RT&L FOCUS AREA(S): General Warfighting Requirements
TECHNOLOGY AREA(S): Biomedical
OBJECTIVE: Develop an innovative solution that will improve the ability to successfully accomplish single-man escape to 600 feet of seawater (fsw) of survivors from a disabled submarine and potentially increase the ability to provide safe deep escape beyond 600 fsw.
DESCRIPTION: All United States Navy (USN) submarines are provided with the equipment certified to support single-man escape of Disabled Submarine (DISSUB) survivors down to a depth of 600 fsw. This equipment is comprised of a flood valve, auto-vent valve, single-man escape suit, and an escape suit hood inflation system, among other components.
The escape trunks onboard are capable of supporting escape of two survivors (also referred to as ‘escapers’) per escape cycle. Two escapers, outfitted with escape suits, enter the escape trunk from the internal submarine compartment. After entering, the lower hatch of the escape trunk is closed and the escapers, using hood inflation valving connected to a 700-pound ship’s service air source, inflate the escape suits. The escape suits fully inflated provide up to 70 pounds of buoyancy to each escaper. This buoyancy is to allow for the rapid ascension of the escaper to the water surface to minimize the risks associated with decompression obligations. After the escape suits are fully inflated, the escape trunk flood valve is opened to fill the trunk with external seawater up to the trunk auto-vent valve. The auto-vent valve is calibrated to ensure that the flooding of the trunk stops at a pre-determined level and when the auto-vent valve fully lifts, the rapid pressurization cycle of the remaining air bubble begins. At 600 fsw, the pressurization cycle is designed to be no greater than 20 seconds before the escape trunk pressure is equalized with the external sea pressure. Once equalized, the upper hatch opens and the escapers automatically exit the upper hatch and ascend to the surface. The design of the escape suits allows the escaper to breathe normally during ascent.
Human subject testing has been successfully accomplished to prove the capability of escape down to 600 fsw. However, that testing highlighted that it is physically challenging and as the depth of the escape is increased, the risks associated with decompression obligations and mortality increase exponentially. In addition to the body’s ability to withstand the designed rapid pressurization, the ability to withstand the heat loads generated by the pressurization cycle is also of a concern. Although the mortality risk increases significantly as depths exceed 600 fsw, it is anticipated that successful escape may be achievable, based upon experimental trials and the theorized mechanical robustness of the submarine escape system and escape suits. At this time, escape protocols only allow for escape from depths greater than 600 fsw in situations when impending death is inevitable if survivors do not initiate immediate escape. Due to advances in technology and biomedical research, it may be possible to decrease the associated risk with escape from deeper depths.
The rescue of survivors from a DISSUB is the preferred method for the Navy. However, internal conditions of the DISSUB may require some, if not all, of the survivors to initiate escape in lieu of waiting for rescue forces to arrive. The time necessary to mobilize rescue forces may be in excess of the available time for survivors to remain onboard the DISSUB. Due to the risks associated with deep escape, the program office is in need of technology that will decrease the risks associated with escape to 600 fsw and potentially increase the ability to provide safe escape deeper than 600 fsw with an objective to allow for reasonable safe escape to 1000 fsw. This may involve addressing the physiological stressors associated with deep escape, the mechanical components used to accomplish escape, or a combination of both.
In addition to being a safety and duty of care issue, continued advancement and modernization of the USN Submarine Escape and Rescue Program is considered an Assistant Secretary of the Navy core field in support of the larger Undersea Warfare and directly aligns to both the National Defense Strategy and the Submarine Commander's Intent by defending the homeland, enabling interagency counterparts to advance U.S. influence and national security interests, ensuring USN submarine warfighting readiness and survivability and strengthening alliances and attracting new partners. The latter was highlighted in the geopolitical outcome following the USN Submarine Escape and Rescue response to the ARA SAN JUAN incident in November 2017.
PHASE I: Develop a design concept, with notional feasibility determined via computer based modeling and simulation, that will support a conceptual solution that improves the ability to escape to 600 fsw and potentially increases the ability to provide safe deep escape beyond 600 fsw. Considerations of the potential design concept should include internal compartment space constraints and minimal increase to stowage requirements, maintenance requirements, and lifecycle costs. The Phase I Option, if exercised, will include the initial design specifications and capabilities description to build a prototype solution in Phase II.
PHASE II: Based on the results of the Phase I and the Phase II Statement of Work (SOW), develop a breadboard design based upon the conceptual solution, including the major components identified, to provide a representative simulation of the proposed solution. Following breadboard testing, refine, as necessary, the design to build and deliver one reduced scale prototype for testing. Due to risks associated with human subject testing, all testing accomplished will be via modeling and simulation in a computer-aided or laboratory environment. The ability to use human subjects in a lab-created or real-world environment would require approval beyond the scope of the SBIR program.
PHASE III DUAL USE APPLICATIONS: The dual use application of proposed technology is dependent upon the technology identified. However, the ability to decrease the risks associated with escape from a USN Submarine has follow-on benefits to partner ally submarine forces and other organizations who support confined space personal recovery, both within and external to the USN and DoD. Conduct further testing and certification in accordance with requirements set forth by the USN Undersea Medical community. It is anticipated that this certification will require human subject testing to be performed at the Pressurized Escape Submarine Tower (PSET) and/or Navy Experimental Dive Unit (NEDU).
- “S9594-AP-SAR-G10, 0910-LP-018-5820, Revision 00, SSN 774 Class Guard Book, Distressed Submarine Survival Guide FWD Escape Trunk, Change A of 1 October 2013, ACN2/B of 7 Feb 2019. https://www.yumpu.com/en/document/read/11295816/774cl-fwd-guard-book-s9594-ap-sar-g10
- “Submarine Rescue Diving and Recompression System Operational Requirements Document.” Chief of Naval Operations, Serial Number 489-87-98, 3 Jun 1998. https://www.navysbir.com/n21_1/N211-040-REFERENCE-2-Operational-Requirements-Document.pdf