Multi-Plane Composite Propeller Blades for Aircraft
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Solution Overview
Problem
Composite propeller blades for aircraft require longer non-aerofoil sections and larger spinner diameters due to abrupt fiber direction changes, leading to increased drag and design challenges in matching the spinner to the nacelle, especially in variable pitch propellers.
Innovation Solution
A propeller design with composite blades mounted in at least two parallel planes, using a cone-shaped spinner and pitch change bearings to reduce the propeller hub and spinner diameter, while maintaining aerodynamic performance and allowing for a streamlined interface with the nacelle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If composite materials are used to form propeller blades, then weight is reduced, but the non-aerofoil portion of the blade must be greater in length to accommodate gradual fiber transitions
Solution Approach 1:
The patent transitions from a single-plane blade arrangement to a multi-plane configuration where blades are distributed across at least two parallel planes perpendicular to the rotation axis. This dimensional change allows the blade roots to be positioned closer to the hub center, reducing the required length of non-aerofoil portions while maintaining structural integrity through the multi-plane distribution of composite fibers.
Solution Approach 2:
The propeller blade structure is segmented into multiple planes, with blades arranged in at least two parallel planes. This segmentation allows each blade's fiber transitions to be optimized independently within its plane, reducing the overall length requirement for gradual fiber transitions while maintaining the weight advantages of composite materials.
2Weight of moving object
If composite blades are used in variable pitch propellers, then weight is reduced, but the propeller diameter and spinner size must be increased to accommodate the longer transition sections
Solution Approach 1:
By distributing blades across multiple planes perpendicular to the rotation axis, the patent reduces the radial distance required for fiber transitions. This multi-plane arrangement allows the blade roots to be positioned closer to the hub, thereby reducing the overall propeller diameter and spinner size requirements while maintaining the structural benefits of composite materials.
Solution Approach 2:
The patent combines the multi-plane blade arrangement with variable pitch capability, allowing the propeller to dynamically adjust blade angles while maintaining a compact diameter. The pitch change mechanism enables performance optimization across different operating conditions without requiring increased propeller size.
3Strength
If composite blades with gradual fiber transitions are used, then structural integrity is maintained, but the spinner diameter must be increased resulting in increased drag
Solution Approach 1:
The multi-plane blade arrangement repositions blade roots closer to the hub center by utilizing the third dimension (axial distribution across planes). This reduces the spinner diameter requirement, thereby reducing aerodynamic drag while maintaining sufficient space within each blade for gradual fiber transitions to preserve structural integrity.
4Weight of moving object
If composite blades are used, then weight is reduced, but design difficulties arise in matching the spinner to the nacelle
Solution Approach 1:
By distributing blades across multiple planes, the patent reduces the spinner diameter to better match typical nacelle dimensions. This multi-plane configuration simplifies the integration and aerodynamic matching between spinner and nacelle, reducing design complexity while maintaining the weight advantages of composite blades.
Data Source
AI summary
One aspect of the present invention provides a propeller for an aircraft. The propeller comprises a propeller hub, a spinner for streamlining the propeller and a plurality of composite propeller blades mounted to the propeller hub. The propeller blades are arranged to rotate together in the same rotational direction in at least two parallel planes substantially perpendicular to an axis of rotation of the propeller. The propeller has a reduced sized spinner with an improved aerodynamic profile that can be better matched to an engine nacelle and also has reduced drag.