Aircraft Wing Spar Structure Direct Connection
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Solution Overview
Problem
Conventional wing spar connections in aircraft either rely on heavy wingboxes or complex spar-to-spar designs that lead to significant shear forces within the fuselage, complicating assembly, maintenance, and increasing weight.
Innovation Solution
A wing spar structure where the spar caps of the left and right wings are directly connected via bolts, eliminating the need for a wingbox and shear web, allowing for efficient transfer of bending moments while using lighter materials and simplifying assembly and maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a wing box is used to transfer bending moments, then structural integrity is improved, but weight increases significantly
Solution Approach 1:
The invention extracts and eliminates the wing box structure from the aircraft design, replacing it with a direct spar-to-spar connection system. The main spars of the left and right wings are connected directly to each other through slot-and-key connections with bolts, allowing bending moments to be transferred without requiring the heavy wing box enclosure. This extraction of the wing box component directly addresses the weight reduction goal while maintaining structural functionality.
Solution Approach 2:
The invention merges the functions of the left and right wing spars by directly connecting them together to form a unified load-bearing structure. The spar-to-spar connection combines the two separate spars into a cooperative system that can transfer bending moments efficiently, eliminating the need for the wing box as an intermediary structural element. This merging approach achieves structural integrity through the combined action of the connected spars rather than through a heavy enclosing box.
2Weight of moving object
If conventional spar-to-spar connection is used, then weight is reduced compared to wing box, but significant shear forces build up in the main spar section
Solution Approach 1:
The invention introduces shear pins as intermediary elements that extend through the main spars of both left and right wings. These shear pins act as mediators to transfer shear forces directly from the wings to the fuselage, preventing the accumulation of significant shear forces within the main spar sections. The shear pins provide a dedicated load path for shear forces, decoupling the shear force transfer function from the bending moment transfer function of the spars.
3Ease of manufacture
If slot-and-key connection with bolts is used, then assembly is simplified, but manufacturing precision requirements increase
Solution Approach 1:
The invention incorporates preliminary alignment features in the form of slot-and-key connections that guide the spars into proper alignment before final bolting. The slots provide preliminary positioning that accommodates minor dimensional variations, while the keys ensure precise alignment in the critical directions. This preliminary action of alignment through slots and keys before final fastening simplifies the assembly process while controlling the precision requirements.
Data Source
Figure 1
Figure 2a~2b
Figure 2c~3
AI summary
The invention relates to a wing spar structure 210 of an aircraft 100. The wing spar structure comprises a left spar 214 associated to a left wing 202b of the aircraft and a right spar 212 associated to a right wing 202a of the aircraft. Each spar 212, 214 has a web portion 230 extending in a substantially vertical direction v and at least one spar cap 232, 232a, 232b extending in a substantially orthogonal to the web portion 230. According to a first aspect of the invention, said left spar 214 is connected to said right spar 212 by connecting the spar cap 232b of the left spar 214 to the spar cap 232a of the right spar 212 at a spar connection portion 240, 240a, 240b. According to a second aspect of the invention, said left spar 214 is connected to said right spar 212 in a fuselage region 224 at a spar connection portion 240, 240a, 240b and a height 234 of the web portion 230 in vertical direction v increases towards the spar connection portion 240, 240a, 240b.