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DDH-161 Hyuga / 16DDH "13,500 ton" ton Class

The DDH-161 Hyuga / 16DDH "13,500 ton" ton Class helicopter-carrying destroyer, similar in design to a small aircraft carrier, would provide the Maritime Self-Defence Force with greater capability for force projection. This program was initially known as the "13,500-ton" helicopter destroyer (DDH). The Defense Agency formally refers to them as the DDH (helicopter destroyer) follow-on mode. It is temporizing to refer to this type of vessel as a DD (destroyer). There had never been a destroyer that exceeded 10,000 tons. In fact, with a full displacement of about 20,000 tons when equipment fuel, water and weapons are counted in, they essentially can be classified as light aircraft carriers. The ships were later code-named 16DDH (16 as in the 16th year of the Heisei emperor in the Japanese calendar).

The 16DDH in JSDF classification is by no means an aircraft carrier. Its characteristic shape, however, is nothing but. The construction of these next-generation helicopter-carrying destroyers signifies a new direction for the MSDF, in which the service realizes decades-old aspirations.

DDH-161 Hyuga / 16DDH - Program

On 15 December 2001, the Japanese Government approved a new mid-term procurement plan for its Self-Defense Forces totaling 25,160 billion yen (US$223.6 billion) over the next five years. The new procurement plan allows the building of two DDH helicopter destroyer. The first two units are intended to replace the Haruna and the Hiei (both about 5,000 tons) that will be out of service in 2008 and 2009, respectively. They were expected to cost 100 billion yen apiece.

The fiscal 2004 defence budget gave the JMSDF (Japanese Maritime Defence Force) the largest warship Japan has had since the disappearance of its Imperial Navy. The first of the DDH 13,500-ton class ship was approved in 2004 as planned, , with another planned for 2005, with the total cost of 116.4 billion yen (US$1.06 billion). The second ship construction was postponed from its original 2005 plan because missile defense and satellite communication network replaced the prioprities.

IHI Marine United (IHIMU), Japan's leading shipbuilding company, received an order for the DDH from the Japan Defense Agency in December 2003. The "13,500-ton" DDH 181 Hyuga was launched on 23 August 2007 at the IHI Marine United shipyard in Yokohama, The Hyuga is named for a World War II-era hybrid battleship/carrier that could carry 22 fighters, a decision not lost on defense analysts. The first ship was expected to be completed in March 2009.

It was anticipated that at least one additional DDH destroyer will be built in the coming years. As of late 2007 the second 16DDH unit was scheduled to be laid down in May 2008. At the IHI Marine United Yokohama Factory at Isogi Ward, Yokohama City, Kanagawa Prefecture, the second Hyuuga Class helicopter-carrying defense ship, nicknamed 18DDH [DDH funded by Fiscal Year Heisei 18 (Fiscal Year 2006) budget], was formally named JDS Ise, scheduled to enter service in 2011 March.

The Hyuga, the MSDF's latest helicopter destroyer, was commissioned in March 2009. The ship has a length of 197 meters and a width of 33 meters. The Hyuga was the largest ship in the MSDF fleet, but the planned 22DDH helicopter destroyer would have that title once it is completed.

A total of four were planned to replace the two Haruna-class and two Shirane-class DDHs in the ASW role. The earlier DDH had an operational life of about 35 years, suggesting that the three further units would be required in the 2015 timeframe. In fact, only two units of this class are to be built, along with two further units of the much larger 22DDH class.

DDH-161 Hyuga / 16DDH Design Features

The new DDH was to be one of the largest naval ships in Japan, with a light displacement of 13,500 tons. The Defense Agency said that in order to simultaneously operate four MH-53E jumbo helicopters that are capable of carrying up to 55 people, the displacement of the ships will reach about 13,500 tons. They are equipped with a sonar and ASROC anti-submarine missiles, along with the MK 15 Phalanx CIWS (Close In Weapon System) and 16 MK 41 VLS (Vertical Launch System). Reports that they carry an Aegis-type air defense system are in error, since this capability is provided by DDG escort ships.

The absence of a well deck in the Hyuga was curious, and explained that the fact that Hyuga would serve as an ASW command ship to lead destroyer squadrons in conducting blue-water ASW operations.

In early 2005 Mitsubishi Electric Corporation (Melco) of Japan and Thales Nederland signed a contract for the delivery of a Thales missile control module that will be incorporated in Melco's new FCS-3 radar. The missile control module will add Thales Nederland's revolutionary ICWI technology to the FCS-3 radar. This radar will be installed on the 16DDH, the first of a new class of helicopter carriers for the Japanese Maritime Self-Defence Force.

ICWI (Interrupted Continuous Wave Illumination) is a technology that enables a missile control system to guide several missiles simultaneously to various threats, greatly enhancing a ship's defence capabilities. The performance of ICWI-based missile defence systems was convincingly demonstrated during the live firing trials of the Royal Netherlands Navy's "De Zeven ProvinciŽn" late 2003 and the live firing trials of the German Navy's "Sachsen" mid 2004. Both ships are equipped with APAR, Thales' highly advanced multifunction radar, especially designed to guide ESSM and SM2 missiles to incoming threats.

With this contract the history of co-operation between Melco and Thales Nederland continues. About twenty years earlier the companies already worked together on Thales' well-known WM25 fire control radar. Thales Nederland is proud to continue this relationship through its state-of-the-art ICWI and APAR technology. Both Melco and Thales expected that their good relationship will be strengthened by further co-operation in the future.

In May 2005 GE Transportation's marine gas turbine business announced it will supply Ishikawajima-Harima Heavy Industries, Co. Ltd. (IHI) with four GE LM2500 aeroderivative gas turbines. The engines will power the first of a new class of Japan Maritime Self-Defense Force's (JMSDF) helicopter-carrying destroyers. The 13,500-ton DDH destroyer will use two propulsion trains, each consisting of two LM2500s in a COmbined Gas turbine And Gas turbine configuration (COGAG), driving a propeller through a gearbox. The engines will each provide 25,000 shaft horsepower.

The DDH will be the largest operational naval ship in Japan with a staff of more than 350. Its equipment density will be many times more than that of commercial ships. There will be four helo landing spots on an axial flight deck and supposedly it will carry three SH-60 Seahawk variants for ASW and an EH-101 Merlin for mine warfare, and it is said to have the capacity to carry MH-53E. Officially, the ship will carry three SH-60J anti-submarine helicopters and one CH-53E Super Stallion multipurpose helicopter, but four helicopters would be only a fraction of the vessel's capacity. Other reports stated that it can handle 11 aircraft in its hangar. The 16DDH is close in size and displacement to the British Invincible class, which can carry up to 22 rotary and VSTOL aircraft.

The design includes two elevators connecting the flight deck and hangar deck. The forward elevator is about 33 feet [10 meters] by 65 feet [20 meters], while the aft elevator is about 45 feet [13.1 meters] by 65 [20 meters] feet. Unofficial artwork shows the F-35B VSTOL strike fighter operating from these ships. The F-35B is has a wingspan of 35.0 ft (10.7 m), and is 50.5-51.1 ft (15.4 m) long. It would seem that there would be more than ample margin on the aft elevator to accomodate the F-35B.

Initial reports on the 16DDH design, funded in the 2004 Japanese Defense Budget, showed that it will have the capability to carry 13-17 VSTOL aircraft. Japanese interest in the F-35 Joint Strike Fighter program (a VSTOL-capable design) is well documented. Thanks to the lift-fan system, the F-35B's total vertical lifting thrust is about 39,700 pounds, more than 14,000 pounds greater than the engine alone would produce without the lift fan. The aircraft's empty weight is about 30,000 pounds, and maximum gross takeoff weight is 60,000 lbs. The F-35B VSTOL version of the F-35 can take off distance in VSTOL of about 550 feet, which can barely be accomodated on the 650 foot long flight deck of the DDH-161 Hyuga with an angled deck configuration. Such a structural modification would add about 10 meters to the width of the flight deck. Alternately, a ski jump could be fitted to the bow of the flightdeck, in which case the F-35B take-off roll would be about 450 feet.

Curiously, while the initial artwork for the flightdeck of the 16DDH indicated an entirely symetrical arrangement, the most schematics depict a notched flightdeck, with the notch located precisely at the root of where an angled flightdeck would protrude to port over the hull.

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