Deploying fins for a gun-launched projectile

Abstract

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

What is claimed is: 
     
         1 . A deployment apparatus for stowable fins, comprising:
 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 disposed upon a respective exterior surface region of the fin hub and a respective exterior recess of the projectile, each fin being urged to a deployed position by a respective torsion spring;   the sub-caliber fin hub further configured to be keyed to the aft portion of the projectile during storage and in-bore in response to urging from a propellant, the fin hub when keyed thereto being rotatably locked with the projectile forebody.   
     
     
         2 . The deployment apparatus of  claim 1 , wherein each of the fins comprises an elongated fin having proximal and distal ends substantially axially aligned with the projectile in the stowed position. 
     
     
         3 . The deployment apparatus of  claim 2 , wherein the proximal and distal ends are substantially radially aligned with the projectile in the deployed position. 
     
     
         4 . The deployment apparatus of  claim 1 , wherein the fins comprise a metal or composite material. 
     
     
         5 . The deployment apparatus of  claim 1 , wherein the fin hub comprises a fiber-reinforced polymer. 
     
     
         6 . The deployment apparatus of  claim 1 , wherein the sub-caliber fin hub is rotatably coupled to the aft portion of the projectile via a metal inner bushing rotating about an outer plastic bushing via low friction contact therebetween. 
     
     
         7 . The deployment apparatus of  claim 1 , wherein each fin has formed thereat a bump stop guide positioned to receive, upon fin deployment, a respective bump stop formed on the fin hub and positioned to hold the fin in an aerodynamically appropriate position. 
     
     
         8 . A sub-caliber fin hub configured to be rotatably coupled to an aft portion of a projectile, comprising:
 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 disposed upon a respective exterior surface region of the fin hub and a respective exterior recess of the projectile, each fin being urged to a deployed position by a respective torsion spring;   the sub-caliber fin hub configured to be keyed to the aft portion of the projectile during storage and in-bore in response to urging from a propellant, the fin hub when keyed thereto being rotatably locked with the projectile forebody.   
     
     
         9 . The sub-caliber fin hub of  claim 8 , wherein each of the fins comprises an elongated fin having proximal and distal ends substantially axially aligned with the projectile in the stowed position. 
     
     
         10 . The sub-caliber fin hub of  claim 8 , wherein the proximal and distal ends are configured to be substantially radially aligned with the projectile in the deployed position. 
     
     
         11 . The sub-caliber fin hub of  claim 8 , wherein the fins comprise a metal or composite material. 
     
     
         12 . The sub-caliber fin hub of  claim 8 , wherein the fin hub comprises a fiber-reinforced polymer. 
     
     
         13 . The sub-caliber fin hub of  claim 8 , wherein the sub-caliber fin hub is rotatably coupled to the aft portion of the projectile via a metal inner bushing rotating about an outer plastic bushing via low friction contact therebetween. 
     
     
         14 . The sub-caliber fin hub of  claim 8 , wherein each fin has formed thereat a bump stop guide positioned to receive, upon fin deployment, a respective bump stop formed on the fin hub and positioned to hold the fin in an aerodynamically appropriate position.