Rotor Blade Actuation System with Pushrod and 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-induced backlash, and single-point failure, which compromise 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 thermal management, and flexible drive tapes, along with a flap mechanism that reacts centrifugal forces and allows for redundant actuation to prevent mechanical jamming and maintain performance.
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 pushrod is used that connects the actuator directly to the trailing edge flap without requiring a bell crank, thereby eliminating the source of increased drag while maintaining flap actuation capability
Solution Approach 2:
The conventional mechanical bell crank system is replaced with a direct pushrod actuation system. The pushrod transmits force directly from the actuator to the flap, eliminating the need for complex mechanical linkages that penetrate the blade profile and create drag
2Strength
If rod end elements are used in the actuation system, then mechanical connection is achieved, but high coulomb friction and uneven stick-slip motion occur
Solution Approach 1:
Rod end elements with spherical joints are replaced by a pushrod with a simple pin connection to the trailing edge flap. This simpler connection reduces coulomb friction and eliminates the stick-slip motion characteristic of rod end elements, while maintaining adequate mechanical connection strength
Solution Approach 2:
The connection geometry is changed from a spherical rod end joint to a pin connection. This parameter change in the joint type reduces friction characteristics and eliminates the uneven motion caused by play in rod end elements
3Ease of operation
If conventional mechanical actuation is used over time, then actuation is achieved, but wear produces backlash from mechanical slop and reduces controllability
Solution Approach 1:
The actuation system uses a pushrod with a pin connection instead of complex mechanical linkages. This simplified mechanism has fewer wear surfaces and less accumulated backlash over time, maintaining controllability. The system also allows for easy replacement of worn components
Solution Approach 2:
The actuation system is designed to accommodate wear through the flexibility of the pushrod connection and the ability to adjust or replace the pushrod. The system maintains acceptable performance levels even as components wear, through the dynamic nature of the connection
4Measurement precision
If a ball screw on an electromechanical actuator is used, then precise actuation is achieved, but it creates a single point of failure susceptible to mechanical jam
Solution Approach 1:
The actuation system segments the actuation function across multiple independent components: the actuator, the pushrod, and the flap connection. This segmentation eliminates the single point of failure inherent in a ball screw system, as failure of one component does not necessarily cause complete system failure
Solution Approach 2:
The ball screw mechanism is replaced with a direct pushrod actuation system. This eliminates the complex threaded mechanism that is prone to jamming, while maintaining adequate actuation precision through the direct mechanical linkage
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, and improved controllability with high bandwidth and displacement capabilities, resistance to fatigue, and redundancy to prevent single-point failures, while maintaining a non-intrusive aerodynamic profile.
Implementation Method 1
heat pipes for thermal management
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.