QF 5.25-inch naval gun

QF 5.25-inch Mark I
QF 5.25-inch Mark I
	5.25-inch turret on HMS Sirius. The empty cartridge cases from firing in support of the Allied invasion of Normandy, June 1944
Type	Dual-purpose gun
Place of origin	United Kingdom
Service history
In service	1940-1985 (naval); 1942-1960s (land)
Used by	Royal Navy; Royal Artillery; Royal Australian Artillery
Wars	World War II; Korean War
Production history
Designed	1935
Variants	Mk I, Mk II
Specifications
Mass	Barrel & breech: 9,616 lb (4,362 kg)
Length	Total: 22 ft 11.5 in (7 m)
Barrel length	Bore: 21 ft 10.5 in (6.67 m) 50 calibres
Shell	133x782 mm R; Separate QF, 80 pounds (36.29 kg)
Calibre	5.25-inch (133 mm)
Elevation	-5 to +70 degrees
Rate of fire	7-8 rpm sustained fire
Muzzle velocity	Naval: 2,672 ft/s (814 m/s); Army AA: 2,800 ft/s (850 m/s)
Effective firing range	Naval: 23,400 yd (21,400 m) at 45 degrees with HE shell at 2,600 ft/s (790 m/s); AA: 36,000 ft (11,000 m)
Maximum firing range	Naval: 24,070 yd (22,010 m) at 45 degrees with HE shell at 2,672 ft/s (814 m/s); AA: 46,500 ft (14,200 m)

The QF 5.25-inch Mark I gun was the heaviest dual-purpose gun used by the Royal Navy during the Second World War. Although considered less than completely successful, it saw extensive service.^[1] 267 guns were built.^[1]

Design

Unlike its French and Italian contemporaries of similar size the QF 5.25-inch gun was designed as dual-purpose equipment capable of engaging both aircraft and surface targets. Combining the secondary and heavy anti-aircraft armament allowed a significant weight savings for the King George V-class battleships, which were designed to meet the Washington Naval Treaty limit of 35,000 tons. The gun fired an 80 lb (36 kg) shell, which was considered the largest that a gun crew could easily handle while still having the rate of fire needed for anti-aircraft use. In 1944, VT-fuzed shells became available, making the gun significantly more effective against aircraft.

The 5.25-inch gun was carried in Mk I twin mountings by the King George V class and in Mk II twin mountings on nine of the first eleven Dido-class anti-aircraft cruisers, the exceptions being HMS Scylla and HMS Charybdis, which mounted QF 4.5-inch Mk III guns due to shortages of the 5.25-inch gun. The last five of the Dido class also known as the Bellona-class anti-aircraft cruisers mounted the 5.25-inch gun in the Remote Power Control RP10 Mk II mountings, which offered much-improved training and elevating speeds. The number of turrets on the Bellona class were reduced from five to four and the number of light AA guns were increased. The RP10 Mk II mountings were also later used to replace the Mk I mountings on HMS Anson. The last of the Royal Navy's battleships which was commissioned after the war, HMS Vanguard, had MK I turrets with enlarged gun houses compared to those fitted to the King George V and Dido-class ships, although the width between the guns remained the same.^[4] A slightly more powerful Mk II variant was also deployed by the British Army as an anti-aircraft and coast-defence gun.

Naval service

The RN Gunnery Pocket Book published in 1945 states:

they fulfil the combined functions of H.A. Long Range Armament and Secondary Armament against surface craft. The 5.25 in. calibre with separate ammunition is used for dual High Angle and Low Angle Armament, since it gives the reasonable maximum weight of shell which can be loaded by the average gun's crew for sustained periods at all angles of elevation. The maximum rate of fire should be 10-12 rounds per minute.^[5]^[6]

A wartime account describes HMS Euryalus demonstration firing her main armament:

...the ship's company closed to action-stations and gave a demonstration of the cruiser's firepower to the army officers... in the form of a low angle barrage. Set to burst at 2000 yds range, a terrific barrage was put up for two minutes and we fired some two hundred rounds of 5.25-inch HE...A wall of bursting shell was thrown up just above sea level and I could see that the army officers were impressed...^[7]

The ballistic performance of the QF 5.25 was very good, with a maximum range of 24,070 yd (22,010 m) at 45 degrees with an 80 lb (36 kg) HE shell.^[8] In comparison, the French 138 mm (5.4 in) Mle 1934 guns as used on the Mogador-class destroyers had a maximum range of 21,872 yd (20,000 m) at 30 degrees with an 88 lb (40 kg) SAP shell.^[9] The Italian 135/45 mm gun as used on the Capitani Romani-class cruisers had a maximum range of 21,435 yd (19,600 m) at 45 degrees with a 72.1 lb (32.7 kg) AP shell.^[10]

The QF 5.25 guns performed well on HMS Prince of Wales during Operation Halberd, escorting a convoy to Malta under, but later Prince of Wales was overwhelmed and sunk while operating along with Repulse when Force Z was attacked by Japanese aircraft, due to factors unrelated to the guns' performance.^[11] No Dido-class cruisers were lost to air attack, although four were sunk by submarine or surface-launched torpedoes.^[12]^{[page needed]} However HMS Spartan, a Bellona-class cruiser (Improved Dido), was sunk at anchor in 1944 by a Luftwaffe guided missile.^[12]^{[page needed]} According to postwar publications the gunhouses were cramped, and the heavy projectile and cartridge cases resulted in a reduced sustained rate of fire to seven or eight rounds per minute rather than the designed twelve rounds per minute.^[13]^[14]^[15] However, these factors do not appear to have reduced Euryalus's rate of fire, over a one-minute period, which was typical for a World War II AA engagement.^[16] The dual-mount turrets 10 deg/s traversal speed was considered too slow to engage higher-speed aircraft at close range.^[14]^{[note 3]} Nevertheless, these elevation and traverse rates were still higher than some contemporary weapons, such as the 10.5 cm SK C/33 twin mounts carried on the German battleships Bismarck and Tirpitz.^[17]

Ship classes

Ships with QF 5.25 inch Mark I guns:

Land service

In early 1942 the Governor of Gibraltar sought 5.25-in guns for dual anti-aircraft/coast defence role. None was forthcoming. However, later that year Anti-Aircraft Command in UK acquired three twin-gun turrets from the Admiralty, which were installed around London in permanent positions. Trials and use led the army to design a single gun mounting in two marks, both with an underground engine room to provide electrical and hydraulic power for traverse, elevation, fuze setting, ramming and other tasks. Fitted with the standard army Machine Fuze Setter No 10, these guns had a rate of fire of 10 rds/min and a maximum height of 50,000 ft, with an effective height of 36,000 ft.^[18] Mark 1A was a mild steel turret for anti-aircraft use only, Mk 1B was an armoured turret for anti aircraft and coast defence use. The gun was designated Mk 2.

By the end of 1943 only 16 of the new guns had been installed, far below projections. By the end of the war 164 guns had been produced.^[19] The high-explosive shells were fuzed with the standard army No 208 mechanical time fuze, used with 3.7 and 4.5-inch anti-aircraft guns. The guns remained in service after World War II, and in 1953 11 guns were installed in Gibraltar.^[20]^[21]

Late in World War II, seven guns were mounted in Australia and three in New Guinea, in enclosed single-gun anti-aircraft/coast defence turrets.^[22]

Specifications

Bore Diameter: 5.25 inches (133 mm)
Barrel Length: 6.668 m (50 calibres)
Shell weight: 80 lbs (36.3 kg)
Range: 24,070 yds (22,000 m) at 45 degrees
Anti Aircraft Ceiling: 46,500 ft (14,170 m)
Rate of Fire: Sustained 7–8 rpm, 18 RPM claimed for HMS Vanguard.^[23]
Penetration: side armour: 3 inches (76 mm) 9,500 yards (8,690 m) or 11,900 m, depending on the sources; the gun was not capable of penetrating 2 inches (51 mm) of deck armour at any range^[24]
Mounting weight: 78.7 metric tons (varied)
Mounting elevation: -5 to +70 degrees
Training & elevating speeds: 10 degrees per second and 20 degrees per second respectively, in RP10 mounts.

Ammunition

Mk II SAP (semi armour-piercing) shell
Crew of HMS Euryalus with shells, August 1942

Surviving examples

Princess Anne's Battery remains overlooking the sea at Gibraltar
a turret originally from PNS Babur (ex HMS Diadem) is at the gate of Pakistan Navy Headquarters in Karachi^{[citation needed]}

References

Notes

^ HMNZS Royalist was not decommissioned until 1966, although she appears to have ended "active service" some years before. All other ships were decommissioned by 1962 except PNS Babur which served until 1985.
^ Britain used Roman numerals to denote "Marks" (i.e. models) of ordnance until after World War II.
^ A 270-knot (500 km/h; 310 mph) target crossing the line of sight at right angles, at 2,000 yd (1,800 m) range, will move across the line of sight at 4.5 degrees per second.^{[page needed]} This simple fact of geometry appears to contradict the assertion that a 10-degree-per-second traverse rate was too slow to track a high-speed aircraft.

Citations

^ a b c Page of Navweapons
^ a b Campbell, Naval Weapons of WW2, p44
^ a b Routledge 1994, page 87
^ Campbell, p.46
^ The Gunnery Pocket Book. 1945. p. 51.
^ Sired, Enemy Engaged, p23, states: "The Italians did not press home their attacks very hard and I thought they had a lot to put up with, as each (10 × 5.25 in gun) cruiser could fire 100 rounds of 5.25" HE shell per minute..." Ronald Sired was a gunnery petty officer on board HMS Euryalus. The accuracy of Sired's account was praised by Captain FC Flynn RN. Official Historian of the Naval Campaigns in the Mediterranean^{[citation needed]}
^ Sired, Enemy Engaged, p 63.
^ DiGiulian, Tony (29 January 2022). "5.25"/50 (13.4 cm) QF Mark I". Navweap.
^ Model 1934 and Model 1934 R1938 Navweapons
^ Models 1937 and 1938 Navweapons
^ Battleship, Middlebrook^{[page needed]}
^ a b Raven, Dido Class Cruisers
^ Williams, Anthony G. "Medium Calibre guns of the Royal Navy in World War II". Military Guns & Ammunition.
^ a b "Britain 5.25"/50 (13.4 cm) QF Mark I". navweaps.com.
^ Garzke&Dullin, 1980. pp. 228–229
^ Hodges, Tribal Class Destroyers, p 32: Diagram of High Level Bomber Attack: A 240 mph target, at 12 thousand feet altitude could expect to be under for fire about 75 seconds, from the time it enters the effective range of the HACS until it flies to within the minimum range of a 5.25 gun elevated to 70 degrees. A Tribal-class destroyer would be able to engage the same target for about 37 seconds.
^ 10.5 cm/65 (4.1") SK C/33 navweaps.com
^ Routledge 1994, page 87, 78. "Effective height" was the greatest at which a 400 mph target could be engaged for 30 seconds using Predictor No. 10 (the all-electric US Bell AAA Computer) : hence with a realistic prospect of damaging the target. The shell could travel up to 50,000 ft but with little tracking capability, hence little effectiveness.
^ Routledge 1994, page 92
^ Hogg pg. 105-106
^ Routledge pg 77, 92,204, 207, 432
^ DW Spethman, "The garrison guns of Australia 1788-1962", pages 145-6. Published by Ron H Mortensen, Inala Qld, 2008. ISBN 978-0-9775990-8-0
^ Garzke & Dulin, p291: " The guns were fully automatic and remotely controlled, with a rate of fire of eighteen rounds per minute."
^ Naval Weapons page gives 3 inches at 9,500 yards

Bibliography

Brown, D.K.Nelson to Vanguard: Warship Design and Development 1923–1945
Campbell, John, British Naval Guns 1880–1945 No 14" article in "Warship Volume VIII
DiGiulian, Tony, Nav Weaps page
Garzke, William H., Jr.; Dulin, Robert O., Jr. (1980). British, Soviet, French, and Dutch Battleships of World War II. London: Jane's. ISBN 0-7106-0078-X.
Hogg, Ian V. 1998. Allied Artillery of World War Two. The Crowood Press: London. ISBN 1-86126-165-9
Horner, David, The Gunners – A History of Australian Artillery. Allen & Unwin: St Leonards. ISBN 1-86373-917-3
Ireland, Bernard, Jane's Battleships of the 20th Century
The Gunnery Pocket Book
Routledge, Brigadier NW. 1994. History of the Royal Regiment of Artillery – Anti-Aircraft Artillery 1914–55. Brassey's: London. ISBN 1-85753-099-3
Sired, Ronald ; edited by Flynn, F.C. 1957 Enemy engaged : a naval rating with the Mediterranean fleet, 1942–44 W. Kimber: London.

External links

Our Navy in Action; newsreel video of 5.25-inch guns engaging Axis aircraft and Italian battleships

[1] HMNZS Royalist was not decommissioned until 1966, although she appears to have ended "active service" some years before. All other ships were decommissioned by 1962 except PNS Babur which served until 1985.

[2] Britain used Roman numerals to denote "Marks" (i.e. models) of ordnance until after World War II.

[19] A 270-knot (500 km/h; 310 mph) target crossing the line of sight at right angles, at 2,000 yd (1,800 m) range, will move across the line of sight at 4.5 degrees per second.^{[page needed]} This simple fact of geometry appears to contradict the assertion that a 10-degree-per-second traverse rate was too slow to track a high-speed aircraft.

[Page_of_Navweapons-3] Page of Navweapons

[Campbell_p44-4] Campbell, Naval Weapons of WW2, p44

[Routledge_1994,_page_87-5] Routledge 1994, page 87

[6] Campbell, p.46

[7] The Gunnery Pocket Book. 1945. p. 51.

[8] Sired, Enemy Engaged, p23, states: "The Italians did not press home their attacks very hard and I thought they had a lot to put up with, as each (10 × 5.25 in gun) cruiser could fire 100 rounds of 5.25" HE shell per minute..." Ronald Sired was a gunnery petty officer on board HMS Euryalus. The accuracy of Sired's account was praised by Captain FC Flynn RN. Official Historian of the Naval Campaigns in the Mediterranean^{[citation needed]}

[9] Sired, Enemy Engaged, p 63.

[10] DiGiulian, Tony (29 January 2022). "5.25"/50 (13.4 cm) QF Mark I". Navweap.

[11] Model 1934 and Model 1934 R1938 Navweapons

[12] Models 1937 and 1938 Navweapons

[13] Battleship, Middlebrook^{[page needed]}

[Raven,_Dido_Class_Cruisers-14] Raven, Dido Class Cruisers

[15] Williams, Anthony G. "Medium Calibre guns of the Royal Navy in World War II". Military Guns & Ammunition.

[NW-16] "Britain 5.25"/50 (13.4 cm) QF Mark I". navweaps.com.

[17] Garzke&Dullin, 1980. pp. 228–229

[18] Hodges, Tribal Class Destroyers, p 32: Diagram of High Level Bomber Attack: A 240 mph target, at 12 thousand feet altitude could expect to be under for fire about 75 seconds, from the time it enters the effective range of the HACS until it flies to within the minimum range of a 5.25 gun elevated to 70 degrees. A Tribal-class destroyer would be able to engage the same target for about 37 seconds.

[20] 10.5 cm/65 (4.1") SK C/33 navweaps.com

[21] Routledge 1994, page 87, 78. "Effective height" was the greatest at which a 400 mph target could be engaged for 30 seconds using Predictor No. 10 (the all-electric US Bell AAA Computer) : hence with a realistic prospect of damaging the target. The shell could travel up to 50,000 ft but with little tracking capability, hence little effectiveness.

[22] Routledge 1994, page 92

[23] Hogg pg. 105-106

[24] Routledge pg 77, 92,204, 207, 432

[25] DW Spethman, "The garrison guns of Australia 1788-1962", pages 145-6. Published by Ron H Mortensen, Inala Qld, 2008. ISBN 978-0-9775990-8-0

[26] Garzke & Dulin, p291: " The guns were fully automatic and remotely controlled, with a rate of fire of eighteen rounds per minute."

[27] Naval Weapons page gives 3 inches at 9,500 yards

v t e British Commonwealth naval weapons of the Second World War
Monitor guns	BL 15-inch
Capital ship main armament	BL 14-inch BL 15-inch BL 16-inch
Heavy cruiser main armament	BL 7.5-inch Mk VI BL 8-inch Mk VIII
Secondary armament and light cruiser main armament	QF 4-inch Mk V QF 4.5-inch QF 5.25-inch BL 5.5-inch BL 6-inch Mk XII BL 6-inch Mk XXII BL 6-inch Mk XXIII
Minesweeper, Sloop, Corvette, Frigate and Destroyer armament	QF 6-pounder 10 cwt QF 12-pounder 12 cwt Mk V QF 4-inch Mk IV BL 4-inch Mk IX QF 4-inch Mk XVI QF 4-inch Mk XIX QF 4.5-inch BL 4.7-inch Mk II QF 4.7-inch Mk IX & XII QF 4.7-inch Mk XI
Submarine guns	QF 12-pounder 12 cwt Mk V QF 3-inch 20 cwt QF 4-inch Mk XII & XXII
Anti-aircraft weapons	Unrotated projectile Holman Projector 20 mm Oerlikon QF 2-pounder "pom-pom" Mk VIII 40 mm Bofors QF 3-inch 20 cwt QF 4-inch Mk V QF 4-inch Mk XVI QF 4.5-inch QF 4.7-inch Mk VIII
Light weapons	.303 Lewis machine gun .50 Vickers Mk III machine gun QF 3-pounder Vickers
Torpedoes	21-inch Mk VII 21-inch Mk VIII 21-inch Mk X 21-inch Mk XI 24.5-inch Mk I
Anti-submarine weapons	Thornycroft depth charge thrower Hedgehog Squid
Small craft armament	Molins 6-pounder Vickers K machine gun 18-inch torpedo
Foreign-sourced weapons	20 mm Oerlikon 40 mm Bofors 3-inch 23 caliber gun (US) 3-inch 50 caliber gun (US) 4-inch 50 caliber Mark 9 gun (US) 5-inch 51 caliber Mark 8 gun (US) Y-gun depth charge projector (US) Mark 8 torpedo (US)

v t e British Commonwealth artillery of World War II
Tank guns	QF 2-pounder QF 3-pounder QF 6-pounder QF 75 mm QF 3-inch howitzer QF 17-pounder 77 mm HV QF 95 mm howitzer
Anti-tank guns	QF 2-pounder QF 6-pounder QF 17-pounder
Field guns and howitzers	75 mm Gun M1917 QF 18-pounder 25-pounder Gun-Howitzer 25-pounder Short QF 4.5-inch howitzer
Medium and heavy guns and howitzers	BL 4.5-inch medium field gun BL 60-pounder gun BL 5.5-inch medium gun BL 6-inch howitzer BL 6-inch gun Mk XIX 155 mm Long Tom BL 7.2-inch howitzer BL 8-inch howitzer BL 9.2-inch howitzer 240 mm howitzer M1
Mountain guns	75mm Pack howitzer M1 3.7-inch mountain howitzer
Mortars	SBML 2-inch mortar ML 3-inch mortar ML 4.2-inch mortar
Anti-aircraft weapons	Z Battery 20 mm Oerlikon 20 mm Polsten QF 1½-pounder Mk III QF 2-pounder naval gun Bofors 40 mm QF 3-inch QF 3.7-inch QF 4.5-inch Mk II QF 5.25-inch Mk II
Coast defence	QF 6-pounder 10 cwt QF 12-pounder QF 4.7-inch Mk I–IV BL 6-inch Mk VII & Mk XXIV BL 7.5-inch Mk VI BL 8-inch Mk VIII BL 9.2-inch Mk X BL 14-inch Mk VII BL 15-inch Mk I
Railway artillery	BL 9.2-inch Mk XIII railway gun BL 12-inch Mk V railway howitzer BL 13.5-inch Mk V railway gun BL 18-inch railway howitzer