Angularly Offset Pylon for Aircraft Propulsion
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Solution Overview
Problem
The increasing bypass ratio of turbojet engines to reduce sound nuisance and fuel consumption leads to a larger propulsion system, necessitating a closer placement to the aircraft wing, which reduces space for the pylon, causing turbulence and drag, and requiring heavy, rigid materials like titanium.
Innovation Solution
An angularly offset pylon positioned outside the secondary air stream flow passage, using lighter composite materials, with horizontal transverse beams and link-and-hinge mechanisms to suspend the engine, allowing closer placement to the wing without disturbing airflow and reducing weight and drag.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the bypass ratio is increased to reduce sound nuisance and fuel consumption, then the propulsion system size increases, but the space available for the pylon decreases
Solution Approach 1:
The pylon is repositioned from a vertical orientation (occupying space between engine and wing) to an angular offset orientation extending laterally from the engine nacelle. This dimensional change allows the pylon to utilize lateral space rather than vertical space, resolving the conflict between engine proximity to wing and adequate pylon space.
Solution Approach 2:
The pylon is positioned asymmetrically with an angular offset from the vertical plane containing the engine longitudinal axis. This asymmetric placement optimizes space utilization and allows the pylon to extend into previously unused lateral regions, accommodating larger engine configurations.
2Strength
If the pylon is made robust and rigid to transfer all forces, then the pylon weight increases, but the structural integrity is maintained
Solution Approach 1:
The patent specifies that the pylon may be made from composite materials, which provide high strength-to-weight ratios. This allows the pylon to maintain the necessary structural integrity for force transfer while significantly reducing its weight compared to traditional solid metal constructions.
Solution Approach 2:
The pylon design utilizes changes in material parameters (using composites instead of traditional metals) and geometric parameters (angular offset configuration) to achieve optimal strength-to-weight ratio, maintaining structural integrity while minimizing weight.
3Device complexity
If the pylon extends into the secondary stream flow passage, then the connection is simplified, but turbulence and drag increase
Solution Approach 1:
The pylon is extracted from the secondary stream flow passage and repositioned to an angular offset location where it does not interfere with the bypass airflow. This separation eliminates the harmful turbulence and drag that would result from the pylon extending into the flow passage.
4Speed
If the engine is moved closer to the wing to ensure ground clearance, then the ground clearance is maintained, but the pylon space is reduced
Solution Approach 1:
The pylon configuration transitions from a vertical arrangement (competing for vertical space between engine and wing) to an angular offset lateral arrangement. This allows the engine to be positioned closer to the wing for ground clearance while the pylon extends laterally into previously available space.
Data Source
AI summary
An aircraft propulsion system (110) comprising a bypass turbojet engine surrounded by a nacelle defining a flow passage for the secondary stream flows, and connection means for connecting the engine to a wing (132) of an aircraft and comprising a pylon (134) substantially parallel to the longitudinal axis (135) of the engine together with suspension means suspending the engine from the pylon, the pylon being angularly offset from a vertical plane (150) containing the longitudinal axis of the engine and from the top of the nacelle, and being situated outside the flow path for the secondary stream.