Non-Planar Wingtip Structure for Span-Constrained Drag Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Traditional methods to address span constraints on aircraft wings due to airport compatibility and flying constraints result in reduced optimal wing span during flight due to aeroelastic effects, especially with flexible wings, leading to performance shortfalls.
Innovation Solution
A wing tip device comprising an upper and lower wing-like element fixed to the outboard end of a wing, where the lower element projects downwardly from the intersection with the upper element, with an included angle less than or equal to 160 degrees, offsetting wing span reduction during flight and optimizing span constraints on the ground.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a winglet or non-planar wing tip extension is used to reduce induced drag, then the effective wing aspect ratio increases and drag reduction is achieved, but the ground span may exceed airport compatibility limits due to span constraints
Solution Approach 1:
The patent transitions from horizontal span extension (raked wing tips) to vertical dimension extension (upper and lower wing-like elements). This dimensional change allows the wing tip device to increase effective aspect ratio for drag reduction while maintaining compliance with horizontal span constraints at ground level.
Solution Approach 2:
The wing tip device is segmented into an upper wing-like element and a lower wing-like element separated by a gap. This segmentation allows the lower element to be positioned such that its tip does not exceed the span constraint at ground level, while the upper element provides the necessary vertical extension for drag reduction.
2Weight of moving object
If the wing is designed with flexible materials to reduce structural weight, then structural weight is reduced, but aeroelastic effects cause greater wing bending under aerodynamic load, further reducing optimal wing span during flight
Solution Approach 1:
The lower wing-like element is pre-positioned to compensate for expected aeroelastic bending. By designing the ground span with the lower element taking up part of the span constraint, the patent anticipates and counteracts the additional span reduction that will occur during flight due to wing bending, thereby maintaining optimal wing span in the flight configuration.
3Loss of energy
If the included angle between upper and lower wing-like elements is reduced to optimize drag reduction, then vortex drag reduction is improved, but the structural complexity and manufacturing difficulty increase
Solution Approach 1:
The patent specifies that the included angle between the upper and lower wing-like elements is greater than 90 degrees, which is a parameter change from conventional designs. This angular parameter optimization balances drag reduction performance with structural feasibility and manufacturing practicality, avoiding excessively complex geometries while still achieving significant vortex drag reduction.
Data Source
AI summary
A wing tip device for fixing to the outboard end of a wing, the wing defining a wing plane, the wing tip device comprising: an upper wing-like element projecting upwardly with respect to the wing plane and having a trailing edge; and a lower wing-like element fixed with respect to the upper wing-like element and having a root chord and a trailing edge, the lower wing-like element root chord intersecting with the upper wing-like element, and the lower wing-like element projecting downwardly from the intersection, wherein the upper wing-like element is larger than the lower wing-like element and the trailing edge of the lower wing-like element is adjacent the trailing edge of the upper wing-like element at the intersection, and wherein an included angle between the upper and lower wing-like elements at the intersection is less than, or equal to, 160 degrees.