5"/54 caliber Mark 45 gun
|Mark 45 5-inch/54-caliber lightweight gun|
The latest version, a 5-inch/62 caliber Mark 45 Mod 4 test firing on USS Forrest Sherman in 2007
|Place of origin||United States|
|Used by||See Operators|
|Manufacturer||United Defense (now BAE Systems Land & Armaments)|
|Shell||Conventional: 31.75 kg (70.0 lb)|
|Caliber||5.0 inches (127.0 mm)|
|Barrels||Single barrel (progressive RH parabolic twist)|
|Rate of fire||16–20 rounds per minute automatic|
|Effective firing range||13 nmi (24.1 km)|
The 5-inch/54 caliber (Mk 45) lightweight gun is a modern U.S. naval artillery gun mount consisting of a 127 mm (5 in) L54 Mark 19 gun on the Mark 45 mount. Originally designed and built by United Defense, it is now manufactured by BAE Systems Land & Armaments after the former was acquired. The latest 5-inch/62 caliber version consists of a longer barrel L62 Mark 36 gun fitted on the same Mark 45 mount. The gun is designed for use against surface warships, anti-aircraft and shore bombardment to support amphibious operations.
The gun mount features an automatic loader with a capacity of 20 rounds. These can be fired under full automatic control, taking a little over a minute to exhaust those rounds at maximum fire rate. For sustained use, the gun mount would be occupied by a six-man crew (gun captain, panel operator, and four ammunition loaders) below deck to keep the gun continuously supplied with ammunition.
Development started in the 1960s as a replacement for the 5-inch/54 caliber Mark 42 gun system with a new, lighter, and easier to maintain gun mounting. In United States Navy use, the Mark 45 is used with either the Mk 86 Gun Fire Control System or the Mk 160 Gun Computing System. Since before World War II, 5 inches has been the standard gun caliber for U.S. Naval ships. Its rate of fire is lower than the British 4.5 in (114 mm) gun, but it fires a heavier 5-inch shell which carries a larger burst charge that increases its per-shell effectiveness against aircraft.
- Mod 0: used mechanical fuze setter. Two-piece rifled construction, with replaceable liner
- Mod 1: electronic fuze setter replaces the mechanical one. Made with a unitary construction barrel, which has a life span approximately twice that of the Mark 42 gun.
- Mod 2: export version of Mod 1, but now used in the US Navy
- Mod 3: same gun with a new control system; never put into production
- Mod 4: longer 62-caliber barrel (versus Mod 1 and 2's 54 caliber) for more complete propellant combustion, higher velocity, range increased to 20 nautical miles (37 km; 23 mi) and thus more utility for land attack.
- Special note
In sustained firing operations (Mode III), the gun is manned by a six-man crew, all located below decks. These are a gun captain, a panel operator, and four ammunition loaders. In fully automatic non-sustained firing operations (Mode IV), the gun can be fired without any personnel inside the mount. However, sustained fire is limited to the capacity of the automatic loader (20 rounds). This means that there will be no one at control panel for the gun to safe the weapon when having to fall back to verbal cease fire to the gun crew.
On 9 May 2014, the U.S. Navy released a request for information (RFI) for a guided 127 mm (5-inch) round that could be fired from Mark 45 guns on Navy destroyers and cruisers. The thinking is that if the technology worked in the 155 mm (6 in) Long Range Land Attack Projectile (LRLAP) for the Advanced Gun System on Zumwalt-class destroyers, it can be applied to a 5 in mount. This RFI comes six years after the cancellation of the Raytheon Extended Range Guided Munition. The shell must have at least double the range of unguided shells for missions including Naval Surface Fire Support (NSFS)/Land Attack, and increasing anti-surface warfare (ASuW) capabilities against fast attack craft (FAC) and fast inshore attack craft (FIAC); the main purpose is to destroy incoming small boats at a greater range with a proximity fuse airburst blast fragmentation warhead to spray shrapnel over swarms. Expected submissions include the BAE Systems Multi Service–Standard Guided Projectile (MS-SGP), Raytheon Excalibur N5, and OTO Melara Vulcano guided long-range projectile.
Naval Sea Systems Command is also looking to fire a version of the hyper velocity projectile (HVP) developed for Navy electromagnetic railguns from conventional 5 in deck guns. Using the HVP could give existing destroyers and cruisers better ability to engage land, air, and missile threats and allow more time to refine the railgun. The HVP would be a cheaper solution to intercepting incoming missiles than a missile interceptor costing hundreds of thousands of dollars. Converting the HVP to fire from conventional guns is not yet a program of record. HVP shells fired 5-inch deck guns would travel at Mach 3, half the speed of a railgun but twice the speed of conventional rounds. The rounds would cost $25,000–50,000, more expensive than unguided shells but cheaper than missile interceptors, and engage air and missile targets out to 10–30 nautical miles (12–35 mi; 19–56 km).
- Anzac-class frigates: Mod 2 being upgraded Mod 4
- Hobart-class destroyer: Mod 4 planned under construction
- Absalon-class command and support ships
- Sejong the Great-class guided missile destroyer: Mod 4
- Chungmugong Yi Sun-sin-class guided missile destroyer: Mod 4
- Incheon-class frigate : Mod 4
- Anzac-class frigates: Mod 2
- Kee Lung-class guided missile destroyers
- Naresuan-class frigates: Mod 2 being upgraded Mod 4
- Salihreis-class frigates (MEKO 200 TN II-B)
- Barbaros-class frigates (MEKO 200 TN II-A)
- Yavuz-class frigates (MEKO 200 TN)
- Tarawa-class amphibious assault ships (later removed)
- Ticonderoga-class guided missile cruisers: Mod 2
- CG-52: Mod 4 after receiving the cruiser modernization
- Arleigh Burke-class guided missile destroyer:
- Extended Range Guided Munition: long range (~60 nautical miles (110 km; 69 mi)) precision guided projectile program by Raytheon for the Mark 45 gun, canceled in 2008.
- Advanced Gun System: US Navy planned 155 mm (6 in) gun for Zumwalt-class destroyer
Weapons of comparable role, performance and era
- 4.5 inch Mark 8 naval gun: contemporary standard naval gun for British ships
- French 100 mm naval gun: contemporary standard naval gun for French ships
- Otobreda 127/54 Compact and Otobreda 127/64: contemporary 127 mm naval gun from Italian manufacturer Oto Melara
- Norman Polmar, pp. 492-493
- "United States of America 5"/54 (12.7 cm) Mark 45 Mod 4". NavWeaps.Com. 18 April 2010. Retrieved 24 October 2010.
- "United States of America 5"/54 (12.7 cm) Mark 45 Mods 0 – 2". NavWeaps.Com. 18 September 2007. Retrieved 24 October 2010.
- "The US Navy Fact File: 5-inch Mark 45 54-caliber lightweight gun". United States Navy. 20 February 2009. Archived from the original on 5 December 2010. Retrieved 24 October 2010.
- "5-inch 62-Caliber Mk 45 Mod 4 Naval Gun System" (PDF). Brochure. BAE Systems. Archived from the original (PDF) on 2012-04-25. Retrieved 5 October 2011.
- Navy Taking a Second Look at A Five-Inch Guided Round – News.USNI.org, 3 June 2014
- Navy seeks guided deck-gun shell – Navytimes.com, 4 June 2014
- Navy Researching Firing Mach 3 Guided Round from Standard Deck Guns – News.USNI.org, 1 June 2015
- The Future of the Navy's Electromagnetic Railgun Could Be a Big Step Backwards - Popularmechanics.com, 6 June 2016
- Pentagon: New Rounds For Old Guns Could Change Missile Defense for Navy, Army - News.USNI.org, 18 July 2016
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