Rotor Blade Actuation System Using Flexible Drive Tapes
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Solution Overview
Problem
Conventional actuation systems for rotor blades face issues such as increased drag, high friction, uneven motion, wear, and potential single-point failures, which affect controllability and aerodynamic performance.
Innovation Solution
A lightweight, compact, and wear-resistant actuation system using linear actuators with inboard and outboard frames, heat pipes for efficient heat dissipation, and flexible drive tapes, along with a flap mechanism that reacts centrifugal forces and allows for opposite chordwise translations to cancel inertial forces, preventing backlash and mechanical jamming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a bell crank is used to actuate the trailing edge flap, then the flap can be controlled, but the bell crank penetrates the rotor blade profile and increases drag
Solution Approach 1:
The bell crank mechanism is completely removed from the rotor blade design. Instead, a push-pull rod is used that connects the actuator to the trailing edge flap without requiring a bell crank, thereby eliminating the penetration into the blade profile and the associated drag increase while maintaining flap actuation capability
Solution Approach 2:
The conventional mechanical bell crank system is replaced with a direct push-pull rod actuation system. This substitution eliminates the need for complex mechanical linkages that penetrate the blade, reducing aerodynamic drag while achieving the same flap control function through a simplified mechanical path
2Device complexity
If conventional rod end elements are used in the actuation system, then the structure can be simple, but high coulomb friction and uneven stick-slip motion occur
Solution Approach 1:
Conventional rod end elements with high friction contacts are replaced with a cable-driven actuation system. The cable mechanism eliminates stick-slip motion by providing continuous, smooth force transmission to the trailing edge flap, while maintaining structural simplicity through the use of flexible cables instead of rigid mechanical joints
Solution Approach 2:
The actuation system uses a cable mechanism that functions similarly to pneumatic or hydraulic systems in providing smooth, continuous motion transmission. The cable allows for flexible, friction-free force application to the flap, eliminating the uneven stick-slip motion characteristic of conventional rod end elements
3Volume of moving object
If mechanical linkages are used for actuation, then the system can be compact, but wear over time produces backlash and reduces controllability
Solution Approach 1:
Mechanical linkages subject to wear and backlash are replaced with a cable-driven actuation system. The cable mechanism eliminates mechanical contact points that wear over time, preventing backlash development and maintaining precise controllability of the trailing edge flap throughout the operational life of the rotor blade
Solution Approach 2:
The actuation system uses flexible cables instead of rigid mechanical linkages. These cables are resistant to wear and do not develop backlash, providing reliable, maintenance-free actuation while maintaining a compact configuration within the rotor blade structure
4Measurement precision
If a ball screw on an electromechanical actuator is used, then precise actuation can be achieved, but it represents a single point of failure susceptible to mechanical jam
Solution Approach 1:
The actuation system is segmented into multiple independent cable-driven actuators rather than relying on a single ball screw mechanism. This segmentation provides redundancy, as the failure of one actuator does not compromise the entire flap control system, while each individual actuator can still provide precise actuation through its cable mechanism
Solution Approach 2:
The ball screw mechanism, which is prone to mechanical jamming, is replaced with a cable-driven actuation system. The cable mechanism has no mechanical threads or gears that can jam, eliminating the single point of failure while maintaining actuation precision through direct cable tension control
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 system provides enhanced aerodynamic performance, reduced vibration, improved controllability, and increased fatigue life by minimizing drag and friction while maintaining redundancy and avoiding mechanical failures.
Implementation Method 1
heat pipes for efficient heat dissipation
Implementation Method 2
a flap mechanism that reacts centrifugal forces
Data Source
AI summary
In accordance with one embodiment of the present application, an actuation system is configured for actuation of an airfoil member with a flap mechanism. The actuation system can include an upper drive tape and a lower drive tape, each partially wrapped around a first bearing and second bearing. An inboard frame can be actuated by at least one linear actuator. Similarly, an outboard frame can be actuated by at least one linear actuator. The inboard frame is coupled to the upper drive tape, while the outboard frame is coupled to the lower drive tape. An actuation of the inboard frame and outboard frame in a reciprocal manner acts move a flap input lever reciprocally upward and downward. A flap mechanism is configured to convert the movement of the flap input lever into rotational movements of the airfoil member.