Tiltrotor Rotor Control System for Aeroelastic Instability
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Solution Overview
Problem
Tiltrotor aircraft are limited by forward airspeed-induced proprotor aeroelastic instability, which restricts their maximum airspeed in forward flight.
Innovation Solution
A local control system for a rotor assembly, comprising an actuator, sensor, and local control computer, communicatively coupled with a central control computer, is used to control motion and provide position feedback, enabling the tiltrotor aircraft to transition between rotary and non-rotary flight modes, thereby overcoming aeroelastic instability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If proprotors are used to provide vertical thrust for takeoff and hovering, then vertical takeoff and landing capability is achieved, but forward airspeed is limited due to aeroelastic instability
Solution Approach 1:
The proprotor system dynamically changes its plane of rotation from horizontal to vertical based on flight phase requirements. During takeoff and hovering, the proprotors rotate horizontally to provide vertical thrust. During forward flight, the proprotors tilt to a vertical plane to provide forward thrust, eliminating aeroelastic instability and enabling high forward airspeed capability.
2Force
If proprotors operate in forward flight mode, then forward thrust is provided, but aeroelastic instability limits maximum airspeed
Solution Approach 1:
The system dynamically reconfigures the proprotor orientation based on flight conditions. In forward flight mode, the proprotors are tilted to a vertical plane where they function more like conventional propellers, providing forward thrust without the aeroelastic instability that plagues horizontal rotation at high forward speeds.
Solution Approach 2:
The plane of rotation of the proprotors is changed as a key parameter to match flight conditions. By transitioning from horizontal to vertical rotation, the aerodynamic loading and structural response characteristics are fundamentally altered, eliminating the aeroelastic instability regime that limits maximum airspeed.
3Device complexity
If a centralized control system is used for the rotor assembly, then system complexity is reduced, but control response time increases
Solution Approach 1:
The control system is segmented into a central control computer and distributed control computers located at the rotor assembly. The distributed control computers process control signals locally, reducing transmission delays and improving response time for time-critical rotor control operations while maintaining overall system coordination through the central controller.
Solution Approach 2:
The control architecture transitions from a purely centralized single-dimension structure to a distributed multi-dimensional hierarchy. This adds a spatial dimension to control signal processing, with control computers distributed throughout the rotor assembly, enabling parallel processing and reduced signal transmission paths while maintaining systematic coordination.
Data Source
AI summary
In one embodiment, a local control system for a rotor assembly of an apparatus includes a first actuator disposed in the rotor assembly and configured to control motion of a first controllable element in the rotor assembly. The rotor assembly is mounted to the apparatus and is rotated responsive to torque and rotational energy provided thereto. The local control system also includes a first sensor disposed in the rotor assembly and configured to provide position feedback in relation to the first controllable element. The local control system also includes a first local control computer disposed in the rotor assembly and communicably coupled to a first central control computer disposed in the apparatus external to the rotor assembly, where the first local control computer is configured to transmit a control signal to the first actuator and receive a feedback signal from the first sensor.