Reported by UK Defence Journal
This latest version of the Mark 45 gun mount was designed to be used with the Extended Range Guided Munition (Mark 171 ERGM) in order to provide over-the-horizon range and improved lethality. Modifications for structural improvements include strengthened trunnion supports and a lengthened recoil stroke to accommodate the higher firing energy (18 vs. 10 megajoules) associated with ERGM. Additionally, the gun mount modifications include a new 62-caliber barrel, an Ammunition Recognition System, a Gun/ERGM interface and a new control system.
The Ammunition Recognition System identifies ERGM projectiles and propelling charges and preclude the unsafe mixing of ERGM and conventional ammunition. A Gun/ERGM interface will provide for the transmission of pre-flight data into the guidance and navigation subsystems of the ERGM prior to loading and firing. The control system is modified to accommodate ERGM changes and to digitally interface with the Mark 160 Mod 8 Gun Computer System. With an ORDALT, existing WM25 Fire Control Systems for the 5″/54 (12.7 cm) Mark 45 may also be used.
However, in March 2008 the Navy abandoned the ERGM, after it failed a series of tests in February 2008. This ended a 12-year, $600 million project that has been plagued with multiple problems. BTERM also failed a series of tests around this same time and was likewise cancelled.
The Republic of Korea has purchased a manufacturing license for these guns in which United Defense delivers most of the upper gun, the shield and the loader, while the Republic of Korea company World Industries Ace (WIA) is responsible for the production of the lower hoist, the panels and the assembly and test of the gun itself. A 19 December 2002 press release by United Defense stated that the Republic of Korea had purchased total of six weapons.
Sejong the Great-class destroyer: Details
Japan has also purchased a manufacturing license for these weapons for use on their Atago class Aegis destroyers. Japan Steel Works will manufacture, assemble and test the weapons. The Republic of Korea has selected this weapon to arm their newest destroyers. Denmark has purchased two of these weapons, the first European country to use this weapon.
United Defense made a proposal in mid-2004 that the British Type 45 destroyers use this weapon, but the proposal was turned down and the Type 45 are being armed with the 114 mm (4.5″) Mark 8 Mod 1 mountings.
In July 2016 BAE Systems announced that they had received a $245 million contract from the UK Ministry of Defence (MOD) to provide the gun system, known as the Maritime Indirect Fires System (MIFS), for the Type 26 Global Combat Ship. Under the contract, BAE will manufacture three MIFS Integrated Gunnery Systems (IGS) and one trainer system for the UK Royal Navy. The MIFS IGS includes the 5-inch, 62-caliber Mk 45 Mod 4 Naval Gun System, along with an automated ammunition handling system, gun fire control system, and qualified ammunition. The contract includes an option for five additional systems for the remainder of the UK Royal Navy’s Type 26 fleet. This same press release also stated that more than 240 Mark 45 guns had been delivered globally. The release does not state if this count includes the older 5″/54 (127 mm) Mark 45 but I believe that it does.
|Designation||Gun: 5″/62 (12.7 cm) Mark 36
Mounting: 5″/62 (12.7 cm) Mark 45 Mod 4
|Ship Class Used On
(see Note 2)
New-construction Arleigh Burke class DDG’s – First installed on USS Winston Churchill DDG-81
Modernized Ticonderoga (Flight II) CG-47 class
Republic of Korea
Chungmugong Yi Sun-sin class (KDX II) and Sejong the Great (KDX III) class
UK Royal Navy
Type 26 class
|Date Of Design||1995|
|Date In Service||2000|
|Gun Length oa||N/A|
|Barrel and Bore Length||310.0 in (7.874 m)|
|Rate Of Fire
(see Note 1)
|16 – 20 rounds per minute|
The Rate of Fire in this table is for conventional ammunition. ERGM or ANSR rounds can be fired at a maximum rate of approximately 10 rounds for the first minute. The sustained rate is 2 to 4 rounds per minute and depends upon the magazine crew’s ability to manually move rounds from the shipping container to the loading position.
As many as 14 Ticonderoga (CG-47) class cruisers were planned to be upgraded to the 5″/62 (12.7 cm) depending upon available funding. Upgrades were to include using the Mark 160 Mod 11 Gunfire Control System (GCS) and two Mark 46 Mod 1 optical sight systems to replace the Mark 86 GCS. Magazine stowage flexibility was to be enhanced with the installation of the universal tie down system in both forward and aft magazines. However, it was not planned to make these ships capable of handling larger rounds such as ERGM or BTERM. In January and February 2004, the Navy decided to save money by not upgrading these ships to the larger guns and $100M was cut from the Cruiser Modernization program. In May 2004, the US Congress sent a letter to the Secretary of the Navy asking the USN to reconsider this decision. In August 2007, BAE announced the awarding of a Basic Ordering Agreement (BOA) from the U.S. Navy which included upgrading the CG-47 Flight II cruisers to the 5″/62 (127 mm) Mod 4. The upgrade package for these cruisers does not include the ability to handle longer rounds such as ERGM.
|Projectile Types and Weights
|Mark 80 HE-PD – 67.6 lbs. (30.7 kg)
Mark 91 Illum-MT – 63.9 lbs. (29.0 kg)
Mark 116 HE-VT – 69.7 lbs. (31.6 kg)
Mark 127 HE-CVT – 68.6 lbs. (31.1 kg)
Mark 156 HE-IR – 69.0 lbs. (31.3 kg)
Mark 172 HE-ICM (Cargo Round) – N/A
ERGM – 110 lbs. (50 kg)
BTERM – 96 lbs. (43.5 kg)
|Bursting Charge||See Note 9|
|Projectile Length||Mark 80 – 26 in (66 cm)
Mark 91 – 26.1 in (66.3 cm)
Mark 116 – 26 in (66 cm)
Mark 127 – 26 in (66 cm)
Mark 156 – 26 in (66 cm)
Mark 172 – 26 in (66 cm)
ERGM – 61 in (155 cm)
BTERM – 61 in (155 cm)
(see Note 8)
|Mark 67 – 18.25 lbs. (8.3 kg) NACO
Cartridge weighs 38.9 lbs. (17.6 kg) filled
EX-167 for ERGM – about 25 lbs. (11.3 kg) EX-99
Cartridge weighs about 40 lbs. (18.1 kg) filled
EX-175 High Energy – about 26 lbs (11.8 kg)
Cartridge weighs about 41 lbs. (18.6 kg) filled
|Muzzle Velocity||Mark 80 projectile with Mark 67 cartridge – 2,725 fps (831 mps)
Mark 80 projectile with EX-175 cartridge – 3,450 fps (1,052 mps)
Mark 91 projectile with Mark 67 – 2,750 fps (838 mps)
ERGM with EX-167 cartridge – 2,750 fps (838 mps)
|Working Pressure||Mark 67 cartridge – 18.5 tons/in2 (2,758 kg/cm2)
EX-167 cartridge – 29.0 tons/in2 (4,570 kg/cm2)
EX-175 cartridge – N/A
|Approximate Barrel Life with Mark 67 cartridge
(see Note 7)
|Ammunition stowage per gun
(see Note 4)
|Arleigh Burke:680 rounds|
This weapon has many different kinds of ammunition. The ones listed above are meant to be representational, but by no means is this a complete listing.
HE-PD = High Explosive, Point Detonating Fuze
Illum-MT = Illumination, Mechanical Time Fuze
HE-VT = High Explosive, Variable Time Fuze
HE-CVT = High Explosive, Controlled Variable Time Fuze
All projectiles have a 0.5 caliber boat-tail.
The ammunition stowage figure above is for conventional projectiles. Each ERGM projectile takes the place of about 1.75 conventional projectiles. It was estimated in 1998 that an Arleigh Burke could carry about 230 conventional projectiles and 230 ERGM. The ready-service loader drum for this mounting has a maximum capacity of 20 ballistic rounds or 10 extended-range rounds (such as ERGM or BTERM). Ballistic and extended-range rounds can be mixed in the drum.
The Arleigh Burke class ammunition magazine takes approximately 16 hours to be loaded out with 680 ballistic projectiles and associated propelling charges during at-sea replenishments. This assumes favorable weather conditions and calm seas.
The addition of extended range guided munitions such as ERGM or BTERM will require a manual magazine reconfiguration to accommodate the specific mix of ammunition provided. These guided munitions will also require additional load cycles because only 16 of these guided rounds will fit on a standard pallet versus 48 conventional ballistic rounds.
The introduction of higher energy, hotter burning propellant for ERGM will reduce the expected gun barrel life. The threshold wear life of the Mark 45 Mod 4 gun barrel for ERGM is 1,500 rounds with an objective of 3,000 rounds. This is compared with the current 5″/54 (12.7 cm) Mark 45 barrel wear life in excess of 8,000 rounds for ballistic ammunition fired with standard NACO propellants. Extended range ammunition such as BTERM that use a “boost to range” concept can be fired using cooler burning propellants such as NACO and therefore will not adversely affect barrel life.
The Mark 67 cartridge uses standard NACO propellant.The EX-167 extended-range guided munitions (ERGM) propelling charge uses EX-99 propellant.
Most conventional rounds have a burster of about 7.75 lbs. (3.52 kg). The ERGM has a burster of 7.2 lbs. (3.3 kg) PBXN-9 explosive.BTERM has a fragmenting warhead made up of 9.9 lbs. (4.5 kg) preformed tungsten fragments plus 7.6 lbs. (3.4 kg) of explosives.
The rocket engine on ERGM burns for 7 seconds. The rocket engine on BTERM provides 20 seconds of burn time.
|Designation||Single Mounting: Mark 45 Mod 4
Arleigh Burke (1)
Ticonderoga (Flight II) (2)
Republic of Korea
Chungmugong Yi Sun-sin (1) and Sejongdaewang-Ham (1)
|Weight||Mounting without lower hoist: 50,456 lbs. (22,886 kg) [est.]
Mounting with four-flight lower hoist: 54,398 lbs. (24,674 kg) [est.]
|Elevation||-15 / +65 degrees|
|Elevation Rate||20 degrees per second|
|Train||+170 / -170 degrees|
|Train Rate||30 degrees per second|
(see Note 3)
|19 to 21 in (48 to 53 cm)|
In general, the design of the Mark 45 Mod 4 mounting is similar to the original Mark 45 mounting and they share many of the same components.
The Mark 45 Mod 4 mounting has a reduced radar signature as compared to the original Mark 45 mounting.
The recoil distances given above are nominal values when firing a conventional projectile with a standard service charge at elevations between 30 and 40 degrees. When fired with a proof charge at max elevation, recoil is about 23 inches (58 cm). If the heavier BTERM or ERGM projectiles are fired at max elevation and at proof pressure, then the gun will recoil about 29.25 inches (74 cm). The absolute, metal-to-metal recoil distance is 30 inches (76.2 cm).
This mounting requires 440 VAC, 60 Hz, 164.35 KW Peak.
Manning is Gun Captain, Panel Operator and four ammunition operators, all below deck.
Type 26 Global Combat Ship: Details