Wingtip Spigot Mounting Formation for Statically Determinate Load Path
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Solution Overview
Problem
Current wing tip devices for aircraft are prone to high loads and stress due to mismatched geometry and differential expansion, leading to weight and cost issues, as well as reduced ease of assembly and interchangeability, due to the use of statically indeterminate systems and materials with different thermal expansion rates.
Innovation Solution
A wing tip device connected to a wing using a spigot mounting formation with three connectors, where the first connector is associated with the rear device spar, the second connector is forward, and the third connector is rearward, providing a rigid and determinate load path, and allowing for thermal expansion through a bush and retainer slot configuration, which aids in assembly and reduces static forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If multiple joining locations are used on the wing skin to spread the applied load, then the load per joining location is reduced, but the system becomes statically indeterminate making the loads at each point difficult to predict and requiring over-engineering
Solution Approach 1:
The invention changes the geometric parameters of the connection interface by providing a spigot on the wing tip device that fits into a slot on the wing with specific orientation and positioning. This geometric constraint transforms the statically indeterminate system into a statically determinate one, allowing precise calculation of loads at each connector while maintaining proper load distribution across multiple joining locations
2Strength
If the wing tip device is rigidly connected to the wing tip, then the structural integrity is improved, but the interface becomes sensitive to geometry mismatches and tolerance build-up
Solution Approach 1:
The invention introduces a slot-based connection that allows for controlled movement and adjustment. The spigot fits into the slot with sufficient clearance to accommodate geometric mismatches and tolerance variations, while still providing rigid connection in the critical load-bearing directions. This dynamic adjustment capability reduces sensitivity to manufacturing tolerances
3Ease of manufacture
If conventional connectors are used to attach the wing tip device, then the assembly is simpler, but the ease of interchangeability in service is reduced
Solution Approach 1:
The invention segments the connection system into distinct, modular components: a spigot on the wing tip device, a slot on the wing, and a retainer mechanism. This segmentation allows the wing tip device to be easily detached and replaced by simply removing the retainer and extracting the spigot from the slot, significantly improving interchangeability while maintaining assembly simplicity
4Adaptability or versatility
If materials with different thermal expansion rates are used for the wing tip device and wing, then the design flexibility is increased, but high stresses are generated at the mounting points due to differential expansion
Solution Approach 1:
The invention explicitly accounts for thermal expansion by designing the spigot-slot- retainer connection to accommodate differential movement between materials with different thermal expansion rates. The slot provides clearance in the direction of thermal expansion, and the retainer can be positioned to allow for thermal movement while maintaining structural integrity, thereby reducing thermal stresses at the mounting points
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration enhances the rigidity and ease of assembly of the wing tip device, reduces weight, and improves interchangeability by creating a statically determinate load path, while accommodating thermal expansion and aerodynamic forces, thus improving the structural integrity and efficiency of the aircraft.
Implementation Method 1
temperature effects and loading in use can cause differential expansion or contraction of the wing tip device and the wing tip, which can cause high stresses at the mounting points
Data Source
AI summary
An aircraft assembly is disclosed having a wing tip device connected to a wing tip of a wing by a first connector, a second connector, and a third connector. The wing tip device includes a front device spar and a rear device spar. The first connector is associated with the rear device spar. The second connector is spaced apart in a chordwise direction forward of the first connector, and the third connector is spaced apart in a chordwise direction rearward of the first connector. The third connector includes a spigot mounting formation.