Aircraft Windshield Conductive Heaters Lightning Protection
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Solution Overview
Problem
Aircraft windshields with conductive heaters face challenges in managing induced currents during lightning strikes, which can lead to excessive current flow and potential damage to controllers, while maintaining visibility and reliability against strong magnetic fields.
Innovation Solution
The implementation of conductive members along the windshield, wire-connected in delta or star configurations, to circulate or cancel out induced currents, preventing excess current flow and reducing the need for electromagnetic shielding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an electromagnetic shield is used to block strong magnetic fields during lightning strikes, then shieldability is improved, but visibility of the windshield deteriorates
Solution Approach 1:
The patent converts the harmful induced current generated by lightning strikes into beneficial heat by connecting heater elements in series configurations. The induced current flows through the heaters during lightning events, dissipating energy as heat rather than damaging the aircraft systems, thereby protecting the aircraft while maintaining windshield transparency.
Solution Approach 2:
The heater elements serve dual functions: providing thermal anti-icing/anti-fogging during normal operation and acting as electromagnetic protection during lightning strikes. This multi-functionality eliminates the need for separate electromagnetic shielding materials that would compromise visibility.
2Area of stationary object
If the conductive members are connected in parallel, then the heater coverage area is improved, but induced current flow increases during lightning strikes
Solution Approach 1:
Instead of connecting heaters in parallel to maximize coverage area, the patent inverts the approach by connecting them in series. This series connection configuration increases the total resistance, thereby limiting induced current flow during lightning strikes while still providing adequate thermal coverage through the heater elements.
3Reliability
If a thick conductive film is used for the heater, then the shieldability against magnetic fields is improved, but the visibility through the windshield deteriorates
Solution Approach 1:
The patent changes the electrical connection parameter (from parallel to series) rather than altering the physical thickness or material properties of the conductive film. This parameter change in connectivity achieves current limitation during lightning strikes while maintaining the thin-film transparency required for windshield visibility.
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 effectively suppresses induced current flow outside the wire connection, ensuring controller safety and maintaining visibility by consuming induced currents as heat, thus enhancing the reliability of the windshield against lightning strikes.
Implementation Method 1
a thin film of ITO (indium tin oxide), gold, silver, or the like is formed on a windshield panel as the heater. The fogging of the windshield and the adhesion of ice thereto are prevented by heat generated from the thin film to which a current is supplied.
Implementation Method 2
the conductive members are wire-connected such that induced currents induced in the respective conductive members by a magnetic field in association with a lightning current are circulated between the conductive members.
Data Source
AI summary
The present invention provides a windshield of an aircraft, including a plurality of conductive members that are disposed along an in-plane direction of the windshield, and are wire-connected together, wherein the plurality of conductive members are heaters that generate heat when supplied with an alternating current, and the conductive members are wire-connected such that induced currents induced in the respective conductive members by a magnetic field in association with a lightning current are circulated between the conductive members.