Helicopter Tail Boom Shear Connection for Interchangeable Airframe Joints
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Solution Overview
Problem
Current shear connections in aircraft require extensive shimming, milling, or sanding for maintenance, leading to increased weight, corrosion issues, and high manufacturing costs, while lacking interchangeability and reliability for easy part exchange during maintenance.
Innovation Solution
A shear connection system that uses a shear bolt to rigidly and interchangeably connect airframe parts, with interface parts attached via bonding, welding, or screws, allowing for precise fitting without overlapping, and optionally incorporating a web for increased stiffness, enabling lightweight, reliable, and cost-effective interchangeability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a double flange connection is used to transfer load between tail boom and fuselage, then the connection can be made, but the wall thickness must be increased and weight increases
Solution Approach 1:
The connection is divided into two separate interface parts (first interface part and second interface part) that overlap and connect through shear bolts, rather than using a single thick flange structure. This segmentation allows load transfer through the overlapping joint area with thinner walls.
Solution Approach 2:
The connection transitions from a face-to-face flange arrangement to an overlapping arrangement where the second interface part extends beyond the first interface part in the longitudinal direction. This dimensional change creates a shear connection that transfers load more efficiently with reduced material.
2Strength
If metals are used for the connection interface, then load transfer is appropriate, but corrosion issues occur
Solution Approach 1:
Interface parts serve as intermediary elements between the tail boom and fuselage, allowing the use of corrosion-resistant materials for these connection components while maintaining structural integrity. The interface parts can be designed to protect the main airframe structures from corrosion.
Solution Approach 2:
The connection system allows for the use of different materials for different components - corrosion-resistant materials for interface parts and bolts, while the main airframe structures can use their optimal materials. This composite approach balances strength requirements with corrosion resistance.
3Manufacturing precision
If extensive shimming, milling, or sanding operations are performed, then precise fitting is achieved, but manufacturing costs and time increase
Solution Approach 1:
The interface parts are designed with predetermined geometries and overlap dimensions that ensure proper alignment and fit when assembled. The shear connection configuration itself provides the necessary positioning, eliminating the need for extensive post-manufacturing adjustments like shimming, milling, or sanding.
4Adaptability or versatility
If the airframe parts are made interchangeable, then easy exchange during maintenance is enabled, but the connection complexity increases
Solution Approach 1:
The shear connection design with overlapping interface parts and standardized shear bolts creates a universal connection system that can accommodate interchangeable airframe parts. The same connection methodology applies regardless of which specific tail boom or fuselage section is being connected, enabling maintenance exchanges without custom fabrication.
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
The shear connection system allows for easy and reliable exchange of airframe parts during maintenance without manufacturer involvement, reducing weight, manufacturing costs, and minimizing corrosion risks, while maintaining structural integrity and aerodynamic efficiency.
Implementation Method 1
means for rigidly and non-interchangeably attaching the first interface part to only the inside surface of the first airframe part and the second interface part to only one of the inside surface or the outside surface of the second airframe part
Implementation Method 2
means for rigidly and non-interchangeably attaching the first interface part to only the inside surface of the first airframe part and the second interface part to only one of the inside surface or the outside surface of the second airframe part
Implementation Method 3
means for rigidly and non-interchangeably attaching the first interface part to only the inside surface of the first airframe part and the second interface part to only one of the inside surface or the outside surface of the second airframe part
Implementation Method 4
a shear bolt that rigidly and interchangeably connects the second interface part with the first interface part at the overlap section
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
The invention is related to a shear connection 60 for interchangeably connecting two airframe parts 11,12 of an aircraft 1. The shear connection 60 may include first and second interface parts 13, 14. The second interface part may overlap in the longitudinal direction 1g at an overlap section 19 with at least one of the first interface part 13 and the first airframe part 11. The shear connection may further comprise means 15a-d that rigidly and non-interchangeably attach the first interface part 13 to the first airframe part 11 and the second interface part 14 to the second airframe part 12 and a shear bolt 17a, 17b that rigidly and interchangeably connects the second interface part 14 with the at least one of the first interface part 13 and the first airframe part 11 at the overlap section 19, thereby interchangeably connecting the first and second airframe parts.