The Navy is ramping up efforts to cut weight from its two Littoral Combat Ship (LCS) variants in advance of new sensors, weapons and armor coming onboard in fiscal year 2019, when the first “frigate” version begins procurement, program managers told Defense Daily.
The frigate program is essentially a flight upgrade for the LCS, Capt. Dan Brintzinghoffer, frigate program manager, said in a June 1 interview. The Navy plans to add a new suite of equipment— such as an over the horizon, surface-to-surface missile, 25mm chain guns and new radar and electronic warfare equipment—to the ships, but the service must first figure out how those new additions affect weight, structure, stability, cooling, power and the availability of space.
“It’s probably an eight- or nine-variable problem,” he said. “We’re continually adjusting models to make sure that we provide as much lethality and survivability as possible within those constraints.”
Much of that planning work is being done during the “pre-preliminary design” phase slated to wrap up this October, Brintzinghoffer said. He is also working with the LCS program office, which has had a weight reduction working group in place since before the decision to acquire the up-gunned frigate.
After the frigate announcement was made, that working group has gone back to the drawing board, combing through the ship designs for opportunities to use lighter materials or strip away bulk, said Capt. Tom Anderson, LCS program manager.
“The number of [weight reduction] candidates that are on the table have been increased lately because the expectation is that the weight additions are going to be larger than we had originally envisioned,” he said. The message to shipbuilders is: “Come forward with all of the ideas that you have, even if in the past some of those ideas have not been acted upon.”
The Navy plans to buy two frigate variants based on the Freedom-class LCS built by Lockheed Martin [LMT] and the Independence-class built by Austal USA. Both ships have different design features—the Freedom is a steel monohull, while the Independence is a trimaran—and thus different weight reduction challenges.
With the Freedom class, the primary concern is stability, not weight, Anderson said. Removal of weight from the bottom of the ship “hurts us [and] it makes us less stable,” while decreasing weight from the top of the ship improves stability. The Independence variant is over 100 feet wide and is very stable, he said. “With that platform, it really is about weight reduction.”
For both variants, the Navy is considering replacing some of the insulation on the ship with a lighter weight product, Anderson said. Because the lightweight insulation is more expensive, the service would likely only use it for targeted applications.
“We have to watch the cost and make sure its cost affordable,” he said. For instance, some of the systems that might be added to the frigate—such as the SEWIP Lite electronic warfare system, SeaRAM Anti-Ship Missile Defense System and MK 53 Decoy Launching System—could compromise the stability of the Freedom variant. Replacing the insulation installed in high places on the Freedom could be a cost-effective way to offset the weight of those systems.
The Navy is also working with Lockheed Martin and Austal on ways to mitigate the increased weight associated with adding armor to the ships’ magazines, such as using lightweight materials to build protective structure, Anderson said.
Another option on both variants is redesigning the containers for the gas turbine engines that propel each hull, Brintzinghoffer said.
“The box that holds those engines…could be made of different materials with a slightly different design that would make them lighter then what’s there now,” he said. “We’re looking at what the feasibility of that is and whether it’s worth spending money and effort to do it.”
On the Independence, the service could replace the welded steel tie downs in the mission bay and flight deck with lighter aluminum Alcoa [AA] ones, Anderson said. “That’s a weight savings, and it’s about at the same height as the magazine.”
Austal and the service are also reevaluating water mist requirements, he said. Independence is equipped with water misters in case of a fire, but that system could be scaled back and replaced with fire hoses. Minimizing the pipes running through the ship is another option.
For the Freedom variant, the Navy is considering increasing the number of buoyancy tanks on the ship, which will increase its stability and improve its ability to stay afloat after taking a hit, Anderson said.
Redesigning the overhead crane system, taking out weight in the helicopter hangars, reducing the weight of shore power stations are options on the table for both variants, he added.
Brintzinghoffer said his team is also looking for frigate-specific opportunities for weight savings, such as eliminating equipment built into the LCS hulls for the mine countermeasure mission, which the frigate will not support.
“There’s an awful lot of [mine countermeasure] equipment that is organic on the ship, that’s part of the core seaframe, including things like heavy cranes and mission equipment…that the frigate doesn’t need to have,” he said.
This spring, the frigate program office finalized its acquisition strategy for LCS 33 through 52. Brintzinghoffer declined to detail the specifics of the strategy, but confirmed that the upgunned ships would not be held to the LCS’s 40-knot speed requirement. However, the sprint speed for the ships would likely not dip under 30 knots, however, he said.
The strategy was signed by the Navy Secretary Ray Mabus on June 1 and sent to the Office of the Secretary of Defense early this week, confirmed Cmdr. Thurraya Kent, a Navy spokeswoman.
That’s about a month later than originally planned, but ultimately will not affect the program’s schedule, said Chris Johnson, a Naval Sea Systems Command (NAVSEA) spokesman.