Aircraft Leading Edge Skin with Embedded Resistive Heating Elements

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Solution Overview

Problem

Existing methods for de-icing and anti-icing of aircraft wing leading edges, such as those using hot air or electrical heating, face challenges in integrating resistive heating elements effectively, leading to inefficiencies and adverse effects on engine performance and aerodynamic quality.

Innovation Solution

A method for manufacturing a leading edge skin with resistive heating elements using a stack comprising adhesive films, preimpregnated fibers, and prepreg carbon fibers, cured in a mold, which allows precise positioning and automation of the elements, reducing manufacturing costs and improving surface quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If resistive heating elements are integrated into leading edge skin using conventional methods, then de-icing and anti-icing functionality is achieved, but manufacturing precision and positioning accuracy deteriorate

Engineering Contradiction:

Improvede-icing functionalityVSAvoidheating element positioning

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent merges the heating element integration process with the composite skin manufacturing process into a single autoclave curing operation. The heating elements, adhesive films, and fiber prepregs are stacked together and cured simultaneously, eliminating separate integration steps and ensuring precise positioning throughout manufacturing.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

Adhesive films serve as intermediaries between the resistive heating elements and the fiber layers. These films facilitate precise positioning and secure bonding during the autoclave curing process, ensuring the heating elements remain accurately positioned while being integrated into the composite structure.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of manufacture

If hot air systems are used for ice protection, then ease of implementation is improved, but engine performance deteriorates

Engineering Contradiction:

Improveice protection system implementationVSAvoidengine performance

Core Design Contradiction:

Ease of manufactureVSLoss of energy

Solution Approach 1:

The patent replaces the mechanical hot air circulation system with an electrothermal system using resistive heating elements embedded in the composite skin. This substitution eliminates the need to extract hot air from the engine compressor, thereby preserving engine thermodynamic efficiency while providing effective ice protection.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system changes the energy source parameter from thermal energy extracted from engine exhaust to electrical energy converted to heat through resistive elements. This parameter change allows ice protection functionality while maintaining engine performance by not interfering with the thermodynamic cycle.

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If manual integration methods are used for heating elements, then manufacturing flexibility is maintained, but productivity and automation capability deteriorate

Engineering Contradiction:

Improvemanufacturing flexibilityVSAvoidmanufacturing efficiency

Core Design Contradiction:

Adaptability or versatilityVSProductivity

Solution Approach 1:

The patent employs preliminary action by pre-positioning the resistive heating elements and adhesive films on the fiber prepregs before stacking. This pre-arrangement allows automated handling and stacking equipment to process the components efficiently, improving productivity while maintaining manufacturing flexibility through standardized preparation procedures.

Inventive Principle:

Principle #10Preliminary action

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 approach results in a high-performance, efficiently manufactured leading edge skin with precise resistive heating element placement, reducing manufacturing costs and improving aerodynamic profile quality while minimizing the risk of porosity and thermal stress, thus enhancing aircraft safety and performance.

Implementation Method 1

resistive heating elements for de-icing and/or anti-icing of the leading edge

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Implementation Method 2

two adhesive films arranged respectively on either side of said assembly, so that the heating elements adhere to each of these two adhesive films

Methodology Applied

Scientific EffectAdhesion: Adhesive

Implementation Method 3

a step of curing a stack in a mold between two molding surfaces opposite

Methodology Applied

Scientific EffectCuring: Heat Treatment

Data Source

PatentEP2817223B1Method for producing a leading edge skin by baking a stack incorporating heating elements and layers of pre-impregnated fibres

Publication Date: 2019.04.03 SONACA SA

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AI summary

The invention relates to a method for producing a leading edge skin for an aircraft, comprising an assembly of resistive heating elements (26) for a system for de-icing and/or anti-icing of the leading edge, the method comprising a step of baking a stack (14) in a mould between two moulding surfaces facing each other, said stack comprising: - the assembly of elements (26); - two adhesive films (24, 28) arranged on either side of the assembly (26); - two layers of pre-impregnated fibres (22, 30) adhering to the two adhesive films; and - a plurality of layers of pre-impregnated carbon fibres (20).