KDX (Korean Destroyer eXperimental) is the Republic of Korea’s big surface combatant shipbuilding program. This 3-phased program involves 3 individual classes of ships. The 3 KDX-I Gwanggaeto the Great Class ships are called destroyers, but at 3,800 tons, their size and armament more properly rank them as small frigates. The last ship of class was commissioned in 2000. The next 6 KDX-II Chungmugong Yi Sun-sin Class ships are indeed destroyers at 6,085 tons full load, with a hull design licensed from Germany’s IABG, and more advanced systems that include SM-2 air defense missiles. They were commissioned between 2003-2008.

With that experience under their belts, Korea entered the 3rd phase of the program. Their KDX-III King Sejong the Great Class destroyers weigh in at 8,500 tons standard displacement and 11,000 tons full load. That’s heavier than the USA’s CG-47 Ticonderoga Class cruisers, making them the largest ships in the world to carry Lockheed Martin’s AEGIS combat system. They’ll form the high end of South Korea’s Navy, while offering a premium showcase for some of the new weapons and electronic systems developed by South Korea’s defense sector.

The KDX III Sejongdaewang-Ham Class

The KDX-III is clearly intended to be a multi-purpose destroyer will full air defense, land attack, anti-shipping, and anti-submarine capabilities. It is also being designed with the ability to add tactical ballistic missile defense capabilities, and important consideration if North Korea is your neighbor. At present, however, the ships do not possess AEGIS BMD modifications, or SM-3 missiles. The ROKN has ordered 3 ships so far, with an option for another 3.

Size
Built by Hyundai Heavy Industries in Ulsan, 415 kilometers (257 miles) southeast of Seoul, the KDX-III King Sejong Class will be significantly larger than the 5,000t KDX-IIs. These ships are 166m / 544 feet long and 21m/ 69 feet wide, and 49m/ 161 feet deep, with a standard displacement of 8,500 tons, and a full load displacement of around 11,000 tons. A set of 4 ubiquitous GE LM2500 naval gas turbines provide main power, giving them a high top speed of 30 knots.

Hangars in the back allow carriage of 2 medium naval helicopters.

Key Sensors
Sometimes described as an enlarged and updated DDG-51 Arleigh Burke Class, KDX-III will also use the advanced AEGIS radar & combat system (initially Baseline 7, Phase 1) combination, with the AN/SPY-1D (V) radar and SPG-62 illuminators.

France’s Sagem provides their Vampir long-range IRST system for passive day and night surveillance of ocean and land targets.

For underwater surveillance, a hull-mounted DSQS-21BZ (ASO 90 family) sonar from Atlas Elektronik is paired with a Korean LIG Nex1 towed sonar.

Weapons
Fixed weapons will include BAE’s 5-inch/ 127mm MK45 Mod 4 naval gun, a pair of 324mm triple torpedo mounts in KMK 32 configuration, a Raytheon RIM-116B Rolling Airframe Missile Block 1 for short-range air defense, and a 30mm Thales “Goalkeeper” CIWS system for close-in defense against aircraft and boats.

KDX-III ships real firepower lies their array of 128 vertical launch cells, which is slightly more than the American Ticonderoga Class cruiser’s 122 cells. On the Korean ships, these VLS cells come in 2 types.

The standard Mk 41 vertical launch cells are split 48 forward, and 32 aft, for a total of 80. They can be loaded with vertically-launched SM-2 Block IIIA/B surface-to-air missiles for anti-aircraft duties, or upgrade to ABM-capable SM-3s with modifications to the radar and combat system. They can also carry a wide variety of other payloads, including quad-packed RIM-162 anti-aircraft missiles, vertically-launched anti-submarine torpedoes, or Tomahawk cruise missiles. South Korea currently seems focused on filling them with SM-2s. This will give the destroyers 3-layer anti-aerial protection (SM-2, RAM, Goalkeeper), which could become 4 layers if South Korea ever buys the long-range SM-3.

Weapons variety comes from a 3rd VLS set of 48 aft-mounted”K-VLS” cells, a Korean system that holds locally-designed weapons like Red Shark “K-ASROC” vertically launched, rocket assisted anti-submarine torpedoes, Hyunmoo cruise missiles, SSM-700K Haesung anti-ship missiles, or other compatible weapons.

Passive Defense
The ships are being designed with a number of low-observable features to reduce their radar profile. These measures also include advanced infrared signature reduction methods designed to give it an IR signature far superior to comparable ships, including its U.S. contemporary the DDG-51 Arleigh Burke class destroyer. If that fails, a locally-designed LIG Nex1 SLQ-200K Sonata ESM system helps the destroyers react to and attempt to jam incoming missiles.


The KDX-III Program


Official statements said that the name Sejongdaewang-Ham (“King Sejong”) was chosen for the first ship because of this importance in Korean history. Besides supporting the creation of the Korean “Hangeul” alphabet, this 15th century Chosun Dynasty monarch is also known for strengthening the country’s national defense capability.

All of this ship class’ contemporaries are classed as DDG (guided missile destroyers) or CG (guided missile cruisers), but the ROK Navy initially designated its KDX ships as DDH. Recent US Navy materials indicate that the KDX-III ships now use the DDG moniker.

After the ROKS King Sejong’s official delivery to the ROK Navy at the end of 2008, 2 other ships of the class were expected to enter service. ROKS Yulgok Yi I was supposed to enter service in 2010, but took until 2011. The 3rd ship (was Kwon Yul, but launched as Seoae Ryu Seong-ryong), was delivered at the end of August 2012 GlobalSecurity.org estimates that each vessel will cost about 1.2 trillion won (roughly $923 million equivalent).

The question is what happens after that.

The program has options for another 3 ships, but the March 2010 sinking of the corvette ROKN Cheonan by a North Korean submarine has shifted the ROKN’s focus away from the globe’s blue waters, and back toward its own littoral regions. Rather than continuing to build more KDX-III destroyers, there has been some talk in South Korea of modernizing the cheaper 5,000t KDX-II light destroyer design, giving the ships smaller radar and emissions profiles, and adding AEGIS radars and combat systems to give them better anti-aircraft coverage.

The key consideration when deciding between “KDX-IIA” light destroyers and KDX-III heavy destroyers is the tradeoff between having a larger number of modern ships in the water to handle submarines and Fast Attack Craft, vs. fleet capability for potential ballistic missile defense (BMD) missions. North Korea fields both kinds of threats. If BMD is confirmed as the greater priority, the KDX-III’s SPY-1D (V) radar and AEGIS combat system have a set upgrade path, thanks to the US Navy’s program to retrofit DDG-51 ships, and the KDX-III destroyers should have enough on-board power and available weight/space growth to handle that mission. It isn’t yet clear that a KDX-IIA would be able to say the same thing. If South Korea opts for the smaller SPY-1F radar that equips ships like Norway’s Nansen Class frigates, for instance, the KDX-IIAs would be unlikely to ever have a ballistic missile defense role.

http://www.defenseindustrydaily.com/...stroyers-0431/

KDX III Promo Video
http://www.youtube.com/watch?v=AsNqPCquhU0

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