N151-037 TITLE: Fat Line Tow Cable

TECHNOLOGY AREAS: Sensors, Electronics, Battlespace

ACQUISITION PROGRAM: PMS401 Submarine Acoustic Systems Program Office

OBJECTIVE: Develop a submarine TB-16 Fat Line Array medium weight tow cable that uses the existing coaxial core that improve compressional ruggedness with modest-weight penalty, when compared to the existing TB-16 lightweight tow cable.

DESCRIPTION: The Navy seeks innovative strength member construction techniques for the TB-16 Fat Line Array tow cable that significantly improves axial compression and cut resistance. Since current lightweight materials in use today are unable to provide the needed compressional strength or resistance to external damage by fish hooks, new materials or application of existing materials for the solution will be needed to meet requirements. Currently available tow cables are either lightweight or heavyweight; there is no available material or construction technique which combines the best properties of each. It is recognized that available lightweight materials (such as Vectran, Zylon) require reinforcement that increases cable density, but the goal is to minimize the impact. The proposed solutions should retain existing coaxial core, and a modest weight increase is permissible.

A modest weight penalty relative to standard lightweight construction will still provide good depth separation between two towed arrays while minimizing the strum energy imparted onto the system. The proposed Fat Line Array tow cable shall be capable of withstanding 220 pounds of axially applied compressional loads that are imparted by the OK-276 fat line handling system, as well as being terminated within the diameter of the tow cable nose cone (3.35 inches). The new tow cable may have a 30% weight increase (as compared to existing light weight TB-16 tow cable) to allow for a more rugged tow cable, with the goal of withstanding axial compressional loads. These loads will be measured on the NAVY�s land-based SSN OK-276 handling system located at NUWCDIVNPT in Newport RI. (Ref 1, 2 and 3). Additionally, the High Density Polyethylene (HPDE) currently used as a jacket material is easily cut by items such as fish hooks. Axial stiffness solutions that include making the cable more cut-resistant are greatly desired.

PHASE I: The small business will develop concepts that demonstrate substantially improved axial compressional resistance for the tow cable variant while providing a range of densities. Options should describe expected cut resistance improvements over the current HDPE. Each identified option should have a supporting simulation/calculation, showing relevant depth trail characteristics (towed array depth relative to tow platform over a range of speed and scope combinations). The small business will demonstrate the feasibility of the concepts in meeting Navy needs and will establish that the concepts can be feasibly developed into a useful product for the Navy. Feasibility will be established by material testing and analytical modeling.

PHASE II: Based on the results of Phase I and the Phase II contract statement of work, the small business will develop a prototype(s) for evaluation as appropriate. The prototype will be evaluated to determine its capability in meeting the performance goals identified above and the Navy requirements for Fat Line Array coaxial tow cables, such as survivability of 150 reeling cycles on the OK-276 handler with the dynamic seal in place These cables will be compliant with push-force requirement of 220 lbs. The Fat Line Array tow cable will be evaluated at both the raw cable level as well as the terminated cable level on the OK-276 LBTF and assessed for repeated handling cycles as well as compressional resistance. Modeling or analytical methods over the required range of parameters including numerous deployment cycles, tension and towing characteristics shall be performed. Evaluation results will be used to refine the prototype into a design that will meet Navy requirements and will be evaluated during a tow test while connected to a TB-16 Fat Line Array at Lake Pend Oreille, Idaho where Navy tow testing is performed. If successful, the small business will prepare a Phase III development plan to transition the technology to Navy use.

PHASE III: If the Phase II prototype is successful, the small business will be expected to support the Navy and array manufacturers in transitioning the new cable design into existing systems for Navy use. The small business will finalize the design of a tow cable for evaluation to determine its effectiveness in an operationally relevant environment. The small business will support the Navy for test and validation to certify and qualify the system for Navy use.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: A medium-weight tow cable is applicable to surface Navy towed array programs. Additionally, oil and seismic exploration arrays could benefit from the innovative construction technique to better control the depth towing profile for varying geographic locations.

REFERENCES:
1. Srivastava, Sanyasiraju, Tamsir. "Dynamic Behavior of Underwater Towed Cable in Linear Profile". International Journal of Scientific & Engineering Research Volume 2, Issue 7, July-2011 ISSN 2229-5518.

2. Barbegelata, Alessandro et al. "Thirty Years of Towed Arrays at NURC". Oceanography Volume 21, Number 2, June 2008: 24-33.

3. Friswell, M. "Steady-State Analysis of Underwater Cables". Journal of Waterway, Port, Coastal, and Ocean Engineering Vol. 121, No. 2, March/April 1995, pp. 98-104.

KEYWORDS: Strength member construction techniques; towed array; Zylon; Vectran; tow cable for towed arrays; cyclic loading of radar arrays

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