Daedam-class submarine

File:ISS Daedamhan.png Daedamhan, first ship of the class
Class overview
Name:	Daedamhan
Builders:	Haepyong-ri Shipyard, Gyŏngsan Dangsa-ri Shipyard, Dongchŏn
Operators:	Menghe
Preceded by:	Gyohwalhan-class submarine
Cost:	₩30.4 billion per unit (1st batch) ($1.36 billion NSD at PPP)
Built:	2008-present
In service:	2013-present
Planned:	30
Building:	8
Completed:	5
General characteristics
Type:	Nuclear Attack Submarine
Displacement:	4,540 tonnes surfaced 6,550 tonnes submerged
Length:	106.1 meters
Beam:	10.52 meters
Draught:	9.45 meters (surfaced, inc. tail)
Propulsion:	1x Pressurized Water Reactor
Speed:	24 knots surfaced 38+ knots submerged (claimed)
Range:	theoretically unlimited
Endurance:	60 days
Complement:	85 (36 officers)
Sensors and processing systems:	1x multifunction search radar and jammer mast 1x VLF receiver antenna
Armament:	Torpedoes: 4 × 533mm torpedo tube (bow) (28 torpedoes carried) 4 × 650mm torpedo tube (bow) (16 torpedoes carried) Missiles: 10 × large launch cell, each with 1 × TY-4 anti-ship ballistic missile or 6 × YDH-29 AShM or SY-51 cruise missile Mines: Can carry mines in place of torpedoes

The Daedamhan-class submarines (Menghean: 대담한급 순항 유도탄 원자력 잠수함, Daedamhan-gŭb Sunhang Yudotan Wŏnjaryŏg Jamsuham), also known as Warship 114 during construction, are a series of nuclear-powered submarines built in the Socialist Republic of Menghe for the Menghean Navy. They are multipurpose vessels capable of serving as both attack submarines and guided missile submaries, and bear the Menghean hull code JSWSY (equivalent to SSGN).

Though using a very different hullform from their predecessors, the Warship 114 project built on many lessons learned from the Gyohwalhan-class submarine, with even greater efforts at noise reduction through changes to both internal and external equipment. They are reported to be among the quietest nuclear submarines in Septentrion, making them exceptionally hard to detect on passive sonar. They also carry a formidable missile and torpedo armament optimized for attacks on enemy surface ships. Even so, their relatively compact size, small crew, and reported 60-day endurance suggest that they are optimized for brief deployments or rapid sorties within the South Menghe Sea and other local waters, rather than long-term patrols in the Meridian Ocean.

Development

Even while production of the Gyohwalhan class was still underway, the Menghean Navy was working to further develop the design, both as a means of improving on the Gyohwalhan’s layout and in order to fill new missions and roles. An early design in 2003, resembling a stretched, enlarged Gyohwalhan with twenty-four vertical cruise missile launch tubes just aft of the sail, laid the groundwork for what later became Warship 114. This early design was intended to support the then-ongoing pivot to expeditionary warfare, allowing Menghean submarines to launch cruise missile strikes at coastal targets far from home territory.

Withdrawal from the Ummayan Civil War, however, forced a radical pivot in the Menghean Navy’s doctrine, from intervention abroad to counter-intervention at home. The new SSGN project evolved accordingly. Much of the preliminary technology associated with the old project was retained, but the hull was redesigned for rapid sorties against surface fleets and supply convoys, with a more compact layout and greater automation. At the same time, the Kwaechŏnggong design bureau was beginning work on the TY-3 short-range ballistic missile, and the Navy expressed interest in an anti-ship version which could be launched from a surface ship or submarine. This led to the adoption of the Warship 114’s new multi-mission vertical missile system.

Construction began on the first ship of the class in February 2008, with plans to reach commissioning in four years. Continued minor delays, including the development of new components and sub-systems, slowed this process somewhat, but in June 2013 the first ship of the class officially entered service. In keeping with Menghean ship nomenclature, it was given the adjective name Daedamhan (대담한), meaning "Daring."

Design

Submarines of the Daedamhan-class follow a fairly conventional SSGN design, with a spherical sonar in the bow, torpedo tubes to either side, a dorsal sail with targeting equipment, a missile farm, a reactor and steam turbines, and an aft proplusion system. They use a double-hull layout, with flood chambers all along the sides, and have a relatively high reserve buoyancy of 38%. In theory, this means that the submarine can still blow its tanks and surface even if one-third of its internal compartments are flooded. For added safety, there are two emergency compartments – one just aft of the sonar, and one just aft of the reactor compartment – where surviving crew members can gather for safety. In the event of a sinking, the compartments can seal off and detach, floating to the surface to await rescue.

These submarines represent continued progress in noise reduction among Menghean submarines. The ships’ acoustic dampening measures include more precisely engineered machine components, decoupling or vibration-dampening mounts on moving components, and an anachoeic coating on the outer hull. The latter not only helps block vibrations from inside the submarine, but also reduces its acoustic return on active sonar. Finally, the use of a shrouded propeller reduces noise and cavitation. The Menghean Navy claims that the Daedamhan-class is “on par with contemporary submarines produced by advanced economies” in terms of its quieting measures, though independent data on its noise levels are not available.

Like their predecessors, the Daedamhan-class carry a number of periscopes in the sail, including a targeting periscope, a surveillance periscope, a compact ECM and radar array, a radio navigation system, a radio antenna, an ESM antenna, and a satellite communications antenna. In a first for Menghean submarines, they also carry a floating radio buoy in a compartment at the rear of the sail. This can be released to allow the submarine to communicate without ascending to periscope depth.

Similarly, the upper rudder contains a large pod for a variable-depth towed sonar array, which can be used to cover the blind spot aft of the submarine, search above or below the thermocline, and improve detection against very quiet hostile submarines.

Armament

The main armament of the Daedamhan-class can be found just aft of the sail, in ten large vertical missile tubes resembling those on a ballistic missile submarine. On the base hull design, these are empty cells, which can be fitted with two types of modular missile container. One carries a single TY-4 anti-ship ballistic missile, with a range of 600 kilometers and a terminal velocity of Mach 7. The other carries six smaller missiles, either cruise missiles, anti-ship missiles, or anti-submarine standoff weapons, in a “revolver” layout. Both cell options are fully modular, with identical interface equipment and containing their own first-stage cold-launch systems to propel the missile clear of the submarine. This allows either cell type to be loaded into the open hatch in port, without the need for extensive internal refits.

During early development, there were also plans for “special forces” cell modules, containing additional living and storage space, airlocks for entry, and inflatable boats for use on the surface. Work on this module type was cancelled in 2005 due to the pivot away from expeditionary warfare, but in recent years the Menghean Navy has revived interest in the project.

The dorsal missile cells are supplemented by a total of eight forward-facing torpedo tubes: four in 533mm caliber, and four in the heavier 650mm caliber. The latter option allows the submarine to fire heavy wake-following torpedoes with longer ranges and larger warheads, an especially useful option when engaging carrier-battlegroups or large amphibious assault ships. With the help of external slip-rings, 533mm torpedoes can be fired from the 650mm tubes. In place of some torpedoes, the submarine may carry additional cruise missiles, anti-ship missiles, anti-submarine standoff weapons, or submarine-deployed naval mine packages, which are all 533mm in diameter but can also be fitted with 650mm slip-rings.

Unlike every Menghe military submarine class since the 1980s, the Daedamhan has its torpedo tubes in vertical rows at either side of the nose, rather than in a group above the sonar. This is because in-service trials of Gyohwalhan-class submarines found that as they neared 30 knots, the edges of the tube seals generated flow noise in close proximity to the main sonar, temporarily blinding the ship with background noise. By moving the torpedo tubes further back and reducing other protrusions near the bow, the Daedamhan is better able to use its sonar while moving quickly, though still prone to “blinding” above a higher threshold.

Propulsion

The Daedamhan and her sister ships are nuclear-powered, driven by a single pressurized water reactor. The PWR design is more compact than less conventional nuclear alternatives, and allows the ship to draw on the surrounding water for secondary coolant. Compared to a diesel-electric or air-independent conventional powerplant, it also allows the submarine to maintain a high speed while submerged without creating fuel concerns. The reactor model used has a fuel lifetime of 20 years, allowing individual submarines of the Daedamhan class to remain in service for roughly four decades with one intensive mid-life refuel and refit period.

The Menghean Navy does not publish official numbers on the submerged top speed of the Daedamhan-class submarine, simply reporting that the top speed is “in excess of 30 knots.” Some Menghean defense analysts, working from what they claim are leaked internal documents, claim that the top speed may lie slightly above 37 knots, with a few proposing figures as high as 40. Even the more modest claim would potentially make the Daedamhan the fastest submarine class in Septentrion. In practice, however, this and similar speeds would create extensive turbulence and flow noise, blinding the submarine’s own sonar and increasing its vulnerability to detection. For that reason, it is believed that the “37-knot” capability would only be used in emergency sprints to evade pursuit.

Service

The first Daedamhan-class submarine entered service with the Menghean Navy in June 2013. One year later, the Daedamhan and her two existing sister ships took part in the Innominadan Crisis, providing attacks on Innominadan warships at sea and cruise missile strikes on hostile land targets and ports. The Menghean Navy has prioritized construction of this submarine class, commissioning three per year in 2014, 2015, and 2016.

To allow a greater retention of nuclear submarine construction skills, work is split between Menghe's two nuclear-submarine-capable facilities, the Haepyong-ri Shipyard (formerly Shipyard No. 120) in Gyŏngsan and the Dangsa-ri Shipyard in Dongchŏn.