Aircraft Window Frame Segmentation for Drag Reduction

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing window elements for aircraft are complex, leading to increased air resistance, difficult installation, and challenges in producing fibre-reinforced composite materials due to complex geometric shapes and aerodynamic interference edges.

Innovation Solution

A window element with a simplified L-shaped or rectangular cross-sectional window frame attached to the outer skin, featuring press-on frame fittings riveted to both the window frame and external skin, reducing protrusion into the window cutout and eliminating the need for eyebolts, allowing for easier installation and production with fibre-reinforced materials.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a complex T-shaped window frame with inclined web is used, then the structural strength is improved, but the aerodynamic drag increases due to multiple interference edges

Engineering Contradiction:

Improvestructural strengthVSAvoidaerodynamic drag

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The window frame is divided into a basic L-shaped structural element and separate press-on frame fittings that are riveted to both the window frame and external skin. This segmentation allows the main frame to have a simple aerodynamic profile while separate fittings provide the necessary structural reinforcement and attachment points.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent enables production with fibre-reinforced composite materials by using the simplified L-shaped cross-section, which is more amenable to composite manufacturing processes compared to the complex T-shaped geometry with inclined webs.

Inventive Principle:

Principle #40Composite materials

2Stability of the object's composition

If a complex T-shaped window frame is used, then the structural integrity is improved, but the manufacturing complexity increases

Engineering Contradiction:

Improvestructural integrityVSAvoidmanufacturing complexity

Core Design Contradiction:

Stability of the object's compositionVSEase of manufacture

Solution Approach 1:

The window frame structure is segmented into the main L-shaped frame and separate press-on frame fittings. This allows the main frame to be manufactured with simple geometry while the fittings provide additional structural integrity through riveted connections.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The press-on frame fittings combine multiple functions: they attach the window package to the window frame, provides structural reinforcement, and enable aerodynamic fairing attachment, eliminating the need for separate eyebolts and complex frame geometry.

Inventive Principle:

Principle #5Merging (Combining)

3Strength

If eyebolts are used to fix the window package, then the attachment strength is improved, but the installation difficulty increases due to alignment requirements

Engineering Contradiction:

Improveattachment strengthVSAvoidinstallation difficulty

Core Design Contradiction:

StrengthVSEase of operation

Solution Approach 1:

Instead of requiring alignment of eyebolts during installation, the press-on frame fittings are pre-riveted to the window frame with threaded stay bolts that are always aligned perpendicularly. The press-on frame is then simply placed over these pre-positioned bolts without requiring alignment, reversing the traditional approach.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The press-on frame fittings with threaded stay bolts are pre-riveted to the window frame during frame manufacturing, eliminating the need for alignment during subsequent window package installation. This preliminary positioning simplifies the installation process significantly.

Inventive Principle:

Principle #10Preliminary action

4Strength

If a complex geometric shape is used, then the structural performance is improved, but the production of fibre-reinforced composite materials becomes difficult

Engineering Contradiction:

Improvestructural performanceVSAvoidcomposite material production

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The structure is segmented into the simple L-shaped window frame and separate press-on frame fittings, both of which have geometries suitable for fibre-reinforced composite material production, eliminating the complex T-shaped geometry that is difficult to manufacture with composites.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS8297556B2Window element for insertion in a window cutout in an outer skin of an aircraft

Publication Date: 2012.10.30 AIRBUS OPERATIONS GMBH

AI summary

A window element for insertion in a window cutout in an outer skin of an aircraft, with a window frame for accommodating a window package and a press-on frame. The window frame can be attached to the inside of the outer skin in the region of the window cutout and can be riveted to the external skin, wherein for attaching the press-on frame at least one press-on frame fitting is connected to the window frame and to the outer skin, in particular is riveted to the window frame and to the outer skin, and the window frame comprises an essentially L-shaped or rectangular cross-sectional geometric shape.