Mirun-class corvette

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DChJ Mirun 2008 200731.png
4-view diagram of Mirun in 2008.
Class overview
Builders:
  • Gyŏngsan Songsu-do Shipyard
  • Kimhae Naval Yard
  • Chilsan South Shipyard
Operators:
Preceded by: list error: <br /> list (help)
Ginam-class frigate
Mugunghwa-class corvette
Succeeded by: Yungju-class corvette
Built: 2005-2013
In commission: 2008-present
Planned: 32
Completed: 32
General characteristics (Mirun, 2008)
Type: Anti-submarine corvette
Displacement:
  • 2,200 tons standard
  • 2,640 tons full load
Length:
  • 106.1 m overall
  • 99.9 m at waterline
Beam: 13.7 m at waterline
Draught: 3.66 m to keel
Propulsion:
  • CODAG
  • 2 Samsan S9000H diesel engines (8,000 shp each)
  • 1 LM2500 turbine (30,000 shp)
Speed: 30 knots
Range: 4,400 nautical miles (8,150 km) at 15 knots
Complement:
  • 14 officers
  • 92 enlisted crew
Sensors and
processing systems:
Electronic warfare
& decoys:
  • 1 × JJ-7 ESM antenna
  • 1 × D-104 datalink
  • 2 × Baram-2 countermeasure launchers
  • 1 × Sebu towed torpedo decoy
Armament:
Aircraft carried: 1 × GH-28 Ppulsoeori
Aviation facilities:

The Mirun-class corvettes (Menghean: 밀운 중형 대잠수함 초계함 / 密雲級中型對潛水艦哨戒艦, Mirun-gŭb Junghyŏng Daejamsuham Chogyeham) are a group of oceangoing anti-submarine corvettes built for the Menghean Navy in the late 2000s and early 2010s. They are sometimes transliterated as the Milun class, and a few sources regard them as frigates due to their size and capabilities.

Although the Mirun-class and Sŏwicho-class are both labeled as corvettes in most foreign-language literature, and were built simultaneously with one another, the Menghean Navy regards them as "medium" and "small" anti-submarine patrol ships, respectively. Unlike the Sŏwichos, which are purely designed for coastal patrol duties, the Mirun-class vessels are able to conduct long-endurance patrols in the open ocean. They displace more than twice as much as their smaller cousins, and carry helicopter facilities and vertical launch boxes for the HŎ-3 Ryongorŭm standoff torpedo weapon. They also have better seakeeping capabilities and a longer at-sea endurance time.

Development

By the early 2000s, the Menghean Navy had a well-established convention of distinguishing between "anti-submarine patrol ships" (DChD, DChJ, and DChS types) and "escort ships" (HJ, H, and HW types). The latter types are designed as well-rounded escort ships able to protect an aircraft carrier or strike package from a variety of threats. Later HJ/H/HW designs are also capable of launching coordinated anti-ship missile strikes, a role borrowed from the Chŏndong-class and Nunbora-class "missile destroyers." "Anti-submarine patrol ships," by contrast, are highly specialized around the anti-submarine role, and are designed to autonomously patrol Menghean waters in search of enemy submarines or escort cargo ships in rear-area waters with less pronounced enemy air and surface threats but a high risk of incursion by submarines. The Mirun-class ships are designated in Menghe as "medium anti-submarine patrol ships," in between the Sŏwicho-class small ASW patrol ships which operate in coastal areas and the Chanjok Jachido-class large ASW patrol ships which lead their formations.

The Mirun-class were first conceived of as a replacement for the nine Mugunghwa-class corvettes which were refitted with towed array sonar for blue-water operations. Although this refit allowed the ships to detect targets below the thermocline, they suffered from poor seakeeping and limited endurance, two problems aggravated by the large tow structure built on top of the quarterdeck. Ten ships were ordered, to allow eight in a combat-ready state and two in major servicing at any given time. While the towed-array Mugunghwas were designated as DChS types, the new corvettes would be designated as larger DChJs, and would have helicopter facilities and anti-submarine missile launch cells. The first hull was laid down on 25 January 2005 at the Gyŏngsan Songsu-do Naval Yard.

Characteristics

Sensors

The Mirun-class ships carry relatively sophisticated sonar equipment. The hull sonar is a Glasic "Spherion" system, and is mounted in a sound-transparent dome under the keel just forward of the superstructure. This placement corrects a problem identified on the Hawŏn-class frigates, where the bow sonar - intended for larger ships - would break above the waterline in rough seas. The towed array sonar is an AN/SQR-19 array licensed from Hallia but built in Menghe. This system is identical to that carried by the larger Chanjok Jachidos and Haejus, and allows long-range detection of submarines operating below the thermocline.

Radar equipment, by contrast, is very minimal. The only air search radar carried is the HR-44D, carried on a solid mast above the bridge. This system has a range of only 40 kilometers against fighter-sized targets, and while it can detect higher-altitude targets than the baseline HR-44G, it is mainly intended to detect surface ships, periscopes, and sea-skimming missiles. It also doubles as a fire-control system for the ship's 76mm gun turret, though in continuous-illumination mode it must stop searching for other targets.

Armament

The ships' most unusual armament consists of a single 8-cell Mk 41 VLS module installed immediately aft of the funnel. This module uses strike-length cells with 6.7-meter-deep launch canisters, the largest type in use in Hallia, Tír Glas, and Dayashina, and along with its exhaust duct system it extends three decks into the hull, resting on top of the aft engine compartment. Given the Miruns' anti-submarine specialization, all eight cells would normally be loaded with HŎ-3 Ryongorŭm rocket-deployed torpedoes. In theory the ships could also be armed with cruise missiles or anti-ship missiles for a strike mission, though their weak air-defense armament would leave them vulnerable to attack in this role.

For closer-range engagements, the ships carry two twin 350mm torpedo tubes in pivoting launchers, one on each side. These are located behind folding covers which protect them from the elements and reduce radar reflection when not in use. Both legacy YŎ-35/1 and new YŎ-35/2 torpedoes are supported, with 12 stored in the magazine space forward of the hangar. Torpedoes from this magazine space can also be loaded onto the ship's helicopter.

Apart from the 76mm dual-purpose gun, the ships' sole anti-air armament consists of a single CIWS turret just forward of the helicopter hangar. This is sometimes incorrectly identified as a Subisu CIWS mount; in fact, it is a GBM-23/5Y Dungji, with a single 5-barrel rotary cannon and non-reloadable YDG-61 missile boxes. The mount's position gives it an excellent field of fire, leaving only a 20-degree gap in coverage directly forward. Captains of Mirun-class ships, like captains of Ginam-class ships, are instructed to turn away from the threat if they detect incoming missiles.

Basic anti-ship armament consists of two dual-cell angled launch boxes for YDH-26 anti-ship missiles. As on the Sŏwicho class, these exist purely for self-defense, and use the lightest dedicated anti-ship missile in the Menghean arsenal.

Propulsion

The powerplant of the Mirun-class corvettes consists of a CODAG system linking a 30,000 shp (22,000 kW) LM2500 gas turbine to two Samsan S9000H 8,000 shp (5,965 kW) diesel engines. At full power, the ships can reach a top speed in excess of 30 knots, allowing them to outrun or keep pace with contemporary Anglian and Sieuxerrian nuclear submarines. A maximum range of 4,400 nautical miles (8,150 kilometers) also allows the Miruns to remain on patrol for a relatively long time, especially with at-sea refueling.

The individual parts of the powerplant are rail-mounted, and all components can be removed through the funnel for maintenance.

Countermeasures

As the Mirun-class corvettes are meant to locate, engage, and destroy enemy submarines, they incorporate a number of design features intended to improve their survivability against undersea threats. All engines, generators, and transmission parts in the Mirun class are mounted on acoustic damping mounts, which absorb vibration and reduce the ships' acoustic signature when operating at low speed. A diesel-electric or all-electric transmission was reportedly considered, as this would reduce vibration even further, but in the end all motor units were directly coupled to the propeller shafts.

For further noise reduction, the ships were fitted with a Prairie-Masker system to mask engine noise from within the hull and counteract cavitation around the propellers. They were among the first Menghean warships to be fitted with such a system.

On the first series of ships produced, there is a single HBDJ-21/6 anti-submarine rocket projector on each side of the helicopter hangar facing aft. These are exclusively used for the torpedo countermeasures role, firing either H-21ŎDG jamming rockets or H-21ŎDN anti-torpedo hardkill rockets. The launchers can be automatically trained, elevated, and fired from the ship's control room, but must be reloaded manually. Twelve reloads per launcher are carried, and are hoisted up from a storage room below deck.

Aircraft facilities

The Mirun-class corvettes are fitted with a landing pad and hangar for a single GH-28 Ppulsoeori. Some early design proposals used a smaller hangar for a navalized GH-30 or GH-34 helicopter, but in the end the GH-28 was deemed adequately compact. As on other oceangoing Menghean ships, the landing pad has a hauldown winch and taxi rail, allowing landing operations in rough seas.

Utility deck

In addition to the towed sonar array handling equipment and towed torpedo decoy, the enclosed deck underneath the helicopter landing pad also has reserved working space for other mission-specific equipment. The ships can be easily refitted to lay mines, including conformal mines, from rails in this working deck, and can also deploy remote-controlled mine-hunting unmanned undersea vehicles. They may be capable of deploying permanent acoustic surveillance devices onto the seabed. Some Menghean media sources claim that the aft utility deck can be used to house a special forces squad and its equipment, but the lack of dedicated boat launch facilities and the limited intersection with the ships' oceangoing anti-submarine role casts some doubt on this claim.

Jedong subclass

Four-view image of a Jedong-class corvette. Note the larger mast and smaller decoy launchers.

Starting with DChJ-667 Jedong, commissioned in 2014, the next 14 corvettes in the series were completed to a modified configuration. Though essentially identical in armament and performance, these ships have a slightly different sensor mast forward, flanked by dedicated kingposts for underway replenishment of solid goods. They also carry Manhwagyŏng-H torpedo countermeasure launchers aft in place of the HBDJ-21/6 depth charge projectors and Baram-2 rather than Baram-1 chaff and smoke projectors. The Menghean Navy treats DChJ-667 through DChJ-680 as a different ship class, though the differences with the preceding group of Miruns are relatively minor.

Ships in the class

Menghean Navy

In keeping with the precedent set by the Ginam class, the Mirun-class corvettes are all named after Menghean prefectures. They share this naming convention with Menghean frigates (Oechung howiham), despite being a different category of ship.

Mirun subclass
Hull No. Name Mengja Builder Laid down Launched Commissioned Status
DChJ-657 Mirun 密雲 Gyŏngsan 2005 01 25 2006 07 16 2008 10 13 In service
DChJ-658 Yŏn'gi 燕岐 Gyŏngsan 2005 03 12 2007 09 06 2009 01 26 In service
DChJ-659 Gangsŏ 江西 Kimhae 2005 08 16 2007 01 12 2009 05 13 In service
DChJ-660 Gŭnju 勤州 Gyŏngsan 2006 07 20 2007 12 02 2009 04 17 In service
DChJ-661 Kosan n/a Gyŏngsan 2006 09 11 2008 03 16 2009 05 31 In service
DChJ-662 Ryŏju 廬州 Kimhae 2007 01 15 2008 05 15 2009 10 26 In service
DChJ-663 Goran 皋蘭 Gyŏngsan 2007 12 07 2009 05 03 2010 08 09 In service
DChJ-664 Soju 韶州 Gyŏngsan 2008 03 20 2009 07 10 2010 11 23 In service
DChJ-665 Anrim 安林 Kimhae 2008 05 19 2009 10 06 2011 02 03 In service
DChJ-666 Noyon n/a Gyŏngsan 2009 05 08 2010 09 26 2012 01 09 In service
Jedong subclass
Hull No. Name Mengja Builder Laid down Launched Commissioned Status
DChJ-667 Jedong 濟東 Chilsan S 2011 06 11 2012 12 29 2014 10 04 In service
DChJ-668 Delgereg n/a Chilsan S 2011 08 27 2013 02 12 2014 11 04 In service
DChJ-669 Giju 冀州 Chilsan S 2012 03 19 2013 08 30 2015 07 25 In service
DChJ-670 Pyŏngho 平湖 Chilsan S 2013 01 04 2014 05 03 2016 03 12 In service
DChJ-671 Bongdan 峯潭 Chilsan S 2013 02 18 2014 10 01 2016 07 07 In service
DChJ-672 Gyegok 薊谷 Kimhae 2013 06 05 2014 11 04 2016 04 05 In service
DChJ-673 Hŭnju 忻州 Chilsan S 2013 09 04 2015 02 20 2016 11 13 In service
DChJ-674 Gwanbuk 關北 Chilsan S 2014 05 07 2015 09 15 2017 08 17 In service
DChJ-675 Daeoe 大隈 Chilsan S 2014 10 04 2016 06 17 2018 07 03 In service
DChJ-676 Gŭmchŏn 錦川 Chilsan S 2015 02 23 2016 08 17 2018 06 14 In service
DChJ-677 Jwajin 左津 Gyŏngsan 2015 03 27 2016 10 24 2018 04 04 In service
DChJ-678 Oju 梧州 Gyŏngsan 2015 07 07 2017 01 30 2018 10 21 In service
DChJ-679 Daepyŏng 大坪 Chilsan S 2015 10 19 2017 04 22 2019 02 29 In service
DChJ-680 Hongnyŏng 弘農 Chilsan S 2016 06 20 2018 01 03 2019 09 13 In service

Idacuan Navy

Idacua ordered five Mirun-class corvettes between 2010 and 2015. The first two were completed to the Mirun configuration, and the last three were completed to the Jedong configuration. All are currently in service with the Idacuan Navy.

Subclass Name Builder Laid down Launched Commissioned Status
Mirun IRNS Kariña Kimhae 2010 08 19 2012 01 18 2013 09 19 In service
Mirun IRNS Sartosa Gyŏngsan 2011 03 13 2012 10 07 2014 05 14 In service
Jedong IRNS Puerto Real Kimhae 2013 12 28 2015 06 10 2017 02 25 In service
Jedong IRNS Tinaco Kimhae 2014 11 09 2016 04 07 2018 02 20 In service
Jedong IRNS Guatiro Kimhae 2015 06 15 2017 01 08 2018 10 07 In service

Polvokian Navy

Menghe built three Mirun-class corvettes for Polvokia between 2009 and 2015. All were built to the baseline Mirun specifications.

Name Builder Laid down Launched Commissioned Status
Rason Kimhae 2009 10 11 2011 03 25 2012 07 16 In service
Ŭndŏk Kimhae 2011 03 29 2012 07 16 2014 01 14 In service
Hyŏndam Kimhae 2012 07 20 2013 12 14 2015 04 09 In service

See also

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