Japan Defense Ministry Gives Details of "27DD" Destroyers, Railgun-Armed Aegis Ships

25 Juli 2015

The Japanese government has allocated the budget and formally begun the process of constructing and adding a new subclass of Aegis destroyers to its existing fleet of Kongo and Atago class Aegis ships. This new subclass is officially called the "27DD". It is widely regarded as the second but a much improved batch of the JMSDF's Atago class destroyer (which in turn is the same improvement of Kongo). The two ships of 27DD will be commissioned in 2020 and 2021. (image : Japan MoD)

According to the Japanese MoD's RfP to bidding contractors, the 27DD will incorporate a number of design changes compared to the first batch of Atagos. First, the hull of 27DD has been enlarged to an empty displacement of 8,200 tons compared to the original Atago's 7,700 tons. It is believed in the Japanese defense community that the enlargement of the hull was conceived in order to provide a necessary growth space for advanced naval weapon systems that are currently under development in Japan, and will be incrementally added to the ships' arsenal as they are developed -- such as railguns and laser point-defense systems.

 JAX high-calibre railgun for naval ships (image : Japan MoD)

And like all Japanese combatant ships now being constructed, The 27DD ships will be powered by a COGLAG propulsion system (these two, as would be explained again later, would represent a series of essential improvements to the ships' space and power management and distribution in light of the new weaponry that they will operate in the near future). On the more minor technical front, the new ships will also equip a new surface-search radar (the AN/SPQ-9B from Northrop Grumman), new anti-ship missiles, a multi-static sonar system, and an enhanced Aegis combat system that will offer better Cooperative Engagement Capability (CEC).

TRDI laser CIWS (image : Japan MoD)

Eventually, the Japanese MoD envisions their new Aegis ships to be the first operating platform of an indigenous naval railgun and laser point-defense system that they are locally developing in Japan. The plan for the railgun armament was outlined in their recently published FY2015 defense budget report. (Japan MoD)


Japan agrees to Aegis tech transfer, re-export

The government of Japan agreed on 23 July to transfer to the United States software and components that will be installed on international versions of the Lockheed Martin-developed Aegis combat system.

The Ministry of Defense (MoD) in Tokyo said that the approval enables the items to be exported to a third country following their transfer to Lockheed Martin. In addition to the United States, existing operators of the Aegis combat system include Australia, Japan, Norway, South Korea, and Spain.

The MoD added that the decision was made by the National Security Council in response to a request from the US Department of Defense for Japanese industry to participate in the production programme. (Jane's)