Variable Pitch Propeller Protection Using Virtual Pitch Calculation
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Solution Overview
Problem
Existing pitch protection systems for variable pitch propeller systems are complex, heavy, costly, and require frequent maintenance due to the use of multiple sensors and hydro-mechanical systems, posing challenges in ensuring fail-safe behavior during primary control system failures.
Innovation Solution
A method and system that utilize virtual pitch calculations based on aircraft flight information to determine virtual propeller pitch or blade angle, reducing the need for physical sensors and simplifying the propeller system, while implementing a pitch protection process to override the primary control system in case of overspeed or low pitch conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple sensors and hydro-mechanical systems are used in pitch protection systems, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent creates a virtual copy of the physical pitch measurement system by calculating virtual propeller pitch from aircraft flight information (airspeed, power setting, propeller RPM) rather than using physical sensors. This virtual model replicates the pitch information needed for protection without requiring physical sensing components.
Solution Approach 2:
The patent replaces hydro-mechanical pitch sensing and protection systems with an electronic/computational system that calculates virtual pitch from flight parameters. This substitution eliminates complex hydro-mechanical components while maintaining the protection function through software-based pitch determination.
2Measurement precision
If multiple sensors are used for pitch protection, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent makes existing aircraft flight information sensors (airspeed indicator, power setting indicators, RPM sensors) serve multiple functions by using them to calculate virtual propeller pitch. These sensors already exist for other flight parameters, so they are repurposed to provide pitch measurement without adding dedicated pitch sensors.
Solution Approach 2:
Instead of directly measuring pitch with physical sensors, the system creates a computational copy of pitch information by combining measurements of airspeed, power setting, and RPM through mathematical relationships that reproduce the pitch state.
3Reliability
If hydro-mechanical systems are used for pitch protection, then reliability is improved, but ease of manufacture worsens
Solution Approach 1:
The patent replaces complex hydro-mechanical protection systems with electronic control systems that calculate virtual pitch and provide protection through software logic. This substitution simplifies manufacturing by eliminating precision hydro-mechanical components that are difficult to manufacture and assemble.
Solution Approach 2:
The system uses computational models to replicate pitch protection functionality without physical hydro-mechanical copies, making the system easier to manufacture through software deployment rather than complex mechanical assembly.
Data Source
AI summary
A method of operating a variable pitch propeller system for an aircraft. The method includes: receiving aircraft flight information; performing a virtual pitch calculation to determine a virtual propeller pitch or virtual blade angle from the aircraft flight information; and performing a pitch protection process in response to low virtual propeller pitch or virtual blade angle being determined.