Propeller Blade Trailing Edge Reinforcement for Bird Impact Tolerance
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Solution Overview
Problem
Propeller blades face a trade-off between aerodynamic efficiency and structural integrity, as reducing thickness and radius for better aerodynamics compromises damage tolerance against foreign object damage, such as bird impacts.
Innovation Solution
A propeller blade design featuring a trailing edge insert with yarn stitches through the shell but not the insert, combined with a laminate sheet and a shell structure, enhances structural integrity while maintaining aerodynamic efficiency by allowing a thinner trailing edge without compromising damage tolerance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the thickness and radius of the propeller blade trailing edge are reduced to improve aerodynamic efficiency, then aerodynamic performance is improved, but structural integrity and damage tolerance are compromised
Solution Approach 1:
The patent employs composite materials consisting of a shell made from fiber-reinforced plastic material and stitching elements made from high-strength yarn (such as Kevlar®, Spectra®, or Zylon®). This composite construction allows the trailing edge to achieve both thin aerodynamic profile and high structural strength, resolving the contradiction between aerodynamic efficiency and structural integrity.
Solution Approach 2:
The trailing edge is segmented into distinct functional components: a thin aerodynamic shell and separate stitching reinforcement elements. The shell provides the aerodynamic profile while the stitching elements provide structural reinforcement, allowing each component to be optimized for its specific function without compromising the other.
2Productivity
If the trailing edge thickness is reduced to improve aerodynamic profile, then aerodynamic efficiency is improved, but damage tolerance against foreign object damage is reduced
Solution Approach 1:
The stitching elements are pre-installed within the shell structure before the blade enters service, creating a hidden reinforcement system that provides damage tolerance without affecting the external aerodynamic profile. This prior cushioning allows the thin shell to withstand foreign object impacts that would otherwise cause catastrophic failure.
Solution Approach 2:
The stitching elements act as intermediary reinforcement within the shell structure, absorbing and distributing the energy of foreign object impacts. These hidden stitching elements mediate between the thin aerodynamic shell and the internal blade structure, preventing damage propagation while maintaining the thin external profile.
3Strength
If yarn stitches are extended through the trailing edge insert to maximize structural strength, then structural integrity is improved, but aerodynamic efficiency is compromised due to increased thickness
Solution Approach 1:
The stitching elements are strategically positioned to provide reinforcement only in specific critical areas of the shell, rather than uniformly throughout the entire trailing edge insert. This localized reinforcement maintains structural integrity while minimizing the impact on aerodynamic profile and allowing for a thinner overall trailing edge design.
Data Source
AI summary
A propeller blade comprises a root, a tip distal from the root, a trailing edge extending from the root to the tip, a trailing edge, e.g. foam, insert, a shell forming an outer surface of the propeller blade and a plurality of stitches of yam extending through two parts of the shell adjacent the trailing edge, wherein the yarns do not extend through the trailing edge insert.