Chungsŏng-class submarine

The Chungsŏng class is a class of nuclear-powered attack submarine designed and built in Menghe during the 1990s and 2000s. There are three major subclasses, known in the West as Chungsŏng-I, Chungsŏng-II, and Chungsŏng-III. With a teardrop hull, a streamlined sail, and a variable-depth sonar pod, they represented a major development leap over the preceding JW-351 class. Menghean news sources also claimed that the Chungsŏng-class had achieved a very high level of acoustic quieting, on par with contemporary nuclear submarines. In reality, while stealthier than the noisy JW-351s, the Chungsŏng-class submarines were still judged insufficient by the Navy, which ordered the development of a more advanced replacement class.

Development

Menghe's first nuclear-powered submarine, JW-351, was laid down in 1978 and commissioned in 1983. Though she carried torpedo armament and combat sensors, the Menghean People's Navy ultimately regarded the JW-351 design as an experimental prototype rather than a production-ready submarine. Before JW-351 even began her sea trials, Institute 72 - tasked with the design of nuclear submarines - began development of a more modern successor class. This project proceeded slowly, however, and as an interim measure the DPRM laid down the JW-352 and JW-353, both of them modified derivatives of JW-351.

After the Decembrist Revolution, the Interim Council for National Restoration decided to cancel the construction of a fourth JW-351 hull, but finish fitting-out of the JW-353. Development of the successor class briefly stalled as well, but in 1990 Institute 72 was ordered to resume design work. The first hull segment of the new submarine class was laid down in secret on December 18th, 1994.

The Ministry of National Defense initially anticipated a production rate of 1 hull per year by the end of the decade. The actual construction process, however, soon encountered delays and cost overruns. Plans to have the first submarine in service in time for the 10th anniversary of the Decembrist Revolution were postponed, and an audit in 1998 found the project to be more than 50% over budget. Faced with a budget that was barely keeping pace with inflation, the Navy scaled back its procurement plan, aiming to have four submarines in service by 2005.

In 1996, it was reported that Menghe had obtained a computer-controlled propeller milling machine from a Hallian shipbuilding company after ordering it through a state-owned civilian shipbuilder. This machine was likely used in manufacturing the low-cavitation propellers for contemporary submarine classes.

The first ship in the class was commissioned on October 9th, 1999, under the name Chungsŏng ("Loyalty"). This made her the first Menghean military submarine in pre- or post-war history to receive a name, rather than a mere hull number. As the Disciplined Society Campaign was still in full swing, the Ministry of National Defense decided to name all four ships after virtues, and future Menghean nuclear submarines carried forward this tradition. Choe Sŭng-min himself reportedly took part in the ship naming process, selecting Chungsŏng from a list of options as the name of the first hull.

Leaked photographs of the Chungsŏng caused considerable surprise in the West, as the submarine's external appearance suggested a major leap in design compared to the JW-351. Menghean news sources fueled additional speculation, claiming that the new submarine was on par with the latest Glasic and Dayashinese designs in terms of stealth and performance.

Speaking to a group of Dayashinese military officers in 2016, Rear Admiral Sun Yŏng-gi claimed that on several occasions Menghe had held simulated acoustic testing exercises in the East Menghe Sea while secretly keeping Chungsŏng in the Kimhae Sea, in order to give the impression that the submarine was present but undetectable to Dayashinese surveillance ships.

Even after her commissioning, Chungsŏng spent the first few years of her service life conducting sea trials. At first trials were held in the East Menghe Sea, but before the end of 1999 they moved to the South Menghe Sea out of fears that Dayashinese intelligence assets would be able to monitor the tests. In addition to familiarizing the crew with the design, these trials aimed to assess the ship's noise levels, identify design defects, and gain experience in developing nuclear submarine doctrine. In classified documents that were released in the late 2010s, officers assigned to the trials related serious issues with the Chungsŏng design, including noise levels well above the expected levels. The cruiser Chanjok Jachido, fitted with an advanced Hallian AN/SQR-19 towed sonar array, proved especially adept at finding the submarine in exercises.