September 9, 2011: STRATEGY PAGE
For its new 22DDH class helicopter carriers, Japan has decided to replace Phalanx anti-missile automatic cannon systems with the SeaRAM missile. This is part of a growing trend. What's interesting about this is that SeaRAM is basically the Phalanx system, with the 20mm automatic cannon replaced with a box of eleven RAM (RIM-116 "Rolling Air Frame") missiles.
The Phalanx was developed in the 1970s, and entered service in 1977. RAM was developed in the 1980s, and didn't enter service until 1993. RAM has a longer range (7.5 kilometers) than the Phalanx (two kilometers) and was originally designed to be aimed using the ships fire control systems. Phalanx, on the other hand, has its own radar and fire control system and, once turned on, will automatically fire at any incoming missiles. This was necessary, as some anti-ship missiles travel at over 500 meters a second. With SeaRAM, you've got a little more time, and can knock down the incoming missile farther from the ship. This is important, because it was feared that a large, very fast anti-ship missile (which the Russians prefer, and sell to foreigners), even when shot up by Phalanx, might still end up having parts of it slam into the target ship. Since SeaRAM has eleven missiles ready to fire, it can also engage several targets at once, something the Phalanx could not do.
The RAM missiles are 127mm in diameter, 3 meters (9.3 feet) long and weigh 73.6 kg (162 pounds) each. The terminal guidance system is heat seeking. Basically, it uses the rocket motor and warhead from the Sidewinder air-to-air missile, and the guidance system from the Stinger shoulder fired anti-aircraft missile. SeaRAM missiles cost about $450,000 each. SeaRAM is meant to provide combat support ships that normally have no defenses, or at least no combat radars and fire control system.
The new 22DDH class destroyers are actually amphibious assault ships, which look like aircraft carriers. These are similar, but larger than the current Hyuga class ships. The 22DDHs are 249 meters (779 feet) long and displace 24,000 tons. The ship can carry 400 troops, 50 vehicles and 14 helicopters.
The two Hyugas recently entered service. These ships are 197 meters (610 feet) long and displace 18,000 tons. They operate up to 11 (mostly SH-60) helicopters from a full length flight deck. Although called a destroyer, it very much looks like an aircraft carrier. While its primary function is anti-submarine warfare, the Hyuga will also give Japan its first real power projection capability since 1945. The Hyuga is the largest warship built in Japan since World War II. The Japanese constitution forbids it to have aircraft carriers, which is the main reason it is called a destroyer. That, and the desire to not make the neighbors anxious. East Asian nations still have bad memories about the last time Japan had lots of aircraft carriers.
The Hyuga also has 16 Mk41 VLS (Vertical Launch System) cells for anti-aircraft and anti-ship missiles. There are also two 20mm Phalanx anti-missile cannon and two triple 12.75-inch torpedo mounts. There is a crew of 350 and a top speed of about 60 kilometers. Vertical takeoff jets like the Harrier and F-35B could also operate from the Hyuga.
The last Japanese warship to be called the Hyuga was a World War II battleship that entered service in 1918, and was converted to a hybrid battleship/aircraft carrier in 1943. The new Hyuga will be used for peacekeeping missions as well, and for that role its many helicopters will be most useful. During World War II, there was also a Japanese battleships named Ise, which was the lead ship of a class of ships that also contained the Hyuga. Both were 35,000 ton warships, and both were sunk, in the same week, in late July 1945. The Ise was also rebuilt, during the war, as an aircraft carrier (actually a hybrid battleship/aircraft carrier.)
Japanese admirals see the new carriers multi-purpose ships, being capable of anti-submarine warfare, as well as amphibious operations and logistical support.
SeaRAM missile - photo US Navy