Stealth Aircraft Lightning Diverter Strip Orientation

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Solution Overview

Problem

Conventional lightning diverter strips on aircraft reflect or return radar signals at multiple angles, compromising the low-observable properties of stealth aircraft.

Innovation Solution

A lightning protection system featuring a lightning diverter strip with thin, flexible dielectric substrate and strategically aligned metal strips or carbon nanotubes that ionize lightning strikes at lower voltages, while maintaining alignment with aircraft surfaces to minimize radar reflection and preserve stealthiness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional lightning diverter strips are used, then lightning protection is provided, but radar signals are reflected at multiple angles compromising stealth properties

Engineering Contradiction:
Improvelightning protectionVSAvoidradar signal reflection
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent applies local quality by making the conductive elements' orientation specific to the radome surface geometry. The conductive elements are arranged to be substantially parallel to the radome surface at each location, creating location-dependent radar reflection characteristics that maintain stealth while providing lightning protection.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent employs asymmetry by orienting conductive elements non-uniformly across the radome surface rather than using a consistent pattern. The orientation varies according to the local surface geometry, creating asymmetric reflection patterns that direct radar energy away from the radar antenna while maintaining lightning diversion functionality.

Inventive Principle:
Principle #4Asymmetry

2Reliability

If conductive elements are added to protect against lightning, then lightning protection is improved, but radar detectability increases

Engineering Contradiction:
Improvelightning protectionVSAvoidradar detectability
Core Design Contradiction:
ReliabilityVSDifficulty of detecting and measuring

Solution Approach 1:

The conductive elements are oriented according to local radome surface geometry, with each element parallel to the surface at its specific location. This local adaptation ensures that radar reflections are directed away from the radar antenna while maintaining effective lightning protection across the entire radome surface.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent converts the potentially harmful effect of conductive elements (increased radar reflectivity) into a beneficial effect by strategically orienting them to reflect radar signals away from the radar antenna. The same conductive elements that could increase detectability are configured to actually reduce it by directing reflections in safe directions.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

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 protects aircraft from lightning strikes while ensuring radar signals are reflected only at specific angles, maintaining the aircraft's low-observable properties and avoiding detection by radar systems.

Implementation Method 1

This occurs due to the ionisation of air between the electrically conductive elements of the lightning diverter strip which creates a low impedance path along the length of the lightning diverter strip

Methodology Applied
Scientific EffectIonisation: Ionisation

Implementation Method 2

This is done to so that the aircraft reflects radar signals that are detectable only in very specific directions relative to the aircraft

Methodology Applied
Scientific EffectReflection: Reflection

Data Source

PatentEP2969768B1Lightning protection system
Publication Date: 2022.05.04 BAE SYSTEMS PLC
  • EP2969768B1 patent drawingFigure 1~2
  • EP2969768B1 patent drawingFigure 3~5
  • EP2969768B1 patent drawingFigure 6~7

AI summary

A system comprising a low observable aircraft (2) having its surfaces oriented at a limited number of directions, and a lightning diverter strip (4, 22, 30) comprising a plurality of electrically conductive elements (8, 24, 32) arranged in a spaced apart relation, each of the electrically conductive elements (8, 24, 32) comprising an elongate portion. The lightning diverter strip (4, 22, 30) is attached to the aircraft in such a way that the conductive elements (8, 24, 32) are located on an exposed outer surface of the lightning diverter strip (4, 22, 30) and exposed to atmospheric conditions. For each conductive element (8, 24, 32), a long axis of the elongate portion of that conductive element (8, 24, 32) is substantially parallel with a surface of the aircraft.