Aircraft Pylon Mounting Structure With Slit Spar For Wing Attachment
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Solution Overview
Problem
The increasing diameter of modern jet engines due to higher bypass ratios creates a restrictive space between the airfoil element and the engine, making it difficult to install mounting pylons and airfoil attachments while maintaining mechanical strength and aerodynamic performance.
Innovation Solution
A primary mounting pylon structure with a slit and additional fixing means, including central angle irons, plies, and flexible washers, is used to securely attach the pylon to the airfoil box, allowing for closer proximity to the wing and efficient load distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the engine diameter is increased to achieve higher bypass ratio, then the propulsion efficiency is improved, but the space between the airfoil element and the engine becomes restrictive
Solution Approach 1:
The top spar is extended to pass underneath the airfoil box, utilizing the vertical space dimension more effectively. This allows the pylon structure to reach closer to the airfoil element without increasing the horizontal footprint, thereby resolving the space restriction caused by larger engine diameter while maintaining propulsion efficiency.
2Area of stationary object
If the mounting pylon is brought closer to the airfoil element to retain ground clearance, then the space utilization is improved, but the mechanical strength and load transmission capability deteriorate
Solution Approach 1:
The top spar is divided into two functional parts: a first part housed within the primary structure and a second part extending underneath the airfoil box. This segmentation allows the load transmission path to be optimized independently from the overall pylon positioning, enabling closer placement to the airfoil while maintaining structural strength through the reinforced spar configuration.
Solution Approach 2:
The primary structure employs a composite construction with lateral panels and transverse reinforcing ribs integrated with the top and bottom spars. This composite architecture enhances the mechanical strength and stiffness of the pylon, allowing it to withstand high loads even when positioned closer to the airfoil element with reduced vertical spacing.
3Strength
If the primary structure dimensions are increased to withstand high loads, then the load transmission capability is improved, but the aerodynamic performance deteriorates due to increased deformation
Solution Approach 1:
Transverse reinforcing ribs are pre-installed within the primary structure to provide stiffness and prevent deformation before loads are applied. This preliminary structural reinforcement ensures that the aerodynamic shape remains stable under high loads, eliminating the need to increase overall structure dimensions that would compromise aerodynamic performance.
Data Source
AI summary
An assembly for an aircraft and comprising a wing comprising an airfoil box partly produced using a front spar, a mounting pylon arranged under the wing and comprising a primary structure formed as a primary box having a top spar extending at least partly under the airfoil box and having a slit, a bottom spar, lateral panels and a transverse reinforcing fixing rib, of which a bottom part is housed and fixed inside the primary structure and of which a top part passes through the slit. A fixing arrangement fixes the top part to the front spar. The fixing arrangement comprises a plurality of fixing bolts, where each fixing bolt fixes the top part to the front spar and has its axis at right angles to the fixing rib. Such an assembly allows the mounting pylon primary structure to be as close as possible to the wing.