Very High Temperature Multi-Exposure Decoy Towline

Navy aircraft deploy towed decoys to disrupt missile radar guidance. Their towlines are very thin, and often contain one or more fiber optic and copper conductors, as well as material for tensile strength and electrical insulation. This SBIR solicitation seeks to improve a typical 0.062” diameter towline that includes 5 copper conductors surrounding a centrally-located fiber optic strand. Materials used in the towline for electrical insulation and to support the 200-lb tow load are polymers that have excellent material properties and light weight. These function as intended at low to moderate temperature. A problem arises when jets maneuver in a way that exposes the trailing towline to jet exhaust. High temperature in the wake rapidly increases temperature of the towline to the point that performance-critical organic polymers are heated to temperatures where they can no longer sustain tensile load, and also begin to chemically decompose, creating electrical shorting issues. Eventually the cable parts, losing the expensive decoy and exposing the aircraft to increased threat of missile attack. The Navy seeks to increase the ability of towlines to operate in an elevate temperature environment. Specifically, it is desired to develop a new configuration that can sustain at least 5 exposures of 30-seconds each in a 700C wake (preferred 1,000C). A significant design constraint is that any new towline must maintain the current cable diameter. ZKxKZ extensively analyzed the thermal response of the existing towline during preparation of this proposal, using the commercial ANSYS finite element code, as well as our own proprietary transient thermo-structural design code (optimized to predict aircraft structural response to blast and thermal pulse from a nearby nuclear detonation). This code was used to develop many important aerospace structures, including the B-2 bomber and the Presidential helicopter. Proposal page limits prevent presentation of this extensive study; however, the conclusion can be simply stated. There is no solution that involves polymer materials, unless the constraint on towline diameter is increased. Thus, a new design must incorporate inorganic material. We offer one such solution in the proposal that should be able to operate with no constraints in the jet exhaust wake (with one exception, discussed in detail in the proposal and specifically indicated to be beyond scope of this SBIR topic during our pre-proposal discussion with TPOCs). In the Phase I Base we will design, analyze and fabricate several variations of a proposed towline, then test to demonstrate ability to withstand minimum bend radius, repeated deployment cycles, and continuous operation without degradation in a 700-1,000C thermal environment (with the one possible exception noted above). In the Option, we will refine material configurations to reflect test results, then demonstrate a near-complete system ready for transition work in Phase II.