Wingtip Attachment Layout for Low-Drag External Fastener Access

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Solution Overview

Problem

Existing wingtip attachment designs are cumbersome, heavy, and require complex access methods, leading to increased in-tank work and reduced airplane performance.

Innovation Solution

A wingtip attachment system with two rows of fasteners, one within and one outside the aerodynamic contour, allowing for easy access and maintenance, using tension bolts with barrel nuts, and covered by aerodynamic fairings for continuous surfaces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a fully contained joint within the aerodynamic contour is used, then aerodynamic continuity is improved, but access for maintenance becomes difficult requiring in-tank work

Engineering Contradiction:

Improveaerodynamic dragVSAvoidaccess for maintenance

Core Design Contradiction:

Object-affected harmful factorsVSEase of operation

Solution Approach 1:

The fastener system is divided into two rows: first row fasteners located within the aerodynamic contour and second row fasteners located outside. This segmentation allows different access methods for different fasteners, resolving the contradiction between aerodynamic continuity and maintenance accessibility.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The solution moves some fasteners from the traditional in-tank location to an external location on the lower panel, changing the spatial dimension of fastener placement. This allows external access while maintaining aerodynamic fairness through strategic positioning.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Strength

If lug and clevis joints with pins are used, then structural strength is improved, but weight increases and damage tolerance decreases

Engineering Contradiction:

Improvejoint strengthVSAvoidwingtip attachment weight

Core Design Contradiction:

StrengthVSWeight of moving object

Solution Approach 1:

The invention changes the fastener type from traditional pins to tension bolts with barrel nuts, altering the mechanical parameters of the joint. This provides equivalent or superior strength while reducing weight and improving damage tolerance through controlled failure modes.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If a pin running along the airstream with in-tank tension joint is used, then structural reliability is improved, but airfoil thickness increases

Engineering Contradiction:

Improvejoint reliabilityVSAvoidairfoil thickness

Core Design Contradiction:

ReliabilityVSLength of moving object

Solution Approach 1:

The second row of fasteners is extracted from the in-tank location and positioned on the external lower panel. This removes the thickness-increasing elements from the aerodynamic contour while maintaining structural reliability through the dual-row fastener configuration.

Inventive Principle:

Principle #2Taking out (Extraction)

4Ease of repair

If tension joint pins accessible from both upper and lower panels are used, then ease of maintenance is improved, but device complexity increases requiring access to both sides

Engineering Contradiction:

Improvefastener accessibilityVSAvoidaccess procedure complexity

Core Design Contradiction:

Ease of repairVSDevice complexity

Solution Approach 1:

Instead of requiring access from both upper and lower panels, the invention inverts the approach by providing access to all fasteners from the lower panel only. This simplifies the maintenance procedure while maintaining ease of access through strategic fastener positioning.

Inventive Principle:

Principle #13The other way round (Inversion)

Data Source

PatentUS12473073B2Wingtip attachment with a reduction in in-tank work and aerodynamic drag

Publication Date: 2025.11.18 THE BOEING CO

AI summary

A wingtip attachment for connection to a wing is disclosed. The wingtip attachment includes a tip rib comprising a first row of fastener openings located within an aerodynamic contour of a wing box and a second row of fastener openings located within a protruding fairing outside the nominal aerodynamic contour of a wing box.