Folding Wingtip Spar Load Path for Lower Weight and Cost
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Solution Overview
Problem
Current folding wingtip designs for aircraft are heavy, costly to manufacture, and not scalable to smaller structures due to reliance on interlocking torque boxes and reinforced skin panels, which increase weight and maintenance costs.
Innovation Solution
A folding wingtip design that carries bending moments in spars instead of skin panels, with a hinge line perpendicular to the spars, allowing for lighter construction and even force distribution among latch pins, reducing weight and maintenance costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If interlocking torque boxes and reinforced skin panels are used in folding wingtip designs, then strength and load transfer are improved, but weight and manufacturing cost increase significantly
Solution Approach 1:
The wing structure is divided into discrete spars that are independently connected through hinge fittings, rather than relying on continuous skin panels for load transfer. This segmentation allows each spar to carry its own bending loads independently, eliminating the need for heavy reinforced skin panels while maintaining overall structural strength.
Solution Approach 2:
Instead of using skin panels to carry bending loads (conventional approach), the invention inverts the load path by having spars directly carry bending moments and transfer loads through hinge fittings. This inversion of the traditional load-bearing mechanism eliminates the need for heavy skin reinforcement.
2Strength
If multiple points of load transfer are implemented, then structural strength is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
Multiple load transfer functions are merged into the hinge fittings, which simultaneously serve as pivot points for folding and as load transfer mechanisms. This consolidation eliminates the need for separate torque boxes and multiple reinforced connection points, reducing overall structural complexity while maintaining strength.
3Adaptability or versatility
If traditional folding wingtip designs are used, then folding functionality is achieved, but the design does not scale down to smaller structures
Solution Approach 1:
The use of discrete spars with individual hinge fittings creates a modular structure that can be scaled to different sizes. Each spar-hinge assembly is an independent unit that can be configured for various span lengths, allowing the design to scale down to smaller aircraft while maintaining structural integrity and folding functionality.
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 design minimizes weight and maintenance costs by distributing loads in spars, enabling space-saving folding and improved aerodynamic efficiency while protecting the main wing from damage.
Implementation Method 1
The hinge line is a pivot axis for the folding wingtip
Implementation Method 2
bending loads of the folding wingtip are carried in the spars
Implementation Method 3
distributing loads in spars
Data Source
AI summary
A folding wingtip and method for folding said wingtip. The folding wingtip includes a multi-spar main box and a hinge fitting attached to the inboard end of each spar. A hinge line passes through each hinge fitting perpendicular to each spar. The wingtip is connected to a main section of an aircraft wing and is foldable with respect to the main section about the hinge line.