Renewable liquid investment seal

An engine comprising:

• a combustion chamber having an outlet port;
• a conduit for juxtaposition with said outlet port;
• said conduit, when juxtaposed with said outlet port, having a common interface therewith;
• first means for providing combustion gas at a variable first pressure in said chamber;
• second means for providing a liquid into said common interface at a variable second pressure which is always greater than said first pressure, whereby said liquid seals said common interface and a portion thereof flows into said combustion chamber.

A gun comprising:

• a gun barrel having a combustion chamber;
• a gun bolt for closing one end of said chamber;
• said bolt including:
• a bolt body having a longitudinal bore therein,
• a piston having a head disposed forward of said body and a stem journaled for reciprocation in said bolt body bore,
• said piston head having a forward face of a first cross-sectional area proximal to and in communication with said chamber, and an aft face of a second cross-sectional area, which is less than said first cross-sectional area, and which is spaced from said bolt body to mutually define a void;
• means for trapping liquid in said void;
• and
• having a mode of operation such that force applied to said piston head forward face at a first pressure is communicated to liquid in said void by said piston head aft face at a second pressure which is greater than said first pressure.

A gun for firing liquid propellant comprising:

• a gun barrel having a bore, a combustion chamber and an antechamber in serial, longitudinal alignment,
• an inlet port opening into said antechamber,
• a bolt journaled for longitudinal reciprocation and having at least two longitudinal dispositions,
• a first disposition, whereat said bolt is aft of said inlet port, and permits liquid flow from said inlet port to said combustion chamber, and
• a second disposition, forward of said first disposition, whereat said bolt obturates said combustion chamber and precludes liquid flow between said inlet port and said combustion chamber;
• said bolt including:
• a bolt body having a longitudinal bore therein,
• a piston having a head disposed forward of said body and a stem journaled for limited reciprocation in said bolt body bore,
• said piston head having a forward face of a first cross-sectional area, and an aft face of a second cross-sectional area, which is less than said first cross-sectional area,
• means urging said piston forward of said bolt body, whereat said aft face of said piston head is spaced forward of said bolt body to mutually define a void;
• said void adapted to receive liquid from said inlet port when said bolt is in its first disposition, and to trap liquid, in conjunction with the wall of said combustion chamber, when said bolt is in its second disposition;
• said bolt having a mode of operation such that force applied to said piston head forward face by combustion gas at a first pressure in said combustion chamber is communicated to liquid trapped in said void by said piston head aft face at a second pressure which is greater than said first pressure.