Navy that saw service in World War II...
destroyers of 1936 and J, K and N classes of 1938. This mounting limited the maximum elevation to 40 degrees, but all twin CP Mk XIX were dual-purpose mountings and were equipped with Fuze Setting Pedestals or Mk V Fuze Setting Trays, to allow the mountings to be fired against aircraft while being controlled by the Fuze Keeping Clock
Fuze Keeping Clock
The Fuze Keeping Clock was a simplified version of the Royal Navy's High Angle Control System analogue fire control computer. It first appeared as the FKC Mk1 in destroyers of the 1938 Tribal class, while later variants were used on sloops, frigates, destroyers, aircraft carriers and several...
fire control computer. Typical maximum rate of fire was twelve rounds per gun, per minute.During gunnery trials in 1930, HMS Basilisk'
HMS Basilisk (H11)
HMS Basilisk was a of the British Royal Navy that saw early World War II service in Norway, before being sunk at Dunkirk in 1940.-Construction:...
' was able to fire "...five rounds in 17 seconds." The Mk XII gun fired a 50lb shell and used a separate cartridge, with both shell and cartridge being loaded via a loading tray, with power ramming, elevation, and traverse. The maximum range at 40 degrees elevation was 16,970 yards (15520m) fired at the new gun muzzle velocity of 2650fps (808m/s). The 40 degree elevation was justified on the grounds that destroyers would be screening the battle-fleet during aerial attack, and 40 degrees elevation was adequate to engage aircraft that were concentrating their attack on other ships.
Admiral Sir Philip Vian describes the use of Tribal Class destroyer mounted Mk XII guns against aircraft during the campaign in Norwegian waters, April through June 1940:
"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 FiordRomsdalsfjordRomsdalsfjord is the ninth longest fjord in Norway. It is long and located in the Romsdal district of Møre og Romsdal county. It flows through the municipalities of Midsund, Haram, Vestnes, Molde, Nesset, and Rauma...
, 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."
The S class
S and T class destroyer
The S and T class was a class of sixteen destroyers of the Royal Navy launched in 1942–1943. They were built as two flotillas, known as the 5th and 6th Emergency Flotilla respectively and they served as fleet and convoy escorts in World War II.-Design features:The S class, introduced the CP ...
, introduced the CP (central pivot) single Mark XXII mounting for the QF Mark XII 4.7 in gun. This new mounting had a shield with a sharply raked front, to allow increased elevation (to 55 degrees), contrasting noticeably with the vertical front of the previous CP Mark XVIII, and easily differentiated the S class onwards from their immediate predecessors. The Savage was the exception in this respect, being fitted with 4.5 inch calibre; a twin mounting forward and two singles aft.
The 4.7 inch calibre was finally superseded by the 4.5 inch calibre on the Z class destroyers in 1943. The new 4.5 inch guns all had 55 degree elevation mounts and actually fired a shell slightly heavier than that of 4.7-inch Mk IX and XII guns, although slightly lighter than that fired by the 4.7 inch Mk XI gun.
See also
- 12.7 cm SK C/34 naval gun12.7 cm SK C/34 naval gunThe 12.7 cm SK C/34 was a German medium-caliber naval gun deployed on destroyers from 1934 through the Second World War. Some of these guns remained in service until 2003 in the coastal defense units of Norway.-Characteristics:...
: equivalent German destroyer gun, firing slightly heavier shell
