Forward and Aft Swept Wingtip Feathers for Aircraft

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Solution Overview

Problem

Conventional aircraft wing designs face challenges in achieving optimal lift distribution and reducing drag while maintaining structural integrity, with existing wingtip devices like winglets having limitations in enhancing wing loading and efficiency, especially under varying flight conditions.

Innovation Solution

The introduction of forward and aft swept wingtip feathers, fixed relative to the wing, which are designed to provide differential loading and pitching moments at different flight conditions, reducing the need for complex deployable devices and minimizing weight and complexity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If wingtip is washed out to reduce lift distribution toward the wing tip, then structural bending loads at the root are reduced, but wing loading is lost and induced drag increases

Engineering Contradiction:

Improvestructural bending loadsVSAvoidwing loading

Core Design Contradiction:

StrengthVSForce

Solution Approach 1:

The wingtip device is segmented into multiple feathers (first feather with forward sweep, second feather with aft sweep) that can be differentially loaded based on flight conditions, allowing the system to optimize between wing loading and structural loads

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent creates a dynamic system where the effective geometry of the wingtip changes based on flight conditions through the differential loading of feathers with different sweep angles, allowing adaptation between cruise and high-load conditions

Inventive Principle:

Principle #15Dynamics

2Force

If conventional wingtip devices like winglets are added to recapture wing loading, then overall lift is increased, but device complexity and weight increase

Engineering Contradiction:

Improveoverall liftVSAvoiddevice complexity

Core Design Contradiction:

ForceVSDevice complexity

Solution Approach 1:

Instead of using a single complex winglet structure, the patent segments the wingtip device into multiple simple feather elements with different sweep angles that can be differentially loaded, reducing overall device complexity while maintaining lift enhancement capability

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent utilizes parameter changes in the sweep angles of the feathers (first feather with forward sweep, second feather with aft sweep) to create different aerodynamic characteristics that adapt to flight conditions, eliminating the need for complex deployable mechanisms

Inventive Principle:

Principle #35Parameter changes

3Ease of manufacture

If fixed feather configuration is used, then manufacturing and installation are simplified, but adaptability to varying flight conditions is reduced

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidadaptability to flight conditions

Core Design Contradiction:

Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The patent achieves adaptability through parameter changes in the aerodynamic characteristics of the feathers themselves (different sweep angles) rather than through mechanical movement, allowing the fixed structure to adapt to varying flight conditions through inherent geometric properties

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

Different portions of the wingtip device have different local qualities (first feather with forward sweep for cruise conditions, second feather with aft sweep for high-load conditions), allowing each region to be optimized for specific flight conditions while maintaining overall simplicity

Inventive Principle:

Principle #3Local quality

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 wingtip feathers enhance wing loading during cruise conditions while mitigating bending moments and delaying stall at high load conditions, improving overall aircraft performance and fuel efficiency by maintaining lift capability and reducing structural stress.

Implementation Method 1

The first tip feather 131a has a forward swept first leading edge 132a... the first tip feather 131a is expected to be highly loaded during cruise flight conditions

Methodology Applied

Scientific EffectAerodynamic lift: Aerofoil

Implementation Method 2

The second tip feather 131b has an aft swept second leading edge 132b... the second tip feather 131b can become aerodynamically effective at high load or other critical conditions

Methodology Applied

Scientific EffectAerodynamic lift: Aerofoil

Implementation Method 3

The arrangement of the first and second tip feathers 131a, 131b can have significant advantages... improving overall aircraft performance and fuel efficiency

Methodology Applied

Scientific EffectInduced drag reduction: Drag

Data Source

PatentUS7900876B2Wingtip feathers, including forward swept feathers, and associated aircraft systems and methods

Publication Date: 2011.03.08 THE BOEING CO

AI summary

Tip feathers, including forward swept tip feathers, and associated aircraft systems and methods are disclosed. A system in accordance with one embodiment includes an aircraft wing having an inboard portion, an outboard portion, and a leading edge having an aft wing sweep angle at the outboard portion. A first feather is fixed relative to, and projects outwardly from, the outboard portion of the wing and has a leading edge with a first, forward sweep angle relative to a pitch axis of the wing. A second feather is fixed relative to, and projects outwardly from, the outboard portion of the wing at least partially aft of the first feather, and has a leading edge with a second, aft sweep angle relative to the pitch axis.