Supersize It: The U.S. Navy Is Seeking an Ultra-Large AUV
In late May of this year, the Office of Naval Research (ONR) issued a broad agency announcement (BAA) seeking the rapid design, build, and testing of an ultra-large autonomous underwater vehicle (UL-AUV) capable of conducting long-range, high-endurance missions while carrying large modular payloads. The initial demonstrator vehicle, "Ocean Explorer" (OEX), will establish the technical feasibility of such an unprecedented platform, and will also inform development of the associated infrastructure required to support a full squadron of UL-AUVs. ONR is also seeking unspecificed, innovative UL-AUV-related technologies, as well as rapid design and fabrication capabilities.Interestingly, the call for a jumbo AUV comes as the Navy's extra-large (Orca) and large (Snakehead) AUV programs are suffering from significant cost overruns, technical issues, and programmatic uncertainty, and as the U.S. submarine workforce is struggling to meet demand for Virginia and Columbia-class hulls. Snakehead’s fate has largely been sealed; the prototype vehicle is now designated as a test platform and is unlikely to transition to a program of record, while the Defense Innovation Unit (DIU) has awarded prototype contracts for commercial off the shelf (COTS) large AUVs to Kongsberg, Oceaneering, and Anduril Industries A recent GAO report indicated that Orca continues to suffer from delays and ballooning costs related to challenges with autonomy, navigation, and endurance, and concluded that it too may fail to become a program of record. Prior to the GAO report, in April of this year, DIU had already issued a solicitation for a COTS extra-large AUV¬—the Combat Autonomous Maritime Platform (CAMP)—suggesting a need to offset or augment the troubled Orca program. Meanwhile, crewed submarine construction is years behind schedule, with limited shipyard capacity, aging infrastructure, and a shortage of skilled labor continuing to cause backlogs across all naval platforms.Chief of Naval Operations (CNO) Adm. Lisa Franchetti toured Boeing’s Orca Extra Large Unmanned Undersea Vehicle (XLUUV) manufacturing facility, met with Boeing contractors and Sailors assigned to Unmanned Undersea Vehicles Squadron (UUVRON) 3, and gave remarks. Credit: U.S. Navy photo by Chief Mass Communication Specialist William SpearsYet, despite these challenges and setbacks, there may be wisdom in pursuing a multi-mission UL-AUV. While the BAA provides no specifics on vehicle construction, objectives, or potential missions, it is possible to infer these by looking at existing AUV systems, analogous platforms like guided missile nuclear submarines (SSGNs), and mission sets that could be enhanced by the greater endurance, range, and internal volume provided by a UL-AUV.One possible objective of the UL-AUV program would be the development of an "underwater mothership" capable of launching and recovering a wide range of uncrewed underwater systems. With range/endurance remaining a limiting factor in AUV operations for the foreseeable future, a UL-AUV could provide a forward-deployed charging station to enable a persistent, wide-area, covert forward undersea presence. The Navy's recent successful testing of the Yellow Moray torpedo tube launch and recovery (TTLR) system suggests that, once mature, this technology, or a scaled-up version, could one day be integrated into an autonomous platform like a UL-AUV. A Yellow Moray-type system could also enable a UL-AUV to serve as a forward undersea logistics hub, enabling clandestine resupply via large or XL-AUVs. Taken a step further, a UL-AUV could potentially accommodate a large special operations payload, making it a scaled-up swimmer delivery vehicle (SDV) capable of semi or fully autonomous deployment of multiple teams of expeditionary or special forces, either directly or by launching/recovering smaller SDVs.Sailors lower a Yellow Moray (REMUS 600) unmanned underwater vehicle (UUV) into the water during a UUV exercise in Haakosnsvern Naval Base in Haakonsvern, Norway. Credit: US Navy/Oliver Cole/Courtesy photoOne of the more likely objectives is the development of an underwater missile barge or arsenal ship. Vertical launch system (VLS)-equipped guided missile surface platforms are increasingly vulnerable to a range of sophisticated airborne threats—in particular, Chinese anti-ship cruise missiles (ASCMs) and anti-ship ballistic missiles (ASBMs). At the same time, the venerable Ohio-class SSGNs are rapidly reaching the end of their service lives. In a hotly contested environment, submersible platforms fitted with launch tubes containing missiles, uncrewed aerial systems (UAS), or strike AUVs would, like SSGNs, offer a stealthy, survivable, powerful precision strike capability. Possible weapons include Tomahawk land attack cruise missiles (TLAMs), ASCMs, torpedoes/autonomous underwater munitions, loitering munitions/SLUAS launched from encapsulated canisters, or even FPV strike drones. The Russo-Ukraine War has demonstrated the power of massed FPV drones for strike warfare. This was particularly apparent during Operation Spider's Web, which saw covertly inserted FPV drones strike strategic bombers and airfields deep within Russian territory.But how could such a range of weapons be stored and autonomously deployed? The Virginia Payload Module (VPM) offers one possibility by offering design and cost advantages in terms of modularity, a common architecture, and supply chain logistics. The VPM is a hull extension added to Block V Virginia-class submarines that enables them to serve as multi-mission platforms capable of performing conventional precision strike, special operations support, and other payload-flexible missions. A VPM can quite significantly enhance strike payload capacity, as it contains four separate payload tubes that are each capable of containing a 7-shot multiple all-up-round canister (MAC) missile launch system, for a total missile loadout of 28 rounds. A squadron of UL-AUVs with integrated MAC-equipped VPMs could bring many dozens of missiles to the fight, offsetting threats to surface platforms, as well as the retirement of the Ohio SSGNs.But with an integrated VPM, a UL-AUV would more closely resemble a crewed submarine in size and displacement than a scaled-up UUV (The VPM is 84 feet in length—nearly as long as a payload bay-equipped Orca XL-UUV). Before such an uncrewed behemoth could put to sea, the technical challenges currently afflicting the Orca XL-UUV would need to be overcome. Still, the concept is entirely plausible—and such an ambitious leap could draw inspiration from the Navy’s large USV (LUSV), which is also set to bring added VLS muscle to the fight.ONR’s call for UL-AUV designs suggests the U.S. Navy is envisioning a fleet of undersea platforms that could act as drone motherships, clandestine forward deployed logistics nodes, or autonomous missile barges to counter China’s narrowing of the “VLS Gap.” With the ability to carry dozens of missiles, UUVs, or strike drones, a VPM-equipped UL-AUV would be a potent tool of power projection on par with an SSGN. Just as the presence of a U.S. carrier or SSGN can influence adversary thinking, the credible threat of a heavily-armed UL-AUV could similarly shape strategic outcomes, making it an instrument of coercion or escalation management. Its development would likely be fraught with technical, operational, and manpower challenges, especially in light of current delays in submarine construction and an overstretched shipbuilding workforce. But if successful, it would mark a significant expansion of uncrewed undersea assets from tactical/operational sensor and effector platforms, to formidable strategic assets capable of posing significant dilemmas for U.S. adversaries.