Aircraft Pylon Attachment Bolted Connection to Wing Box
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Solution Overview
Problem
The increasing diameter of modern turbofan engines poses a challenge for aircraft engine mounting pylons, as they need to be positioned closer to the wing while maintaining ground clearance, requiring more efficient force transmission with reduced bulk and secondary moments to ensure mechanical strength and aerodynamic performance.
Innovation Solution
The use of a row of bolts for attaching the engine mounting pylon's primary structure to the wing box, allowing for a more direct force transfer and reducing secondary moments, enabling the pylon to be positioned closer to the wing, thus accommodating larger engines and increasing ground clearance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the mounting pylon is positioned closer to the wing to accommodate larger engine diameters, then ground clearance is improved, but the force transmission efficiency deteriorates due to increased secondary moments
Solution Approach 1:
The attachment system is divided into multiple discrete bolt connection points distributed along the pylon's upper structure. This segmentation allows the pylon to be positioned closer to the wing while distributing the force transmission across multiple points, reducing the lever arm for secondary moments and maintaining force transmission efficiency.
Solution Approach 2:
The attachment mechanism transitions from conventional single-point or limited-point connections to a distributed row of bolt connections extending along the pylon's upper structure. This dimensional expansion of the attachment interface reduces the moment arm and improves force transmission efficiency while allowing closer positioning to the wing.
2Force
If conventional attachment means with significant bulk are used, then force transmission is achieved, but the vertical space available for installation is reduced
Solution Approach 1:
The attachment function is extracted from bulky conventional mechanisms and implemented through a streamlined row of bolts. This extraction of the essential attachment function eliminates unnecessary bulk while maintaining force transmission capability, thereby preserving vertical installation space for larger engine diameters.
Solution Approach 2:
The attachment system changes from conventional high-bulk mechanisms to a bolt row configuration with optimized geometric parameters. This parameter optimization reduces the vertical footprint of the attachment means while maintaining sufficient force transmission capacity, enabling closer positioning of the pylon to the wing.
3Adaptability or versatility
If the pylon is positioned closer to the wing to accommodate larger engines, then bypass ratio requirements are improved, but mechanical strength requirements become more stringent
Solution Approach 1:
The load-bearing function is segmented across multiple bolt connection points distributed along the pylon's upper structure. This distribution reduces the concentration of stress at any single point, allowing the pylon to be positioned closer to the wing while maintaining mechanical strength through the collective capacity of the distributed connection system.
Solution Approach 2:
The force transmission is expanded from conventional concentrated connections to a distributed row of bolts extending along the pylon. This dimensional expansion of the attachment interface reduces stress concentration and maintains mechanical strength while enabling closer positioning to accommodate larger engines with higher bypass ratios.
Data Source
AI summary
In order to bring the primary structure of an engine mounting pylon of an aircraft as close as possible to a wing box: an aircraft wing includes a wing box made partly by a front spar and an intermediate spar; a mounting pylon including a primary structure in the form of a box having transverse reinforcement ribs; and attachment means for attaching the primary structure of the mounting pylon on the wing box. These attachment means include a row of bolts along which each bolt passes through a structural part of the pylon on one hand, and on the other hand a fitting attached to one of the front and intermediate spars.