Wing-Pylon Spherical Joint Assembly for Low-Clearance Engine Mounting
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Solution Overview
Problem
Conventional aircraft engine mounting pylons require significant vertical clearance due to their design, making them unsuitable for large diameter engines, and the assembly process is time-consuming due to the need for machining to achieve close contact between the curved wing surface and the flat pylon surface, which is not compatible with high-rate manufacturing.
Innovation Solution
Aircraft assembly featuring three fastening locations arranged in a triangle with spherical surfaces on both the wing and pylon components, allowing direct contact and effective load transfer, enabling a compact and fast assembly process even with manufacturing tolerances, using tension fasteners that transfer only vertical loads and optional thrust-transferring connections for lateral loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If conventional couplings are used to attach the engine mounting pylon to the wing box, then the assembly allows freedom of movement and transmits forces, but the vertical distance between the top of the engine and the lower surface of the wing cannot be minimized
Solution Approach 1:
The invention introduces spherical bearing surfaces at the coupling interface between the pylon and wing. The pylon has a spherical upper surface and the wing has a corresponding spherical lower surface, allowing rotational freedom while maintaining minimal vertical clearance. This curved surface geometry enables the pylon to pivot relative to the wing without requiring the vertical spacing needed by conventional flat-surface couplings.
2Manufacturing precision
If the wing lower surface and pylon upper surface are machined to ensure close contact, then effective load transmission is achieved, but the assembly process becomes time consuming
Solution Approach 1:
The spherical bearing surfaces are designed with standardized radii that accommodate normal manufacturing tolerances. The curved geometry provides a self-aligning feature where small variations in surface flatness or positioning do not prevent contact. This eliminates the need for time-consuming field machining operations while ensuring reliable load transmission through the spherical contact interface.
Solution Approach 2:
The invention changes the geometric parameters of the coupling interface from flat surfaces requiring precise parallelism to spherical surfaces with defined radii. This parameter change transforms the tolerance sensitivity, allowing the assembly to achieve adequate contact pressure and load transmission without requiring ultra-precise manufacturing or post-assembly machining.
3Ease of manufacture
If the pylon upper surface is made flat for easy manufacturing, then production is simplified, but close contact with the curved wing lower surface cannot be achieved
Solution Approach 1:
Instead of making the pylon surface flat, the invention applies a spherical curvature to the pylon's upper surface. This curved surface is easier to manufacture than a flat surface that must precisely match the complex curved geometry of the wing. The spherical form provides a simple, repeatable manufacturing process while naturally accommodating the wing's curvature and tolerances through the bearing contact.
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
This configuration allows for a compact and efficient assembly of large diameter engines, facilitating high-rate aircraft manufacturing by ensuring close contact and effective load transfer between the wing and pylon, reducing assembly time and accommodating manufacturing variations.
Implementation Method 1
The wing component comprises three first spherical surfaces positioned such that the centre of each first spherical surface is at a different one of the fastening locations. The engine mounting pylon component comprises three second spherical surfaces having equal and opposite curvature to the first spherical surfaces. Each of the second spherical surfaces is in contact with a different one of the first spherical surfaces.
Data Source
Figure 1a~1c
Figure 2a~2b
Figure 3~4c
AI summary
There is provided an aircraft assembly comprising a wing component and an engine mounting pylon component. The wing component comprises three fastening locations arranged in a triangle such that they define a plane. The engine mounting pylon component is connected to the wing component by three tension fasteners, wherein each of the tension fasteners passes through a different one of the fastening locations. The wing component comprises three first spherical surfaces positioned such that the centre of each first spherical surface is at a different one of the fastening locations. The engine mounting pylon component comprises three second spherical surfaces having equal and opposite curvature to the first spherical surfaces. Each of the second spherical surfaces is in contact with a different one of the first spherical surfaces.