Aircraft Wing Strut Load Transfer for Retro-fit
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Solution Overview
Problem
Existing methods for retro-fitting or forward-fitting wing tip devices to aircraft wings face challenges in efficiently distributing loads, often requiring significant structural reinforcement, which can add weight and complexity, especially when the wing was not originally designed to accommodate the device.
Innovation Solution
An external strut is used to transfer loadings from the wing tip device to a location inboard of the wing root, reducing the need for structural modifications and allowing for a larger or more effective wing tip device to be installed with fewer reinforcements, by connecting the strut to the wing at a second location closer to the wing tip than the wing root.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If wing tip device is attached using splice plates or tension bolts at the wing tip, then the wing tip device can be installed, but the loads are concentrated in a small area requiring significant structural reinforcement
Solution Approach 1:
The patent moves the load transfer location from the two-dimensional wing tip area to a one-dimensional inboard location along the wing span. By positioning the strut attachment at an inboard location rather than directly at the wing tip, the bending moment is reduced and loads are distributed over a larger area of the wing structure, eliminating the need for concentrated structural reinforcement at the wing tip.
Solution Approach 2:
The patent introduces an external strut as an intermediary element between the wing tip device and the wing structure. This strut acts as a load transfer mechanism that redirects the forces from the wing tip device to an inboard location on the wing where the structure can better handle the loads without requiring significant reinforcement.
2Strength
If structural reinforcement is added to cope with high loads at the wing/wing tip joint, then the load bearing capacity is improved, but weight and complexity increase
Solution Approach 1:
The patent changes the spatial dimension of load transfer by moving from direct attachment at the wing tip to inboard attachment along the wing span. This dimensional change in load path reduces the bending moment and allows the existing wing structure to bear the loads without additional reinforcement, thereby avoiding weight increase.
Solution Approach 2:
The patent extracts the load transfer function from the wing tip structure itself and relocates it to an inboard location. By separating the load transfer function from the wing tip area and placing it at an inboard location, the wing tip structure can remain lightweight while still supporting the wing tip device through the external strut.
3Strength
If two mounting formations spaced apart in spanwise direction are used, then the bending moment is reacted over a large moment arm reducing loads, but the structural modifications to the wing become too significant for retro-fit or forward fit applications
Solution Approach 1:
The patent uses an external strut as an intermediary to achieve load distribution benefits without requiring complex structural modifications to the wing. The strut connects the wing tip device to an inboard location, creating an effective moment arm that reduces bending moments on the wing while avoiding the need for multiple mounting formations or significant structural changes to the wing box.
Data Source
AI summary
An aircraft wing (1) has a wing tip device (3) joined thereto. The root (7) of the wing tip device (3) is joined to the tip of the wing (1) at a first connection (11). An external strut (9) extends between the wing (1) and the wing tip device (3), the strut (9) being joined to the wing (1) at a second connection (13). The second connection (13) is inboard of the first connection, such that loadings on the wing tip device (3) generated during use, are transferred, via the strut (9), to a location on the wing (1) that is inboard of where the root (7) of the wing tip device (3) is joined to the tip of the wing.