Thrust Reverser Blocker Door Folding Linkage for Bypass Drag Reduction
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Solution Overview
Problem
Existing aircraft propulsion systems with thrust reversers suffer from increased bypass duct drag due to drag links that extend across the duct even when not in use, reducing engine efficiency during typical operation.
Innovation Solution
The implementation of a folding linkage system that includes a translating structure, a blocker door, and a folding linkage with a roller, which allows the blocker door to pivot radially inward as the translating structure moves from a stowed to a deployed position, minimizing drag by retracting the linkage when not in use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If drag links are used to pivot blocker doors, then the blocker doors can be deployed effectively, but the drag links extend across the bypass duct even when not in use, increasing drag and reducing engine efficiency
Solution Approach 1:
The folding linkage is designed to be dynamic rather than static, automatically transitioning between extended and retracted positions based on the thrust reverser state. The linkage folds into a compact configuration during normal engine operation to minimize drag, and extends only when needed for thrust reverser deployment, thus resolving the contradiction between maintaining functionality and reducing energy loss.
Solution Approach 2:
The folding linkage employs a nested configuration where linkage members are folded into each other when not in use, similar to nested dolls. This nesting allows the drag links to be retracted into a compact space within the thrust reverser mechanism, eliminating their presence in the bypass duct during normal operation and thereby reducing drag and energy loss while preserving thrust reverser functionality when needed.
2Loss of energy
If the folding linkage is retracted when not in use, then drag is reduced and engine efficiency is improved, but the mechanism complexity increases
Solution Approach 1:
The folding linkage utilizes dynamic mechanical elements including pivots, rollers, and linkages that automatically transition between extended and retracted states. These dynamic components enable the mechanism to adapt its configuration based on operational requirements, achieving drag reduction through automated motion rather than complex control systems.
Solution Approach 2:
The folding linkage is divided into multiple segmented members connected by pivots and joints. This segmentation allows each component to move independently and fold into a compact nested configuration, simplifying the overall retraction mechanism while maintaining the ability to extend when needed for thrust reverser operation.
3Productivity
If the blocker door pivots radially inward simultaneously with the translating structure moving, then thrust reversal effectiveness is improved, but the linkage must maintain precise geometric relationships
Solution Approach 1:
The folding linkage employs dynamic mechanical elements including pivots, rollers, and linkages that automatically transition between extended and retracted states. These dynamic components enable the mechanism to adapt its configuration based on operational requirements, achieving drag reduction through automated motion rather than complex control systems.
Solution Approach 2:
The folding linkage is divided into multiple segmented members connected by pivots and joints. This segmentation allows each component to move independently and fold into a compact nested configuration, simplifying the overall retraction mechanism while maintaining the ability to extend when needed for thrust reverser operation.
Data Source
AI summary
An assembly is provided for an aircraft propulsion system. This assembly includes a fixed structure, a translating structure, a blocker door and a folding linkage. The translating structure is configured to move between a stowed position and a deployed position. The blocker door is pivotally attached to the translating structure at a first pivot joint. The folding linkage links the blocker door to the fixed structure. The folding linkage includes a member pivotally attached to the blocker door at a second pivot joint that is radially outboard of a skin of the blocker door when the translating structure is in the stowed position. The second pivot joint is radially outboard of the first pivot joint when the translating structure is in the stowed position.