N221-020 TITLE: Heat Tolerant Decoy Towline for Towed Decoy

OUSD (R&E) MODERNIZATION PRIORITY: General Warfighting Requirements (GWR)

TECHNOLOGY AREA(S): Air Platforms;Battlespace Environments;Electronics

OBJECTIVE: Develop an advanced heat tolerant towline for towed decoy with an operating temperature limit of at least 700 �C with a goal operating temperature limit of 1000 �C.

DESCRIPTION: The current Navy towed decoy deployment system location places the trailing towline in a position where hot engine exhaust encroaches on it during high Angle of Attack (AOA) maneuvers that use engine afterburners. The hot engine exhaust encroachment causes material failure of the towline that can cause towline separation or prevent operation of the decoy. A towline typically contains from two to five high-voltage wires and a single-mode optical fiber. Zylon fibers provide towline tensile strength in excess of 200 lb (90.72 kg). The towline diameter is restricted by available spool volume to about 0.062 in. (1.57 mm), and a bend radius of approximately 0.25 in. (6.35 mm) is required to meet unspooling functionality. The towline must remain flexible over a storage temperature range between -60 �C to +85 �C. The current decoy insulated wire consists of the polyimide EKJ (DuPont) that is tape-wrapped around a fine-gauge conductor. Studies and material analysis have shown that the EKJ insulation tends to electrically break down on exposure to temperatures above 550 �C for more than 30 seconds (s) at the high voltages (> 2,500 V) necessary to properly energize the decoy electronics. The electrical breakdown of the insulation leads to arcing and current leakage between conductors, which causes the decoy power supply to shut down due to overcurrent. The Zylon fibers that provide tensile strength also fail rapidly above 650 �C, resulting in parting of the towline and loss of the decoy. Ideally, as a near-term goal, a towline operating temperature of 700 �C for six towline exposures of > 30 s each is sought, and as a longer term goal, an operating temperature as high as 1000 �C with the same or greater exposure times is desired. This can possibly be achieved by perfecting the existing science in the towline systems, and/or devising novel towline systems, e.g., the conducting and strength members may ultimately be a single entity. Such advanced tow cables may also require materials that are not entirely organic in nature as they will most likely not survive extreme conditions up to 1000 �C. In this regard, innovative research involving inorganic/ceramic and other hybrid material systems may be useful and such innovative ideas are sought in this SBIR topic.

PHASE I: Demonstrate the feasibility of an advanced heat tolerant tow cable concept, including addressing in detail how each component of the proposed tow cable will meet the material and structural demand with regard to the sought requirements. Preliminary component level testing results supporting the design, i.e., proof-of-concept results are highly desirable although not a must. Propose Phase II cable fabrication and test effort that will fully demonstrate the sought requirements. The Phase I effort will include prototype plans to be developed under Phase II.

PHASE II: Develop a prototype tow cable. Perform component level testing supporting the design to demonstrate the sought parameters of both near-term and long-term goals. Fabricate and test multiple lengths, i.e., from 10�100 ft (3.05�30.48 m) of tow cables.

PHASE III DUAL USE APPLICATIONS: Once an effective, affordable, and improved temperature towed decoy cable design has been demonstrated, the Navy can reflect the new capability in performance specifications. The Navy and the small business can negotiate to provide that improved performance to the Navy.

Improved high temperature cables would be useful for commercial aircraft wiring around hot engines and for cables for sensors in deep earth drilling operations.

REFERENCES:

1. Kolel-Veetil, M. K., & Keller, T. M. (2007). Polymeric protection of Navy fighter jet towlines. Naval Research Laboratory. https://apps.dtic.mil/dtic/tr/fulltext/u2/a516758.pdf.
2. Texas A&M. (n. d.). Materials for extreme environments. Engineering Magazine. Retrieved March 16, 2021, from https://engineeringmagazine.tamu.edu/materials-for-extreme-environments/.
3. The Grainger College of Engineering. (n. d.). Mechanical properties and materials for extreme conditions. University of Illinois Urbana-Champaign. Retrieved March 16, 2021, from https://matse.illinois.edu/research/mechanical-properties-and-materials-extreme-conditions.
4. Glenn Research Center. (n. d.). Materials & structures for extreme environments. NASA. Retrieved March 16, 2021, from https://www1.grc.nasa.gov/research-and-engineering/materials-structures-extreme-environments/.
5. Reference added 01/12/2022 - Towline Cable Design - https://navysbir.com/n22_1/N221-020_Reference_5_Towline_Cable_Design.pdf.

KEYWORDS: Towline; high temperature; HT; HT wire insulation; HT fibers with tensile strength; decoy; HT fibers