Atago-class destroyer

JS Ashigara
Class overview
Name	Atago class
Builders	Mitsubishi Heavy Industries
Operators	Japan Maritime Self-Defense Force
Preceded by	Kongō class
Succeeded by	Maya class
Cost	¥140 billion[1] $1.48 billion (constant 2009 USD)
Built	2004–2008
In commission	2007–
Completed	2
Active	2
General characteristics
Type	Guided-missile destroyer
Displacement	7,700 tons standard 10,000 tons full load[2]
Length	165.0 m (541 ft 4 in)[2][3]
Beam	21.0 m (68 ft 11 in)[2]
Draft	6.1 m (20 ft 0 in)[2]
Propulsion	4 IHI/GE LM2500-30 gas turbines Two shafts 5-bladed CP props 100,000 shp (75,000 kW)
Speed	30 knots (56 km/h)
Boats & landing craft carried	2 × 11-meter work boats 1 × Rigid hull inflatable boat
Complement	300
Sensors and processing systems	AN/SPY-1D(V) multi-function radar OPS-28E surface search radar (later replaced by SPQ-9B) 3 × AN/SPG-62 illuminators AN/SQQ-89 with SQS-53C and OQR-2 (later replaced by SQR-20) Mk. 46 Optronic director
Electronic warfare & decoys	NOLQ-2B intercept and jammer 4 × Mk. 36 SRBOC Chaff and Decoy Launching System
Armament	1 × 5-inch (127 mm)/62 Mk 45 Mod 4 gun 8 × Type 90 (SSM-1B) anti-ship missile in quad canisters 2 × 20 mm Phalanx CIWS 2 × HOS-302 triple torpedo tubes: Mark 46 torpedo Type 73 torpedoes 96-cell Mk 41 Vertical Launching System: SM-2MR surface-to-air missiles SM-3 anti-ballistic missiles VL-ASROC anti-submarine missiles RIM-162 surface-to-air missiles
Aircraft carried	1 × SH-60K helicopter
Aviation facilities	Flight deck and enclosed hangar for one helicopter

The Atago class of guided-missile destroyers (あたご型護衛艦, Atago-gata Goeikan) in the Japan Maritime Self-Defense Force is a modified version of the Kongō class equipped with the Aegis Combat System.^[2][4]

The Maritime Self-Defense Force (MSDF) began construction of the Aegis-equipped Kongō class in FY1988 as the core ship for air defense of its fleet. With the commission of the Kongo class, each of the four escort flotillas (護衛隊群, Goei-tai-gun) had one Tartar-equipped destroyer and one Aegis-equipped destroyer.^[4]

In the 2000s, the steam-powered Tachikaze-class destroyers were nearing the end of their life, and their Tartar Weapon Systems were becoming obsolete. As their replacements, two Aegis-equipped destroyers, Atago class, were built in the FY2002 and 2003 budget.^[4]

The design is fundamentally an improved and scaled-up version of the Kongō-class destroyers with a 4-meter extension of the hull. Just as the Kongō class, the superstructure is larger than aboard the American counterparts, Arleigh Burke-class Flight IIA.^[5]

One of the most obvious changes is an additional hangar to carry one SH-60K helicopter. In comparison to the Kongō class which only had a helicopter deck, these ships have better helicopter handling facilities.^[5]

Another external feature is the reduction of the radar cross-sectional area. For example, the Atago class use a new stealthier plain-structure mast, which was originally designed in Japan, rather than familiar sturdy truss mast. A new modified smokestack and other improvements were also introduced to make the Atagos stealthier.^[5]

The propulsion systems are almost the same as those of the Kongō class and Arleigh Burke class, powered by four Ishikawajima-Harima LM2500 gas turbines giving them a top speed of 30 knots (56 km/h; 35 mph).^[2] The installation of three generators is also retained, but the output per unit is increased to 2,800 kilowatts.^[5]

The class is equipped with the Aegis Weapon System (AWS). The system version was Baseline 7.1 immediately after they were put into service; then both ships have been updated to Baseline 9C with modernization.^[6]

As surface-to-air missiles, The SM-2MR Block IIIA/B has been used. Since FY 2016, they have also been equipped with a missile defense capability with an Aegis BMD 5.0CU system to launch SM-3 Block IA and IB anti-ballistic missiles.^[6]

The missile launcher is the same Mark 41 Vertical Launching System as the Kongo class, but the missile reloading crane has been omitted, so the number of missile cells is increased by 3 cells each on the bow and stern sides. The Kongo class had 29 cells on the foredeck and 61 cells on the afterdeck, but the Atago class has a hangar, so 64 cells are placed on the foredeck and 32 cells on the afterdeck.^[6]

These cells contain not only RIM-162, SM-2, and SM-3, but also VL-ASROCs.^[2] Additionally, they are equipped with HOS-302, one of the Japanese variant of the Mark 32 Surface Vessel Torpedo Tubes, as anti-submarine weapons.^[6] While the Kongō class is equipped with domestic sonar and ASW combat system, the Atago class is equipped with American-made AN/SQQ-89(V)15 with AN/SQS-53C sonar. Only the towing sonar was a domestic OQR-2D-1, which was later replaced with an American-made SQR-20 Multi-Function Towed Array (MFTA).^[6]

The 127mm bore gun's barrel has been extended from the 54 caliber of the Kongō class to the 62 caliber with strengthened powder charge enabling a 38 km (24 mi) firing range. As with other Japanese ships being refit, the American-made Harpoon missiles (such as in the initial configuration of the Kongō class) can be replaced with the Japanese-made Type 90 (SSM-1B) surface-to-surface missiles; those interfaces are compatible.^[6]

• List of naval ship classes in service
• List of active Japan Maritime Self-Defense Force ships

• "Technical characteristics of Atago-class DDG". Ships of the World (in Japanese) (918). Kaijin-sha: 81–99. February 2020. NAID 40022135570.
• Kōda, Yōji [in Simple English] (December 2015). "History of Domestic Built Destroyers of JMSDF". Ships of the World (in Japanese) (827). Kaijin-sha. NAID 40020655404.
• Wertheim, Eric (2013). Guide to Combat Fleets of the World (16th ed.). United States Naval Institute. ISBN 978-1-59114954-5.
• Yamazaki, Makoto (August 2014). "Development of Japanese DDG". Ships of the World (802). Kaijin-sha: 69–75. NAID 40020135975.

Wikimedia Commons has media related to Atago class destroyers.

• GlobalSecurity.org; JMSDF DDG Atago Class