Flight Envelope Protection System for Aircraft Stall Prevention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Human error and adverse conditions, such as bad weather, can lead to dangerous situations in aircraft operations, necessitating advanced safety controls to prevent stalls, icing, buffeting, high load on the horizontal stabilizer, low speed, and high pitch attitude.
Innovation Solution
A flight control system that uses feedback control laws to compute an augmentation command based on pilot inceptor position, combining feed-forward, integral, and state feedback commands to stabilize the aircraft, with a logic module dynamically adjusting gains and command shaping functions to limit the aircraft envelope and engage protection functions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If flight control systems are designed to handle complex aerodynamic conditions (stalls, buffeting, high attitudes), then flight safety and envelope protection are improved, but system complexity and computational requirements increase
Solution Approach 1:
The flight control system is divided into separate functional modules: a flight envelope protection system that monitors flight parameters and a flight control system that executes control commands. This segmentation allows independent optimization of safety monitoring and control execution, reducing overall system complexity while maintaining comprehensive protection against stalls, buffeting, and high attitudes.
Solution Approach 2:
The system pre-calculates and stores aerodynamic model data, stall boundaries, and control surface effectiveness characteristics before flight. During flight, the flight envelope protection system compares real-time sensor data against these pre-established limits and triggers protective actions before dangerous conditions develop, improving safety response time without requiring complex real-time computation of all aerodynamic parameters.
2Measurement precision
If aerodynamic models and control surface effectiveness data are continuously updated in real-time, then accuracy of flight envelope prediction is improved, but computational load and processing time increase
Solution Approach 1:
Aerodynamic models, stall boundaries, and control surface effectiveness characteristics are determined and stored before flight through ground-based testing and simulation. During flight, the system retrieves and applies these pre-computed models rather than performing complex aerodynamic calculations in real-time, achieving accurate envelope prediction while minimizing computational load and processing time.
Solution Approach 2:
The system replaces complex real-time aerodynamic computation with lookup tables and simplified comparison logic against pre-established flight envelope boundaries. This substitution of heavy computational mechanics with lighter data retrieval and comparison operations maintains prediction accuracy while dramatically reducing processing time for flight control decisions.
3Reliability
If multiple sensors and redundant systems are implemented for envelope protection, then reliability and fault tolerance are improved, but weight and device complexity increase
Solution Approach 1:
The flight envelope protection system and flight control system are integrated within a unified control architecture that shares sensors, processors, and communication buses. This merging eliminates redundant components while maintaining fault tolerance through cross-monitoring and shared redundancy, reducing overall system weight compared to completely separate protective and control systems.
Solution Approach 2:
The flight control system is designed to perform multiple functions: normal flight control, flight envelope protection, stall prevention, and buffeting suppression. By making the control system universal and multi-functional rather than dedicated to single tasks, the patent reduces the need for separate protective systems, thereby reducing weight while maintaining comprehensive safety coverage.
Data Source
AI summary
A flight control system moves elevators according to a pilot command summed with an automatic command. The flight control system monitors a set of flight parameters to determine if the flight vehicle is operating inside a permitted envelope. The flight controls system incorporates automatic protections thru the automatic elevator command if the flight vehicle is close to its envelope limits. The exemplary illustrative non-limiting implementation herein provides automatic protections in order to protect the flight vehicle from low speeds, high attitude, stalls and buffetings.