Aircraft Control-Surface Flutter Generation Below Critical Speed
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Solution Overview
Problem
Existing methods for suppressing flutter on aircraft are risky and do not effectively evaluate the robustness or effectiveness of flutter suppression systems, as they require bringing the aircraft close to its critical speed, which poses safety risks and lacks real-time adaptability.
Innovation Solution
A method and device using sensors, an avionics computer, and control surfaces to generate a flutter mode on an aircraft without reaching critical speed, involving data processing, control commands, and real-time adjustments to simulate flutter conditions safely.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the aircraft is brought close to its critical speed to test flutter suppression, then the effectiveness of flutter suppression can be evaluated, but safety risks increase significantly
Solution Approach 1:
Instead of bringing the aircraft close to critical speed to generate flutter naturally, the patent inverts the approach by using control surfaces to actively generate flutter at sub-critical speeds. The control law commands control surfaces to move in a way that excites flutter modes, allowing safe evaluation of suppression systems without approaching dangerous speed thresholds.
Solution Approach 2:
The patent applies preliminary anti-action by having control surfaces pre-positioned or pre-moved according to a control law that anticipates and generates flutter conditions. This allows the flutter suppression system to be tested in advance under controlled conditions, preventing the need to later expose the aircraft to uncontrolled flutter at critical speeds.
2Stability of the object's composition
If the aircraft speed is reduced to revert from flutter conditions, then stable flight is restored, but the response time is not instantaneous
Solution Approach 1:
The patent replaces the mechanical approach of speed reduction with an electronic/control system approach. Instead of mechanically changing aircraft speed to restore stability, the system uses avionics computers and control laws to electronically command control surfaces that rapidly generate or suppress flutter, achieving near-instantaneous stability restoration without the time delay associated with speed changes.
Solution Approach 2:
The patent makes the flutter control system dynamic and adaptive by continuously monitoring aircraft state and adjusting control surface commands in real-time. The control law dynamically modifies control surface positions based on current flight conditions, allowing the system to rapidly respond to flutter onset and restore stability much faster than static speed-based methods.
3Reliability
If control surfaces are used to generate flutter mode, then flutter can be simulated without reaching critical speed, but device complexity increases
Solution Approach 1:
The patent applies universality by using existing control surfaces and avionics systems for multiple purposes: normal flight control and flutter generation/suppression testing. The same control surfaces that steer the aircraft are also commanded by the control law to generate flutter modes, eliminating the need for separate dedicated testing equipment and reducing overall system complexity.
Solution Approach 2:
The aircraft's own control system serves the dual purpose of normal operation and flutter testing. The avionics computer and control surfaces, which are already part of the aircraft's standard configuration, are utilized to generate and suppress flutter, allowing the system to be self-sufficient without requiring external or additional complex testing equipment.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables controlled and safe simulation of flutter effects, allowing evaluation of flutter suppression systems and rapid return to stable conditions, enhancing safety and effectiveness in testing flutter suppression methods.
Implementation Method 1
an aircraft is subjected to aerodynamic forces which deform its structure. These deformations coupled with the flow of air over the outer surfaces of the aircraft can generate undesirable vibratory effects, notably on the wings. Indeed, for an aircraft speed greater than a critical speed, aeroelastic instabilities appear leading to an oscillation effect called flutter.
Data Source
AI summary
A device comprising a plurality of sensors arranged on an aircraft and configured to measure input data, an avionics computer configured to determine, based on the input data, at least one control command for at least one control surface of the aircraft by using a control law comprising at least one gain value, the control law being configured to obtain a control command making it possible to generate a flutter mode on at least a part of the aircraft, and a control system configured to control the control surface of the aircraft so as to generate the flutter mode by using the control command determined by the avionics computer.