4.5 inch Mark 8 naval gun
4.5 inch Mk 8 Mod 1 naval gun on HMS Northumberland. The multi-faceted gunhouse is designed to reduce radar cross section.
Type	Naval gun
Place of origin	United Kingdom
Service history
In service	1972 - present
Wars	Falklands war Invasion of Iraq 2003 Libya 2011
Production history
Designer	Mod 0 : Royal Armament Research and Development Establishment Mod 1 : Royal Ordnance Defence
Variants	Mod 0, Mod 1
Specifications
Barrel length	244.75 inches (6.217 m) bore (55 calibres)
Shell	Fixed QF 46 pounds (21 kg) HE
Calibre	4.45-inch (113 mm)[1]

The 4.5 inch Mark 8 is a British naval gun system which currently equips the Royal Navy's frigates and some British destroyers and frigates sold to other countries.

Background[link]

The 4.5 inch gun has been the standard medium-gun calibre of the Royal Navy for use against surface, aircraft and shore targets since 1938. The current 55-calibre Mark 8 gun replaced the World War II era 45-calibre QF 4.5 inch Mk I - V naval guns. Like all British 4.5 inch naval guns, it actually has a calibre of 4.45 inches (113 mm).^[1]

Design[link]

A completely new type of 4.5 inch gun with a longer 55-calibre barrel, it was designed in the 1960s for the Royal Navy's new classes of frigates and destroyers. The new weapon, built by Vickers^{[citation needed]}, was developed by the Royal Armament Research and Development Establishment using the Ordnance, QF 105 mm L13 of the Abbot self-propelled gun as a starting point (it used electrical primers). The outer shell of the gunhouse is built from glass-reinforced plastic (GRP).

The new weapon emphasised reliability over a high rate of fire, allowing a switch to a lighter, single barrel mounting and ammunition of a one-piece design.

The gun system has a combination of electrical and hydraulic components and the full system penetrates up to three deck levels below the weather deck; deep magazine, gun control room and power room, gunbay and the gunhouse.

The weapon is semi-automatic, therefore needing fewer people than its predecessors to operate. With no personnel in the gunhouse loading is supported by personnel in the gunbay to load the feed ring and in the deep-magazine to pass ammunition to the gunbay. The Captain of the Gun in the control room ensures continued weapon readiness and the gun controller in the Operations Room operates the aiming and firing process. The weapon has a rate of fire of about 25 rounds per minute and a range of 12 nm (22 km; 27.5 km with the newer High Explosive Extended Range round).

The first recipient of the new gun and mount, the Mark 8, was the Iranian frigate Zaal in 1971. The gun entered Royal Navy service in 1973 on the new destroyer Bristol.

These guns proved to be less reliable than the older 4.5 inch Mark 6 (Mark V gun) during the Falklands War, being forced to cease fire on several occasions due to faults.^[2]

The first major modification to the mounting, the Mod 1, was developed in the late 1990s; replacing the gunhouse with a reduced radar cross section assembly and replacing the hydraulic loading mechanism with an all electric system. This particular gun has been nicknamed the "Kryten gun" by members of Royal Navy, after the odd shaped head of a robot from the British Sci-fi comedy series Red Dwarf.^[3][4]

155 mm variant[link]

The Ministry of Defence is investigating a proposal from BAE Systems to "up gun" the 4.5 inch to accept the 155 mm (6.1 inch) gun barrel and breech from the AS-90 self propelled gun.^[5] This would introduce a common gun calibre with the British Army and Royal Navy, helping with ammunition logistics, and encouraging joint Army-Navy development of extended range and precision guided shells.^[6] A £4m contract has been awarded to develop a prototype, and firing trials had been scheduled for 2009.^[7]

Usage[link]

• Type 45 Daring-class air defence destroyer
• Type 23 Duke-class frigate
• Type 22 Broadsword-class frigate
• Type 21 Amazon-class frigate
• Type 42 Sheffield-class guided missile destroyer
• Type 82 destroyer, Bristol

• Niteroi class (Brazil)
• Inhauma class (Brazil)
• Alvand class (Iran)
• Dat Assawari (Libyan Navy)
• HTMS Makut Rajakumarn (Royal Thai Navy)

Gallery[link]

• 

  Spent shells from HMS Cardiff's Mod 0 gun during the Falklands War. The top of her worn Sea Dart launcher can also be seen in the bottom right corner.

• 

  The ladder to Cardiff's Mod 0 gun can be seen here, damaged by a freak wave.

• 

  HMS Sutherland's Mod 0 gun

• 

  HMS Grafton's Mod 0 gun

See also[link]

• QF 4.5 inch Mk I - V naval gun - British predecessor
• 5"/54 caliber Mark 45 gun - American equivalent to the Mark 8
• Advanced Gun System - BAE's new 155 mm long-range gun system for the US Navy's Zumwalt class destroyers

Notes[link]

References[link]

• Tony DiGiulian, British 4.5"/55 (11.4 cm) Mark 8 Mod 0 114 mm/55 (4.5") Mark 8 Mod 1

External links[link]

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