Chunchŏn-class frigate

Class overview
Builders:	Gyŏngsan Songsu-do Shipyard Kimhae Naval Yard
Operators:	Menghe Azbekistan Sundan Ummayah
Preceded by:	Ansa-class frigate
Succeeded by:	Chunchŏn-class frigate
Built:	2010-present
In commission:	2013-present
Planned:	39
On order:	6
Building:	12
Completed:	21
Active:	21
General characteristics (Chunchŏn, 2014)
Type:	Frigate
Displacement:	5,200 tons full load
Length:	138.2 m overall 125.7 m at waterline
Beam:	17.1 m overall 15.3 m at waterline
Draught:	5.44 m to keel
Propulsion:	CODLOG 2 × LM2500+ turbine (30,200 kW each) 4 × Samsan 6EY33LW diesel generator (3,450 kWe each) 2 × Samsan electric motor (4,000 kW each) 2 shafts
Speed:	34 knots
Range:	5,400 nautical miles (10,000 km) at 15 knots
Complement:	23 officers 154 enlisted crew
Sensors and processing systems:	1 × SMART-S MK2 air-search radar AN/SQS-53C hull sonar Ŭ-100 variable-depth sonar AN/SQR-19 towed array sonar
Electronic warfare & decoys:	2 × JJ-9 ESM/ECM antenna 2 × D-107 datalink 8 × Nun-8 electro-optical sensor 2 × Baram-2 countermeasure launchers 2 × Manhwagyŏng-H torpedo countermeasure launcher
Armament:	1 × HP-130/1 single 130mm turret 32 × Mk 41 VLS cell 32 × strike-length cell 8 × YDH-29 Chŏngryong anti-ship missile 2 × GBM-23/5Y Dungji CIWS 2 × 2 350mm torpedo tube
Aircraft carried:	2 × GH-28 Ppulsoeori
Aviation facilities:	landing pad with hauldown winch hangar

The Chunchŏn-class frigates (Menghean: 春川級外層護衛艦 / 춘천급 외충 호위함, Chunchŏn-gŭb Oechung Howiham) are a class of guided missile frigate built in Menghe. Developed as successors to the Yechŏn class, they share the same battlegroup escort capabilities but are also designed to carry out coastal bombardment and anti-shipping missions. The basline Chunchŏn type has been exported to Azbekistan, Sundan, and Ummayah. Menghean ships from hull HO-348 onward were completed with a different sensor suite, and are officially designated as the Sŏnsan class, though most analysts consider them a subclass of the Chunchŏn class.

Development

The Menghean Navy ordered design work on a new frigate class in the mid-2000s, not long after the breakdown of relations with Innominada. Because the two countries shared a coastline on the South Menghe Sea, this development raised the need for naval operations along an enemy-controlled coast.

As such, the Navy's procurement office required that the new ship be able to conduct coastal bombardment as effectively as the larger Haeju-class destroyer. The reasoning behind this decision held that because Menghean doctrine required that frigates be relatively inexpensive but well-armed for self-defense, an improved frigate class would be able to defend itself against anti-ship missiles and would allow the more expensive Haeju-class destroyers to stay further back. The Nunbora-class destroyers, pressed into the coastal bombardment role after becoming obsolete in the anti-shipping role, were also nearing the ends of their useful lifespans during this period, and the Navy hoped to use the new frigate class as a better-protected one-for-one replacement.

Along similar lines, the Navy required that the new class be better-equipped for anti-shipping missions. The Chŏndong-class destroyers had proven effective in naval combat during the Ummayan Civil War, and Menghe hoped to use later batches of this frigate class to replace them. The YDH-29 Chŏngryong missile, still in development at the time, would serve as the main armament. One early blueprint, marked Plan 84, carried eight forward-facing missile boxes on either side of the bridge like the Chŏndong class, but the final design mounted the anti-ship missiles between the bridge and the funnel because the launch box's exact dimensions were still unknown and an open deck space would also make it easier to refit the ship for other missile options.

These requirements caused some debate in the Navy, as more conservative officers viewed them as a form of mission creep: as initially envisioned, HO-type frigates (Oechung Howiham, "outer-layer escort ships") were supposed to specialize in the battlegroup defense role, sacrificing all capabilities not directly relevant to this mission in order to minimize cost and reduce the loss in capability from a sinking. Advocates for the expanded ship concept argued that the new capabilities required relatively little space, cost, and mass, and coincided with the baseline HO hull's demands for a high-speed, low-cost ship with good self-defense capabilities.

Navy design teams ultimately produced four competing designs for the new frigate project. Plan 84, mentioned above, had forward-facing missile launch boxes, and was eliminated early on. The initial favorite was Plan 87, which was 142 meters long with a taller superstructure, but conservative officers managed to block it on the basis that it was too large for the HO escort role. Its size would have also required modifications to the drydocks at the Gyŏngsan Songsu-do Shipyard. Instead, the Navy opted for a proposal designated Plan 85. This version had a lower "flush deck" hull, more like the Yechŏns, while retaining the same armament and capabilities. Plan 87 did, however, provide design experience for the Insŏng-class destroyers which followed later in the decade.

The first Plan 87 warship, named HO Chunchŏn, was laid down at the Kimhae Naval Yard on November 8th, 2010. It entered service on December 29th, 2013, after construction was rushed through the Yusin week festival. Chunchŏn and her sister ship Myŏngju were both completed in time to see service during the Innominadan Crisis, supporting landing operations off the Innominadan coast at the end of the year.

Characteristics

Propulsion and machinery

The Chunchŏn-class frigates use a CODLOG powerplant with two electric motors and two LM2500+ gas turbines, split across two propeller shafts. The two 4,000 kW electric motors use energy from four Samsan 6EY33LW diesel generators, each producing 3450 kWe of electricity. In addition to driving the ship's powerplant, these diesel generators also power the ship's systems, and any combination of the four can be run at once to provide the amount of power needed. The diesel generators are split between three machinery rooms to distribute propulsion equipment and enhance survivability, though because the aft generator is in the same compartment as both electric motors and both transmission units, a hit to that section would still immobilize the ship apart from its auxiliary propeller forward.

All machinery components are enclosed in sound-proof capsules and mounted on vibration-absorbing rafts, which makes the frigate especially quiet when running in electric mode. A prairie-masker air valve system further reduces cavitation and machinery noise.

Gun armament

While the Yechŏn class carried a 76mm dual-purpose gun forward, the Yechŏn is armed with a 130mm HP-130/1 Type 03 gun turret. This system has a rate of fire of 30 rounds per minute, and fires from two 20-round carousels at the bottom level of the hull, well below the waterline. It can fire programmable time-fuse shells, as well as point-detonation contact-fused shells, laser-guided shells, and Chŏl-u cluster munition shells. With a rocket-propelled long range shell, it has a claimed maximum firing range of over 100 kilometers.

Self-defense gun armament comes in the form of two GBM-23/5 Dungji CIWS mounts. This is the same number of guns as the Yechŏn class, but they are arranged in a fore-aft position over the bridge and helicopter hangar. This placement gives better coverage, with no blind spot forward and overlapping coverage on a 90-degree arc to each side. The "Dungji" variant of the mount carries sixteen YDG-61 anti-air missiles on each turret, complementing the gun for interception at greater ranges.

Despite its intended coastal role and despite the threat of Innominadan fast inshore attack craft, the Chunchŏn class does not carry dedicated autocannons for defense against small boats. Instead, standard practice is to rely on the GBM-23/5 guns, which have a reduced rate-of-fire setting for use against surface targets. The ships are fitted for but not with five 12.7mm heavy machine guns, with one pintle mount on the bow and four more flanking the bridge and the helicopter hangar. After the Innominadan Crisis, these are almost always left empty.

Missile armament

The Chunchŏn class carries four eight-cell Mark 41 VLS modules, for 32 launch cells in total. This is the same VLS armament as the Dŏkju subclass of the Yechŏn-class frigates, mounted in the same arrangement, with 16 forward and 16 aft. All cells are able to load strike-length canisters. The following loadouts are typical:

• Battlegroup escort mission
  • 8 × YDH-28 or YDH-90 anti-ship missile
  • 8 × YDG-60 long-range SAM
  • 8 × HŎ-3 Ryongorŭm anti-submarine rocket
  • 32 × YDG-64 medium-range SAM (quadpacked, 8 cells)
• Surface attack mission
  • 20 × YDH-28 or YDH-90 anti-ship missile
  • 32 × YDG-64 medium-range SAM (quadpacked, 8 cells)
  • 4 × HŎ-3 Ryongorŭm anti-submarine rocket
• Coastal bombardment mission
  • 8 × SY-51 cruise missile
  • 16 × YGJ-82N light anti-ship missile (quadpacked, 4 cells)
  • 8 × TY-10 short-range ballistic missile
  • 32 × YDG-64 medium-range SAM (quadpacked, 8 cells)
  • 4 × HŎ-3 Ryongorŭm anti-submarine rocket

Between the bridge and the funnel are eight angled box launchers for the YDH-29 Chŏngryong supersonic anti-ship missile. From HO-348 Sŏnsan onward, these have been replaced with twelve angled box launchers for long, narrow cruise missiles or anti-ship missiles, likely YDH-28 or YDH-90. Though smaller than the YDH-29, these missiles have greater range, and the YDH-90 has a greatly reduced radar cross section.

Sensors and countermeasures

The tower over the superstructure carries a SMART-S MK2 air-search radar. This system operates in the E/F band and has an instrumented range of 250 kilometers at 13.5 RPM and 150 kilometers at 27 RPM. Mounted over 28 meters above the waterline, it has a surface-level radar horizon of 22 kilometers. Though less capable than the AN/SPY-1D system on the Haeju-class destroyers, the SMART-S radar confers adequate range to target YDG-60 missiles against patrol aircraft and detect anti-ship missiles incoming on the horizon.

For missile guidance and fire control, the Chunchŏn class carry two STIR 2.4 radar antennas, one forward and one aft. This is the same configuration used on the Dŏkju group of Yechŏn-class frigates. In addition to guiding YDH-60 and -64 missiles fired by the frigate and other ships in the formation, these antennas also provide target tracking, fire-solution generation, and shell correction for the forward 130mm gun turret.

The shipboard electronic warfare suite is built around two JJ-9 ESM/ECM modules, which are designed to detect radar signals from incoming anti-ship missiles, classify them, and jam them in the same frequency. Two Baram-2 countermeasure launchers provide an inner layer of defense, complemented by eight Munje fast-deploying inflatable radar decoys which float on the surface of the water, mimicking the ship's radar signature.

Aviation facilities

The aft hangar structure can accommodate two GH-28 helicopters, double the capacity of the Yechŏn-class frigates. A hauldown device allows recovery operations in heavy seas. The flight deck control room is centered between the hangars overlooking the landing area. Torpedoes and sonobuoys are stored in an internal magazine room at waterline level, and torpedoes from this magazine are also used to reload the ship's two 350mm twin torpedo launchers.