27DDG DDG-177 Atago (DDG 7,700 ton) Class

Planning by the Japan Defense Agency Maritime Staff Office included two additional Aegis ships in the FY2000 five-year budget. At least two Improved Kongo-class DDGs were planned, with displacement of 7,700 tons standard to 10,000 tons full load. The first of these, the Atago, was commissioned on 15 March 2007. The new class of Guided Missile Destroyer will be equipped with the latest version of Aegis system and will have a hanger that is capable ot storing 2 helicopters. Construction will start as soon as 2002. Currently there is the possibility that at least four more Kongo Class DDG will be constructed, these four will be able to house at least one SH-60J ASW helicopter, much like the USN Burke Flight IIA's.

The US Navy's Program Executive Officer-Theatre Surface Combatants (PEO TSC) has played an integral part in Japan's shipbuilding program. The JMSDF, with support from PEO TSC, is in the process of identifying the combat systems and configuration for use in the DDG-2317 Aegis ship construction effort. The proposed baseline for DDG-2317 is Aegis Weapon System Baseline 7 phase 1 and includes a combination of U.S. and Japanese manufactured systems to make up the total Aegis system. Japanese industry participation was expected to be more prevalent in DDG-2317 and subsequent construction programs. The Japan Defense Agency, Maritime Staff Office, has advocated Japanese industrial participation as its most important initiative toward improving operational readiness and expanding the country's technical infrastructure. The JMSDF, Japanese shipbuilders, and Japanese manufacturers have gained considerable knowledge about integration and testing of complex weapon systems by working with the Aegis program.

The new Aegis programs will present a significant challenge to JMSDF, as well as Navy IPO and PEO TSC, necessitating innovative management to coordinate and analyze critical timelines and ensure that FMS, direct commercial sales (DCS), and domestically manufactured materiel, were properly phased to meet DDG-2317 construction and commissioning milestones.

Although the basic hull structure is based on the Kongo class design, the reference displacement is 500 tons greater, and the total length is about 5 meter increase. It is the first Japanese Aegis-system destroyer equipped with the BMD (Ballistic Missile Defense) capability from the beginning of commissioning, and Japan-US joint development is in progress. It also has the launch capability of SM-3 Block IIA.

In addition, 27DDG has the CEC (Cooperative Engagement Capability) to integrate the sensor information, such as short-range low-altitude target-to-excellent in the search operation detection ability of water radar (SPQ-9B) and other destroyers equipped with the joint battle for the network. For the first time in response to the CEC, because it enabled the sharing of high-precision data of the level that can be used for shooting, you can only be in the missile attack sensor information of the other ship if CEC corresponding ship to each other.

With the addition of four Komagata type vessels already having BMD capability and two specialized remodeling plans to give the same capacity, and the addition of 27DDG and 28DDG, the maritime SDF's ability to cope with ballistic missile attacks and the air defense capability of the fleet will definitely improve dramatically. Furthermore, since it also has the ability to control command and communication, we can also greatly expect to play a role as a command ship and dispatch mission abroad such as international peace cooperation activities and international emergency relief activities, and large scale missions.

The Arleigh Burke class missile destroyer is at the head of the US Navy, with high command functions and functions of the Maritime Self Defense Force It is an escort ship that has been devised according to operational requirements. Although it inherits the hull structure of the warmed-type escort ship, it is not an exaggeration to say that this class is a complete type of Japan's Aegis system equipped escort ship, as it is designed based on the performance of the Kongo type and the Hokkaido type .

Atago type differs in RCS: the shielding reduce the conscious fittings of (Radar Cross Section radar effective reflection area) has been decorated throughout. It is also noteworthy that aircraft maintenance capabilities are newly added and the airplane operational capability is greatly enhanced as compared with other types. As other features of the hull, it seems to be designed considering the ship of the SDF from the time of commission.

One change is the equipped boats of later 27DDG, 2 vessels 11m work boat in Atago type, 7.5m RHIB the (composite type work boat) one vessel had been mounted, one ship in 11m work boat 27DDG and 7.5m RHIB (Combined type work boat) One of them is mounted on both sides of the bridge structure, and the structure is enlarged somewhat forward as the mounting position of RHIB is changed. The 27DDG seems to be shielding the base of the loading boat, the middle sliding pad and the periphery, the ship's side passage to the front deck, etc., and considering the reduction of RCS over the details.

Atago type is equipped with a hangar as a model the Arleigh Burke-class Flight (flight) 2A of the US Navy, but it does not have is to develop the ability of the aircraft. From the budgetary relationship also the landing restraint which is required for the aircraft equipped escort ship is also set as equipment at a later date. In order to operate the aircraft, a lot of equipment such as aircraft maintenance equipment, aircraft operation ammo, aircraft material warehouse, TACAN (Tactical Air Navigation), etc. are necessary in addition to the ship restraint equipment. 27DDG is supposed to mount one ship restraint Mk6 RAST adopted from an Akuki type, and the aircraft is supposed to be stored along the port because the Mk 41 VLS is equipped in the center of the upper part of the rear part.

In the FY2005 plan, 168 billion yen was included as a part of procurement costs for the name ship construction cost and the Aegis system for two vessels. In addition, the estimation request of the FY2008 plan includes 167.5 billion yen as the construction cost of No. 1 ship. There were construction records of the missile destroyers "Kon-so", "Kirishima", "Miyougo", "Atago" and "Ashigara" since MHI (Mitsubishi Heavy Industries) Nagasaki Shipyard has a building track record, as does IHI. JMU (Japan Marine United) was established by IHI-MU (Ishikawajima Harima Heavy Industries Marine United) and Universal Shipbuilding merged in 2013.

The biggest feature of the design is that the engine type was changed to COGLAG (Combined Gas turbine eLectric And Gas turbine: hybrid propulsion system) like 25DD. The COGLAG system is a propulsion system that combines an existing organization promotion system with a new electric propulsion system and is adopted by the Maritime Self Defense Force from 25 DD. Its characteristic is that fuel economy efficiency at the time of low-speed navigation is remarkably improved as compared with the conventional COGAG method, fuel consumption can be suppressed, it becomes possible to respond to longer-term action and mission, and life cycle as an escort ship It is said that a significant reduction in cost was also expected.

As a result of adopting the COGLAG system, the hull length has been extended by about 5 meters to accommodate high-voltage switchboards, propulsion motors, propulsion and power supply gas turbine generators and so on, so that the reference displacement was expanded from 7,500 tons to 8,000 tons. Also, the size of the second chimney has been reduced since two of the four main gas turbine engines were replaced by propulsion motors.

The 8,200t type escort ship is equipped with the latest battle system program (Aegis BMD 5.1) from the beginning of service, and together with the SM - 3 Block IIA, the new signal processing device of SPY - 1D (V) radar MMSP (Multi Mission Signal Processor), it becomes possible by modification of the link 16 message and it becomes EOR (Engage on Remote) function. In addition, although the air defense capability was limited when operating in the BMD mode, the IAMD (Integrated Air and Missile Defense) mode introduced by the 8,200t type escort ship is based on the SPY With flexible allocation of -1 D (V) radar resources, it is possible to cope with ballistic missiles, aircraft and anti-ship missiles etc. automatically. Furthermore, SA (Situation Awareness) ability improves by sharing track information of high precision level usable for shooting control with addition of CEC.

The 8,200t type destroyer is similar to the Asago type, and further strengthening of the anti - submarine search capability is planned. Although the sonar system is a Harmoner SQS - 53C introduced from the United States and a counter - phone sonar system SQQ - 89 (V) introduced from the United States, the related equipment has been improved in capacity and many functions are added. In addition, while the Tomago type was equipped with a domestically produced towed passive sonar, the 8200t type escort ship is equipped with the US Navy's towed passive sonar, MFTA (Multi-Function Towed Array). MFTA is superior in passive reception performance for detecting sound radiated from a submarine which is the original function of a towed passive sonar, and bistatic function is added.

The anti-submarine attack weapons are Vertical Launching ASROC (VLA: Vertical_Launching_ASROC) launched from Mk 41 VKS and the triple torpedo launcher HOS - 303. From this HOS - 303, it is now possible to launch conventional Mk 46 torpedoes, 97 torpedoes and 12 torpedoes.

For the Aegis and weapons system Mk7, are planning a new type of base line 9C, with significantly upgraded the ability to handle aircraft goals and ballistic missiles simultaneously, such as aircraft and anti-ship missiles, compared to existing ones. In addition, MMSP (Multi-Mission Signal Processor) corresponding to jamming seems to be introduced, MMSP is a system complementing baseline 9, it has high expansion capability and it is easy to upgrade to Aegis BMD.

Even with the current Aegis system (Baselines 5 and 7), there is a capability to cope with ballistic missiles and aircraft / anti-ship missiles simultaneously. In fact "USS CG 70 Lake Erie (Lake Erie) has succeeded in simultaneously simulating simulated ballistic missiles and simulated air target with SM-3 block 1A and SM-2. Baseline 9 is these upward compatible versions, so once installation is complete you will not be forced to choose whether it is an air-to-air match or a ballistic missile.

On December 10, 2012 the Defense Security Cooperation Agency notified Congress of a possible Foreign Military Sale to Japan for the upgrade of previously provided AEGIS Combat Systems, as well as associated equipment, parts, training and logistical support for an estimated cost of $421 million. The Government of Japan requested a possible sale for the upgrade of previously provided AEGIS Combat Systems as part of the modernization of two Atago Class Ships (DDG-177 ATAGO and DDG-178 ASHIGARA) with Integrated Air Missile Defense capability. This sale will enhance Japan’s Ballistic Missile Defense (BMD) capabilities by modernizing and upgrading the AEGIS technology on its two Atago-class destroyers.

The State Department has made a determination approving a possible Foreign Military Sale to Japan for DDG 7 and 8 AEGIS Combat System, Underwater Weapon System, Cooperative Engagement Capability and associated equipment, parts and logistical support for an estimated cost of $1.5 billion. The Defense Security Cooperation Agency delivered the required certification notifying Congress of this possible sale on August 4, 2015.

The Government of Japan requested a possible sale of two (2) ship sets of the MK 7 AEGIS Weapon System, AN/SQQ-89A (v) 15J UWS and CEC. Additional items include associated equipment, training and support for its Japan Fiscal Year (JFY) 2015 and JFY2016 new construction destroyers (DDGs). The ACS and associated support will be procured over a six (6) to seven (7) year period, as approved by Japan in budgets for JFY2015 and JFY2016. The estimated value of this proposed sale is $1.5 billion.

The ACS/UWS/CEC support ship construction for a new ship class of DDGs based upon a modified Atago-class hull (Ship Class not yet named) and a new propulsion system. The equipment and services to be provided include: two (2) ship sets of installation support material and special purpose test equipment, as well as the systems engineering, technical services, on-site vendor assistance, spare parts, systems training and staging services necessary to support ship construction and delivery. Post-construction Combat System Qualification Testing is expected to be procured in a future Foreign Military Sales (FMS) case.

The addition of two (2) new AEGIS DDGs to Japan’s fleet will afford more flexibility and capability to counter regional threats and continue to enhance stability in the region. Japan currently operates AEGIS ships and is proficient at using evolving ballistic missile defense capability and effective at employing the AN/SQQ-89 UWS for undersea surveillance and detection. Japan has demonstrated the capability and commitment necessary to incorporate CEC into its fleet and will capably assimilate this technology into its operations.