Composite Trailing Edge Control Surface with Pre-Drilled Skin

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Solution Overview

Problem

Conventional trailing edge control surfaces require complex and costly assembly jigs for drilling fastener holes, which limits manufacturing efficiency and flexibility, and typically rely on a spar element for load support.

Innovation Solution

A composite trailing edge control surface is fabricated using a contiguous one-piece composite control surface skin with pre-drilled fastener apertures, stiffening cores, and hinge fittings, eliminating the need for conventional spar elements and simplifying the manufacturing process by allowing the skin to wrap around internal components, thus forming a closed torsion cell to carry loads.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional assembly jigs are used to drill fastener holes in assembled control surfaces, then manufacturing precision can be achieved, but device complexity and manufacturing cost increase significantly

Engineering Contradiction:
Improvefastener hole positioning precisionVSAvoidassembly jig complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The skin is provided with pre-drilled fastener apertures before assembly with internal components. This preliminary action eliminates the need for complex assembly jigs during the drilling operation, as the holes are already positioned and sized correctly for receiving fasteners that will attach ribs and hinge fittings.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The manufacturing process is segmented into independent steps: skin preparation with pre-drilled apertures, separate fabrication of internal components, and final assembly. This segmentation allows the skin to be prepared independently with precise apertures without requiring complex jigs to hold all components in position during drilling.

Inventive Principle:
Principle #1Segmentation

2Manufacturing precision

If complex assembly jigs are used for drilling fastener holes, then fastener hole alignment is achieved, but manufacturing cost and resource requirements increase

Engineering Contradiction:
Improvefastener hole alignmentVSAvoidmanufacturing cost
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

Fastener apertures are pre-drilled in the skin before assembly, eliminating the need for expensive custom assembly jigs. The preliminary preparation of the skin with accurately positioned apertures simplifies the overall manufacturing process and reduces costs.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent replaces expensive, complex, and reusable assembly jigs with a simpler approach where the skin itself serves as the positioning reference for fastener apertures. This eliminates the need for costly jig fabrication and maintenance.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

3Strength

If a spar element is used to carry bending, shear, and torsion loads, then structural strength is provided, but device complexity and weight increase

Engineering Contradiction:
Improveload carrying capacityVSAvoidstructural complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The skin is designed to directly carry bending, shear, and torsion loads without a separate spar element. The skin is strengthened by increasing ply thickness in specific regions, merging the functions of the skin and spar into a single integrated structure that reduces overall complexity.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The spar element is extracted or removed from the control surface structure. The patent explicitly eliminates the need for a spar by redesigning the skin to assume all load-carrying functions, simplifying the overall structure.

Inventive Principle:
Principle #2Taking out (Extraction)

4Strength

If multiple machined parts are assembled to form the control surface, then structural integrity is achieved, but manufacturing time and resource requirements increase

Engineering Contradiction:
Improvestructural integrityVSAvoidmanufacturing efficiency
Core Design Contradiction:
StrengthVSProductivity

Solution Approach 1:

The control surface is segmented into the skin and internal components (ribs, hinge fittings) that can be fabricated independently and assembled. This segmentation allows parallel manufacturing of components, improving overall productivity while maintaining structural integrity through proper fastening.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The skin is prepared in advance with pre-drilled fastener apertures and reinforced regions before assembly. This preliminary action enables faster assembly operations and allows the skin to be manufactured independently of internal components, improving manufacturing efficiency.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3126125B1Structural arrangement and method of fabricating a composite trailing edge control surface
Publication Date: 2021.10.20 THE BOEING CO
  • EP3126125B1 patent drawingFigure 1
  • EP3126125B1 patent drawingFigure 2
  • EP3126125B1 patent drawingFigure 3

AI summary

The present disclosure is generally directed to a composite trailing edge control surface including a contiguous one-piece composite control surface skin wrapped around a plurality of stiffening cores, a plurality of hinge fittings, and a plurality of substantially parallel ribs. The contiguous one-piece composite control surface skin provides a control surface on opposing sides of the trailing edge control surface and substantially distributes bending, shear and torsion loads of the trailing edge control surface to the plurality of hinge fittings and the plurality of substantially parallel ribs. A method of manufacturing the trailing edge control surface includes positioning a contiguous one-piece composite control surface skin on a substantially flat tool. A plurality of stiffener cores having a plurality of thin covering skins are positioned on the contiguous one-piece composite control surface skin and are cured to create a laminate sandwich composite structure skin that is trimmed and has fastener apertures and hinge fitting access apertures provided there-through.