Split Blended Winglet Reverse Curve Ventral Fin
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Solution Overview
Problem
Existing winglets, while reducing drag and improving cruise performance, redistribute lift and increase the bending moment on the wing, necessitating further improvements in fuel burn reduction and drag minimization with lower structural impact.
Innovation Solution
The design of a split blended winglet with an upper and lower winglet section, featuring a reverse curve and ventral fin configuration, which reduces bending moment and drag by optimizing winglet placement and cant angle, providing a more effective wingspan without increasing structural load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If winglets are added to reduce induced drag, then drag is reduced and fuel burn is improved, but the bending moment on the wing increases
Solution Approach 1:
The winglet is divided into multiple segments (first winglet portion and second winglet portion) that can be independently positioned and angled. This segmentation allows optimization of drag reduction while controlling the bending moment distribution along the wing span, as each segment can be tailored to specific aerodynamic requirements without uniformly increasing structural load.
Solution Approach 2:
The invention introduces a vertical dimension to the wingtip structure by adding winglets that extend perpendicular to the wing plane. This third dimension (vertical z-axis) allows the winglet to interfere with vortex formation in a new spatial direction, reducing induced drag while the segmented design controls the moment arm effects that would otherwise increase bending moment.
2Loss of energy
If winglets are designed with higher sweep angles, then induced drag is reduced, but structural complexity and manufacturing difficulty increase
Solution Approach 1:
The winglet is segmented into distinct portions (first and second winglet portions) with different sweep characteristics. The first portion can have a higher sweep angle for drag reduction, while the second portion can have a lower sweep angle for structural simplicity. This segmentation allows each segment to be optimized independently, reducing overall structural complexity while maintaining drag reduction benefits.
Solution Approach 2:
Different portions of the winglet are given different geometric properties (sweep angles) according to their specific functional requirements. The leading edge portion can have higher sweep for vortex control, while the trailing edge portion can have lower sweep for structural ease. This local differentiation optimizes performance without uniformly increasing complexity across the entire winglet structure.
3Length of stationary object
If winglets extend further vertically, then effective aspect ratio is increased and induced drag is reduced, but the bending moment penalty increases
Solution Approach 1:
The vertical extension is segmented into first and second winglet portions at different vertical levels. This segmentation allows the lower portion to provide the primary drag reduction benefit while the upper portion can be designed with smaller dimensions or different orientation to limit the moment arm effect, thereby increasing effective aspect ratio without proportionally increasing bending moment penalty.
Solution Approach 2:
Instead of having a single continuous vertical extension that maximizes both aspect ratio and bending moment, the invention uses a segmented approach where the second winglet portion may be positioned or oriented to provide aerodynamic benefit while its vertical leverage is reduced. This inverts the conventional approach by prioritizing drag reduction through segmentation rather than maximum vertical extension.
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 split blended winglet achieves a drag reduction of 1.6% to 2.0% and a greater cant angle for the ventral fin, effectively lowering the bending load on the airplane wing, enhancing fuel efficiency and cruise performance.
Implementation Method 1
The split blended winglet achieves a drag reduction of 1.6% to 2.0%
Implementation Method 2
Winglets are generally used to increase the effective aspect ratio of a wing, with less structural impact than adding wingspan. Winglets are generally near vertical extensions of the wing tip. Wing tip devices may increase the outboard lift generated at the wing tip, and reduce the induced drag caused by wingtip vortices
Implementation Method 3
The ventral fin counters vortices generated by interactions between the wingtip and the lower wing surface
Implementation Method 4
Although winglets reduce drag generated by wingtip vortices, winglets re-distributes the lift that increases the bending moment on the wing. A split winglet is designed to reduce drag with a lower bending moment penalty than existing winglets
Data Source
AI summary
High-performance winglets are provided for attachment to an airplane wing. A split blended winglet includes a blended or upper winglet smoothly extending from the wing tip above a chord plane of the wing and a lower winglet including a ventral fin projecting below the chord plane from a lower surface of the upper winglet. The upper winglet includes a blade section that projects vertically along a reverse curve before transitioning to a linear upper blade portion. Upper and lower surfaces of the upper winglet are bound by leading and trailing edges that are swept toward an airstream direction, parallel with the chord plane, and curve toward the airstream direction before terminating at a point distal of the wing tip. Upper and lower surfaces of the lower winglet are bound by leading and trailing edges that curve toward the airstream direction and terminate at a point distal of the wing tip.