Flexible Composite Packer for Aircraft OML Tolerance
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Solution Overview
Problem
Current aircraft airframe production methods face challenges in achieving tight tolerance bounds for the Outer Mould Line (OML) of the fuselage, which affects the accuracy and consistency of the aircraft skin attachment and aerodynamic performance.
Innovation Solution
A flexible carbon fibre composite packer is used, sandwiched between the airframe and the aircraft skin, which can be machined to define a precise Inner Mould Line (IML), improving the attachment process and reducing the need for clamping devices, thereby enhancing the bond quality and reducing air entrapment and manufacturing tolerances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional rigid packers are used for airframe shaping, then structural support is provided, but achieving tight tolerance bounds for Outer Mould Line is difficult and air entrapment occurs
Solution Approach 1:
The patent employs a flexible packer made from compliant material that can deform to conform to the airframe surface and define the desired Outer Mould Line. This flexibility eliminates the need for complex clamping devices while preventing air entrapment through conformal contact, directly resolving the technical contradiction between manufacturing precision and device complexity
Solution Approach 2:
The packer's material properties are specifically designed to exhibit compliance and deformability, allowing it to adapt to surface variations and achieve tight tolerance bounds. The material parameter changes enable the packer to transition from a rigid support structure to a conformal shaping tool, improving OML precision without increasing device complexity
2Manufacturing precision
If tight tolerance bounds are enforced for OML, then aerodynamic performance is improved, but manufacturing complexity and time increase
Solution Approach 1:
The flexible packer is pre-formed to define the desired Outer Mould Line geometry before the skin attachment process. This preliminary shaping action eliminates the need for post-assembly adjustments or rework, achieving tight tolerance bounds while maintaining manufacturing efficiency and reducing overall production time
Solution Approach 2:
The packer serves as an intermediary tool between the airframe structure and the skin, providing a compliant surface that facilitates accurate skin attachment. This intermediary element absorbs manufacturing variations and enables tight tolerance achievement without requiring complex manufacturing processes or extending production time
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 flexible packer allows for precise shaping and improved bonding of the aircraft skin to the airframe, ensuring the OML is within specified tolerance, enhancing the aerodynamic performance and reducing the risk of disbonds, moisture ingress, and corrosion.
Implementation Method 1
A flexible carbon fibre composite packer is used, sandwiched between the airframe and the aircraft skin, which can be machined to define a precise Inner Mould Line (IML)
Implementation Method 2
A flexible carbon fibre composite packer is used, sandwiched between the airframe and the aircraft skin
Data Source
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AI summary
A packer (200) for application to an aircraft airframe (100), the packer (200) comprising: a sheet of material having a first surface and a second surface opposite to the first surface; and a plurality of voids (208) defined through the sheet of material from the first surface to the second surface, thereby to provide that the sheet of material is flexible. The sheet of material may define a frame (202) and a plurality of struts (202) extending from one side of the frame (202) to an opposite side of the frame (202). The frame (202) and the struts (206) may define, at least in part, the voids (208).