Ejectable Aft Fin Housing for Projectile Stabilization
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Solution Overview
Problem
Small form factor aero-bodies face challenges in passive stabilization due to size and cost constraints, with high angles of attack exacerbating the difficulty, as they have a different center of pressure to center of gravity relationship compared to traditional missiles, leading to longer stabilization times.
Innovation Solution
A projectile design featuring an ejectable aft fin housing assembly that alters the center of pressure to improve passive stabilization, combined with a control action system using maneuvering fins and motors for active stabilization, allowing for rapid pitch rate reduction and weight distribution optimization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If traditional passive stabilization methods are used for small form factor aero-bodies, then the structure remains simple and low cost, but the stabilization time is excessively long (approximately 5 seconds)
Solution Approach 1:
The patent applies dynamics by making the fin housing ejectable rather than fixed. The fin housing is initially deployed to provide strong passive stabilization forces during the critical early phase, then is ejected after serving its purpose. This dynamic configuration allows the system to adapt its stabilization characteristics over time, reducing stabilization time from 5 seconds to under 2 seconds without requiring a permanently complex active stabilization system.
Solution Approach 2:
The patent implements preliminary action by deploying the aft fin housing before launch to establish passive stabilization capability. The fins are positioned in advance to create the necessary aerodynamic forces immediately upon launch, addressing the stabilization problem during the most critical initial phase before active control can take over.
2Loss of time
If active stabilization systems are used to reduce stabilization time, then stabilization performance improves, but cost and size constraints of small form factor aero-bodies make these systems not feasible
Solution Approach 1:
The patent segments the stabilization function into two distinct phases: passive stabilization handled by the ejectable fin housing during the initial critical phase, and active stabilization handled by the control action system afterward. This segmentation allows each subsystem to be optimized for its specific phase, avoiding the need for a full active stabilization system throughout, thereby reducing cost and complexity while maintaining performance.
Solution Approach 2:
The ejectable fin housing acts as an intermediary between passive and active stabilization systems. It provides the necessary stabilization during the transition phase when the aero-body is most unstable, bridging the gap until the active control system can take over. This intermediary component enables the use of simpler, lower-cost systems while achieving the stabilization performance previously requiring expensive active systems.
3Ease of operation
If small form factor aero-bodies are launched at high angles of attack, then deployment capability is improved, but passive stabilization becomes more difficult due to different center of pressure to center of gravity relationship
Solution Approach 1:
The patent applies parameter changes by positioning the center of pressure aft of the center of gravity through the fin housing configuration. This specific geometric arrangement creates the necessary aerodynamic moment arm to generate stabilizing forces even at high angles of attack, where traditional stabilization methods fail. The parameter change in center of pressure location directly addresses the stabilization difficulty posed by high-angle deployment.
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 enables rapid passive stabilization within two seconds and subsequent active stabilization, reducing the pitch rate to a stable level, even at high angles of attack, while maintaining a low cost and small form factor.
Implementation Method 1
Center of pressure is a point where resultant aerodynamic force act on the projectile
Implementation Method 2
The center of pressure and the center of gravity of the projectile shifts towards the nose
Implementation Method 3
a control action system including maneuvering fins and maneuvering motors that alter an orientation of the maneuvering fins
Data Source
AI summary
A projectile including an ejectable aft fin housing assembly. The aft fin housing assembly includes aft fins that increase a distance between a center of gravity and a center of pressure of the projectile, improving passive stabilization of the projectile. Once the projectile has been passively stabilized, the aft fin housing assembly is ejected, decreasing a distance between the center of gravity and the center of pressure, improving active stabilization of the projectile.