[Defense Contribution] 'Korean-style Zumwalt-class'... KDDX Is

[Military Analyst Kim Daeyoung] The KDDX, Korea’s next-generation destroyer, is a new surface combatant acquisition project being pursued by the Republic of Korea Navy following the KDX, the Korean destroyer program. The KDDX, with a displacement of 6,500 tons, will differ from previous KDX ships in that, except for the propulsion system and gas turbine engines, all other components?including the hull, armaments, combat system, multifunction radar, and sonar?will be domestically developed and installed.

The hull form, or shape of the ship, also shows significant differences compared to earlier Korean destroyers. Notably, the bow design adopts a wave-piercing shape for the first time in a Korean naval destroyer. A representative warship currently employing a wave-piercing bow design is the U.S. Navy’s Zumwalt-class destroyer. The Zumwalt-class, the U.S. Navy’s latest destroyer, boasts advanced stealth capabilities. The wave-piercing bow offers advantages in stealth performance and reduces hull resistance and pitching caused by waves. Additionally, the KDDX model unveiled by Hyundai Heavy Industries at the 2021 International Maritime Defense Industry Exhibition (MADEX) held on the 12th shows minimized hull protrusions to secure high stealth performance.

The KDDX plan was first revealed during the 2009 National Assembly audit of the Navy Headquarters. At that time, a proposal was made to build six 5,000-ton-class Korean next-generation destroyers, known as “mini Aegis ships,” from 2019 to 2026 to strengthen naval power and form a mobile task force. However, the project was deprioritized and only approved on December 26, 2018, through the 118th Defense Acquisition Program Promotion Committee as the “KDDX Project Promotion Basic Strategy.” In 2020, Hyundai Heavy Industries was preliminarily selected as the preferred bidder for the basic design of the KDDX through competition among companies, and Hanwha Systems was chosen as the preferred bidder for the combat system and multifunction radar development project.

Additionally, LIG Nex1 was selected for the sonar system development. To enhance stealth capabilities, the KDDX will be the first domestic ship to feature an integrated mast. The integrated mast will incorporate detection sensors and communication antennas?including a dual-band multifunction phased array radar, infrared detection and tracking equipment, and Identification Friend or Foe (IFF) systems?in a planar form, all integrated into the mast. The basic armament will include a 127mm naval gun and a domestically developed close-in weapon system (CIWS-II) planned for future installation. Furthermore, the new Korean Vertical Launching System-II (KLVS-II) will be applied, expected to carry domestically produced long-range surface-to-air missiles as well as supersonic anti-ship missiles.

Unlike the KDX, the KDDX will use a hybrid or integrated electric propulsion system instead of a mechanical propulsion system. The hybrid propulsion system combines the advantages of mechanical and integrated electric propulsion: electric motors operate at low speeds, while gas turbines operate at high speeds. In contrast, the integrated electric propulsion system uses electric motors for all speed ranges, powered by diesel generators at low speeds, gas turbine generators at medium speeds, and both diesel and gas turbine generators at high speeds to provide propulsion and electrical power to the ship’s systems.

Hybrid and integrated electric propulsion systems produce less noise than traditional mechanical propulsion, making them highly advantageous for anti-submarine warfare. They are also reported to occupy less internal space on the ship. The propulsion method for the KDDX is expected to be decided as early as July, after which the selection of the gas turbine engine will accelerate.