Single Spar Composite Airfoils Reducing Fastener Count
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Solution Overview
Problem
Conventional structural composite airfoils for aircraft require large numbers of fasteners, increasing costs, manufacturing time, and weight, which complicates their construction and aerodynamic performance.
Innovation Solution
The design incorporates a primary structural element with an upper skin panel, a lower skin panel, and a middle C-channel spar, where the upper skin panel extends from the leading edge to the trailing edge, and the lower skin panel is coupled to the upper leading edge end within the leading edge region, reducing the need for splice straps and other fasteners, and utilizing core stiffened materials for enhanced strength and aerodynamics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional construction with three spars is used, then structural strength is improved, but fastener count and manufacturing complexity increase
Solution Approach 1:
The patent removes one spar from the conventional three-spar configuration, extracting only the necessary structural support elements. This reduces the number of fasteners required to attach spars to skin panels, directly addressing the contradiction by simplifying the assembly while maintaining adequate structural strength through the remaining two spars positioned at critical locations.
Solution Approach 2:
The patent merges the functions of multiple structural elements by integrating the spar attachments directly into the skin panel design. The skin panels are configured to work in conjunction with the reduced number of spars, combining the load-bearing functions that would otherwise require separate components and fasteners, thereby reducing overall complexity.
2Strength
If conventional construction with three spars is used, then structural strength is improved, but manufacturing cycle time increases
Solution Approach 1:
By extracting one spar from the conventional three-spar design, the patent reduces the number of attachment operations required during manufacturing. This directly decreases manufacturing cycle time while the remaining spars are positioned to maintain necessary structural strength at critical load-bearing locations.
Solution Approach 2:
The skin panels are designed with pre-configured attachment features that facilitate easier and faster connection to the reduced number of spars. This preliminary design of the skin panel structure enables more efficient assembly operations, reducing manufacturing cycle time without compromising the strength of the final assembly.
3Strength
If conventional construction with three spars is used, then structural integrity is improved, but weight increases
Solution Approach 1:
The patent extracts one spar from the conventional three-spar configuration, directly reducing the weight of the airfoil structure. The remaining two spars are strategically positioned to maintain structural integrity at critical locations, achieving weight reduction while preserving necessary strength characteristics.
4Shape
If core stiffened materials are used, then aerodynamic performance is improved, but manufacturing complexity increases
Solution Approach 1:
The patent employs core stiffened composite materials that provide enhanced aerodynamic shaping and structural performance. The composite construction allows for complex aerodynamic contours to be formed as integral parts of the skin panels, achieving superior aerodynamic performance while the composite nature of the materials enables these complex shapes to be manufactured as single pieces, reducing overall manufacturing complexity.
Data Source
AI summary
Structural composite airfoils include a primary structural element and a secondary structural element defining the trailing edge of the structural composite airfoil. The primary structural element includes an upper skin panel, a lower skin panel, and a middle C-channel spar that is coupled to the upper skin panel and the lower skin panel. The upper skin panel extends from an upper leading edge end to an upper trailing edge end, and the lower skin panel extends from a lower leading edge end to a lower trailing edge end. The lower leading edge end of the lower skin panel is coupled to the upper leading edge end of the upper skin panel within the leading edge region of the primary structural element.