The Navy faces a range of steep technical and funding challenges in trying to reach what once was billed as an easier, less expensive goal for upgrading its destroyer fleet, Congress' watchdog agency reported Tuesday.
The fleet's restarted Flight IIA Arleigh Burke-class destroyers are going to be more expensive than their predecessors, concluded the Government Accountability Office, as will the Flight III follow-on -- which also could be much tougher to design and build. Tomorrow's planned Air and Missile Defense Radar will push the 1980s-era Burke hull past its limits, GAO warns, and the Navy may have to make a lot of sacrifices to shoehorn it on there.
Service officials are debating between a new radar with 12-foot arrays or one with 14-foot arrays. Both concepts require more power and cooling than today's DDG 51s can generate, meaning they'd need to cram more support equipment aboard, and they also will add significant amounts of new weight. The new radars and their supporting systems mean designers must increase the ships' "design density" -- in other words, their complexity -- which could cause a lot of problems, GAO concludes. The Navy might have to remove weapons or other equipment to free up weight, giving tomorrow's DDGs less of a punch, "effectively reducing the multi-mission functionality of the class."
Just building them could be tough, the report said:
Not only can density complicate design of the ship as equipment needs to be rearranged to fit in new items, but Navy data also show that construction of dense vessels tends to be more costly than construction of vessels with more open space. For example, submarine designs are more complicated to arrange and the vessels are more complicated and costly to build than many surface ships. DDG 1000 was designed in part to have reduced density, which could help lower construction costs. According to a 2005 independent study of U.S. naval shipbuilding, any incremental increase in the complexity of an already complex vessel results in a disproportionate increase in work for the shipbuilder, and concluded that cost, technical and schedule risk, and the probability of cost and schedule overrun all increase with vessel density and complexity. Therefore, further adding to the density of DDG 51 to incorporate AMDR is likely to result in higher construction costs and longer construction schedules than on Flight IIA ships.The submarine force got really frustrated with its highly complex three-hull Seawolf class, and one of the reasons it loves its Virginia-class boats is they're much simpler to build and maintain. As you read, the surface force also learned this lesson on DDG 1000, but with that ship also truncated at three copies, it doesn't help tomorrow's shipbuilders or sailors.
Big Navy does not get a very flattering depiction in GAO's latest report. When investigators worried that Flight III would exceed the DDG 51 hull's service life allowance -- the amount of load its hull can safely bear over the ship's design life -- Navy officials said, aaah, that's not that big of a deal. GAO then ginned up a table describing cases in which over-loaded hulls have caused the surface force problems before:
Adding Aegis to the Spruance-class destroyer hull to create the Ticonderoga-class cruisers has led to cracking and buckling in the ships' superstructures -- a well-known deformation in the fleet. The ships in the fleet today need "structural modernization" to get them to serve for the Navy's goal of 35 years apiece. As for the Oliver Hazard Perry-class frigates, low growth margin meant the ships were maxed out of potential upgrades, and 21 of 49 "have been retired early after an average lifespan of only 17 years."
All right, Big Navy said, but look, we might go with a smaller 12-foot radar array, which would help with the hull load situation. OK, said GAO, but by your own metrics, that would provide less capability than "marginally adequate" for the scenarios you've envisioned in tomorrow's battle space. What's the deal? Oh, don't worry about that, Big Navy responds:
[T]he Navy now envisions multiple ships that they can operate in concert with different ground and space-based sensor assets to provide cueing for AMDR when targets are in the battlespace ... However, this program (envisioned as a constellation of missile tracking satellites) is currently in the conceptual phase, and the independent Radar/Hull Study red team stated that the development timeline for this system is too long to consider being able to leverage this system for Flight III.Yes -- it's the old "system of systems" concept -- oh, sorry, "family of systems," as we say now. How... transformational. GAO goes on:
Senior Navy officials told us that the concept of sensor netting is not yet well defined, and that additional analysis is required to determine what sensor capabilities currently exist or will be developed in the future, as well as how sensor netting might be conceptualized for Flight III. Sensor netting requires not only deployment of the appropriate sensors and for these sensors to work alone, but they also need to be able to share usable data in real-time with Aegis in the precise manner required to support BMD engagements. Though sharing data among multiple sensors can provide greater capabilities than just using individual stand- alone sensors, officials told us that every sensor system has varying limitations on its accuracy, and as more sensors are networked together and sharing data, these accuracy limitations can compound. Further, though there have been recent successes in sharing data during BMD testing, DOD weapons testers responsible for overseeing BMD testing told us that there have also been issues with sending data between sensors. Although sensor technology will undoubtedly evolve in the future, how sensor netting will be leveraged by Flight III and integrated with Navy tactics to augment Aegis and the radar capability of Flight III is unknown.Keep in mind that the original concept here was that the Navy would take a stable, proven design -- its workhorse DDG 51 -- and just bolt on some wham-o-dyne new accessories to get improved new copies at an affordable price. Now the Navy apparently has two choices: A middling upgrade that relies on an as-yet uninvented new form of battle space sensor fusion, and a better system that its ships might not be able to handle.
Still reading? Thanks for sticking with it -- here's the point: All this technical risk and uncertainty in the centerpiece of the Navy's long-term shipbuilding plans does not help the odds it will close the projected shortfall in its number of large surface combatants, as we heard about at the Surface Navy Association show. The Navy does not plan to buy a new-model destroyer, given the placeholder name "Flight IV," until 2032. Until then, this DDG 51 plan is it for large warships. If it doesn't pay off or starts to slip, tomorrow's fleet could wind up short that many more combatants.