Turbojet Pylon Attachment Layout Without Rear Mount
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Solution Overview
Problem
Existing propulsion systems for aircraft turbojets under the wing face challenges in achieving reduced weight and efficient load transfer to the pylon.
Innovation Solution
A propulsion system design featuring a turbojet with a cylindrical pin and shackle articulations, along with reaction rods, that allows for isostatic assembly without a rear attachment, optimizing load transfer and reducing weight by utilizing a single plane articulation system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a traditional rigid pylon structure with multiple attachment elements is used, then the structural strength and reliability are improved, but the weight of the propulsion system increases
Solution Approach 1:
The attachment system is segmented into distinct functional components: cylindrical pin for positioning, shackle for articulation, and reaction rods for load bearing. This segmentation allows each component to be optimized independently, reducing overall weight while maintaining strength.
Solution Approach 2:
The system transitions from a completely rigid attachment to a dynamic articulation system where the shackle and reaction rods allow controlled movement. This enables the structure to adapt to thermal expansion and contraction, reducing the need for over-engineering rigid connections.
2Force
If multiple attachment elements including rear attachment are used, then the load transfer to the pylon is improved, but the device complexity increases
Solution Approach 1:
The rear attachment element is extracted/removed from the system. The patent demonstrates that adequate load transfer can be achieved without rear attachment by optimizing the front attachment geometry and using the reaction rods to bear thrust loads, thereby simplifying the overall attachment system.
Solution Approach 2:
The reaction rods serve multiple functions: they bear thrust loads, provide structural support, and enable articulation between the engine and pylon. This multi-functionality reduces the need for separate specialized components, simplifying the overall system while maintaining effective load transfer.
3Manufacturing precision
If the articulation points are located at a single plane, then the manufacturing precision and assembly ease are improved, but the adaptability to different load conditions decreases
Solution Approach 1:
While the articulation points are positioned at a single plane for manufacturing simplicity, the reaction rods extend in multiple directions and the shackle provides rotational freedom. This effectively adds dimensional flexibility, allowing the system to adapt to various load conditions while maintaining precise articulation alignment.
Data Source
AI summary
A propulsion system comprising a turbojet with a fan casing and a central casing, a pylon with an upper spar, a front wall and on either side of a vertical median plane, a fitting rigidly fixed to the rigid structure, a cylindrical pin as one with the fan casing and inserted in a hole of the upper spar, a shackle with at the vertical median plane, an upper articulation between the shackle and the front wall and on either side of the vertical median plane, a lower articulation between the shackle and the central casing, and two reaction rods disposed on either side of the median plane, where each rod is articulated, at a front end, on the central casing, and, at rear end, on the fitting.