Baffled start section for ram accelerator

Abstract

A ram accelerator for accelerating a projectile is provided. The ram accelerator includes a baffle section configured to start the projectile in the ram accelerator without an obturator. The ram accelerator generally includes a tube having a projectile bore; and a baffle section operably coupled to a proximal end of the tube. The baffle section has an annular baffle wall defining a central bore axially aligned with the projectile bore; and a propellant chamber arranged adjacent to the annular baffle wall, wherein the propellant chamber is configured to enclose a propellant. The propellant can be ignited as the projectile passes through the baffle section by pressure created by the projectile, by an ignition source, or by a flame carried by the projectile to start the ram acceleration of the projectile.

1 . A ram accelerator for accelerating a projectile, the ram accelerator comprising:
 a tube having a projectile bore; and   a baffle section operably coupled to a proximal end of the tube, the baffle section having:
 an annular baffle wall defining a central bore axially aligned with the projectile bore; and 
 a propellant chamber arranged adjacent to the annular baffle wall, wherein the propellant chamber is configured to enclose a propellant, 
   wherein the propellant is ignited as the projectile passes through the baffle section to start ram acceleration of the projectile.   
     
     
         2 . The ram accelerator of  claim 1 , wherein the baffle section comprises a plurality of baffle members arranged axially in a series, and wherein each of the baffle members includes an annular baffle wall and at least one propellant chamber. 
     
     
         3 . The ram accelerator of  claim 1 , wherein the propellant chamber is a first propellant chamber, and wherein the baffle section further comprises a second propellant chamber separated from the first propellant chamber by a radially inwardly projecting fin. 
     
     
         4 . The ram accelerator of  claim 3 , wherein the baffle section further comprises a third propellant chamber and a fourth propellant chamber, each of the first, second, third, and fourth propellant chambers being separated from each other by a radially inwardly projecting fin. 
     
     
         5 . The ram accelerator of  claim 1 , wherein the baffle section further comprises an ignition port extending through the baffle section and into the propellant chamber. 
     
     
         6 . The ram accelerator of  claim 4 , wherein the propellant is ignited by a spark plug operably positioned within the ignition port. 
     
     
         7 . The ram accelerator of  claim 1 , wherein the propellant is ignited by compression of gas by the projectile within the propellant chamber. 
     
     
         8 . The ram accelerator of  claim 1 , wherein the propellant is ignited by a flame carried by the projectile as the projectile passes through the propellant chamber. 
     
     
         9 . The ram accelerator of  claim 1 , wherein the central bore is smaller in diameter than the projectile bore. 
     
     
         10 . The ram accelerator of  claim 1 , wherein the tube comprises a plurality of tube sections operably coupled together. 
     
     
         11 . A method of starting a ram accelerator without an obturator, the method comprising:
 operably coupling a baffle section to a proximal end of a ram accelerator tube having a projectile bore, the baffle section having:
 an annular baffle wall defining a central bore axially aligned with the projectile bore; and 
 a propellant chamber arranged adjacent to the annular baffle wall, wherein the propellant chamber is configured to enclose a propellant; 
   filling the propellant chamber with the propellant;   launching the projectile into the baffle section; and   igniting the propellant in the propellant chamber as the projectile passes through the baffle section to start the ram acceleration of the projectile.   
     
     
         12 . The method of  claim 11 , wherein the baffle section comprises a plurality of baffle members arranged axially in a series, wherein each of the baffle members includes an annular baffle wall and a propellant chamber, and wherein igniting the propellant in the propellant chamber includes igniting the propellant in each of the propellant chambers of each of the baffle members as the projectile passes through the baffle member. 
     
     
         13 . The method of  claim 11 , wherein the propellant chamber is a first propellant chamber, and wherein the baffle section further comprises a second propellant chamber separated from the first propellant chamber by a radially inwardly projecting fin. 
     
     
         14 . The method of  claim 11 , wherein the baffle section further comprises an ignition port extending through the baffle section and into the propellant chamber. 
     
     
         15 . The method of  claim 14 , wherein igniting the propellant comprises energizing a spark plug operably positioned within the ignition port. 
     
     
         16 . The method of  claim 11 , wherein the propellant is ignited by compression of gas by the projectile within the propellant chamber. 
     
     
         17 . The method of  claim 11 , wherein the propellant is ignited by a flame carried by the projectile as the projectile passes through the propellant chamber. 
     
     
         18 . The method of  claim 11 , wherein the propellant is a first propellant, wherein the method further comprises filling the ram accelerator tube with a second propellant having a different energy than the first propellant. 
     
     
         19 . The method of  claim 18 , wherein the second propellant has higher energy than the first propellant.