Submarines: SSGNs Finally See Combat

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August 30, 2011: With nearly all of Libya overrun by rebels, it was possible to get a close look at how well the American Tomahawk TLAM-E did in its first combat use. The missile performed as predicted. Most of these Tomahawks were fired during the initial air attack on March 19th. Moreover, most of the Tomahawks (over a hundred) launched on that day were fired by one ship; the nuclear submarine USS Florida.  This was the first time an SSGN saw combat, but not the first time nuclear subs have fired missiles in wartime (U.S. SSNs have fired Tomahawks several times.)

The USS Florida was one of four Ohio class ballistic missile submarines (SSBN) converted to cruise missile submarines (SSGN). The USS Florida and the other three SSGNs entered service over the last five years, and this is the first time one of them fired its missiles in combat. Each of these Ohio class boats now carry 154 Tomahawk cruise missiles, and provides space for 66 commandos (usually SEALs) and their equipment.

The idea of converting ballistic missile subs, that would have to be scrapped to fulfill disarmament agreements, has been bouncing around since the 1990s. After September 11, 2001, the idea got some traction. The navy submariners love this one, because they lost a lot of their reason for being with the end of the Cold War. The United States had built a powerful nuclear submarine force during the Cold War, but with the rapid disappearance of the Soviet navy in the 1990s, there was little reason to keep over a hundred nuclear subs in commission. These boats are expensive, costing over a billion each to build and over a million dollars a week to operate. The four Ohio class SSBN being converted each have at least twenty years of life left in them.

The idea of a sub, armed with 154 highly accurate cruise missiles, and capable of rapidly traveling under water (ignoring weather, or observation) at a speed of over 1,200 kilometers a day, to a far off hot spot, had great appeal in the post-Cold War world. The ability to carry a large force of commandos as well was also attractive. In one sub you have your choice of hammer or scalpel. More capable cruise missiles are in the works as well. Whether or not this multi-billion dollar investment will pay off remains to be seen, but it certainly worked off Libya.

And then there’s the new Tomahawk. The RGM-109E Block IV Surface Ship Vertical Launched Tomahawk Land Attack Missile weighs 1.2 ton, is six meters (18 feet) long, has a range of 1,600 kilometers, getting there at a speed of 600-900 kilometers an hour, flying at an altitude of 17-32 meters (50-100 feet) and propelled by a jet engine generating only 600 pounds of thrust. Accuracy is on a par with JDAM (10 meters/ 31 feet). The Block IV Tomahawk can be reprogrammed in flight to hit another target and carries a vidcam to allow a missile to check on prospective targets.

But there’s always something new. Last year, there was a successful test of the new JMEW (Joint Multi-Effects Warhead System) warhead for the Tomahawk Block IV cruise missile. The new, 450 kg (1,000 pound) warhead is designed mainly for penetrating underground bunkers, but it will also provide excellent blast effect for less robust targets. Exact penetration was not revealed. JMEW uses laser terminal guidance, enabling it to hit within a few meters (ten feet) of its aiming point. JMEW can also hit moving targets.