Aircraft Engine Pylon Torque Box Load Path Design
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Solution Overview
Problem
Existing aircraft engine mounting structures, such as truss frames, face challenges in efficiently transferring engine loads while maintaining structural integrity and minimizing weight, particularly in the event of an uncontained engine rotor failure, and often complicate propeller drive shaft alignment and maintenance access.
Innovation Solution
A pylon structure comprising a torque box with wing mounts, first and second engine mounts, connecting rods, and thrust links, which forms a load path through a skeletal frame and stressed skins to direct engine loads into the wing, providing a structurally efficient and resistant design that reduces the distance between the engine output and propeller drive shaft, and allows for easier maintenance access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional truss frame mounting structures are used, then structural integrity is maintained, but weight increases and structural complexity increases
Solution Approach 1:
The mounting structure is divided into discrete functional components including engine mounts, torque box, connecting rods, and thrust links. Each component performs a specific function in the load path, allowing for optimized design of individual elements rather than a monolithic truss structure.
Solution Approach 2:
The torque box is extracted as a separate functional element from the traditional truss structure. This torque box serves as a dedicated component for resisting engine torque while the remaining structure handles other loads, enabling more efficient structural design.
2Strength
If traditional truss frame mounting structures are used, then structural integrity is maintained, but device complexity increases
Solution Approach 1:
The mounting structure is divided into discrete functional components including engine mounts, torque box, connecting rods, and thrust links. Each component performs a specific function in the load path, allowing for optimized design of individual elements rather than a monolithic truss structure.
Solution Approach 2:
The torque box serves multiple functions: it resists engine torque, provides a mounting structure for the engine, and integrates with the wing mounting system. This multi-functionality reduces the need for separate dedicated components.
3Ease of manufacture
If the torque box is located below the engine, then structural support is simplified, but propeller aerodynamics deteriorate and maintenance access becomes difficult
Solution Approach 1:
Instead of placing the torque box below the engine as in conventional designs, the torque box is inverted to a position above the engine. This inversion improves propeller aerodynamics by clearing the propeller arc and enhances maintenance access to the engine and propeller drive shaft.
Solution Approach 2:
The torque box is repositioned from a vertical arrangement (below engine) to a horizontal arrangement (above engine along the longitudinal axis). This dimensional change allows the propeller to rotate in clear space while maintaining structural support functionality.
4Ease of manufacture
If the distance between engine output and propeller drive shaft is increased, then structural support is simplified, but propeller aerodynamics and efficiency deteriorate
Solution Approach 1:
Instead of placing the torque box below the engine as in conventional designs, the torque box is inverted to a position above the engine. This inversion improves propeller aerodynamics by clearing the propeller arc and enhances maintenance access to the engine and propeller drive shaft.
Solution Approach 2:
The torque box is positioned above the engine in advance of the propeller rotation arc, allowing the propeller to rotate without interference while maintaining a compact overall structure that preserves propeller efficiency.
Data Source
Figure 1
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AI summary
A pylon structure (10) for mounting an aircraft engine to a wing. The pylon structure comprises a torque box (12) having a wing mount (14) on the aft portion, a first engine mount (16) on the fore portion and second engine mount (18) on the aft portion.