Aircraft Hinge Assembly With Dual Seals for Drag and Leakage
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Solution Overview
Problem
Aircraft wing tip devices with folding mechanisms face aerodynamic penalties due to small steps or gaps between the wing and the wing tip, leading to drag and pressure leakage, and existing seal solutions struggle to balance stiffness, flexibility, and resilience for complex surfaces and harsh environments.
Innovation Solution
A hinge assembly with dual seal assemblies, where the first seal assembly is flush with the aerodynamic surface and fills gaps between fingers, and the second seal assembly addresses voids under the hinge plates, using resilient flexible strips and extension seals to maintain an aerodynamic profile and prevent pressure leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a seal is introduced between the moving parts of the hinge assembly to reduce aerodynamic penalties, then drag and pressure leakage are reduced, but the seal must balance competing requirements of stiffness, flexibility, and resilience
Solution Approach 1:
The seal assembly is divided into multiple segments including a first seal assembly for sealing between aerodynamic surfaces and a second seal assembly for sealing voids underneath hinge plates. This segmentation allows each seal to be optimized for its specific function, resolving the contradiction by breaking down the complex sealing requirement into manageable, specialized components
Solution Approach 2:
The seal acts as an intermediary element between the fixed wing and movable wing tip device, filling gaps and sealing voids to prevent pressure leakage while maintaining aerodynamic continuity. The seal material serves as a mediator that provides both structural bridging and aerodynamic smoothing
2Shape
If the seal is made sufficiently stiff to maintain the aerodynamic profile, then the aerodynamic shape is preserved, but the seal becomes less flexible and may interfere with movement between configurations
Solution Approach 1:
The seal is constructed using flexible seal members that can deform and adapt to the movement between flight and ground configurations. These flexible elements maintain the aerodynamic profile when needed while naturally accommodating the range of motion required for folding the wing tip device
Solution Approach 2:
The seal assembly is designed to be dynamic rather than static, allowing it to change its configuration and sealing characteristics based on the position of the wing tip device. The seal maintains aerodynamic continuity in flight configuration while permitting full movement range in ground configuration
3Reliability
If a flat rubber seal covering a barrel-type hinge assembly is used, then sealing is provided, but it is difficult to integrate in components having complex surfaces and unsupported edges can disrupt airflow
Solution Approach 1:
The seal assembly is customized to match the local geometry of the hinge assembly, with seal members conforming to the specific contours of the fixed wing and wing tip device. This local adaptation allows effective sealing on complex doubly-curved surfaces while maintaining aerodynamic flow over the hinge area
Solution Approach 2:
The seal design extends into the third dimension by including both upper surface sealing elements and underside void sealing elements. This multi-dimensional approach addresses the complex geometry of the hinge assembly by providing sealing at multiple levels and orientations
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 dual seal system effectively reduces drag, noise, and pressure leakage while allowing smooth movement between flight and ground configurations, maintaining the aerodynamic profile and durability in harsh conditions.
Implementation Method 1
the seal also needs to be sufficiently flexible so as not to interfere with movement of the wing tip device between the flight and ground configurations. The seal must also be sufficiently resilient to be able to withstand the harsh operating environment of the aircraft
Data Source
Figure 1~2a
Figure 2b
Figure 3a
AI summary
A hinge assembly 8a for an aircraft component comprises first and second hinge plates 9, 10, having an aerodynamic surface. A first seal assembly 28-32 is provided and arranged to seal between the aerodynamic surfaces of the hinge plates. A second seal assembly 38-42 is arranged to seal between the undersides of the hinge plates in order to reduce pressure leakage between voids under the hinge. The provision of two seal assemblies, each having a dedicated function, addresses the competing demands made on the sealing arrangement of an aircraft hinge assembly in use.