Donghan-class corvette
| Class overview | |
|---|---|
| Builders: | Gyŏngsan Songsu-do Shipyard |
| Operators: | Menghe |
| Preceded by: | Saebyŏk-class corvette |
| Built: | 2019-present |
| In commission: | 2022-present |
| Planned: | 10 |
| On order: | 2 |
| Building: | 8 |
| Completed: | 0 |
| General characteristics (as built) | |
| Type: | Corvette |
| Displacement: | 2,500 tons full |
| Length: |
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| Beam: |
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| Draught: |
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| Propulsion: |
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| Speed: | 35 knots |
| Range: | 2,150 nautical miles (4,000 km) at 20 knots |
| Complement: |
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| Sensors and processing systems: |
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| Electronic warfare & decoys: |
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| Armament: |
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| Aircraft carried: |
1 × GH-30HG light helicopter, or 2 × Chogwan Air Corporation CK-205 UAV |
| Aviation facilities: | Flight deck and hangar |
The Donghan-class corvettes are a type of warship currently being built in Menghe for the Menghean Navy. Officially labeled "medium coastal destroyers" (junghyŏng yŏnan guchugham) in the Menghean Navy's ship classification scheme, they are typically regarded as large corvettes or small frigates in foreign sources. Ordered as a premature replacement for the Saebyŏk-class corvettes, and influenced by the sinking of GYS-231 Bŏmram during the Innominadan Crisis, they have much better anti-aircraft and anti-submarine capabilities than their predecessors, though these capabilities are largely limited to self-defense. To conduct their primary mission of shore bombardment, the Donghan-class corvettes sport a 130mm gun in a single turret as well as vertical and angled launch boxes for YDH-26 anti-ship missiles or SY-26 land-attack missiles.
Development
During the late 2000s and early 2010s, the Menghean Navy had built two classes of "coastal destroyers," the Saebyŏk-class corvettes and Taepung-class corvettes. These vessels were tasked with engaging Innominadan light craft and missile boats, bombarding coastal targets, and escorting short-range amphibious landings. In contrast to proper destroyers or frigates, they were given minimal anti-ship, anti-air, and anti-submarine armament, with both classes carrying no surface-to-air missiles of any kind as built. The original rationale behind this decision was that they would operate with the support of land-based long-range surface-to-air missile systems and dedicated anti-submarine corvettes, and that they should be made as compact and inexpensive as possible to reduce the cost of inevitable losses.
The Innominadan Crisis showcased the usefulness of the coastal destroyer concept, but also showcased its vulnerability. GYJ-231 Bŏmram, a Taepung-class corvette, was sunk on 7 October 2014 after a low-flying MiG-21 fighter engaged her with unguided bombs. Analysis of combat data from the ship's recording box revealed that her 2D search radar detected the range and bearing to the target, but could not generate an altitude reading, leaving the ship's 76mm and 23mm guns unable to engage. In early 2015, after analyzing a report on the sinking of the Bŏmram, the Menghean Navy cancelled the 13th through 16th Saebyŏk-class corvettes and announced plans to retire the existing ships ahead of schedule, primarily by selling them to other members of the Namhae Front.
The resolution of the Innominadan Crisis also led Menghe to re-evaluate the rightful role of coastal destroyers. Most of Innominada's light missile boats had been destroyed during Menghe's intervention, and the lion's share had been sunk by aircraft or helicopters rather than naval gunfire. With the movement of the front line, the Menghean Navy now faced a greater focus on controlling the Strait of Portcullia, with amphibious combat along the shoreline a secondary priority.
The Menghean Navy responded by updating its coastal destroyer concept. The core requirements remained the same: a compact vessel with a 130mm gun and hangar space for a single GH-30 helicopter, capable of traveling at 35 knots, on a hull displacing under 2,500 tonnes. Beyond this, however, the coastal destroyer would need to carry at least 32 YDG-64 surface-to-air missiles for self-defense, along with a 3D multipurpose radar system capable of tracking targets effectively within the missile's range. Signature reduction was also a major design priority, as a smaller radar cross-section would help the vessel evade detection by mimicking the radar return of a small fishing boat. As with the preceding Saebyŏk class, the ship would operate close to friendly ports and deploy consistently in assigned areas, so range and endurance would be sacrificed in order to remain within cost and tonnage limits.
In 2018, the Menghean Navy began advertising a preliminary design under the label Plan 588. It appeared as computer-generated concept art and as a scale mockup. The initial version apparently sported no anti-submarine systems or sensors apart from a mine and obstacle avoidance sonar protruding under the keel. A revised model, Plan 588N, added a hull sonar, six 350mm torpedo tubes, and Manhwagyŏng-H torpedo decoy launchers. Given the lack of HŎ-3 Ryongorŭm anti-submarine rockets, a towed sonar array, or an ASW-capable helicopter, it appears that these systems are intended purely for self-defense against submarines operating in shallow coastal areas.
The first ship built to Plan 588N's design was laid down on 21 August 2019. In 2020 it was announced that the ship, still under construction, would bear the name Donghan, which at the time was still carried by a Chŏndong-class destroyer; independent analysts interpreted this as evidence that GY-217 Donghan and other early-model Chŏndongs would be retired by 2022 at the latest, to avoid a situation where two warships carried the same name simultaneously.
Design
Armament
The main armament of the Donghan-class corvette is a HP-130/1 Type 102 130mm naval gun. This is the same gun used by the Haeju-class destroyers, Insŏng-class destroyers, and Chunchŏn-class frigates, all of which are much larger in displacement. The gun can fire at a rate of 30 rounds per minute and is fed from two 20-round carousels within the hull. Its longest-range shell, which uses a rocket-assist base, has a claimed range of over 100 kilometers, though conventional shells have ranges of 21 to 25 kilometers depending on type and payload. Additional rounds and charges are stored in a magazine compartment aft of the autoloader compartment, roughly below the VLS module, and are manually transferred to the autoloader.
Facing aft is a twin 35mm close-in weapon system with a DGP-35-2 anti-aircraft gun. This system feeds from two large drums containing 430 rounds in total, and can select contact-fused or smart-fused ammunition depending on the threat and the availability of smart-fused rounds. This turret has its own fire-control radar and electro-optical sight, and is cued to targets by the ship's other sensors. It can engage fixed-wing aircraft, helicopters, anti-ship missiles, and surface craft.
Unlike previous coastal destroyers in the Menghean Navy, the Donghan-class is also fitted with a 16-cell Mark 41 VLS module. The self-defense-length cells can carry quadpacked YDG-64 missiles, quadpacked YDG-66 missiles, single YDH-26 anti-ship missiles, or single SY-26 land-attack cruise missiles. A typical loadout might consist of 16× YDG-64, 16× YDG-66, and 8× SY-26. The surface-to-air missiles allow the Donghan-class corvette to defend itself against aircraft and engage anti-ship missiles at greater ranges, making it more survivable against peer-opponent threats while operating in contested coastal waters. Menghe is also reportedly working on a 210mm land-attack rocket which can be quadpacked into these cells, improving the ships' land-attack capabilities.
Other armament consists of two quad-box angled launchers for YDH-26 anti-ship missiles, six fixed launch tubes for YŎ-35/2 torpedoes, and five mounting points for 12.7mm machine guns, which are normally stowed inside the ship to reduce radar returns and fitted when there is a threat from enemy light craft. No onboard torpedo reloads are carried, and the tubes are reloaded externally while in port.
Sensors and electronics
Atop the main mast of the Donghan-class corvette is a Thales NS50 radar with integrated IFF interrogator. This radar has a maximum instrumented range of 180 kilometers and can support 1000 target tracks while spinning at 15 or 60 rpm. In addition to detecting airborne threats, it can also designate contacts for active radar homing surface-to-air missiles and correct fire control for the ship's main gun. A small-size CEAMOUNT radar forward of the main sensor mast provides backup fire control and illumination in a jamming-heavy environment, and two Nun-10 electro-optical sensors flanking the sensor mast allow the ship to detect incoming missile, aircraft, and surface threats without emitting radar signals.
Under the hull is a single Ŭ-104 medium-frequency hull sonar, the same type used on the Yungju-class corvettes and Muran-class corvettes. Neither a towed sonar array nor a variable depth sonar are fitted, and there are no provisions to fit either system in containerized form. This primarily reflects the self-defense focus of the Donghan's anti-submarine armament, with a hull sonar adequate for detecting torpedo launches and nearby submarines. It also reflects the ship's optimization for littoral areas in the tropics, where the sea is typically too shallow to enable the use of towed sonar arrays and the upper thermal layer extends all the way to the seabed. A separate high-frequency hull sonar helps the ship detect mines, divers, and underwater obstacles.
For electronic warfare, the ship carries the Metturi ECM suite, with active and passive panels arranged around the base of the main sensor mast at 45-degree angles off the centerline. This system can automatically detect, classify, and jam radar signals from a variety of aircraft and anti-ship missiles, and can also jam enemy communications within a small range. Like other Menghean ships, the Donghan-class corvette is itself optimized to operate in a jamming-intensive or emissions-restricted environment, and features secure UHF datalinks, SHF backup antennas, and FSO laser datalinks, the latter in a new reduced-RCS housing atop the sensor mast.
Power and propulsion
Like the last two coastal destroyers before it, the Donghan-class corvette uses a CODAG WARP powerplant in which two cross-connected diesel engines drive conventional propellers and a single LM2500+ gas turbine drives a central waterjet. The waterjet possesses neither steering nor reversing capabilities, and is only used for forward sprinting, while the propellers are reversible and followed by conventional rudders. On the Donghan class, the diesel engines are license-built MTU 16V 1163 M84 units, each generating 5200 kW of power. On diesels alone, the corvette can cruise at 20 knots. The GE LM2500G+ turbine generates an additional 30,200 kW at full power. On trials, GYJ-250 Donghan comfortably exceeded 36 knots at full power, though at more realistic combat loads her rated top speed remains 35 knots.
Aviation facilities
The ship's quarterdeck contains a landing pad for a Saebyŏk SS-30HN multi-purpose naval helicopter, with a hangar in the aft superstructure. The SS-30HN has an advanced electro-optical camera, side pylons for rocket pods or light guided missiles, and internal seating for six passengers. It carries neither a dipping sonar nor a magnetic anomaly detector, and it lacks the payload to carry both a sonobuoy ejector and a 350mm torpedo, making it ineffective in the anti-submarine role. Instead, the SS-30HN would be launched to search for small boats beyond the horizon and engage them with rockets or missiles if necessary. It can also provide laser illumination, coordinate calculation, and fire correction against coastal targets.
In place of the single manned helicopter, the Donghan-class corvettes will also reportedly be able to carry two helicopter UAVs. This capability was first advertised alongside a 2019 mockup, with the notional UAVs carrying electro-optical sights and identifying and designating targets beyond the horizon. In July 2022 the Menghean Navy unveiled the Chogwan Air Corporation CK-205 as the Donghan-class's helicopter UAV option. The CK-205 has an electro-optical unit, a surface search radar, and two hardpoints which can be used to mount small rocket pods or Brimstone missiles.
Special forces support
Though it is not primarily designed for delivering special forces to coastal targets--a mission reserved for other dedicated littoral ship types--the Donghan-class corvette does have the ability to transport up to 12 additional personnel in austerity berths and send small teams to shore via the ship's helicopter or its boats.
