Aircraft Window Periphery Seal for Thin Sidewall Thermal Isolation

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Solution Overview

Problem

Newer aircraft designs with thinner sidewalls face challenges in insulating cabin windows effectively due to reduced space, leading to cold air intrusion and window icing, despite the use of insulation materials.

Innovation Solution

A seal is provided around the periphery of the window, forming a thermal and physical barrier that prevents cold air from reaching the window, using materials like cross-linked closed cell rigid foam, and can be integrated with insulation to enhance insulation efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of moving object

If sidewall thickness is reduced to increase cabin width, then cabin width is improved, but thermal insulation performance deteriorates

Engineering Contradiction:
Improvecabin widthVSAvoidthermal insulation performance
Core Design Contradiction:
Area of moving objectVSTemperature

Solution Approach 1:

The seal is divided into multiple functional segments: an insulating seal portion for thermal insulation, a sealing portion for creating physical barriers, and attachment features for secure mounting. This segmentation allows each portion to optimize its specific function while working together to resolve the contradiction between reduced sidewall thickness and thermal insulation performance.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The insulating seal is constructed from composite materials including foam core layers (such as closed-cell foam) combined with elastomeric or rubberized outer layers. This composite structure provides both thermal insulation properties and mechanical sealing capabilities, enabling effective thermal barrier function even in thinner sidewall configurations.

Inventive Principle:
Principle #40Composite materials

2Quantity of substance

If conventional insulation materials are used in thinner sidewalls, then material quantity is reduced, but insulation effectiveness deteriorates due to voids and air leaks

Engineering Contradiction:
Improveinsulation material quantityVSAvoidinsulation effectiveness
Core Design Contradiction:
Quantity of substanceVSReliability

Solution Approach 1:

The seal incorporates flexible elastomeric or rubberized portions that can deform and conform to irregular surfaces and fill gaps. This flexibility allows the seal to maintain reliable thermal and air barriers even in thinner sidewall configurations where rigid insulation materials might leave voids or fail to seal properly around windows.

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The seal acts as an intermediary component between the window assembly and the sidewall structure, filling the gap space and creating a continuous thermal and air barrier. This intermediary seal prevents cold air infiltration and thermal conduction through the window periphery, compensating for the reduced insulation material quantity in thinner sidewalls.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Temperature

If insulation material is added to compensate for thinner sidewalls, then thermal insulation is improved, but device complexity and weight increase

Engineering Contradiction:
Improvethermal insulationVSAvoidinsulation structure complexity
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The seal performs multiple functions simultaneously: thermal insulation, air sealing, structural attachment, and vibration damping. By integrating these functions into a single component rather than using separate insulation layers and sealing elements, the design achieves improved thermal insulation without increasing overall device complexity or weight.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The insulating seal merges the functions of thermal insulation and sealing into a single integrated component. The foam core provides insulation while the elastomeric outer layer provides sealing, combining what would traditionally require separate materials and assembly steps into one unified part that simplifies the overall insulation structure.

Inventive Principle:
Principle #5Merging (Combining)

4Ease of manufacture

If traditional sealing methods are used, then manufacturing is simple, but thermal insulation at window periphery is insufficient

Engineering Contradiction:
Improveseal manufacturing simplicityVSAvoidwindow periphery insulation
Core Design Contradiction:
Ease of manufactureVSTemperature

Solution Approach 1:

The insulating seal is pre-formed with integrated attachment features (adhesive layers, mechanical fastening points) and configured to fit specific window assemblies. This preliminary preparation allows for easy installation on the aircraft without requiring complex on-site manufacturing or assembly procedures, while still providing enhanced thermal insulation at the window periphery compared to traditional sealing methods.

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

The seal effectively blocks cold convection currents and thermal conduction, reducing the need for additional insulation materials and preventing window icing, while being lightweight and cost-effective.

Implementation Method 1

The seal effectively blocks cold convection currents

Methodology Applied
Scientific EffectConvection: Convection

Implementation Method 2

The seal effectively blocks cold convection currents and thermal conduction

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 3

The sidewall cavity includes insulation configured to thermally insulate the inner sidewall from the outer skin

Methodology Applied
Scientific EffectThermal insulation: Thermal Insulation

Data Source

PatentEP4671119A1Aircraft sidewall having cabin windows with insulating seals
Publication Date: 2025.12.31 THE BOEING CO
  • EP4671119A1 patent drawingFigure 1
  • EP4671119A1 patent drawingFigure 2
  • EP4671119A1 patent drawingFigure 3

AI summary

A window assembly (56) for an aircraft fuselage (22) includes a seal (76) surrounding the periphery of a window (32) in a cabin sidewall (45). The seal (76) fills voids (88) within the sidewall (45) and forms a physical and thermal barrier against cold air (95) within the sidewall cavity (62) from reaching the window (32).