JS Izumo (DDH-183)
Conventionally-Powered Helicopter Carrier / Destroyer
Attempting to keep pace with China, the Japanese Navy unveiled the JDS Izumo helicopter carrier in August of 2013 for commissioning in 2015.
Authored By: JR Potts, AUS 173d AB and Dan Alex | Last Edited:
JDS Izumo (DDH-183) leads the new 22DDH-class of helicopter destroyers and forms a key component of the Japanese Maritime Self-Defense Force (JMSDF) which serves as the naval branch of the Japan Self-Defense Forces (JSDF) established after the end of World War 2 and the American post-war occupation. The JMSDF is tasked with the naval defense of Japan and its territorial waters including her wide-reaching shipping lanes which are critical to the overall economy. Japanese authorities purposely do not classify the Izumo as an "aircraft carrier" due to the prohibitions stated in the Japanese post-war national constitution (and also to quell any angst from her Pacific neighbors) hence the formal classification of "helicopter destroyer" being used instead. Generically, the vessel is categorized as a "helicopter carrier".
The need for the Izumo is due to the arms race emerging between the nations bordering the Sea of Japan as well as the East and South China Seas. The area is dotted by hundreds of islands and reefs which also places them in regular dispute - both territorial and for the natural resources they hold. This geopolitical location provides an abundance of fish, natural gas and oil reserves making the South China Sea particularly attractive to industrialized (and emerging) nations like Japan, China, Taiwan, the Philippines, North and South Korea, Vietnam, Thailand and Cambodia. Add to this the fact that one-third of all global shipping transits through these disputed waters and interest in the region's stability expands beyond Southeast Asia and the Pacific. Advanced Chinese destroyers, carrying cruise missiles, have been spotted near the gas fields of the East China Sea during 2013 - such measures not going unnoticed and serving to heighten tensions for all parties. Indeed the American focus is turning from the Middle East to the Pacific.
The 22DDH-class helicopter destroyers were partly designed to patrol the disputed sea lanes and protect Japanese merchant shipping with the intent that they will eventually replace the aging Shirane (DDH-143) and her sister ship Kurama (DDH-144) as well as four other destroyers scheduled to begin decommissioning in fiscal 2014 with no other replacement ships being constructed. The JMSDF feels that two 22DDH-class warships can fill the loss of these six destroyers without the need to add more ships, thus reducing military naval spending.
Izumo was laid down on January 27th, 2012 and launched from the Yokohama dockworks on August 6th, 2013. The unveiling date also served as remembrance for the atomic bomb strike on the city of Hiroshima in 1945. The dimensions of the Izumo allow the vessel to respond adequately to emergency assistance missions in home waters and through international peacekeeping requests. The helicopter destroyer has a capability to transport up to 4,000 personnel or some fifty military trucks. Additionally, the class holds the capacity to provide fuel to other Japanese warships in the fleet as required. This underway replenishment would eliminate the need for ships to drop anchor to refuel, saving steaming time. As such, the decision was made not to construct dedicated destroyer or supply ship types - instead to design, develop and construct "multi-mission" platforms consistent with other world powers, ships to serve multiple purposes on the high seas. So the "bigger the better" approach has allowed the Izumo to expand her base mission capabilities considerably. When compared to previous helicopter destroyer models, Izumo is 165 feet longer and 22 feet wider with a hanger deck 150 feet longer and 20 feet wider - all told close to a 50% increase in internal volume and deck space.
The 22DDH-class is powered with a propulsion arrangement similar to the Hyuga-class helicopter destroyers. In the Hyuga-class, a COGAG (COmbined Gas And Gas) turbine propulsion system is configured through 2 x General Electric / IHI Marine LM2500IEC gas turbines driving 1 x shaft while making 75,000 horsepower (42,000 kW). This configuration is now doubled in the 22DDH-class as two COGAG systems utilizing 4 x GE/IHI gas turbines connected to 2 x shafts making a total of 150,000 horsepower allowing for a maximum of 30 knots (56 km/h). The COGAG system was chosen due to the fuel efficiency of a gas turbine at its maximum power level and for its more economical fuel usage at cruise speeds.
The Izumo can accommodate up to nine helicopters simultaneously operating on its large flight deck and 14 to 17 helicopters can be stored in the hangar deck. Different helicopters also require different storage space so more or less can be assigned based on the helicopter type and mission requirement. Due to the lack of a launch catapult on the flight deck, conventional jet-powered naval aircraft cannot be used on the deck of the Izumo. However, the in-development Lockheed F-35B variant represents a Short Take-Off and Vertical Landing (STOVL) single-seat, single-engine, fifth generation multirole fighter designed for operations from limited deck space. This aircraft can perform air defense, ground attack and reconnaissance missions and is in line to become the central component of the Japanese Pacific Theater arsenal - perhaps aided in the near-future by the arrival of a smaller, combat-ready VSTOL Unmanned Combat Air Vehicle (UCAV). As such, observers in the region do not consider it a coincidence that the start of the American F-35B sea trials and the launch of the Izumo occurred in the same week. Once the technologically-advanced F-35B is operational, the list of strike-capable ships that can carry F-35B aircraft in the Pacific will increase in turn, possibly changing the balance of power in the region to an extent. Neighboring China does not share a close military relationship with the United States and therefore is relying on its own in-house fifth generation fighter and UCAV initiatives.
If procured, the F-35B could theoretically be served from both the 22DDH-class and Hyuga-class ships. Australia is building two Canberra-class Landing Helicopter Dock ships while the US operates eight Wasp-class Landing Helicopter Dock ships and two America-class amphibious assault ships - all of which could have the fighter operate from their flight decks. To side-step the F-35B issue, Japan has suggested that the reason for the increase in the 22DDH-class's size over the Hyuga-class is that Japan intends to use the V-22 Osprey tilt-rotor transport helicopter as its main aircraft. Currently, Japan is negotiating a purchase of a number of V-22 Osprey's from the US. China, Vietnam and the Philippine governments are, of course, watching the situation closely and will most likely respond in turn.
Aside from her assumed air arm, the Izumo is outfitted for defense against surface, undersea and aerial threats. 2 x 20mm Phalanx Close-In Weapons Systems (CIWSs), one mounted on the port side and the other along starboard, serve to counter the threat posed by low-flying aircraft and cruise missiles and are digitally-controlled for quick-reaction and accuracy. Additional defense is managed by 2 x SeaRAM (RIM-116 Rolling Airframe Missile) launchers which counter both aircraft and submarine threats. The SeaRAM couples the radar/electro-optical system of the Phalanx CIWS (Mk-15 Block 1B) with an 11-cell missile launcher on a trainable mounting. This system works directly with the OYQ-12 combat direction suite as well as the OPS-50 AESA radar and OPS-28 surface-search radar systems. The missile is a surface-to-air weapon and developed by Raytheon/Diehl BGT Defence using a blast fragmentation warhead and three-mode guidance system. The OQQ-23 bow sonar is used for standard "bottom-tracking" of submarines and through general Anti-Submarine Warfare (ASW) operations.
The JOS Izumo DDH-183 helicopter destroyer was formally commissioned on March 25th, 2015. Its assigned homeport is Yokosuka. The vessel is named after the Izumo Province, only the second Japanese warship to carry the name. The second vessel of the class is yet unnamed (as of 2015) and saw its keel laid down on October 7th, 2013 with an expected launch date sometime in middle-to-late 2015 and commissioning during 2017. Its homeport is unassigned as of this writing (2015).