Aircraft Joint Concealing Fastener Head for Laminar Flow
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Solution Overview
Problem
Aircraft wing leading edge panels face challenges in maintaining laminar flow due to surface roughness from conventional fasteners, and frequent replacements are time-consuming and costly, especially with the tighter tolerance requirements of natural laminar flow aerofoils.
Innovation Solution
A kit of parts for an aircraft joint featuring a fastener with a retainer that conceals the fastener head within the overlap region, allowing for easy assembly and disassembly while maintaining laminar flow, including a fastener shank that extends through a hole in the retainer and into the first component, with the retainer attached to the second component to secure the fastener.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional fasteners (heads and holes) are used to attach leading edge panels, then the panels can be securely joined to ribs and wing covers, but the surface roughness increases and laminar flow is disrupted
Solution Approach 1:
The fastener head is extracted from the visible aerodynamic surface and concealed within the overlap region between components. Only the fastener shank remains visible, extending through the hole in the first component and into the second component, thereby eliminating the harmful fastener head protrusion that disrupts laminar flow while maintaining secure attachment.
Solution Approach 2:
The fastener head is nested within the overlap region formed by the first and second components. The fastener shank extends through the hole in the first component and into the second component, with the head concealed in the overlapping area, creating a nested arrangement that hides the fastener head from the external aerodynamic surface.
2Ease of repair
If many fasteners are removed and installed for leading edge panel replacement, then the panel can be replaced, but the maintenance time increases
Solution Approach 1:
The fastening system is segmented into modular components: the fastener retainer attached to the second component, the fastener shank extending through the first component, and the fastener head concealed in the overlap region. This segmentation allows for easier assembly and disassembly compared to conventional through-fasteners, reducing maintenance time while enabling panel replacement.
3Manufacturing precision
If fastener heads are exposed on the aerodynamic surface, then fastening is achieved, but the step height exceeds the 50 micron tolerance required for laminar flow
Solution Approach 1:
The fastener head is extracted from the aerodynamic surface and relocated to the overlap region. This extraction eliminates the step height problem caused by exposed fastener heads while maintaining the fastening function through the concealed fastener shank and head arrangement within the overlap.
Solution Approach 2:
The fastener head is moved from the two-dimensional aerodynamic surface to the three-dimensional overlap region between components. This dimensional relocation allows the fastener head to be concealed while maintaining the fastening function, thereby achieving both surface smoothness and operational ease.
Data Source
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AI summary
An aircraft joint (40) between overlapping first (31) and second (35) components includes a fastener (42) having a head (42a) and a shank (42b), and a fastener retainer (43) fixedly attached to the second component at the overlap region. The fastener retainer has a recess (43a) and a through hole (43b). The fastener head is situated in the recess and between the fastener retainer and the second component. The fastener shank extends through the hole in the fastener retainer and into the first component to fasten the first component to the second component. The joint may be between an aircraft wing cover and a wing panel.