Fin Deployment Mechanism Using Pin Delay for Launcher Ejection
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Solution Overview
Problem
Air vehicles launched from launchers often face issues with fin deployment, where pressurized gases can push fins outward, causing damage and affecting the vehicle's trajectory, and centrifugal forces from rifled launchers can also urge fins outward prematurely, leading to undesirable contact with the launcher walls.
Innovation Solution
A release mechanism with a longitudinally oriented pin in a cavity of the fuselage is used, which is activated by pressurized gases to delay fin deployment until the air vehicle exits the launcher, preventing early contact with the launcher walls by controlling the timing of fin release.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fins are stowed during launch to fit in the launcher, then the air vehicle can be launched, but pressurized gases may push fins outward causing damage and affecting trajectory
Solution Approach 1:
The release mechanism is pre-positioned within the fuselage cavity, and the pin is pre-configured with a specific length to determine the delay period. When the air vehicle enters the low-pressure region, the release mechanism is automatically actuated, and the pin's predetermined length ensures fins are released at the optimal moment after exiting the launcher, preventing premature deployment while maintaining reliability.
Solution Approach 2:
The pin acts as an intermediary element between the release mechanism and the fins. It provides a mechanical delay function by its specific length, allowing the release mechanism to be actuated by pressure differential while the pin maintains the restraint for an additional controlled period, thereby preventing harmful fin deployment during high-pressure phases.
2Stability of the object's composition
If the launcher is rifled to spin the air vehicle for stabilization, then the vehicle gains stability in flight, but centrifugal forces may urge fins outward prematurely
Solution Approach 1:
The release mechanism and pin are pre-configured within the fuselage before launch. The pin's length is specifically selected to provide the required delay period. When the air vehicle is subjected to centrifugal forces during rifled launch, the pre-positioned release mechanism remains inactive until the pin's delay period expires, ensuring fins are released only after the vehicle has exited the launcher and centrifugal forces are minimized.
3Reliability
If the pin length is increased to delay fin release longer, then fins are more likely to be released after exiting the launcher, but the release mechanism becomes more complex
Solution Approach 1:
The delay function is extracted from the complex release mechanism and embodied solely in the pin's length. By making the pin length the sole parameter that provides the delay, the mechanism avoids the need for additional timing components, springs, or control systems, thereby maintaining simplicity while achieving reliable timing control.
Solution Approach 2:
The release mechanism's timing characteristic is controlled by changing the parameter of pin length rather than adding complex control systems. By selecting an appropriate length for the pin, the delay period is adjusted to ensure fins are released after the air vehicle exits the launcher, achieving reliable timing with minimal structural complexity.
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 solution effectively prevents fin deployment within the launcher, ensuring safe ejection and stable trajectory by controlling the roll rate, internal pressurization, and fin moments of inertia, enhancing the performance and reliability of air vehicle launches.
Implementation Method 1
Pressurized gases produced for propulsion during launch may get underneath the fins during the launch process
Implementation Method 2
The release mechanism is ejected from a cavity in the fuselage when the vehicle reaches a low-pressure region of the launcher where a muzzle brake is located
Implementation Method 3
The release mechanism includes a pin with a length selected so that it releases the fins after a delay, preventing the fins from beginning deployment while still in the launcher
Implementation Method 4
a valve that selectively lets pressurized gasses into the cavity through the valve
Data Source
AI summary
An air vehicle that is launched from inside a launcher, includes a release mechanism for releasing fins of the vehicle from a stowed condition to a deployed condition. The release mechanism includes a pin that is located within a cavity in the fuselage of the air vehicle. Pressurized gasses initially fill the cavity in the fuselage. The launcher includes a reduced-pressure portion such as from a muzzle brake. When the air vehicle passes into the reduced-pressure portion of the launcher, the gas pressure behind the air vehicle is reduced. This causes the pressurized gas within the cavity to drive the release mechanism backwards out of the cavity. The length of the pin may be used to control the timing of the fin deployment, the delay between the initial movement of the release mechanism out of the cavity, and when the fins are released.