Active Prop Rotor Stability System for Tilt Rotor Aircraft

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Solution Overview

Problem

Tilt rotor aircraft face challenges with prop rotor aeroelastic instability and rotor flap-lag instability, particularly during high-speed airplane mode flight, due to adverse forces from rotor flapping and destabilizing shear forces, which can lead to wing failure and reduced stability.

Innovation Solution

A control system with sensors on the wing to detect rotational and bending movements, adjusting rotor blades to counteract adverse forces, incorporating a subsystem that senses disturbances and relays signals to actuators to adjust pitch and control movements, thereby reducing or eliminating destabilizing forces on the wing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If traditional control systems with mechanical swashplate arrangements are used, then the aircraft can achieve helicopter mode flight capability, but the system becomes complex and susceptible to aeroelastic instability during high-speed airplane mode flight

Engineering Contradiction:
Improveflight mode capabilityVSAvoidcontrol system complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent replaces the traditional mechanical swashplate control system with an electronic control system that uses sensors, actuators, and a control computer to manage rotor blade pitch angles. This substitution eliminates the mechanical complexity while maintaining the ability to control flight modes, thereby reducing aeroelastic instability during high-speed flight.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent implements feedback control by using sensors to detect rotor blade position and flight conditions, then using this information to automatically adjust pitch angles through actuators. This closed-loop control system maintains stability during mode transitions and high-speed operation without requiring complex mechanical linkages.

Inventive Principle:
Principle #23Feedback

2Productivity

If rotor blade count is increased to improve lift and control, then flight performance improves, but aeroelastic instability and flapping forces increase

Engineering Contradiction:
Improveflight performanceVSAvoidaeroelastic stability
Core Design Contradiction:
ProductivityVSStability of the object's composition

Solution Approach 1:

The patent employs dynamic pitch control where the control system continuously adjusts rotor blade pitch angles in real-time based on detected flight conditions and rotor position. This dynamic adjustment allows the system to maintain stability even with higher rotor blade counts by actively compensating for aeroelastic effects during operation.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The feedback control system uses sensors to monitor rotor blade position and flight conditions, then automatically adjusts pitch angles to counteract aeroelastic instability. This enables the aircraft to operate with increased rotor blade counts while maintaining stability through active compensation rather than passive mechanical design.

Inventive Principle:
Principle #23Feedback

3Stability of the object's composition

If delta-3 position is adjusted to reduce flapping, then rotor stability improves, but control precision and response accuracy deteriorate

Engineering Contradiction:
Improve rotor stabilityVSAvoidcontrol precision
Core Design Contradiction:
Stability of the object's compositionVSManufacturing precision

Solution Approach 1:

The patent uses dynamic pitch control to adjust rotor blade angles in real-time based on actual flight conditions rather than relying on fixed delta-3 position settings. This allows the system to optimize stability during each operational phase while maintaining precise control response through electronic actuation that can compensate for aerodynamic effects.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system dynamically changes pitch angle parameters based on detected flight conditions, rotor position, and aeroelastic state. This parameter adjustment allows the control system to achieve both stability and precision by adapting pitch angles to current operational requirements rather than relying on fixed mechanical positioning.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP2589534B1Active prop rotor stability system
Publication Date: 2014.07.02 BELL HELICOPTER TEXTRON INC
  • EP2589534B1 patent drawingFigure 1~3
  • EP2589534B1 patent drawingFigure 4~5
  • EP2589534B1 patent drawingFigure 6~7D

AI summary

A system and method for adjusting a rotor blade upon detection of a harmful force exerted on an aircraft wing (111) includes a sensor (805) attached to the wing (111) and a subsystem (801) operably associated with the sensor (805). The method includes sensing (1303) the force exerted on the wing (111) with the sensor (805) and determining (1305) whether the sensed force is potentially harmful to the structural integrity of the wing (111). The method further includes counteracting (1307) the harmful force by adjusting the rotor blade movement.