Single-Piece Composite Propeller Using Foam Core and RTM Skin
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Solution Overview
Problem
Conventional propeller designs, particularly fixed-pitch propellers, face challenges in weight reduction and maintenance due to their material constraints, with solid aluminum and wooden designs being heavy and labor-intensive, while composite designs with solid carbon fiber cores are also heavy and require complex retention mechanisms.
Innovation Solution
A propeller design featuring a lightweight foam core with a structural skin laminate, where the skin laminate encapsulates the hub and blade portions, using a resin-transfer-molding process with fibrous braid material, and a crush-resistant laminate hub, significantly reducing weight and maintenance needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If solid aluminum or wooden materials are used for propeller construction, then structural strength is ensured, but weight increases significantly
Solution Approach 1:
The patent employs composite materials consisting of a foam core surrounded by a structural skin laminate. The foam core provides lightweight structural support while the laminate skin provides strength and stiffness. This composite construction achieves the required structural strength while significantly reducing weight compared to solid aluminum or wooden propellers.
Solution Approach 2:
The patent applies different material properties to different parts of the propeller: the foam core provides bulk structural support with low density, while the laminate skin provides high-strength surface coverage. This local differentiation of material quality allows the propeller to achieve necessary strength characteristics only where required, minimizing overall weight.
2Strength
If solid carbon fiber cores are used in composite propellers, then structural loads are carried, but weight increases and maintenance complexity increases
Solution Approach 1:
The patent uses foam core material instead of solid carbon fiber, providing structural load capacity through the combination of foam core and laminate skin rather than relying on solid carbon fiber. This local optimization of material selection reduces weight while maintaining the necessary structural load capacity.
Solution Approach 2:
The patent employs a composite structure with foam core and laminate skin that works together to carry structural loads, replacing the solid carbon fiber core approach. This composite material system achieves comparable load capacity with reduced weight.
3Adaptability or versatility
If separate propeller blades with retention mechanisms are used, then blade replacement is possible, but device complexity increases
Solution Approach 1:
The patent integrates the blades and hub into a single seamless composite structure where the laminate skin continuously encapsulates both components. This merging eliminates the need for separate retention mechanisms, reducing device complexity while maintaining the ability to service the propeller as a unit.
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 resulting propeller is approximately half the weight of conventional aluminum designs, is easily bolted onto aircraft, and offers seamless composite construction with reduced maintenance and labor requirements.
Implementation Method 1
a structural skin laminate deposed outside the core... the skin laminate substantially encapsulates a hub portion along with at least one blade portion
Implementation Method 2
the structural skin is formed using a sleeve made of fibrous braid material as part of a resin-transfer-molding (RTM) process
Data Source
AI summary
A method for making a propeller product is disclosed. The propeller is formed using polyurethane cores adhered to a laminate hub to form a core assembly. An encapsulating structural laminate skin is then formed on the core assembly using a resin-transfer-molding process to create a single-piece composite propeller.