Movable Wing Tip Spar Extension for Span Reduction
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Solution Overview
Problem
Large passenger aircraft face challenges in reducing wing span for ground operations due to technical issues with moving wing tip devices, including aerodynamic leakage and the need for bulky, heavy components that complicate flight load transmission and actuation mechanisms.
Innovation Solution
A wing assembly design featuring a spar extension that transmits flight loads between the wing tip device and the inboard wing, allowing for the wing tip device to move between flight and ground configurations, reducing span, and utilizing a combination of linear and rotary actuators for efficient movement without protruding components, and incorporating a compression seal to mitigate aerodynamic leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a movable wing tip device is provided to reduce span on ground, then the aircraft can meet airport clearance requirements, but the mechanism requires bulky and heavy components that complicate the wing design and actuation system
Solution Approach 1:
The spar extension is nested within the wing tip device structure, with the second end portion disposed inside the wing tip device in flight configuration. This eliminates the need for external bulky components and integrates the load-bearing structure directly into the moving component, reducing overall system complexity and weight.
Solution Approach 2:
The moving mechanism is divided into two independent movement stages: vertical translation followed by rotational folding. This segmentation allows each movement to be optimized separately, with the vertical movement clearing obstructions and the rotational movement achieving span reduction, simplifying the overall actuation system design.
2Length of moving object
If the wing tip device is moved to reduce span on ground, then airport clearance requirements are met, but aerodynamic leakage occurs at the interface between wing and wing tip device
Solution Approach 1:
A flexible seal is provided at the interface between the wing and wing tip device, utilizing a flexible membrane or shell structure to maintain aerodynamic sealing during movement. The seal accommodates both vertical and rotational movements while preventing air leakage, eliminating the harmful aerodynamic effects without compromising the span reduction capability.
3Shape
If wing box thickness is decreased to improve aerodynamics, then aerodynamic efficiency increases, but the ability to accommodate flight loads and heavy actuation components is reduced
Solution Approach 1:
The spar extension is nested within the wing tip device, allowing the load-bearing structure to be integrated into the moving component itself rather than requiring a deeper wing box. This enables thin-wing box designs while maintaining the structural integrity needed to accommodate flight loads and actuation components.
Solution Approach 2:
The spar extension extends in the spanwise direction rather than requiring increased depth in the vertical dimension. This dimensional shift allows the wing box to remain thin while still providing adequate structural capacity for load bearing, as the extension utilizes the spanwise space within the wing tip device.
Data Source
AI summary
A wing assembly for an aircraft is disclosed having a wing and a wing tip device at the tip of the wing, wherein the wing tip device is moveable between a flight configuration and a ground configuration. The wing has a spar extension which extends spanwise away from a distal end of the wing, the spar extension having a first end portion fixed in the wing and a second end portion which, in the flight configuration, is disposed in the wing tip device such that, in the flight configuration, the spar extension transmits flight loads between the wing tip device and flight-load bearing structure in the wing. The wing assembly may have an actuation assembly to move the wing tip device.