ARLINGTON, Va. — As the U.S. Navy works through the detail design of its Constellation-class frigate and the concept design of its DDG(X) destroyer, the service wants to add all the latest offensive and defensive systems.

But at least as important, leaders say, is leaving room for new systems down the road.

Rear Adm. Paul Schlise, the director of surface warfare on the chief of naval operations’ staff (OPNAV N96), said last month that a fight against an adversary like China would be “a missile-to-missile game” and that the U.S. Navy’s current destroyers lack the magazine depth for that kind of battle.

The Navy is considering innovative ways to maximize the effectiveness of the limited vertical launching system cells on a ship, he said, but the real difference-maker will be fielding directed-energy weapons that give a ship as many shots for which it can generate electrical power.

“If you want to incorporate some of these directed-energy systems that have this capability to potentially give us that bottomless magazine, we need to restore the SWAP-C — space, weigh, power and cooling — margins that we’ve burned through on the DDG 51 class,” Schlise said of the current Arleigh Burke-class destroyers in the fleet while speaking during a Jan. 11 panel at the Surface Navy Association’s annual conference.

The Arleigh Burke ships have increased from 8,300 tons to 10,200 tons as they progressed through various flight upgrades, he said, and the design is maxed out at the current Flight III design. The Navy needs more space and power in its DDG(X) future destroyer without the design growing too large or too costly, leaders have said — a challenge made clear in current frigate design efforts, where the FREMM frigate parent design had to be made larger and therefore more expensive to accommodate Navy specifications, let alone to save margin for future upgrades.

Despite the challenge, naval engineering experts say the Navy must prioritize SWAP-C for future technologies that will emerge throughout the decades these two ship classes are in service.

“The challenge for us is that SWAP-C is not necessarily the sexiest thing to talk about: it’s not that future missile, it’s not that future laser. But without that as a capability, you don’t have the room to accommodate that growth,” Carey Filling, the director for surface ship design and systems engineering at Naval Sea Systems Command, said Feb. 1 at an American Society for Naval Engineering conference.

“It truly is a capability against the future threat,” he added.

John Hootman, who serves as Schlise’s civilian deputy director at N96, said at the ASNE conference that “margin is a warfighting capability, and we have to value that” the same way the Navy values other ship attributes while considering cost versus capability. He praised the DDG(X) program office for building in significant margin now and doing the engineering upfront to allow for additional margin to be added later if needed.

DDG(X) design

Chief of Naval Operations Adm. Michael Gilday approved the DDG(X) top-level requirements in December 2020, and the program office continues to look at design trades using the draft capability development document that was approved in October 2021, deputy program manager Katie Connelly said in January at the SNA conference.

Though much still remains to be determined about this ship, the CNO’s top-level requirements lay out significant room for growth: weight margin of 10%; cooling margin of 20%, with the ability to upgrade that to 40%; and power margin of 20%, with the ability to pull additional power when needed from the propulsion system via the Integrated Power System.

When asked by Defense News about the margins on DDG(X), Filling said at the ASNE conference that those margins, despite their cost, are “worth protecting.”

“I don’t think right now that DDG(X) as planned has too much margin, that it incurs too much cost. I think it’s the right approach right now; I think we have a balanced design, Filling explained. “Based on all the threats we can anticipate, we put enough SWAP-C on that ship to accommodate that growth in the future.”

That margin could be consumed quickly, based on the Navy’s plans for DDG(X).

Connelly said the first ship would deliver with a baseline capability: “essentially a new hull, Flight III combat system, two [Rolling Airframe Missile] launchers and an [Integrated Power System].”

Future design updates would be made when new technology is ready: laser weapons, larger radar arrays, an updated X-band radar, more vertical launching system cells or large-missile launchers, and an integrated power and energy system.

A “destroyer payload module” could be inserted in the back half of the ship — essentially a segment added into the hull between the bridge and the helicopter hangar — to increase the size of the ship and “allow for additional capability in the future,” Connelly said.

Hootman, on the ASNE panel, praised this effort to do the engineering now to allow for growth down the line.

Frigate design

The frigate program has also relied on elongating the ship to stay within SWAP-C margins. But in that program’s case, the change was made to accommodate Navy standards for survivability and habitability, rather than preserving area and weight for future offensive and defensive systems.

Capt. Kevin Smith, the guided-missile frigate program manager, said in a program briefing at SNA event that the Constellation-class frigate would not look quite like the FREMM on which it’s based. The FFG(X) design has “all the goodness of that parent — the hull, the way it’s laid out — all of that is in the design. But you have to take U.S. Navy standards and apply those.”

He pushed back on accusations that the cost and size of the ship design had grown since FREMM-builder Fincantieri was selected in April 2020.

Noting that five companies using five different parent hulls ultimately bid on the program, he said those firms were all asked to mesh their parent design with Navy-required system specifications.

“The FREMM came along with a hull, accommodations, it came along with a propulsion plant layout, mechanical systems, electrical systems and a physical integrated plant,” Smith said. “All that goodness is in the FFG(X). But what we did as a Navy, as we were going through the concept design phase where we were collaboratively working with those parent designs and all those five shipbuilders, we were looking at the [U.S. Navy] standards that we have in our shipbuilding, which is why our ships, quite honestly, are better. We have reliability things we want to make sure are taken care of, survivability, maintainability, habitability, lethality.

“In this particular instance with Fincantieri, they went off and looked at what are those standards and requirements against our FREMM parent, and they had to lengthen the hull a little bit, they had to look at the stateroom requirement as far as survivability.”

Redundancy and reliability were also added to the propulsion, mechanical and electrical systems, Smith said. A longer ship, therefore, was needed so the design could stay within the proper space and weight margins as these new features were adding into the FREMM design to create the final Constellation-class design.

“So when someone says, ‘Well, you’ve changed the design,’ no, that was in their bid, this is how they did the bid,” he said.

Megan Eckstein is the naval warfare reporter at Defense News. She has covered military news since 2009, with a focus on U.S. Navy and Marine Corps operations, acquisition programs and budgets. She has reported from four geographic fleets and is happiest when she’s filing stories from a ship. Megan is a University of Maryland alumna.

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