TECHNOLOGY AREA(S): Ground/Sea Vehicles

ACQUISITION PROGRAM: Virginia Class Submarines

OBJECTIVE: The U.S. Navy (USN) seeks to develop enabling capabilities for launch and recovery (L&R) operations of Unmanned Underwater Vehicles (UUVs) from submarines at prescribed submergence conditions. More specifically, there is a need to launch vehicles of different hull diameters from a standard 21-inch diameter by 25-foot long tube (ocean interface). To prevent damage to the tube and vehicles, and to stabilize the vehicle’s orientation throughout the launch event, a UUV Sabot System (UUVSS) is sought. Vehicles will be launched under their own power and the UUVSS will separate from the vehicle upon exiting the tube. The UUVSS can be designed as either expendable or nonexpendable.

DESCRIPTION: The current state of inflatable soft structures technologies can provide unique solutions to many challenges limiting today’s Undersea Warfare (USW) operations, capabilities and system designs. Inflatable soft structures have been successfully developed for DoD, NASA, and industry and are generally categorized in the following sectors:
• Inflatable control surfaces
• Deployable energy absorbers
• Temporary “on-demand” structures

Expendable UUVSS’s must exit the tube with the vehicle; once reaching the free field, the UUVSS will detach from the vehicle with no hardware connections remaining between the UUVSS and the tube. Nonexpendable UUVSS’s shall remain inside the tube throughout the launch event and will be recovered for reuse by the weapons crew. The UUVSS will eliminate the need for multiple launch tubes of different sizes to support launch operations for the range of UUV sizes required and will minimize mission reconfiguration activities.

The minimum operational and associated requirements for the UUVSS follow:
• Launch capable for UUV’s in the 12-inch to 18-inch diameter sizes
• Launch from submarine standard 21-inch diameter by 25-foot long tube
• Launch at submergence depths to 100.0 feet
• Launch in crossflow speeds up to 5.0 knots
• Inflate to 2.5x depth pressure in 15.0 seconds
• Maintain internal pressure to 3.5x depth pressure for 24 hours
• Provide pressure relief for internal pressure exceeding 2.5x depth pressure within 5.0 seconds
• Protect UUV control surfaces
• Perform 30 launch cycles
• Prevent interference with tube opening/closing operations


Successful design and performance of soft inflatable structures is attributed to technological advancements derived from:
• High Performance Fibers (HPF) including, but not limited to, Vectran®, DSP® (dimensionally stable polyester), PEN (polyethylene napthalate), Spectra® (ultra-high molecular weight polyethylene), Kevlar®, and others
• Novel fabric architectures and 3-dimensional preforms capable of unique mechanical behaviors
• Continuous weaving processes for elimination of seams
• Robust Physics-Based Modeling (PBM) methods with Fluid-Structure Interaction (FSI) capabilities
• Material test methods for characterization of multi-axial mechanical behaviors for inputs to numerical models

Collectively, these advancements have established a sound technology base; one that can be readily leveraged for innovative solutions to soft structure designs requiring significant load-carrying capacities, shock mitigation, dynamic energy absorption, rapid deployment, large deployed-to-stowed volume ratios, and fail-safe modes of operations.
   
The UUVSS shall consist of a generally soft or soft/rigid hybrid inflatable structure and a seawater pump interface (SPI). The SPI will connect the UUVSS soft structure to the tube seawater pump, which will be used to controllably inflate and deflate the UUVSS with seawater as the inflation medium. Both inflation and deflation operations will be performed after the UUVSS is configured onto the vehicle and the vehicle is positioned inside the tube.

The soft structures considered for use in developing the UUVSS may include, but are not limited to, control volumes constructed of inflated skins, membrane bladders, coated fabrics, and hybrid (soft/rigid) material systems. Hybrid sabots may include inflatable elements with semi- or fully-rigid reinforcements serving as deployment shaping controls, friction minimizing contact interfaces, etc. The pressurization media for all inflatable components will be limited to seawater.

PHASE I: Provide concept designs, simulations of initial prototype designs, test results from laboratory experiments, or other relevant documentation to demonstrate that the proposed technical solutions are feasible for accomplishing the stated objectives and meeting the performance parameters set forth in the Description.

By submitting Phase I proof of feasibility documentation, the small business asserts that none of the funding for the cited technology was reimbursed under any federal government agency’s SBIR/STTR program. Demonstrating proof of feasibility is a requirement for a Direct to Phase II award.

PHASE II: Round I: Optimize the UUVSS design including material selections for the soft structural components, hydraulic layout design and manifolding, inflation/deflation sequencing, porting to a generic tube seawater pump, hard-to-soft-goods connections, and environmental factors. Testing of the UUVSS prototype shall be conducted by the U.S. Navy in accordance with stated objectives. As stated in the solicitation, the period of performance for Round I shall not exceed 6 months and the total fixed price shall not exceed $250,000.

Round II: Identify operational, safety, and environmental issues of proposed UUVSS designs. Perform risk identifications, risk assessments, and risk mitigation plans from the concept development stage. As stated in the solicitation, the period of performance for Round II shall not exceed 6 months and the total fixed price shall not exceed $500,000.

Round III: Build a prototype of the proposed UUVSS and test to validate the above requirements for launching UUVs from a 21-inch tube. Deliver the prototype UUVSS to the Naval Undersea Warfare Center, Newport, RI for testing in accordance with the stated operational requirements. As stated in the solicitation, the period of performance for Round III shall not exceed 6 months and the total fixed price shall not exceed $750,000.

PHASE III DUAL USE APPLICATIONS: Launch and recovery of commercial watercraft (e.g., Jet Skis) is an opportunity space for dual use.

REFERENCES:

1. Hulton, A., Cavallaro, P., and Hart, C. “MODAL ANALYSIS AND EXPERIMENTAL TESTING OF AIR-INFLATED DROP-STITCH FABRIC STRUCTURES USED IN MARINE APPLICATIONS.” , 2017 ASME International Mechanical Engineering Congress and Exposition, Tampa, FL November 3-9, 2017, IMECE2017-72097. http://proceedings.asmedigitalcollection.asme.org/proceeding.aspx?articleid=2669415

2. Cavallaro, P., Hart, C., and Sadegh, A. “MECHANICS OF AIR-INFLATED DROP-STITCH FABRIC PANELS SUBJECT TO BENDING LOADS.” , NUWC-NPT Technical Report #12,141, 15 August 2013. https://apps.dtic.mil/dtic/tr/fulltext/u2/a588493.pdf

3. Sadegh, A. and Cavallaro, P. “MECHANICS OF ENERGY ABSORBABILITY IN PLAIN-WOVEN FABRICS:  AN ANALYTICAL APPROACH.” Journal of Engineered Fibers and Fabrics, vol. 62, pp. 495-509, March 2012. https://www.jeffjournal.org/papers/Volume7/7.1.2Sadegh.pdf

4. Cavallaro, P., Sadegh, A., and Quigley, C. “CONTRIBUTIONS OF STRAIN ENERGY AND PV-WORK ON THE BENDING BEHAVIOR OF UNCOATED PLAIN-WOVEN FABRIC AIR BEAMS.”, Journal of Engineered Fibers and Fabrics, Vol 2, Issue 1, 2007 pp. 16-30. https://www.jeffjournal.org/papers/Volume2/Sadegh.pdf

5. Avallone, Eugene A., Baumeister III, Theodore, and Sadegh, Ali M.
 Marks’ Standard Handbook for Mechanical Engineers, 11th Edition (Chapter: Air-inflated fabric Structures by P. Cavallaro and A. Sadegh), McGraw-Hill, 2006, pp. 20.108-20.118. https://www.amazon.com/Marks-Standard-Handbook-Mechanical-Engineers/dp/0071428674

6. Cavallaro, P., Sadegh, A., Quigley, C. “BENDING BEHAVIOR OF PLAIN-WOVEN FABRIC AIR BEAMS:  FLUID-STRUCTURE INTERACTION APPROACH.”, 2006 ASME International Mechanical Engineering Congress and Exposition, Chicago, Ill, November 05, 2006, IMECE2006-16307. https://apps.dtic.mil/dtic/tr/fulltext/u2/a456155.pdf

7. Cavallaro, P., Sadegh, A. and Johnson, M. “MECHANICS OF PLAIN-WOVEN FABRICS FOR INFLATED STRUCTURES.” Composite Structures Journal, Vol. 61, 2003, pp. 375-393.

8. Quigley, C., Cavallaro, P., Johnson, A., and Sadegh, A. “ADVANCES IN FABRIC AND STRUCTURAL ANALYSES OF PRESSURE INFLATED STRUCTURES.” Conference Proceedings of the 2003 ASME International Mechanical Engineering Congress and Exposition, IMECE2003-55060, November 15-21, 2003, Washington, DC. http://proceedings.asmedigitalcollection.asme.org/proceeding.aspx?articleid=1595613

KEYWORDS: Unmanned Underwater Vehicles; UUV; Launch and Recovery Systems; Soft Structures; Inflatables