Aircraft Yaw Trim Control for P-Factor and Asymmetric Thrust
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Solution Overview
Problem
Existing automated systems for controlling and trimming yaw in aircraft often rely on complex maps based on flight conditions and engine parameters, which may not account for all scenarios, especially in multi-engine propeller aircraft, leading to incorrect yaw commands due to differences in thrust and power/torque effects.
Innovation Solution
An automatic yaw enhancement method that provides a pilot command and avionic data for airspeed, angle of attack, and thrust to a flight controller, determining P-factor compensation and adjusting the rudder position to nullify persistent biases, using a feedback loop to minimize differences between desired and actual yaw motion, and incorporating a trim device to alleviate rudder force inputs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If complex maps based on flight conditions and engine parameters are used for yaw control, then the system can provide automated yaw commands, but the system may not account for all scenarios leading to incorrect yaw commands
Solution Approach 1:
The system continuously monitors actual aircraft yaw motion and compares it to desired yaw motion, using feedback to detect when corrective rudder input is needed. This closed-loop approach improves reliability by adapting to actual flight conditions rather than relying solely on pre-programmed maps that may not cover all scenarios.
Solution Approach 2:
The system automatically detects yaw deviations and applies corrective rudder input without pilot intervention, making the system self-correcting. This enhances both automation extent and reliability by allowing the system to handle unexpected scenarios autonomously based on real-time sensor data.
2Measurement precision
If P-factor compensation is determined based on multiple parameters (airspeed, angle of attack, thrust), then the compensation accuracy is improved, but the computational complexity increases
Solution Approach 1:
The flight controller performs multiple functions including determining P-factor compensation, monitoring yaw motion, and controlling rudder input using a single integrated system. This multi-functionality approach maintains measurement precision while managing complexity by consolidating operations rather than adding separate systems for each function.
Solution Approach 2:
The system dynamically adjusts P-factor compensation based on changing flight parameters (airspeed, angle of attack, thrust) rather than using fixed compensation values. This allows high accuracy across varying flight conditions while the computational complexity is managed through efficient parameter-based calculations rather than complex mechanical systems.
3Measurement precision
If a feedback loop is used to minimize differences between desired and actual yaw motion, then the yaw control precision is improved, but the response time may be delayed
Solution Approach 1:
The feedback loop continuously monitors yaw motion and makes incremental adjustments rather than waiting for large deviations. This continuous correction maintains high precision while minimizing response time by addressing yaw errors as they develop rather than after they become significant.
Solution Approach 2:
The system determines P-factor compensation in advance based on current flight parameters and applies it proactively before yaw deviations occur. This preliminary action reduces the burden on the feedback loop and allows faster response times while maintaining precision.
4Ease of operation
If trim device is used to alleviate rudder force inputs, then the pilot workload is reduced, but the device complexity increases
Solution Approach 1:
The trim device is integrated with the existing rudder control system and flight controller, combining multiple functions (yaw control, P-factor compensation, and trim) into a unified system. This merging approach reduces pilot workload through automated trim while managing complexity by consolidating rather than adding separate independent systems.
Solution Approach 2:
The trim device automatically adjusts rudder position based on detected yaw deviations and calculated P-factor compensation without requiring pilot intervention. This self-service capability significantly reduces pilot workload while the complexity is managed through software control rather than complex mechanical systems.
Data Source
AI summary
An automatic yaw enhancement method for an aircraft having at least one propeller includes providing to a flight controller a pilot command from a pilot interface and avionic data for an airspeed, an angle of attack, and a thrust. A P-factor compensation is determined based on one or more of the airspeed, the angle of attack, and the thrust. A command to a trim device is determined based on a P-factor compensation. When a rudder bias persists, the command to the trim device is repeatedly updated until a rudder force input is nullified. The methods provide automatic pilot assistance for controlling yaw during asymmetric flight conditions and automatic turn coordination while allowing intentional side-slip for facilitating crosswind landings.