Metal-stabilized propellant grain for gun-fired rocket motor, and rocket motor baffled end cap for reliable gunfire

A gun-fired projectile assembly comprising:

• a rocket motor that includes:
• a burnable propellant grain;
• a rigid structure integrated into an aft portion of the burnable propellant grain to stabilize the burnable propellant grain;
• wherein the rigid structure extends over only a portion of a length of the burnable propellant grain along a longitudinal axis of the burnable propellant grain, and transmits stresses from an aft face of the burnable propellant grain into an interior of the burnable propellant grain away from the aft face in a direction of the longitudinal axis of the burnable propellant grain;
• and
• wherein the rigid structure provides stiffness to the burnable propellant grain to reduce a change in length of the burnable propellant grain in the direction of the longitudinal axis of the burnable propellant grain during gun firing of the projectile assembly;
• a cartridge case coupled to an aft end of the rocket motor;
• wherein the cartridge case contains a gun propellant;
• wherein the rigid structure is configured to expose the aft face of the burnable propellant grain to gun gas from the gun propellant, when the rocket motor is gun fired;
• and
• wherein the rigid structure is a rigid matrix structure having a longitudinal axis that is aligned with the longitudinal axis of the burnable propellant grain;
• a nozzle;
• and
• an end cap that is arranged to cover the nozzle and defines a baffled path for gas flow through the end cap;
• wherein an outer diameter of the baffled path is equal to or greater than the outer diameter end of the nozzle.