A-Frame Strut Counteracting Vertical Moment in SBW Aircraft
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Solution Overview
Problem
Aircraft with strut-braced, swept-wing designs experience a significant vertical moment due to the aft offset of the strut-fuselage joint, leading to undesirable wing pivoting and structural inefficiencies.
Innovation Solution
The implementation of an A-frame strut structure with a strut front spar and a strut rear spar, where the spar inboard ends are spaced apart at the strut-fuselage joint to transfer tension and compression loads into the fuselage, and the strut spar outboard ends converge at the strut-wing joint, allowing for effective counteraction of the vertical moment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the strut-fuselage joint is located aft of the wing-fuselage joint to reduce interference drag, then aerodynamic performance is improved, but a large vertical moment is generated causing wing pivoting
Solution Approach 1:
The strut is divided into two separate spars (front spar and rear spar) that are spaced apart at the fuselage attachment point. This segmentation allows the structure to resist the vertical moment through the spacing between the spars, preventing wing pivoting while maintaining the aft offset configuration that reduces interference drag.
Solution Approach 2:
The solution moves from a single-strut configuration to a two-spar configuration, adding a dimensional separation at the fuselage attachment point. This spacing in the longitudinal dimension creates a moment-resisting mechanism that counteracts the vertical moment without requiring the strut to be positioned directly under the wing root.
2Device complexity
If a single strut is used to support the wing, then structural simplicity is maintained, but the vertical moment cannot be effectively counteracted
Solution Approach 1:
The single strut is segmented into two spars (front spar and rear spar) that are spaced apart at the fuselage attachment point. This segmentation creates a distributed load path that can effectively resist the vertical moment through the spacing between the spars, transforming a simple single-strut design into a moment-resisting structure.
Solution Approach 2:
The solution transitions from a one-dimensional single-strut configuration to a two-dimensional spar system with longitudinal spacing. This dimensional change enables the structure to resist vertical moments through the separation distance between spars, significantly improving moment resistance while maintaining reasonable structural complexity.
Data Source
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AI summary
An aircraft (100) includes a fuselage (102) and a pair of wings (200). Each wing (200) is coupled to the fuselage (102) at a wing-fuselage joint (204), and is supported by a strut (300) coupled to the fuselage at a strut-fuselage joint (304) and coupled to the wing at a strut-wing joint (306). The strut-fuselage joint (304) is located below and at least partially aft of the wing-fuselage joint (204). The wing (200) generates a lifting force (600) when air passes over the wing (200). The lifting force (600) induces a vertical moment about the wing-fuselage joint (204) due to the location of the strut-fuselage joint (304) below and at least partially aft of the wing-fuselage joint (204). The wing (200) and/or the strut (300) has a structural arrangement configured to counteract the vertical moment.