Electromechanical Coupler for Weather Vaning Air Vehicle Control Surfaces
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Solution Overview
Problem
Current electromechanical steering systems for laser-guided bombs are expensive, unreliable, and lack the ability to allow control surfaces to weather vane during captive carriage and free flight prior to laser detection, leading to increased drag and limited ground testing capabilities.
Innovation Solution
An air vehicle control system featuring a fuselage with movable control surfaces and an electromagnetic actuator, where the control surfaces can be mechanically decoupled to weather vane and then actively positioned using a coupler mechanism involving a sleeve and nut system, allowing independent movement before being coupled to the actuator for controlled positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pyrotechnically actuated fin locks are used, then the control surfaces can be locked in position, but the system becomes expensive and reduces reliability
Solution Approach 1:
The patent replaces the pyrotechnic actuation system with an electromechanical actuator system. The electromechanical actuator uses an electric motor to drive a screw mechanism that moves a coupler between engaged and disengaged positions, eliminating the need for pyrotechnic charges and associated safety systems.
Solution Approach 2:
The patent implements a dynamic coupling mechanism where the coupler can transition between engaged and disengaged states during flight. The spring-loaded coupler allows automatic engagement/disengagement based on aerodynamic forces and actuator position, providing adaptive control surface coupling rather than a static locked state.
2Ease of operation
If control surfaces are locked during captive carriage, then positioning is maintained, but drag increases and weather vaning is prevented
Solution Approach 1:
The coupler mechanism allows the control surfaces to dynamically transition between locked and free states. During captive carriage, the coupler remains disengaged allowing weather vaning and reduced drag. Upon launch, the electromechanical actuator engages the coupler to lock the control surfaces in the desired position.
Solution Approach 2:
The electromechanical actuator is positioned and ready to engage the coupler before launch. The system is pre-configured to automatically engage the control surfaces at the appropriate moment, ensuring they are locked in the correct position immediately after launch without requiring manual intervention.
3Reliability
If pyrotechnic fin locks are used, then one-shot locking is achieved, but ground testing over full range of travel becomes impossible
Solution Approach 1:
The electromechanical actuator with spring-loaded coupler allows the control surfaces to be dynamically engaged and disengaged multiple times. During ground testing, the actuator can move the coupler through the full range of travel while engaged, then disengage for repositioning, enabling repeated testing cycles that are impossible with one-shot pyrotechnic locks.
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
This solution reduces captive flight drag and enhances reliability by enabling control surfaces to weather vane passively, while allowing for active positioning, thus improving the overall performance and cost-effectiveness of the air vehicle control system.
Implementation Method 1
an actuator having a movable actuator shaft... allowing for active positioning using the electromagnetic actuator
Implementation Method 2
allowing the control surfaces of the air vehicle to weather vane by being passively positioned by air flow
Data Source
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AI summary
An air vehicle, such as a munition like a guided bomb or missile, has a control system that allows control surfaces to be mechanically uncoupled from one or more actuators to allow the control surfaces to freely move (rotate) relative to a fuselage of the vehicle, for example allowing the control surfaces to “weather vane” by assuming an orientation corresponding to the direction of airflow past the air vehicle (direction of airflow relative to the air vehicle). When active positioning of the control surfaces is desired, the control surfaces may be mechanically coupled to one or more actuators that are used to position the control surfaces. The selective coupling of the actuator(s) and the control surfaces may be accomplished by selectively coupling together a sleeve that is mechanically coupled to the control surfaces, and a nut that moves along a shaft of an actuator, for example using a resilient device.