Balhae-class submarine

The Balhae-class is a of    in service in the Republic of Zhenia Navy. Primarily replacing the older Chang Munmu-class submarines that have historically fulfilled similar roles, the Balhae-class is expected to fulfill several roles as the primary undersea warfare platform in the Republic of Zhenia Navy, with several innovations in stealth, sensors, weapons systems and nuclear propulsion technology. They are designed to perform an array of missions both in open oceans and littoral waters alike, including anti-submarine roles and long-range surface strike within contested waters, thus earning its name "hunter-killer".

Submarines of the class are named after historic Zhenian entities and modern-day Zhenian provinces, most notably Balhae Province and the Empire of Balhae, the namesake of the class. Expected to be operated in tandem with newer Munmu-class submarines, their production is set to continue well into the 2030s, with later units to remain in service until 2060 or later. It is thus expected to form the main tip of the spear of Zhenia's nuclear submarine fleet for the decades to come.

History
Designs for a new nuclear attack submarine initiated on December 1990, when limitations to the then-new Chang Munmu-class submarines in RZN service, particularly concerning endurance and quieting during operations, were revealed following an assessment from the Naval War Institute of the Zhenian Navy.

At an attempt to speed up the development process, it utilized several (COTS) components and technologies in its combat systems, computers and displays, allowing for higher compatibility and ease of repair. It also leveraged technologies, systems and equipment used in the Daeseong-class submarines, which had been developed and built mostly parallel to the Balhae-class. Similarities between the two ships include the general design of the reactors, aft sonars, pump-jet propulsor and turbine, although the overall layout of the ships themselves have significant differences with one another.

Armament


The primary armament of the Balhae-class is seen on its six 533 mm torpedo launcher tubes, which can not only fire anti-submarine or anti-surface torpedoes but also anti-ship and land attack cruise missiles. The launchers are in turn linked to an air turbine pump that aids the propelling the torpedo or missile out of the submarine. Many of the ship's 70 torpedoes and missiles are launched through any of the six launcher tubes.

In addition to its torpedo launcher tubes, it is also equipped with a total of 20 (VLS) cells, each grouped into five cells and allocated into four separate compartments.

Sensors
Many of the sensors, periscopes and electronics masts equipped on the Balhae-class are built into the telescoping mounts within its 6.1-meter. Rather than utilizing traditional periscopes, it uses a set of high-resolution cameras, light-intensification and infrared sensors, (ESM) array among other sensors to allow for better situational awareness. Many of the optical sensors replacing the traditional periscope are built into dedicated photonic masts and mounts in the sail, outside the pressure hull. Data from such sensors are sent into the control centers via a network of optical fibers and signal processors that altogether form a circuit around the ship.

In addition to its mast, the ship is equipped with a sonar suite surrounding the ship, including a bow-mounted spherical active/passive sonar array, wide aperture fiber optic sonar arrays mounted as panels on the hull's sides, high-frequency active sonars on the sail, bow and sides of the sail. Altogether, they provide a high-resolution, 360-degree coverage around the submarine. The sonar suite is built with adaptability and modularization in mind, allowing for simpler insertion of new hardware and software when available, compared to its predecessors. In addition to the onboard sonar suite, the ship can also be equipped with a towed sonar array across multiple frequencies, further increasing the coverage surrounding the boat.

Propulsion and power systems
The ship is powered by a HGN-30 built by Jinmu Heavy Industries. Compared to the HGN-25 pressurized water reactors on the Chang Munmu-class, the HGN-30 has achieved significant downsizing as well as a 12% increase in power output, the latter of which is partly attributed to higher uranium enrichment in the fuel the reactor uses.

The ship is primarily propelled by a propulsor, which is in turn linked to the turbine adjacent to the reactor via a shaft. The propulsor consists of shrouded propellers, which minimize underwater clutter and. Although its details are unknown, there are speculations that its quietness in operation is comparable to that of conventional diesel-electric submarines operating in similar speeds.