Tilt Rotor Hub Shear Feedback for Whirl Flutter Control
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Solution Overview
Problem
Tiltrotor aircraft experience aeroelastic instabilities at high speeds and altitudes, leading to potential damage and severe vibrations, which existing control methods struggle to effectively manage.
Innovation Solution
A control system that utilizes accelerometers, strain gauges, and sensors to detect destabilizing hub shears and whirl flutter, adjusting rotor blade pitch and engine power to stabilize the aircraft, incorporating a tiered response system to automatically mitigate these instabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If tiltrotor aircraft operate at high speeds and altitudes, then forward flight performance is improved, but aeroelastic instabilities increase causing damage and severe vibrations
Solution Approach 1:
The patent implements a feedback control system using accelerometers mounted on the rotor hub to detect destabilizing hub shears and whirl flutter. The control system processes these signals and adjusts rotor blade pitch through swashplate actuation to actively suppress aeroelastic instabilities, enabling safe operation at high speeds while maintaining reliability
Solution Approach 2:
The patent replaces passive mechanical stability designs with an active control system using sensors (accelerometers, strain gauges) and electronic actuators. This substitution allows dynamic suppression of whirl flutter and hub shears through electronic feedback, achieving stability at speeds where traditional mechanical designs would fail
2Object-affected harmful factors
If existing control methods are used to manage aeroelastic instabilities, then some vibration suppression is achieved, but the methods struggle to effectively manage instabilities at increasing speeds
Solution Approach 1:
The patent employs dynamic control through real-time sensor feedback and active actuation of rotor blade pitch. The control system continuously adapts to changing flight conditions and instability characteristics, adjusting control inputs dynamically to maintain effectiveness across the full speed envelope, unlike static control methods
Solution Approach 2:
The control system uses feedback from accelerometers and strain gauges to detect and suppress whirl flutter and hub shears. This closed-loop approach allows the system to adapt to increasing speeds and changing instability modes, maintaining vibration suppression effectiveness where open-loop or static control methods fail
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
The control system effectively reduces and eliminates whirl flutter, enhancing the stability and safety of tiltrotor aircraft by providing real-time feedback and adaptive adjustments to maintain mechanical stability margins.
Implementation Method 1
at least one accelerometer disposed in a shear plane of the rotor hub and configured to detect destabilizing hub shears
Implementation Method 2
The control system may comprise at least one strain gauge disposed in and/or on the rotor mast
Implementation Method 3
The controller applied small amounts of oscillatory swashplate motion to produce multiharmonic blade pitch variations
Data Source
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AI summary
Systems and methods of operating a tiltrotor aircraft (100) include providing a control system (200) that includes sensors (204, 206) and/or gauges (208) that provide feedback regarding hub shear forces in rotor systems (108) of the aircraft (100) that produce aeroelastic instability known as whirl flutter. Feedback from the sensors (204, 206) and/or gauges (208) is communicated to a flight control subsystem (202) that includes an algorithm that provides a cascading set of responses to control whirl flutter and a failsafe that adjusts operational characteristics of the aircraft (100) in response to the continuation or excitation of the whirl flutter.