Rotorcraft Tail Boom Attachment Assembly for Fatigue-Tolerant Load Transfer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing attachment interfaces for tail booms in rotorcrafts are either inefficient in terms of tolerance, interchangeability, and maintenance, or prone to fatigue and failure due to complex load interactions, leading to high maintenance costs and safety risks.
Innovation Solution
A novel attachment assembly comprising a ring-shaped interconnecting carrier with discrete angularly positioned shear and axial load transfer bodies, forming a crown-shaped structure that separates load paths to optimize load transfer and reduce secondary loads, using flexible lug arms and stiff shear panels to enhance safety and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single beam element tail boom is used with conventional attachment interfaces, then the structure can be manufactured separately and transported easily, but the attachment interface is prone to fatigue and failure due to complex load interactions
Solution Approach 1:
The attachment interface is segmented into distinct functional zones: a crown-shaped attachment assembly with multiple load transfer bodies distributed around the tail boom perimeter, separating shear load transfer from axial load transfer. This segmentation allows each component to be optimized for its specific function, reducing complex load interactions that cause fatigue
Solution Approach 2:
A crown-shaped attachment assembly serves as an intermediary structure between the tail boom and the aircraft fuselage. This intermediate structure distributes and redirects loads through multiple discrete load transfer bodies, preventing direct complex load interactions at a single attachment point and reducing fatigue on the tail boom structure
2Adaptability or versatility
If conventional attachment interfaces are used, then the tail boom can be attached to the fuselage, but tolerancing is complex and fastener sensitivity is high
Solution Approach 1:
The crown-shaped attachment assembly provides a universal interface that can accommodate various tail boom designs and fuselage configurations. The distributed load transfer bodies and flexible lug arms create a standardized attachment mechanism that simplifies tolerancing and enables interchangeability of tail booms across different aircraft configurations
Solution Approach 2:
The attachment interface utilizes parameters such as the angular distribution of load transfer bodies, the flexibility of lug arms, and the geometry of the crown-shaped assembly to accommodate manufacturing tolerances. These parameter variations allow for simplified tolerancing while maintaining attachment reliability and interchangeability
3Ease of repair
If maintenance is required on conventional attachment interfaces, then access is possible, but maintenance needs are frequent and costs are high
Solution Approach 1:
The tail boom is designed as a separable component that can be easily detached from the fuselage using the crown-shaped attachment assembly. This extraction capability allows the tail boom to be removed for maintenance, inspection, or replacement without complex disassembly procedures, reducing maintenance frequency and costs while improving access when needed
4Strength
If the tail boom design prioritizes structural strength and stiffness, then fatigue resistance improves, but mass increases
Solution Approach 1:
The tail boom is constructed using composite materials that provide high strength-to-weight ratio, maintaining the required bending and torsional stiffness while minimizing mass. The crown-shaped attachment assembly and load transfer bodies are also designed using composite structures to achieve optimal strength without excessive weight
Solution Approach 2:
The attachment interface uses localized reinforcement through the crown-shaped assembly and distributed load transfer bodies, providing structural strength and stiffness only where needed at the attachment points. The rest of the tail boom structure can be optimized for minimum weight while maintaining overall structural integrity through this localized quality approach
Data Source
Figure 1
Figure 2(A)~2(C)
Figure 3(A)~3(C)
AI summary
An attachment assembly (10) for attachment of a tail boom (3) to a rear fuselage of a rotorcraft (1), comprising: a ring-shaped interconnecting carrier (10c) with a predetermined wall thickness; a predefined number of shear load transfer bodies (15a) connected at first discrete angular positions (17a, 17b, 17c, 17d) to the interconnecting carrier for transfer of loads essentially in circumferential direction (10e) of the interconnecting carrier; and a plurality of axial load transfer bodies (13b) connected to the interconnecting carrier at second discrete angular positions (17e, 17f, 17g) for transfer of loads in a direction (10f) essentially perpendicular to both the predetermined wall thickness (10d) and the circumferential direction, wherein the predefined number of shear load transfer bodies and the plurality of axial load transfer bodies extend from the interconnecting carrier at least approximately in the direction essentially perpendicular to both the predetermined wall thickness and the circumferential direction.