Helicopter Rotor Blade Tension-Torsion Strap Retention System
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Solution Overview
Problem
The challenge lies in connecting a helicopter rotor blade to a hub using a bearingless rotor system while maintaining structural parameters close to the original design, especially in minimizing gaps that increase bending moments on pins and addressing the weight and cost issues associated with current solutions.
Innovation Solution
A retention system comprising a housing with aligned channels and bushings that guide and secure a tension-torsion strap to the hub, reducing bending moments and providing an environmental barrier, and using a pin that spreads shear forces across a wider surface area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a bearingless rotor system with flexible structural member is used to connect blade to hub, then the capability to control blade position accurately is improved, but gaps between the flexible structural member and hub increase causing higher bending moments on pins
Solution Approach 1:
A retention system with a housing and alignment features is introduced as an intermediary between the flexible structural member (tension-torsion strap) and the hub. The housing includes channels with alignment features that guide and align the strap during installation, ensuring proper positioning and minimizing gaps between the strap and hub, thereby reducing bending moments on pins while maintaining accurate blade position control capability
2Strength
If current solutions for connecting tension-torsion strap are used, then structural integrity is maintained, but weight and cost increase
Solution Approach 1:
The connection system is segmented into modular components: a retention system housing, alignment features, and the tension-torsion strap. This segmentation allows for optimized design of each component, using minimal material where needed while maintaining overall structural integrity, thereby reducing total weight compared to monolithic connection solutions
Solution Approach 2:
The patent replaces traditional mechanical connection systems (such as multiple pins, bearings, or complex fastening mechanisms) with a streamlined retention system that uses the flexible structural member's inherent properties combined with simple alignment features and minimal fastening elements, reducing weight while maintaining structural integrity
3Stability of the object's composition
If traditional hinge and journal-type bearings are used at blade-hub connection, then structural stability is maintained, but device complexity and cost increase
Solution Approach 1:
The patent extracts and removes traditional hinge and journal-type bearings from the blade-hub connection system, replacing them with a simplified retention system that uses the flexible structural member itself to provide the necessary stability and movement capabilities, thereby reducing device complexity and cost while maintaining connection stability
Solution Approach 2:
The patent changes the fundamental parameter of the connection system from rigid mechanical joints (hinges and bearings) to a flexible structural member that provides stability through its material properties and geometric configuration, enabling the same functional stability with simpler components
Data Source
AI summary
An apparatus may comprise a housing, a first member, and a second member. The housing may have a first end, a second end, a first side, a second side, an opening located in the first end, and a passage extending from the opening. The first member may extend from the first side. The first member may have a first channel in communication with the passage and the channel has a first center axis. The second member may extend from the first side. The second member may have a second channel in communication with the passage and the second channel has a second center axis substantially aligned with the center axis of the channel in the first member.