Composite Airfoil Front Spar Design Reduces Fastener Count
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Solution Overview
Problem
Conventional structural composite airfoils for aircraft require large numbers of fasteners, increasing manufacturing costs, cycle time, and weight, while also complicating the manufacturing process.
Innovation Solution
The structural composite airfoil design features a primary structural element with an upper and lower skin panel and a front C-channel spar, where the upper and lower flanges form acute angles with the elongated span, reducing the need for splice straps and nutplates, and utilizing a trailing edge closeout cover with an integral wedge, thereby simplifying assembly and reducing fastener count.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional construction methods with multiple spars and fasteners are used, then structural integrity is maintained, but manufacturing cost and weight increase
Solution Approach 1:
The patent combines multiple discrete fastening components (splice straps, nutplates, fasteners) into an integrated C-channel spar structure. The C-channel spar acts as a unified structural element that directly couples skin panels without requiring separate splice straps and nutplates, thereby reducing weight while maintaining structural integrity through the continuous C-channel geometry.
2Strength
If conventional construction with multiple fasteners and components is used, then structural integrity is maintained, but manufacturing complexity increases
Solution Approach 1:
The invention merges multiple discrete components (C-channel spar, splice straps, nutplates, fasteners) into a single integrated structure. The C-channel spar incorporates the functions of structural support and fastening in one element, eliminating the need for separate splice straps and nutplates, thereby simplifying the manufacturing process and reducing assembly steps.
Solution Approach 2:
The C-channel spar serves multiple functions simultaneously: it provides structural support, couples skin panels together, and eliminates the need for separate fastening components. This multi-functional design reduces the number of different component types required and simplifies the overall manufacturing process.
3Strength
If conventional construction with numerous fasteners is used, then structural integrity is maintained, but manufacturing cycle time increases
Solution Approach 1:
By combining multiple fastening operations into a single C-channel spar assembly process, the invention reduces the number of discrete fastening steps required. The C-channel spar is installed as one component rather than requiring separate installation of splice straps, nutplates, and multiple fasteners, thereby reducing manufacturing cycle time while maintaining structural integrity.
4Strength
If conventional construction with multiple components is used, then structural integrity is maintained, but the number of fasteners and weight increase
Solution Approach 1:
The invention consolidates multiple discrete fastening components into a single C-channel spar structure. Instead of using separate splice straps, nutplates, and multiple fasteners, the C-channel spar provides integrated fastening functionality, thereby reducing the total number of fasteners and components required while maintaining structural integrity.
Data Source
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AI summary
Structural composite airfoils include a primary structural element (26), a secondary structural element (24) defining the trailing edge of the structural composite airfoil, and a leading edge skin panel (54) defining the leading edge (22) of the structural composite airfoil. The primary structural element (26) includes an upper skin panel (34), a lower skin pane (36)l, and a front C-channel spar (38). A first channel of the front C-channel spar (38) faces the leading edge (22) of the structural composite airfoil, and an upper flange of the front C-channel spar (38) forms an acute angle with an elongated span of the front C-channel spar (38). The leading edge skin panel (54) is positioned adjacent the leading edge region of the primary structural element, with a first end region of the leading edge skin panel (54) being coupled to the upper flange of the front C-channel spar (38), and a second end region being coupled to the lower flange of the front C-channel spar (38).