Composite Blade Design for Aircraft Windshield Wiper Drag Reduction
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Solution Overview
Problem
Existing windshield wiper systems for aircraft suffer from tip bending and overshooting due to riveted links and stainless steel inertia, as well as significant aerodynamic drag from their bridge-type frame construction, which affects performance and visibility during high-speed operations.
Innovation Solution
A composite blade design featuring a carbon fiber frame and a nitrile rubber blade with ceramic coating, where the blade is adhered to the frame using adhesion elements, allowing for airflow through through-holes or grooves to reduce drag and increase stiffness, thereby minimizing over-sweep and matching the windshield curvature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a bridge-type frame construction with riveted links is used, then the blade assembly can be assembled with traditional components, but the tips bend and overshoot the required sweep angle at high speed operations due to frame inertia
Solution Approach 1:
The patent replaces traditional stainless steel riveted links with a carbon fiber composite frame structure. The composite frame maintains structural integrity and stiffness while reducing overall weight and inertia, preventing tip bending and overshooting during high-speed operations. The composite material provides both the necessary strength and reduced mass to eliminate the sweep angle precision problem.
Solution Approach 2:
The patent changes the physical parameters of the frame by transitioning from solid stainless steel links to a carbon fiber composite construction with through-holes. This parameter change reduces the frame's mass and moment of inertia while maintaining structural strength, directly addressing the tip bending issue during high-speed operation.
2Strength
If a bridge-type frame construction with stainless steel links is used, then the frame has sufficient strength, but it generates substantial aerodynamic drag
Solution Approach 1:
The patent incorporates through-holes in the carbon fiber composite frame, creating a porous structure that allows airflow to pass through rather than around the frame. This reduces aerodynamic drag significantly while the carbon fiber material and strategic hole placement maintain the necessary frame strength for operation.
Solution Approach 2:
The carbon fiber composite material provides high strength-to-weight ratio, allowing the frame to maintain sufficient strength while the open porous design reduces aerodynamic resistance. The composite construction enables both strength requirements and drag reduction simultaneously.
3Ease of manufacture
If traditional riveted links are used, then the frame can be manufactured with conventional methods, but the blade assembly has excessive weight due to stainless steel components
Solution Approach 1:
The patent replaces heavy stainless steel riveted links with a carbon fiber composite frame. Carbon fiber composites have approximately one-quarter the density of steel, dramatically reducing the blade assembly weight while maintaining structural strength. The composite frame can be manufactured using automated fiber placement or molding techniques suitable for aerospace applications.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enhances the stiffness of the blade assembly, reduces over-sweep and aerodynamic drag, and ensures effective debris removal while maintaining structural integrity and visibility during high-speed operations.
Implementation Method 1
The composite frame 140 can be formed of carbon fiber and is receivable within the space delimited between the base 131 and the sidewalls 132 of the holder element 130
Implementation Method 2
The blade 150 has a length L1 (see FIG. 5) which is normally (i.e., in an unstretched state) shorter than a corresponding length L2 (see FIG. 5) of the composite frame 140
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
A windshield wiper system (WWS) blade assembly (120) includes a composite frame (140) and a blade (150) that has a length (L1) which is normally shorter than a corresponding length (L2) of the composite frame (140). The blade (150) includes first and second ends (151, 152) attachable to corresponding first and second ends (141, 142) of the composite frame (140), respectively.