Multirotor Aircraft Active Flutter Reduction via Propeller Thrust Control
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Solution Overview
Problem
Electrically powered multirotor aircrafts adapted for vertical take-off and landing face challenges in achieving lightweight designs with improved flutter stability, as traditional methods for flutter suppression often result in significant weight penalties and complex systems.
Innovation Solution
The implementation of an electrically powered multirotor aircraft with a fuselage, aircraft lifting surfaces, propellers, a sensor unit, a flutter reduction unit, and a settings adjustment device, which actively controls propeller thrust to mitigate adverse wing/tailplane motions by introducing stabilizing unsteady loads to the aerodynamic surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If structural stiffening is used to improve flutter stability, then flutter stability is improved, but weight increases significantly
Solution Approach 1:
The patent applies active control elements that dynamically adjust rotor blade settings (pitch, roll, or yaw) in response to detected flutter conditions. This dynamic adjustment allows the system to achieve flutter stability through active control rather than passive structural stiffening, thereby avoiding significant weight increases while maintaining reliability.
Solution Approach 2:
The system incorporates sensors that detect flutter conditions and feed this information back to control mechanisms. The control mechanisms then adjust rotor blade settings in real-time to counteract flutter, creating a closed-loop feedback system that achieves stability without requiring heavy structural modifications.
2Reliability
If active control elements are added to rotor blades, then flutter stability is improved, but device complexity increases
Solution Approach 1:
The patent utilizes existing rotor blade control mechanisms (pitch, roll, yaw controls) for dual purposes: normal flight control and active flutter suppression. By making the existing control system multi-functional, the patent avoids adding separate complex dedicated flutter control systems while still achieving improved flutter stability.
Solution Approach 2:
The system merges flutter detection and suppression functions with the existing rotor blade control system. Rather than implementing separate dedicated flutter control mechanisms, the patent combines these functions into the existing control architecture, thereby reducing overall device complexity while achieving the desired stability improvement.
3Reliability
If mass is added close to rotor blade leading edge for chord wise blade balancing, then flutter stability is improved, but weight increases
Solution Approach 1:
Instead of physically adding mass to rotor blades, the patent achieves chord-wise balancing by adjusting rotor blade settings (pitch, roll, or yaw angles). This parameter-based approach allows the system to achieve the same stabilizing effect as mass addition without the associated weight penalty, by changing the operational parameters of existing blade components.
Data Source
AI summary
An electrically powered multirotor aircraft that is adapted for vertical take-off and landing, comprising a fuselage, at least one aircraft lifting surface that is connected to the fuselage, at least one propeller that is connected to the at least one aircraft lifting surface, a sensor unit, a flutter reduction unit, and a settings adjustment device. The sensor unit is configured to generate sensor data that is indicative of flutter of the at least one aircraft lifting surface. The flutter reduction unit is configured to receive the sensor data to generate flutter reduction signals. The settings adjustment device is configured to receive the flutter reduction signals and to adjust current settings of the at least one propeller based on the flutter reduction signals to reduce flutter of the at least one aircraft lifting surface.