Aircraft Stall Detection Using Acceleration-Based Gain Factor
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Solution Overview
Problem
Current aircraft stall detection systems are inadequate for early anticipation during low-altitude flight phases, particularly during landing and takeoff, and are prone to errors due to reliance on incidence probes, leading to potential CFIT accidents.
Innovation Solution
A method and device that determine a limit angle of incidence for stalling based on aircraft configuration and normal acceleration, using a gain factor to alert pilots of impending stall risks, allowing for early intervention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional stall detection systems using incidence probes are used, then stall detection is provided, but false alerts occur due to erroneous probe data in turbulent conditions and early anticipation capability is insufficient
Solution Approach 1:
The patent transforms the stall detection parameter from direct angle of incidence measurement (prone to turbulence errors) to a derived parameter based on normal acceleration and aircraft configuration. By changing the detection parameter from probe-based angle measurement to acceleration-based calculation, the system achieves more reliable stall detection that is immune to probe turbulence errors
Solution Approach 2:
The patent introduces normal acceleration as an intermediary parameter between the physical aircraft state and the stall detection decision. Instead of directly measuring angle of incidence with vulnerable probes, the system uses acceleration data (which is more reliable in turbulence) combined with configuration information to infer stall risk, thereby mediating the measurement process to avoid probe-related false alerts
2Ease of operation
If a fixed limit angle of incidence is used for stall detection, then simple detection logic is provided, but adaptation to different aircraft aerodynamic characteristics and flight conditions is insufficient
Solution Approach 1:
The patent makes the stall detection threshold dynamic by introducing a gain factor that varies with normal acceleration and aircraft configuration. Instead of a static limit angle, the system dynamically adjusts the effective threshold based on current flight conditions (acceleration) and configuration (flaps, slats), enabling adaptation to different aerodynamic states while maintaining relatively simple detection logic through standardized calculation procedures
Solution Approach 2:
The system changes the detection parameter from a fixed angle threshold to a dynamically calculated threshold that incorporates acceleration-based gain factors. This parameter transformation allows the same basic detection logic to adapt to different aircraft types, configurations, and flight conditions by modifying the threshold value rather than the detection algorithm itself
3Measurement precision
If incidence probes are heavily relied upon for stall detection, then direct angle measurement is provided, but system vulnerability to probe errors and turbulence increases
Solution Approach 1:
The patent extracts the stall detection function from dependence on incidence probes by using alternative measurement data (normal acceleration from accelerometers) combined with configuration information. This extraction removes the system's vulnerability to probe turbulence errors while maintaining the ability to detect stall conditions through a different measurement pathway that is not susceptible to the same errors
Data Source
AI summary
A method and a device for protecting an aircraft in the flight phase, said aircraft exhibiting several configurations of slats and flaps, comprises the following steps: determining, for at least one configuration of slats and flaps, of a limit angle of incidence beyond which the aircraft runs a risk of stalling, determining a gain factor as a function of the normal acceleration of the aircraft, comparing the current angle of incidence of the aircraft with the limit angle of incidence weighted by the gain factor, and, emission of an alert indicating that the aircraft runs a risk of stalling, if the current angle of incidence of the aircraft is greater than the limit angle of incidence weighted by the gain factor.