Takeoff Thrust Asymmetry Compensation for Lower VMCG
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Solution Overview
Problem
Current aircraft control systems face challenges in reducing minimum ground control speeds (VMCG) during takeoff with asymmetric thrust conditions, as existing automatic systems can inadvertently command rudder deflection in the wrong direction or lead to wing stall when linking additional control surfaces to the pedal, compromising safety and effectiveness.
Innovation Solution
The implementation of an automatic takeoff thrust asymmetry compensation system (ATACS) that provides temporary, pulse-shaped commands to rudder, ailerons, and spoilers upon engine failure detection, allowing for rapid corrective action without increasing system failure risks or poor handling qualities, and seamlessly transitioning control back to the pilot.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If automatic rudder deflection is commanded upon engine failure detection, then VMCG is reduced, but the system may inadvertently command rudder deflection in the wrong direction
Solution Approach 1:
The system continuously monitors aircraft yaw rate and lateral acceleration to detect actual engine failure conditions and verify corrective action effectiveness. Sensors provide real-time feedback to the flight control computer, which adjusts rudder commands dynamically based on measured aircraft response, ensuring accurate correction while preventing wrong-direction deflection.
Solution Approach 2:
The system pre-configures rudder deflection commands based on predicted aircraft behavior during engine failure. The flight control computer contains pre-programmed correction profiles that are automatically activated upon failure detection, enabling immediate corrective action before the pilot can react, thus reducing VMCG while maintaining reliability through validated pre-computed commands.
2Speed
If additional control surfaces are linked to the pedal, then VMCG is reduced, but the system may lead to wing stall
Solution Approach 1:
The system dynamically adjusts control surface deflection angles and duration based on real-time aircraft state parameters including angle of attack, airspeed, and flight phase. The flight control computer continuously modifies the command signals to ailerons and spoilers, reducing deflection magnitude as aircraft speed increases, thereby achieving VMCG reduction while preventing wing stall through adaptive control.
Solution Approach 2:
The system applies control surface commands in controlled pulses or sequences rather than continuous maximum deflection. The flight control computer activates correction surfaces for specific time intervals, then reduces or reverses deflection based on aircraft response, preventing sustained high-angle-of-attack conditions that could lead to wing stall while maintaining effective yaw correction.
Data Source
Figure 1
Figure 1A
Figure 2~2A
AI summary
In the event of a failed engine, an automatic takeoff thrust asymmetry compensation system ("ATACS") for an aircraft improves capabilities to reduce VMCG and deal with the potential side-effects simultaneously. The system commands selected control surfaces (which can be e.g., rudder and/or ailerons and/or spoilers or any combinations thereof) for a short period of time, improving the capability to reduce the VMCG without increasing the penalty on system failures or poor handling qualities.