Naval Air: Japan's Secret Aircraft Carriers

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August 25, 2007: Japan launched the first of its new helicopter-carrying destroyers, the Hyuga, amid great fanfare. This vessel, officially 13,500 tons, will be able to carry helicopters. Plans are for them to mostly carry SH-60 helicopters, but the Hyuga will give Japan its first real power projection capability since 1945.

Japan plans to build at least two Hyuga-class vessels, which can carry up to 11 helicopters, displace 13,500 tons, and are equipped with a Mk41 VLS, giving them the ability for fire air-defense missiles like the Standard and the ESSM, and a vertically-launched ASROC, but also the Tomahawk cruise missile, if Japan wished to do so. It also has two triple 12.75-inch torpedo mounts.

The name of the lead ship is probably the first clue that this ship is more than meets the eye. The HIJMS Hyuga was a battleship commissioned in 1918, and which served in World War II. After the battle of Midway in 1942, the Hyuga was converted into a hybrid battleship/aircraft carrier. The new Hyuga looks like a carrier, and her mission sounds like that of a carrier.

This ship in the same weight range of the European "Harrier carriers" (the British Invincibles, the Italian Garibaldi, the Spanish Principe de Asturias, and the Thai Chakri Narubet-classes). While this ship is currently planned to carry helicopters only, European experience (particularly from the British) has shown that this can be an effective platform for fixed-wing aircraft, like the F-35B. That makes the designation of "helicopter carrying destroyer" technically true, but in reality a useful fiction. In essence, they could act as small aircraft carriers or as a landing platform helicopter like HMS Ocean if transport helicopters are used.

Such looseness with designations is nothing new for Japan. In its older incarnation as the Imperial Japanese Navy, there were numerous instances of these involving surface units. The most glaring were the heavy cruisers of the Mogami-class. Supposedly light cruisers displacing 8,500 tons (and fifteen 155-millieter guns), these were really heavy cruisers of over 13,000 tons (with ten eight-inch guns). The claims that those ships were compliant with naval arms limitation treaties were on the disingenuous side.

Another instance involved the super-battleships Yamato and Musashi. The guns had been called "special 40-centimeter", leading many Allied intelligence officers to believe the vessels used sixteen-inch guns. As it is known now, the main battery consisted of nine eighteen-inch (40-centimeter) guns.

In essence, Japan will have a ship about the size of the vessels that were the centerpiece of the British response to a crisis halfway around the world 25 years ago, with a flight deck and an offset island. They performed well, too - just ask Argentina. The Hyuga means that Japan is back in the power projection business. - Harold C. Hutchison ([email protected])