CABLES & CONNECTORS FEATURE TAKING AN APPLICATION


DEVOTED APPROACH TO AVIATION AND MILITARY CABLE DESIGN


Jeff Wood, sales director at mil-spec cable specialist


WireMasters, looks into the importance of both performance and resilience in wiring solutions for aviation and military


S


uccessful cable design is often associated with its speed or bandwidth, with durability being overlooked. A


resilient cable, however, provides longevity, ruggedness and reliability – crucial factors in aerospace and military applications. A cable’s performance refers to its ability


to deliver consistent, reliable data power or signal transmission. High performance cables, like Ethernet cable CAT8, are suitable for data centre applications like switch-to-switch communications, due to braided copper shielding that minimises electromagnetic interference (EMI). This level of EMI resistance from shielding maintains signal integrity which is responsible for delivering consistent transmission. Resilience is more about whether the cable


keeps functioning, especially when deployed in hostile environments. So, when designing a rugged cable, materials are important: Polyurethane (PUR) in jacketing, for example, provides resistance to abrasion, fluid exposure and chemical wear, with PUR-jacketed cables commonly achieving an Ingress Protection (IP) rating of IP65 to IP69<. However, in some aerospace and military


applications, high performance isn’t enough. While a lightweight Ethernet cable – with bandwidth ranging from 250 megahertz (MHz) to 1000 MHz and minimal signal loss –may seem suitable for military mobile radar trackers, in the field these have failed within weeks as they are unable to withstand hydraulic fluid exposure, a constant presence in radar trackers.


PERFORMANCE & RESILIENCE Designing a cable that intertwines both


performance and resilience means everything from material selection to technical specifications must be considered. High-bandwidth cables are constructed with


precision. Low loss dielectrics, tightly wound foil shielding and copper alloy conductive cores amount to high performing flexible cables, but limitations arise from their lightweight nature, making them less rugged. For example, foil shielding, which serves as an efficient mitigation method for EMI suppression, can crinkle or even tear under vibration, a frequent occurrence in an aircraft. On the other hand, resilient cables encounter


trade-offs with mechanical flexibility. Thicker jacketing and heavy insulators make them heavier, less space efficient and harder to route. In an aircraft, flexibility is essential for routing through tight bends and spaces, so while these ruggedised cables withstand the constant vibrations, they’re insufficient for some aircraft applications like avionics bays and line-replaceable units (LRUs), which are confined and require cables to bend sharply without causing signal loss. When it comes to both performance and


resilience individually, a cable can meet all of its specifications on paper yet still fail in the field. To combat this, engineers need to understand: where the cable will be used, external factors, whether it is for a temporary mission or expected to last for 30 years, and what happens if it fails. Understanding this, engineers can make smarter decisions about design, materials, shielding and routing to ensure durability and performance.


DEVELOPING A SOLUTION When designing cables beyond performance


specs, engineers must pay attention to materials that withstand the real-world conditions of the application, with shielding and jacketing falling into key consideration areas. In shielding, materials often facilitate reduced EMI and radio-frequency interference (RFI). For example, foil shielding comprised of aluminium- polyester tape combined with braided shields uses the properties of both features to optimise performance and durability. Braiding acts as an additional layer which protects the thin foil from vibration damage, ensuring high-frequency EMI protection and physical resilience. Extra levels of armour come from jacketing, both PUR and Perfluoroalkoxy (PFA). Suitable for dynamic defence applications like naval vessel galleries, PUR and PFA offer a low smoke alternative to polyvinyl chloride (PVC). While both have similar properties, providing exceptional fluid resistance and chemical inertness, PFA is superior from a temperature perspective, operating in up to 260˚C; while PUR offers greater abrasion resistance with many PUR- jacketed cables meeting IP67–IP69K ratings. As for the future, both miniaturisation and hybrid cable configurations hold promise in enabling lightweight components that are both powerful and resilient enough to handle critical aerospace and military systems, even in the world’s most ruthless environments. When configuring aerospace and defence


cable solutions, WireMasters collaborates closely with engineers who require both performance and reliability, ensuring the right solution for their application requirements.


WireMasters UK www.wiremasters.com


JUNE 2025 DESIGN SOLUTIONS 41


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