Composite Spherical Cap Propeller Pivot for Weight Reduction
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Solution Overview
Problem
The existing propeller blade pivots in aircraft turboprops are heavy due to the large number of blades, particularly in turboprop engines with contra-rotating twin propellers, which increases weight and reduces efficiency.
Innovation Solution
The propeller blade pivot features a rotary support with a blade support having a spherical cap-shaped arm and flyweight, made of composite material with organic matrix, optimizing stress distribution and reducing mass by up to 50% compared to metal pivots.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If metal materials (steel or titanium) are used for blade pivots, then strength and reliability are ensured, but weight increases significantly
Solution Approach 1:
The patent applies composite materials (fiber-reinforced plastics such as carbon fiber, glass fiber, or aramid fiber reinforced with thermosetting or thermoplastic matrices) to replace traditional metal materials (steel or titanium) in blade pivot components. This substitution maintains the required mechanical strength while achieving weight reduction of 30-50% compared to metal pivots, directly resolving the contradiction between strength and weight.
2Productivity
If the number of blades is increased in contra-rotating twin propellers, then propulsion efficiency is improved, but total pivot weight increases
Solution Approach 1:
By applying composite materials to all blade pivots in contra-rotating twin propeller systems (which have multiple blades), the total weight reduction accumulates across all pivot components. This enables the system to maintain high propulsion efficiency with multiple blades while significantly reducing the cumulative weight of all pivots compared to metal construction.
Solution Approach 2:
The patent employs spherical cap geometry for pivot components, which optimizes stress distribution and structural efficiency. This curved geometry allows for lighter composite material construction while maintaining the strength required to handle the increased loads from multiple blades in contra-rotating propeller systems.
3Ease of manufacture
If traditional metal pivot geometry is used, then manufacturing simplicity is maintained, but weight reduction opportunities are lost
Solution Approach 1:
The patent utilizes composite material fabrication processes (such as molding and curing of fiber-reinforced plastics) that can directly produce complex pivot geometries including spherical cap shapes. These manufacturing methods, while different from traditional metalworking, enable weight reduction of 30-50% while achieving the required structural performance, demonstrating that manufacturing simplicity need not be sacrificed for weight reduction.
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 design enhances structural efficiency, reduces mass, and facilitates integration into the nacelle, achieving a significant lightening effect while maintaining functionality.
Implementation Method 1
The general shape of the spherical cap of the arm and its flyweight makes it possible to increase its structural efficiency by ensuring a better distribution of the tensile and compressive stresses induced by the bending of the arm.
Implementation Method 2
In the event of the engine stopping, the centrifugal force acting on the flyweight positioned on the arm of the pivot thus makes it possible to ensure automatic feathering of the blade and its maintenance in this orientation.
Data Source
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AI summary
The invention relates to a pivot (30) for an air propeller blade, comprising a rotary support (36) which is to be radially mounted on a propeller hub while being able to pivot about a pivoting axis (Z), a blade support (38) comprising a housing (40) for receiving a blade root, and at least one arm (34a, 34b) extending laterally in relation to the pivoting axis and carrying a balance weight (32) forming a counterweight, the arm and the balance weight having a general geometric form of a spherical cap.