Composite Joint Protection for Aircraft Covers
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Solution Overview
Problem
Aircraft components made from composite materials face issues with aerodynamic erosion and increased drag due to the thickness of conventional metallic butt-straps, as well as vulnerability to bird strikes and collisions.
Innovation Solution
A laminar composite cover with a stack of layers forming a joggle shape, including a ramp and a clamp or fastener system that aligns external sides for a smooth aerodynamic surface, and a protector, potentially made from composite or rubber materials, to reduce erosion and enhance structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metallic butt-strap is used to fasten covers to the wing skin, then the covers are securely fastened and aligned, but aerodynamic erosion occurs and drag increases due to the thickness of the metallic strap
Solution Approach 1:
The patent replaces the conventional metallic butt-strap with a composite material strap. This composite strap maintains the necessary mechanical strength for secure fastening while being thinner and more aerodynamic, thereby reducing both aerodynamic erosion and drag compared to traditional metallic straps.
Solution Approach 2:
The invention changes the material parameters from metallic to composite materials, which allows for a thinner profile with equivalent or superior fastening capability. This parameter change directly addresses the aerodynamic erosion and drag issues while preserving the security of the fastening.
2Object-affected harmful factors
If the D-nose skin is made thicker to overhang the leading edge, then erosion resistance is improved, but drag increases
Solution Approach 1:
The patent uses composite material for the D-nose skin, which provides high erosion resistance due to the inherent properties of composite materials. This allows the skin to be thinner than conventional metallic designs while maintaining or improving erosion resistance, thereby reducing drag.
Solution Approach 2:
The invention changes the material composition to composite materials, which fundamentally alters the erosion resistance-to-thickness ratio. This parameter change enables achieving better erosion protection with reduced thickness, directly lowering drag.
3Strength
If a metallic butt-strap is used for fastening, then structural strength is provided, but vulnerability to bird strike and collisions increases
Solution Approach 1:
The patent replaces metallic butt-straps with composite material straps that have superior impact resistance properties. Composite materials are more resilient to bird strikes and collisions due to their layered structure and material composition, which dissipates impact energy more effectively than metallic materials.
Solution Approach 2:
The invention changes from metallic to composite materials, fundamentally improving the resilience parameter against impact events like bird strikes. This material substitution maintains structural strength while significantly enhancing reliability under impact conditions.
Data Source
AI summary
The present invention relates to a joint between a laminar composite cover (12) and a second cover (15) (which may or may not be also formed from a composite material). The invention also relates to a method of manufacturing such a joint and a method of manufacturing a composite cover suitable for use in such a joint. The laminar composite cover (12) comprises a stack of layers, substantially all of the layers being shaped to form a joggle, each joggle comprising a first portion, a second portion where the layer extends substantially parallel with the first portion, and a ramp (33) between the first and second portions where the layer extends at an angle to the first and second portions, the number of layers being substantially the same on both sides of the ramp. The second cover (15) partially overlaps with the composite cover, and a clamp or fastener (31) holds the covers together where they overlap. The covers have external sides which are substantially aligned with each other so as to form a smooth aerodynamic surface.