Aircraft Thrust Control for Reduced VMC
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Solution Overview
Problem
Reducing the mass of the vertical stabilizer and rudder in aircraft to improve performance increases the minimal control speed (VMC) when an engine fails, limiting flight capabilities.
Innovation Solution
A method to control aircraft thrust by determining the current weight and calculating a reduced thrust value proportional to it, applying this reduced thrust to operational engines to maintain a consistent gradient and reduce VMC, allowing for balanced flight without excessive rudder usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the dimensions of the vertical stabilizer and rudder are reduced to decrease aircraft mass, then aircraft performance is improved, but the minimal control speed VMC increases
Solution Approach 1:
The invention changes the thrust parameter of the operational engine based on aircraft weight. By reducing thrust to a value proportional to current weight when an engine fails, the yaw moment is reduced, allowing smaller vertical stabilizer and rudder dimensions while maintaining acceptable VMC characteristics across different weight conditions
Solution Approach 2:
The invention implements dynamic thrust adjustment on operational engines based on real-time weight conditions. The thrust is made variable rather than fixed, adapting to different flight phases and weight conditions to optimize both performance and control characteristics
2Speed
If the thrust of operational engines is reduced to lower VMC, then minimal control speed is improved, but flight gradient may become insufficient
Solution Approach 1:
The invention carefully selects the thrust reduction parameter to achieve the desired VMC improvement while maintaining sufficient gradient. The reduced thrust is set proportional to aircraft weight with a proportionality constant that ensures both lower VMC and adequate gradient for safe flight
Solution Approach 2:
The invention applies partial thrust reduction rather than complete thrust cutoff. By reducing thrust to a proportional value rather than eliminating it entirely, the system achieves VMC improvement while retaining sufficient engine power to maintain necessary flight gradient
Data Source
AI summary
A method and device control the thrust of a multi-engine aircraft. At least one engine command is determined by a command determining unit, with the determined command commanding each engine that has not failed to deliver a thrust substantially equal to a reduced thrust value. A command application unit is configured to apply the determined command to each aircraft engine that has not failed. The reduced thrust value is determined, by a weight determining device, according to the current weight of the aircraft and according to a reduced thrust value FOEI, which is calculated by a thrust calculation unit.