Two-phase projectile with a distal compression chamber

Abstract

A projectile having a proximal tube and distal tube is described. A piston that is formed with a vent covers the distal end of the proximal tube. The piston is inserted into an open proximal end of the distal tube to establish a compression chamber in the distal tube between the axially moveable piston and a closed distal tube end. A valve is positioned at the proximal end of the proximal tube to selectively pressurize a space in the proximal tube between the valve and piston. The space, in turn, is in fluid communication with the compression chamber through the vent formed in the piston. The vent is formed as a constriction allowing fluid to flow into the compression chamber during an initial pressurization, while allowing for pressure buildup in the compression chamber during the initial relative movement between the proximal and distal tubes that occurs immediately after projectile launch.

What is claimed is: 
     
         1 . A device which comprises:
 a distal tube formed with a lumen and defining an axis, and wherein the distal tube has an open proximal end and a closed distal end;   a proximal tube formed with a lumen and having a proximal end and a distal end; the proximal tube engaged with the distal tube to provide for a back and forth axial movement of the proximal tube in the lumen of the distal tube;   a piston covering the distal end of the proximal tube, wherein the piston is formed with a vent;   a valve at the proximal end of the proximal tube to selectively pressurize a space in the lumen of the proximal tube between the valve and piston, the space being in fluid communication with the distal tube lumen through the vent to establish a compression chamber therein between the piston and the closed distal end of the distal tube; and   a launcher for generating an axially-directed driving force on the proximal tube to propel the proximal tube onto a flight path in the axial direction with an initial relative movement between the proximal and distal tubes to compress gas in the compression chamber and generate potential energy in the compressed gas for use in separating the proximal and distal tubes in flight.   
     
     
         2 . A device as recited in  claim 1  wherein the piston further comprises an O-ring assembly positioned in a retention groove formed in the piston to establish a seal between the piston and the distal tube. 
     
     
         3 . A device as recited in  claim 2  wherein the retention groove is formed with at least one vent hole to establish fluid communication for equalizing pressure between the retention groove and the compression chamber, and wherein the O-ring assembly comprises:
 an outer ring positioned in the retention groove for contact with the distal tube; and 
 an inner ring positioned in the retention groove to produce a force against the outer ring to urge the outer ring into contact with the distal tube. 
 
     
     
         4 . A device as recited in  claim 3  wherein the inner ring is made of rubber and the outer ring is made of polytetrafluoroethylene (PTFE), and further wherein the outer ring is formed with a diagonal split to permit contraction and expansion of the outer ring. 
     
     
         5 . A device as recited in  claim 1  wherein the piston is formed with a wall and the vent comprises a hole extending through the wall of the piston. 
     
     
         6 . A device as recited in  claim 1  wherein the valve is a Schrader valve positioned in the proximal tube lumen. 
     
     
         7 . A device as recited in  claim 1  wherein the proximal tube has an outer surface, the distal tube has an inner surface and the proximal tube is engaged with the distal tube to establish a sleeve chamber between the inner surface of the distal tube and the outer surface of the proximal tube. 
     
     
         8 . A device as recited in  claim 7  wherein the proximal tube is formed with an opening to establish fluid communication between the space in the proximal tube and the sleeve chamber. 
     
     
         9 . A device as recited in  claim 8  wherein the device further comprises an O-ring disposed between the inner surface of the distal tube and the outer surface of the proximal tube. 
     
     
         10 . A device as recited in  claim 9  wherein the device further comprises an annular ring mounted on the outer surface of the proximal tube and positioned in the sleeve chamber, the annular ring axially moveable relative to the O-ring during a pressurization of the sleeve chamber to deform the O-ring and increase a sealing force between the O-ring, the annular ring and the inner surface of the distal tube. 
     
     
         11 . A device as recited in  claim 1  wherein the vent is formed in the shape of a labyrinth passageway. 
     
     
         12 . A device as recited in  claim 1  wherein the launcher is man-powered. 
     
     
         13 . A device as recited in  claim 12  wherein the launcher is a vertical bow. 
     
     
         14 . A device which comprises:
 a proximal tube formed with a lumen;   a piston covering the distal end of the proximal tube;   a distal tube formed with a lumen and having an open proximal end and a closed distal end; the distal tube engaged with the proximal tube to establish a compression chamber in the lumen of the distal tube between the piston and the closed distal end of the distal tube;   a means for regulating an introduction of fluid into the proximal tube lumen to pressurize the compression chamber; and   a launcher for generating a driving force on the proximal tube to propel the proximal tube onto a flight path with an initial relative movement between the proximal and distal tubes to compress gas in the compression chamber for use in separating the proximal and distal tubes in flight.   
     
     
         15 . A device as recited in  claim 14  wherein the regulating means comprises a valve at the proximal end of the proximal tube to selectively pressurize a space in the lumen of the proximal tube between the valve and piston, the space being in fluid communication with the compression chamber through a vent formed in the piston. 
     
     
         16 . A device as recited in  claim 15  wherein the piston is formed with a wall and the vent comprises a hole extending through the wall of the piston. 
     
     
         17 . A device as recited in  claim 15  wherein the vent is formed in the shape of a labyrinth passageway. 
     
     
         18 . A device as recited in  claim 14  wherein the proximal tube has an outer surface, the distal tube has an inner surface and the proximal tube is engaged with the distal tube to establish a sleeve chamber between the inner surface of the distal tube and the outer surface of the proximal tube. 
     
     
         19 . A device as recited in  claim 18  wherein the proximal tube is formed with an opening to establish fluid communication between the space in the proximal tube and the sleeve chamber and the device further comprises an O-ring disposed between the inner surface of the distal tube and the outer surface of the proximal tube. 
     
     
         20 . A device as recited in  claim 19  wherein the device further comprises an annular ring positioned in the sleeve chamber, the annular ring axially moveable relative to the O-ring during a pressurization of the sleeve chamber to deform the O-ring and increase a sealing force between the O-ring, the annular ring and the inner surface of the distal tube. 
     
     
         21 . A method for assembling a device, the method comprising the steps of:
 providing a distal tube formed with a lumen, and wherein the distal tube defines an axis and has an open proximal end and a closed distal end;   covering the distal end of a proximal tube with a piston; the piston formed with a vent;   engaging the distal tube with the proximal tube to provide for a back and forth axial movement of the proximal tube in the lumen of the distal tube, the proximal tube formed with a lumen and having a proximal end and a distal end; the proximal tube engaged with the distal tube; and   using a valve at the proximal end of the proximal tube to selectively pressurize a space in the lumen of the proximal tube between the valve and piston, the space being in fluid communication with the distal tube lumen through the vent to establish a compression chamber therein between the piston and the closed distal end of the distal tube.   
     
     
         22 . A method as recited in  claim 21  wherein the space and the compression chamber are pressurized to a pressure in the range of 70 to 90 psig. 
     
     
         23 . A method as recited in  claim 21  wherein the piston is formed with a wall and the vent comprises a hole extending through the wall of the piston. 
     
     
         24 . A device as recited in  claim 7  further comprising a friction ring mounted on the inner surface of the distal tube and positioned in contact with the outer surface of the proximal surface to prevent the distal tube from separating from the proximal tube prior to launch.