Aircraft Control Surface Steering Angle Limiting System
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Solution Overview
Problem
Traditional systems for limiting the steering angle of an aircraft's control surface do not account for abnormal flight conditions, leading to excessive forces on the tail fin during successive control surface deflections, potentially causing structural damage or failure.
Innovation Solution
A process and system that detect yaw configurations and reduce the permissible steering angle by limiting the control surface's authority, using a device to determine the maximum steering angle based on aircraft speed and detecting critical configurations such as successive deflections in opposite directions or non-zero lateral acceleration, implemented through a logical circuit with AND gates, delays, and flip-flops to adjust the strut length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the control surface is allowed to deflect at maximum steering angle during abnormal flight conditions, then the pilot can compensate for engine failure and yaw, but excessive forces on the tail fin may cause structural damage
Solution Approach 1:
The patent applies dynamics by making the steering angle limitation adjustable based on flight conditions. The system dynamically modifies the maximum permissible steering angle depending on whether the aircraft is in normal or abnormal flight conditions, detected through yaw rate sensors and flight condition monitors. This resolves the contradiction by allowing full control authority when needed (abnormal conditions with yaw) while limiting it when safe (normal conditions), thus protecting the tail fin structure while maintaining pilot effectiveness.
2Ease of operation
If the pilot sends successive control surface deflection commands in opposite directions at maximum angle, then the pilot can respond to changing flight conditions, but the forces on the tail fin become significant and may cause structural failure
Solution Approach 1:
The patent implements feedback by continuously monitoring the aircraft's yaw rate and flight conditions through sensors, then using this information to dynamically adjust the maximum permissible steering angle. The system detects when the aircraft is in abnormal conditions (yawing) and temporarily allows maximum deflection for pilot compensation, but automatically limits subsequent maximum angle commands when the aircraft returns to normal conditions. This feedback loop prevents excessive forces while maintaining pilot responsiveness during actual emergencies.
3Reliability
If the traditional limitation system allows maximum steering angle during engine failure, then the pilot can compensate for dissymmetry, but the system does not prevent excessive forces during other abnormal situations
Solution Approach 1:
The patent applies universality by creating a single limitation system that handles multiple types of abnormal flight conditions, not just engine failure. The system uses yaw rate detection and flight condition monitoring to identify various abnormal situations (engine failure, wind shear, turbulence, pilot-induced oscillations) and applies appropriate steering angle limitations for each. This multi-functional approach maintains the ability to compensate for engine failure while also preventing excessive forces during other abnormal conditions, making the system versatile and adaptable.
Data Source
AI summary
The disclosed embodiments concerns a process for limiting the control surface steering angle of an aircraft, including operations to:determine the maximum permissible steering angle in function of the speed of the aircraft,detect a yaw configuration of the aircraft following a first order for control surface deflection at a maximum steering angle and a first direction,apply a limit to the maximum permissible steering angle.The disclosed embodiments also concern a system for implementing the process.