Waterproof Towed Array Hosewall
Navy SBIR 2014.1 - Topic N141-056
NAVSEA - Mr. Dean Putnam - dean.r.putnam@navy.mil
Opens: Dec 20, 2013 - Closes: Jan 22, 2014

N141-056 TITLE: Waterproof Towed Array Hosewall

TECHNOLOGY AREAS: Sensors, Electronics, Battlespace

ACQUISITION PROGRAM: PMS401, Submarine Acoustic Systems Program Office

OBJECTIVE: The objective is to develop a towed array hosewall that prevents water molecules from migrating through and saturating the Isopar inside the array.

DESCRIPTION: Fat Line Towed Arrays (ref 1,2) are experiencing hydrophone failures due to interaction with water molecules and require extensive repairs after limited use. The Navy seeks an innovative hosewall material, coating, or additives that preserve all of the existing hosewall properties, while also preventing water permeation. The ideal solution is one that completely prevents water permeation for more than two years in the underwater environment. The objective is to slow down permeation by a factor of five (5).

The existing hose material is a polyether-based thermoplastic polyurethane (TPU) manufactured by the Lubrizol Corporation, designated at 58300 Estane. The extrudable material was tailored for towed array applications; with abrasion resistance and ultraviolet resistance built-in. Water molecules from the ocean environment are able to permeate through the hosewall in the Navy’s towed array application. Under typical pressure and temperature profiles, water molecules can migrate through the ¼ inch hosewall in 2 to 3 months. These molecules eventually saturate the Isopar fill fluid used in the array, and attack critical array internal components.

The challenge is to preserve all of the hose properties (tan delta, density, flexure resistance, Isopar compatibility, abrasion resistance) that required a substantial test program to qualify, while providing this new capability. The end result will be a hosewall that does not impact the existing beneficial properties of the hose; acoustic self-noise, specific gravity, hoop strength, tensile modulus and manufacturability by extrusion. An ideal solution is an additive that is sufficiently small to minimize hose property changes while making the array waterproof. This improvement will greatly reduce repair costs and improve the operational availability of Fat Line towed arrays by allowing the arrays to remain within specification and fielded.

PHASE I: The company will develop concepts that demonstrate substantial improvement in the reduction of water permeation in the towed array hosewall either by innovative material, coatings, or additives. The concepts will also make a detailed comparison to all mechanical hose properties of the Lubrizol 58300 Estane baseline material, to aid in quantifying the risk of using this new hose as a substitute for the baseline. The company will demonstrate the feasibility of the concept in meeting Navy needs and will establish that the concept can be feasibly developed into a useful product for the Navy. Feasibility will be established by material testing and analytical modeling. The small business will provide a Phase II development plan that addresses technical risk reduction and provides performance goals and key technical milestones.

PHASE II: Based on the results of Phase I and the Phase II development plan, the small business will develop a prototype for evaluation. The prototype will be evaluated to determine its capability in meeting the performance goals defined in Phase II development plan and the Navy requirements for the Fat Line towed array hosewall. System performance will be demonstrated through prototype evaluation and modeling or analytical methods over the required range of parameters, including toe testing and critical array self-noise properties. Evaluation results will be used to refine the prototype into an initial design that will meet Navy requirements. The company will prepare a Phase III development plan to transition the technology to Navy use.

PHASE III: If the Phase II prototype is successful, the company will work with the Navy and array manufacturers to transition the new cable design into existing systems. The company will be expected to support the Navy in transitioning the technology for Navy use. The company will develop a Fat Line towed array hosewall according to the Phase III development plan for evaluation to determine its effectiveness in an operationally relevant environment. The company will support the Navy for test and validation to certify and qualify the system for Navy use.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: Innovative improvement techniques to reduce or eliminate water permeation are applicable to other Navy towed array programs, as well as oil and seismic exploration applications.

1. Navy Programs, "TB-34 Towed Array". Director, Operational Test &Evaluation (DOT&E)
<http://www.dote.osd.mil/pub/reports/FY2010/pdf/navy/2010tb34.pdf >.

2. National Research Council. C41SR for Future Naval Strike Groups. Washington, DC: The National Academies Press, 2006 <http://www.nap.edu/openbook.php?record_id=11605&page=267>.

KEYWORDS: Self-noise acoustic properties of towed arrays; towed array; hosewall; permeability of towed array; 58300 Estane; thermoplastic polyurethane (TPU)

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