Sub-Caliber Fin Hub Deployment for Gun-Launched Projectile Stability
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Solution Overview
Problem
Existing projectile fins are complex, costly, and occupy excessive internal volume, making them difficult to deploy in gun-launch or tube-launch environments and impacting payload capacity.
Innovation Solution
A sub-caliber fin hub system with torsion springs deploys fins using a rotatable coupling mechanism, minimizing internal space usage and maximizing payload capacity by stowing fins on the projectile's outer peripheral space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If traditional fins are added to a projectile to provide aerodynamic stability, then aerodynamic stability is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The fin assembly is segmented into multiple independent fins that can be deployed separately from the projectile body. Each fin is independently mounted on the fin hub, allowing them to be deployed at different times or in different configurations. This segmentation reduces the complexity of the overall fin system while maintaining aerodynamic stability.
Solution Approach 2:
The fins transition from a static fixed configuration to a dynamic deployable system. The fins are mounted on a fin hub that can rotate and deploy the fins from a stowed position on the projectile surface to a deployed position in the air. This dynamic deployment mechanism simplifies the overall design by allowing the fins to be compact during storage and only deployed when needed for aerodynamic stability.
2Stability of the object's composition
If traditional fins are added to a projectile to provide aerodynamic stability, then aerodynamic stability is improved, but manufacturing cost increases
Solution Approach 1:
Multiple fins are merged into a single fin hub assembly that can be manufactured as one integrated unit. The fin hub serves as a common mounting structure for all fins, allowing them to be produced together in a single manufacturing process rather than individually. This merging reduces the overall manufacturing cost while maintaining the aerodynamic stability provided by multiple fins.
Solution Approach 2:
The fin hub serves multiple functions: it acts as the mounting structure for all fins, provides the rotation mechanism for deploying fins, and serves as the structural connection between the fins and the projectile body. This multi-functionality reduces the total number of separate components needed, thereby reducing manufacturing cost while maintaining aerodynamic stability.
3Stability of the object's composition
If super-caliber fins are used in gun-launch environment, then aerodynamic stability is improved, but internal volume occupied increases and payload capacity decreases
Solution Approach 1:
The fins are nested within the fin hub assembly, which itself is nested within the projectile's internal volume. When not deployed, the fins are stored in a compact configuration within the fin hub, minimizing the space they occupy. This nesting arrangement allows super-caliber fins to be stored without significantly reducing the available internal volume for payload, while still providing aerodynamic stability when deployed.
Solution Approach 2:
The fins transition from a two-dimensional stored configuration on the projectile surface to a three-dimensional deployed configuration in the air. When stored, the fins occupy minimal volume by lying flat against the projectile surface. When deployed, they extend outward to provide aerodynamic stability. This dimensional transformation allows the fins to be compact during storage while still functioning effectively in flight.
4Ease of operation
If deployment mechanisms are added to retain and deploy fins, then fin deployment capability is improved, but device complexity and internal space requirements increase
Solution Approach 1:
The fin deployment mechanism is self-actuating, using the kinetic energy and aerodynamic forces already present during projectile flight to automatically deploy the fins. The system uses the projectile's own motion and the aerodynamic pressure differential to rotate the fin hub and deploy the fins without requiring external control systems or additional actuators. This self-service approach simplifies the deployment mechanism while maintaining reliable fin deployment capability.
Solution Approach 2:
The deployment mechanism replaces complex mechanical actuation systems with a simpler aerodynamic deployment system. Instead of using motors, sensors, or control electronics to deploy the fins, the system uses the natural aerodynamic forces and kinetic energy of the projectile flight to automatically rotate the fin hub and deploy the fins. This substitution of mechanical systems with aerodynamic forces significantly reduces device complexity.
5Stability of the object's composition
If fins are deployed immediately upon launch, then aerodynamic stability is improved, but roll damping increases and maneuverability decreases
Solution Approach 1:
The fin hub and fins are pre-positioned in a stowed configuration on the projectile surface, ready for deployment. The fin hub is mounted to rotate freely during flight, allowing it to be deployed at the optimal moment. This preliminary positioning allows the fins to be deployed at the right time to provide aerodynamic stability without interfering with early maneuvering, as they remain compact and low-drag during the initial launch phase.
Solution Approach 2:
The fin hub is designed to rotate dynamically in response to aerodynamic forces and kinetic energy during flight. The system transitions from a static stowed configuration to a dynamic deployed configuration based on real-time flight conditions. This dynamic deployment allows the fins to be deployed at the optimal moment to provide aerodynamic stability while minimizing roll damping during critical maneuvering phases.
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 aerodynamic stability and maneuverability while increasing payload capacity by deploying fins after launch, using torsion springs to minimize roll damping and optimize bank-to-turn control schemes.
Implementation Method 1
Each fin is urged toward a deployed position by a respective torsion spring, which operates to deploy the fin after the project has left the barrel or tube
Implementation Method 2
The sub-caliber fin hub is further configured to be keyed to the aft portion of the projectile during storage and while within the bore of the barrel or tube in response to urging from a propellant
Data Source
AI summary
A fin deployment apparatus for stowable fins that comprises a sub-caliber fin hub configured to be rotatably coupled to an aft portion of a projectile, the fin hub having a plurality of flat, planar exterior surface regions, each surface region having pivotably coupled thereto a respective set of fins. Each fin in a stowed position is disposed upon a respective exterior surface region of the fin hub and a respective exterior cavity or recess of the projectile. Each fin is urged toward a deployed position by a respective torsion spring, which operates to deploy the fin after the projectile has left the barrel or tube. The sub-caliber fin hub is further configured to be keyed to the aft portion of the projectile during storage and while within the bore of the barrel or tube in response to urging from a propellant, the fin hub when keyed thereto being rotatably locked with the projectile forebody