Aircraft Hinge Assembly With Finger Seals for Aerodynamic Sealing
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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 are difficult to integrate with complex surfaces and may disrupt airflow.
Innovation Solution
A hinge assembly with interleaved fingers and a seal assembly comprising resilient, flexible strips that are overmoulded onto the fingers, providing a triangular cross-section for sealing contact and an under-seal to prevent pressure bleed, while maintaining an aerodynamic profile and allowing smooth movement between configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a flat rubber seal is used on a barrel-type hinge assembly, then sealing function is provided, but the seal is difficult to integrate with complex surfaces and may disrupt airflow
Solution Approach 1:
The seal assembly is divided into multiple finger seals, each conforming to a specific finger of the hinge assembly. This segmentation allows the seal to adapt to the complex doubly-curved surface of the wing while maintaining sealing effectiveness and aerodynamic profile.
Solution Approach 2:
Each finger seal is customized to match the local geometry of its corresponding finger, with varying cross-sections and orientations. This local adaptation enables the seal assembly to conform to the complex overall surface while each individual seal maintains simple, manufacturable geometry.
2Shape
If a seal is made sufficiently stiff to maintain aerodynamic profile, then aerodynamic performance is improved, but the seal becomes less flexible and cannot accommodate movement between configurations
Solution Approach 1:
The seal assembly is divided into multiple independent finger seals that can move relative to each other. This segmentation allows the overall seal to maintain a stiff aerodynamic profile while individual segments remain flexible enough to accommodate movement between flight and ground configurations.
Solution Approach 2:
The finger seals are designed with dynamic characteristics, allowing them to flex and move as the hinge assembly transitions between configurations. The seals maintain their aerodynamic profile in the flight configuration while adapting their shape during movement.
3Reliability
If the seal is made sufficiently resilient to withstand harsh operating environment, then durability is improved, but the seal may interfere with movement of the wing tip device
Solution Approach 1:
The seal assembly is divided into multiple finger seals that can move independently. This segmentation reduces the overall resilience requirement for each individual seal, allowing them to be more compliant and less likely to interfere with movement while still providing adequate sealing and durability.
Solution Approach 2:
The physical parameters of the finger seals (cross-section, material properties, mounting configuration) are optimized to balance resilience and flexibility. The seals are designed with specific geometric parameters that allow them to withstand harsh environments while maintaining smooth movement characteristics.
4Reliability
If unsupported edge of the seal faces into the direction of airflow, then sealing contact is maintained, but airflow over the hinge is disrupted
Solution Approach 1:
The finger seals are designed with asymmetric cross-sections and orientations that are optimized for aerodynamic flow. The sealing surface is positioned to maintain contact while the overall seal geometry is shaped to allow smooth airflow over the hinge assembly, reducing turbulence and drag.
Solution Approach 2:
The seal geometry is locally optimized at each finger position to balance sealing contact and aerodynamic flow. The unsupported edge orientation and seal cross-section are tailored for each location to maintain sealing effectiveness while minimizing airflow disruption.
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 effectively reduces aerodynamic drag and pressure leakage by creating a seamless seal between the wing and wing tip, maintaining the aerodynamic profile and enabling safe taxiway usage while withstanding harsh aircraft environments.
Implementation Method 1
each finger seal has a triangular cross section and is arranged to make sealing contact with a correspondingly chamfered surface along an edge of a finger of the other hinge plate
Implementation Method 2
The under seal helps to fill voids under the hinge plates and thereby prevent or reduce pressure bleed
Data Source
AI summary
A hinge assembly 8a for an aircraft component comprises first and second hinge plates 9, 10, each hinge plate including a plurality of fingers 13 to 17. The fingers of the first and second hinge plates are interleaved. A seal assembly 28 to 32 is provided between at least some of the fingers. The provision of a hinge including interposed fingers allows for a hinge assembly having a complex aerodynamic profile to be made, while the sealing function is performed by the seals filling the gaps between the fingers.