Lightning Protection for CFRP Fairings Using Conductive Plates
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Solution Overview
Problem
Conventional CFRP sandwich panels used in aircraft aerodynamic fairings have high transition resistance, making them unsuitable for providing adequate lightning protection to electronic units such as antennae, as they cannot effectively divert lightning currents, which can cause thermal and mechanical damage.
Innovation Solution
A lightning protection arrangement featuring electrically conductive mounting and rear plates, along with attachment means, is integrated into the CFRP sandwich panels to divert lightning currents with low resistance onto the aircraft fuselage, utilizing a wire mesh for additional protection and minimizing corrosion risks with materials like titanium or aluminum.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If conventional CFRP sandwich panels are used for aerodynamic fairings, then weight is reduced and mechanical stability is improved, but transition resistance becomes too high to effectively divert lightning currents
Solution Approach 1:
The patent applies composite materials by integrating a conductive mesh (metal or carbon fiber) into the CFRP sandwich panel structure. This creates a hybrid composite that combines the weight-saving benefits of CFRP with the electrical conductivity of metal or carbon fiber networks, enabling effective lightning current diversion while maintaining the low weight requirement for aerodynamic fairings.
Solution Approach 2:
The conductive mesh is strategically positioned within the CFRP sandwich panel at locations where lightning strike protection is most critical, particularly near electronic units. This local reinforcement of electrical conductivity allows the panel to maintain low overall weight while providing targeted high-conductivity pathways for lightning current diversion at specific zones.
2Weight of moving object
If the thickness of CFRP layers is reduced to minimize weight, then weight decreases, but electrical conductivity and lightning protection capability deteriorate
Solution Approach 1:
The patent compensates for the low electrical conductivity of thin CFRP layers by embedding a conductive mesh within the sandwich structure. This composite approach allows the use of thin CFRP layers for weight reduction while the integrated metal or carbon fiber mesh provides the necessary electrical conductivity pathway to divert lightning currents and prevent thermal and mechanical damage.
3Adaptability or versatility
If electronic units are attached to the outer skin of the aircraft fuselage, then functional capability is improved, but the area available for attachment is restricted due to minimum distance requirements between units
Solution Approach 1:
The patent utilizes the thickness dimension of the aerodynamic fairing by integrating the conductive mesh within the sandwich panel structure, rather than adding external protective layers. This internal integration allows electronic units to be mounted on the outer skin with adequate spacing while the lightning protection function is embedded within the fairing's internal structure, effectively using the available three-dimensional space.
4Ease of manufacture
If lightning conductor strips made of thermoplastic polymer with conductive particles are used, then some lightning protection is provided, but transition resistance remains too high for adequate current diversion
Solution Approach 1:
The patent replaces thermoplastic polymer-based conductive strips with a metal or carbon fiber mesh integrated into the CFRP sandwich panel. This composite material provides significantly lower transition resistance and superior electrical conductivity for lightning current diversion, while still maintaining ease of manufacture through integration during the fairing fabrication process.
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
This solution allows electronic units to be securely attached to CFRP sandwich panels while ensuring effective lightning protection, reducing transition resistance to less than 5 mΩ, minimizing damage, and enabling easy replacement of the panels.
Implementation Method 1
an electrically conductive mounting plate (9A) arranged on an outer side of a CFRP sandwich panel (1) of the aerodynamic fairing, and an electrically conductive rear plate (9B) arranged on an inner side of the CFRP sandwich panel (1)
Implementation Method 2
utilizing a wire mesh for additional protection
Data Source
AI summary
Lightning protection arrangement for diverting a current, caused by a lightning strike, from an electronic unit which is fitted to an aerodynamic fairing of an aircraft. The device includes an electrically conductive mounting plate which is arranged on an outer side of a CFRP sandwich panel of the aerodynamic fairing. Furthermore, the device has an electrically conductive rear plate which is arranged on an inner side of the CFRP sandwich panel of the aerodynamic fairing and is connected electrically to the mounting plate. In this respect, a first group of attachment means provided for the electronic unit connects the electrical unit electrically to the rear plate. An electric current generated during a lightning strike is diverted with low resistance from the electrical unit via the rear plate and the mounting plate onto the fuselage of the aircraft.