Surface Forces: Corrosion Cripples The LCS


June 21, 2011: Just as the U.S. Navy decides to put its new "Littoral Combat Ship" (LCS) into mass production, serious structural flaws have been discovered in both ships. The most serious problem is in the USS Independence, a radical trimaran design. It seems that a "dissimilar metals" situation arose when salt water, the aluminum hull and some other metals got into close proximity with each other, and extensive corrosion resulted. Aluminum hulls tend to corrode more than steel, but the problem became so bad with the USS Independence that, 18 months after entering service, it is headed for dry dock, corrosion repairs and design changes to eliminate the problem. The more conventional design, the monohull USS Freedom has developed cracks, as long as 15 cm (six inches).

Cracks and corrosion are common in new warship designs, especially designs that are radically different (like the broad trimaran shape of the USS Independence.) Usually, these problems can be fixed, but there's always the risk that the new design will be seriously flawed, requiring extensive rework and a halt in building more ships of that class. 

This is all part of the expected years of uncertainty and experimentation, as this radical new combat ship design seeks to find out what works, to what degree, and what doesn't. There is some nervousness about all this. The U.S. Navy has not introduced a radical new design for nearly a century. The last such new design was the aircraft carrier, which required two decades of experimentation, and a major war, to nail down what worked. Even the nuclear submarines of the late 1950s and early 60s were evolutionary compared to what the LCS is trying to do.

In the last five years, two different LCS designs were built, and put into service. Problems were encountered. The much smaller crew required some changes in how a crew ran a ship, and how many sailors and civilians were required back on land to support an LCS at sea. It was found that, so far, the interchangeable mission modules take far longer (2-3 days instead of 2-3 hours) to replace. The LCS has still not seen combat, and the navy wants the first violent encounter to be successful, or at least not disastrous. It is expected that there will be surprises, which is about all that can be guaranteed at this point.

The navy surprised everyone last year by choosing both designs, and requesting that the fifty or so LCS ships be split between the two very different looking ships. While both ships look quite different (one is a traditional monohull, while the other is a broader trimaran), they both share many common elements. One of the most important of these is the highly automated design, and smaller crew. Both ships have accommodations for only 75 personnel. Normally, a ship of this size would have a crew of about 200. The basic LCS crew is 40, with the other 35 berths occupied by operators of special equipment.

The LCS crews are also modularized, so that specialized teams can be swapped in to operate specific modules. Thus about 40 percent of the ship is empty, with a large cargo hold into which the mission package gear is inserted (and then removed, along with the package crew, when it is no longer assigned to that ship.) Thus the LCS has two crews when underway, the "ship" crew and the mission package crew. The captain of the ship crew is in charge, and the officer commanding the mission package is simply the officer in charge of the largest equipment system on board. There are a variety of interchangeable modules (e.g., air defense, underwater warfare, special operations, surface attack, etc.), which allow the ships to be quickly reconfigured for various specialized missions. Crews will also be modularized, so that specialized teams can be swapped in to operate specific modules. The design and crew requirements for these modules is still a work in progress, but also shows a need for more people, or more automation.

So far, the heavy workload has not hurt morale. The small crew means that everyone knows everyone, and it's standard for people to handle a number of different jobs. Even officers pitch in for any task that needs to be done. This kind of overworked enthusiasm is actually typical of smaller naval craft. These included World War II era PT boats, with crews of up to 17, and current minesweepers (with crews similar to an LCS) and larger patrol boats. There's also the "new" factor. In addition to being new ships, there is a new design and lots of new tech. This gets people pumped. But the experience of using the LCS has to be used to develop changes that will make these ships viable for the long haul.

The two different LCS designs are from Lockheed-Martin (monohull) and General Dynamics (trimaran). The first LCS, the monohull USS Freedom, completed its sea trials and acceptance inspections two years ago. The ship did very well, with far fewer (about 90 percent fewer) problems (or "material deficiencies") than is usual with the first warship in a class. USS Independence (LCS-2) was laid down by General Dynamics in late 2005 and commissioned in January 2010. Corrosion and hull cracks were expected eventually, but appeared much earlier than anticipated.

Both LCS designs were supposed to be for ships displacing 2,500 tons, with a full load draft of under 3.3 meters/ten feet (permitting access to very shallow "green" and even "brown" coastal and riverine waters, where most naval operations have taken place in the past generation). Top speed was expected was to be over 80 kilometers with a range of 2,700 kilometers. Basic endurance is 21 days, and final displacement was closer to 3,000 tons.

LCS is currently armed with a 57mm gun, four 12.7mm machine-guns, two 30mm autocannon and a 21 cell SeaRam system for aircraft and missile defense. The RAM (RIM-116 "Rolling Air Frame") missiles replace Phalanx autocannon. SeaRAM has a longer range (7.5 kilometers) than the Phalanx (two kilometers). Last year, the navy decided to equip LCS with a surface launched version of the Griffin air-to-surface missile. The Griffin is an alternative to the Hellfire II, which weighs 48.2 kg (106 pounds) and carries a 9 kg (20 pound) warhead and has a range of 8,000 meters. In contrast, the Griffin weighs only 16 kg (35 pounds), with a 5.9 kg (13 pound) warhead which is larger, in proportion to its size, than the one carried by the larger Hellfire missile. Griffin has a pop-out wings, allowing it to glide, and thus has a longer range (15 kilometers) than Hellfire. UAVs can carry more of the smaller missiles, typically two of them in place of one Hellfire. The surface-launched Griffin weighs about twice as much as the air launched version, because of the addition of a rocket to get it into the air, after which it can glide to the target.

Ultimately, the navy hoped to have between 50 and 60 LCSs by 2014-18, at a cost of $460 million (after the first five.) The USS Freedom ended up costing nearly $600 million, about twice what the first ship in the class was supposed to have cost. The navy believes it has the cost down to under $450 million each as mass production begins.




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