Stepped Wingtip Device for Drag Reduction and Weight Control
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Solution Overview
Problem
Existing wingtip devices increase structural weight and bending moment, affecting flutter characteristics while attempting to reduce drag, and there is a need to minimize these effects while maintaining aerodynamic performance.
Innovation Solution
A wingtip device with a stepped configuration, comprising a transition part and a wingtip part with decreasing chord lengths, where each wingtip section's wing root is connected to the outer end of the previous section, reducing vortex strength and structural weight, and formed integrally with the airplane wing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a winglet is added to the airplane wing, then the induced drag is reduced and lifting force is increased, but the weight of the wing is increased and the bending moment of the wing root is increased
Solution Approach 1:
The wingtip device is divided into multiple sections (first section, second section, third section) with progressively smaller chord lengths. This segmentation allows the device to reduce induced drag through its multi-section structure while using progressively smaller sections to reduce the overall weight and bending moment compared to a single large winglet.
Solution Approach 2:
Different sections of the wingtip device have different chord lengths, with the first section having a larger chord length than the second section, and the second section having a larger chord length than the third section. This local variation in dimensions allows optimization of drag reduction in different areas while controlling overall weight.
2Loss of energy
If a wingtip device with large chord length is used, then the drag reduction effect is significant, but the bending moment of the wing root is relatively larger and the structural weight is increased
Solution Approach 1:
The wingtip device is segmented into multiple sections with decreasing chord lengths from the wing root outward. This segmentation distributes the aerodynamic loads across multiple smaller structures rather than one large structure, reducing the peak bending moment at the wing root while maintaining drag reduction benefits.
Solution Approach 2:
The wingtip device extends in multiple dimensions with varying chord lengths across the span. By distributing the drag reduction function across multiple sections with different dimensions, the device achieves significant drag reduction while each individual section contributes less to the bending moment than a single large winglet would.
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 stepped configuration suppresses wingtip vortices, reducing drag and structural weight, and minimizes the impact on flutter characteristics, achieving a balance between weight reduction and aerodynamic efficiency.
Implementation Method 1
The stepped configuration suppresses wingtip vortices, reducing drag and structural weight
Data Source
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AI summary
An aircraft wingtip device, comprising a transition part (1) and a wingtip part (2); the inner end of the transition part (1) is connected to the far end of an aircraft wing, and the outer end of the transition part is connected to the wingtip part (2); the wingtip part comprises a plurality of wingtip sections (3n), and each wingtip section (3n) comprises a wingtip (4n) and a wing root (5n) respectively; the wing root (51) of the first wingtip section (31) is connected to the outer end of the transition part (1), the wing root (5n+1) of the n+1 wingtip section (3n+1) is located on the wingtip (4n) of the n wingtip section (3n), and the chord length of the wing root (5n+1) of the n+1 wingtip section (3n+1) is smaller than or equal to the chord length of the wingtip (4n) of the nth wingtip section (3n), where n > 0. Because the wingtip device of the present invention is disposed in a stepped fashion, more than one discontinuity surface is added to the wingtip thereof, so that the wingtip vortices induced by the wingtip suppress each other, thereby reducing the strength of the vortices, and thus achieving drag reduction effect. In addition, the wing root of the present invention has a smaller bending moment increment, thus reducing the structural weight of the airplane and having less effect on the flutter properties.