|Comparison of current JN "DDH" (foreground) with new design in background|
Details of the propulsion system for the new Helicopter Carrier of the Japanese Navy / Maritime Self-Defence Force (JMSDF) have been announced. To be built by IHI of Tokyo, the LOA 814 ft (248 m) and beam of 124 ft (38 m) vessel will have a fully loaded displacement of around 27,500 tons. The official Japanese 22DDH designation of the ship is of a “destroyer” but in reality it is a helicopter carrier. The reason for the diplomatic designation lies in the post World War 2 constitution which prohibits Japan to own aircraft carriers.More info from here:
The propulsion system comprises four GE LM2500 gas turbines of 33,600 hp (25 MW) each giving a total power of around 135,000 hp (100 MW) in a COGAG arrangement giving a speed of 30 kt. The ships will also be using GE’s smaller turbine, the LM500 with an output of approximately 6,000 hp (4.5MW) in a turbo-electric configuration for on board power generation.
Japanese accounts suggest that one of the reasons for the drastic increase in size of the 22DDH design is a planned shift to the V-22 Osprey as the primary air group element for these ships. It is not clear whether these would be replacements for or supplemental to the SH-60Ks that equip the Hyuga class. These accounts also make it clear that the F-35B short takeoff and vertical landing variant of the Joint Strike Fighter is seen as a key system for these ships. Apparently, provision for the operation of UAVs is being included within the design.