Aircraft Fuselage Internal Current Return Network for Lightning Protection
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Solution Overview
Problem
Newer lightweight aircraft made of less conductive composite materials are vulnerable to the indirect effects of lightning strikes, which can compromise structural integrity and damage electronics, as they do not readily conduct away electrical currents or shield cabling and electronic components from electromagnetic forces, leading to increased weight and space occupancy from traditional lightning strike protection systems.
Innovation Solution
An improved lightning strike protection system featuring an external and internal current return network using conductive foil material, providing low impedance paths on the aircraft's exterior and interior surfaces to direct lightning currents and reduce electromagnetic interference, without adding excessive weight or occupying valuable space, by utilizing wide planar sheets of expanded copper foil for increased surface area and efficient current path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional LSP systems use conductive cables, metal rods, and brackets inside the aircraft, then lightning strike protection is improved, but aircraft weight increases and valuable space is occupied
Solution Approach 1:
The patent replaces traditional mechanical LSP components (cables, metal rods, brackets) with an electrical field-based solution using conductive foil materials applied to the aircraft fuselage. This substitution eliminates the need for heavy internal structural components while maintaining lightning protection functionality through electrical conductivity and electromagnetic shielding.
Solution Approach 2:
The patent changes the physical form and distribution of conductive material from discrete internal components to continuous external foil layers applied to the fuselage surface. This parameter change in material configuration provides equivalent or superior protection while dramatically reducing weight and space requirements.
2Reliability
If conductive foil material is applied to the exterior fuselage surface, then current conduction is improved, but AC resistivity remains high without internal current return paths
Solution Approach 1:
The patent merges the external current return network (conductive foil on exterior) with the internal current return network (conductive foil on interior fuselage surface) to create a unified, continuous conductive path. This integration allows lightning currents to flow efficiently through both external and internal pathways, eliminating high AC resistivity by providing multiple parallel current return paths.
Solution Approach 2:
The patent adds an internal dimension to the current return path by applying conductive foil to the interior fuselage surface, creating a three-dimensional conductive network that complements the external two-dimensional foil layer. This dimensional expansion provides additional current pathways that reduce overall AC resistivity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system effectively minimizes both direct and indirect effects of lightning strikes, reduces AC resistivity, and provides a continuous zero voltage reference plane, enhancing the aircraft's structural integrity and reducing electromagnetic interference while maintaining efficiency and range.
Implementation Method 1
The LSP system minimizes or eliminates both the direct and indirect effects of lightning strikes on the aircraft and reduces AC resistivity
Implementation Method 2
The conductive foil material is provided in wide planar sheets, and in one embodiment, is formed of expanded copper foil mesh
Implementation Method 3
The internal current return network also eliminates electromagnetic interference with data and signal cables and provides a continuous zero voltage reference plane throughout the aircraft
Data Source
AI summary
A lightning strike protection (LSP) system minimizes or eliminates both the direct and indirect effects of lightning strikes on aircraft with composite fuselages without adding excessive weight to the aircraft. The LSP system comprises an external current return network and an internal current return network. The internal current return network comprises a wide plane of conductive foil material adhered to, or embedded within, an innermost surface of the fuselage and other portions of the aircraft formed primarily of composite materials. The conductive foil material is provided in wide planar sheets, and in one embodiment, is formed of expanded copper foil mesh. The internal current return network is installed in all areas or zones of the aircraft where cables and wires are routed.