Multi-shot Launcher Comprising External Propellant

Abstract

An underwater gun for firing stacked munitions includes external propellant bays. In some embodiments, after a first munition is launched from the barrel of the launcher, propellant in one of the external propellant bays is ignited. The gas that is generated upon ignition is routed to the bore of the barrel and expels water that is in the barrel. A munition is then immediately launched through the cleared barrel.

Description

STATEMENT REGARDING FEDERALLY-SPONSORED RESEARCH

This invention was made with Government support under N00014-07-C-1103 awarded by the U.S. Navy. The Government has certain rights in the invention.

FIELD OF THE INVENTION

The present invention relates to munitions in general, and, more particularly, to weapons capable of launching multiple stacked projectiles underwater.

BACKGROUND OF THE INVENTION

FIG. 1 depicts a partial, simplified view of barrel 102 of multi-shot grenade launcher 100. In launcher 100, three grenades 104-1, 104-2, and 104-3 are “stacked” one behind another in barrel 102. Grenade 104-1 is in position 1 (i.e., first to be launched), grenade 104-2 is in position 2 and grenade 104-3 is in position 3 as the third grenade to be launched. This “stacked” grenade launcher technology is available from Metal Storm Inc. as the “3GL” 3-shot semi automatic modular grenade launcher.

Attached to the aft end of each grenade is propulsion base 108. The propulsion base contains propellant that is used to launch the grenade. Pusher plate 106 is disposed between each grenade and its accompanying propulsion base. The pusher plate transmits the pressure generated by the propellant to the grenade being launched. The purpose of the pusher plate is to distribute the force across the surface of the tail of the munition, thereby preventing damage.

The stacked-round approach discussed above is useful for other weapons applications as well. For example, it would be desirable to use stacked rounds to create a multi-shot gun that fires “supercavitating” projectiles underwater. Underwater guns are useful as anti-mine and anti-torpedo devices. Recently, autonomous underwater vehicles (AUVs) have been fitted with underwater guns for torpedo defense and underwater “hunter-killer” CONOPs.

A gun, especially one that fires a projectile at a high muzzle velocity, cannot be fired when water is in its barrel. If a firing where to incur in a water-filled barrel, a very high breach pressure would result as the ignited propellant charge forces (or tries to force) the water out of the barrel. The likely result would be material failure of the barrel. Moreover, even if the weapon doesn't catastrophically fail, the muzzle velocity of the projectile would be reduced, because of the additional water mass that requires expulsion.

The prior art has proposed a number of solutions for waterproofing the barrel of an underwater gun or for clearing water from its barrel before firing. But in the context of an underwater weapon having a high muzzle-velocity, most prior-art solutions solve one problem—clearing the barrel of water—only to create other problems.

U.S. Pat. No. 5,639,982 discloses a means for firing a fully automatic gun underwater using a blank barrel-clearance round. Blank barrel-clearance rounds are alternated with live rounds of ammunition. To begin the process, a blank barrel-clearance round is first detonated. This creates gas and steam within the chamber that forms a bubble at the muzzle end of the barrel, thereby displacing water from the chamber. A live round is then immediately fired. The process is repeated, whereby the subsequent detonation of a blank barrel-clearance round displaces any water that has re-entered the barrel subsequent to the firing of the live round.

The application of this solution to an underwater gun that fires stacked, “supercavitating” rounds is problematic. In particular, to achieve the high muzzle velocities required for a projectile to supercavitate, tremendous pressure must be developed in the barrel upon propellant ignition. The barrel-clearance rounds remaining in the barrel will be exposed to an extreme static load—a load that is in fact sufficient to damage barrel-clearance rounds—when a live round is fired.

SUMMARY OF THE INVENTION

The present invention provides a way to clear water, between firings, from an underwater multi-shot weapon that launches stacked projectiles at very high velocities.

The illustrative embodiment of the present invention is an underwater multi-shot launcher that includes external propellant bays. The external propellant bays contain propellant that, when ignited, expels water from the barrel of the launcher. A small window of time is provided after water is expelled to launch a projectile.

In the illustrative embodiment, the launcher includes a water seal over the muzzle to keep the barrel clear of water prior to launching the first projectile. In some embodiments, the water seal is a rupture disc. As the pressure rises within the barrel upon ignition of the propellant that launches the first projectile, the rupture disc will eventually burst. After the rupture disc bursts and the first projectile is launched, water is free to enter the barrel. To the extent that projectiles are not fired in rapid succession, water must be cleared from the barrel prior to firing each subsequent projectile.

To that end, and in accordance with the illustrative embodiment, external propellant bays are disposed outside of the launcher, but are placed in fluidic communication with bore of the barrel through a pressure relief system and several conduits/channels. Each external propellant bay includes propellant that, when ignited, generates a gas. The gas, which is conveyed to the bore of the barrel, raises the pressure in the bore to a level sufficient to expel water therefrom. This provides a brief window of time in which a projectile can be launched.

In the illustrative embodiment, the pressure relief system comprises two pressure relief devices, at least one of which couples directly to the external propellant bay. The pressure relief device that is coupled to the external propellant bay, which in the illustrative embodiment is a rupture disc, relieves (e.g., bursts in the case of a rupture disc) when substantially all propellant is consumed such that a maximum amount of gas is generated. When this pressure relief device relieves pressure, the gas enters a high-pressure conduit that leads to the second pressure relief device. In the illustrative embodiment, the second pressure relief device is fitted to an opening through the side of the barrel. A channel leads from this opening to the bore of the barrel.

When exposed to the pressure in the high-pressure conduit, the second pressure relief device relieves pressure, permitting the gas in the high-pressure conduit to flow (via the channel) to the bore of the launcher. As a consequence, the pressure in the bore rapidly rises to a level that is sufficient to expel water. In the illustrative embodiment, the second pressure relief device is a rupture disc. During launch of a projectile, the second pressure-relief device holds pressure and thereby prevents propellant gas (that is generated during launch of a projectile) from entering the high pressure conduit and it also prevents water that enters bore (after the launch of a projectile) from entering the high pressure conduit.

In some embodiments, the invention comprises a launcher for launching stacked munitions under water, wherein the launcher comprises:

• • a barrel having a bore, wherein the bore is dimensioned to contain at least a first munition in a first position for launch, a second munition in a second position for launch, and a third munition in a third position for launch, and wherein the munitions are arranged one behind another;
  • a first channel leading from the bore to a first opening through the external surface of the barrel; and
  • a first external propellant bay that contains an amount of propellant that is sufficient for clearing water from the bore after the first munition is fired, wherein the first external propellant bay is in fluidic communication with the first opening and the bore through a first pressure relief system.

In some other embodiments, the invention comprises a launcher for launching stacked munitions under water, wherein the launcher comprises:

• • a barrel having a bore, wherein the bore is dimensioned to contain at least three munitions that are arranged one behind another; and
  • an external propellant bay that is fluidically coupled to the bore, wherein the external propellant bay comprises:
    • (a) an amount of propellant sufficient for clearing water from the bore;
    • (b) a chamber into which the propellant expands as a gas when ignited; and
    • (c) a pressure relief system that is configured to permit the gas to egress from the external propellant bay when propellant contained therein is consumed.

In yet some additional embodiments, the invention comprises a method for launching stacked munitions under water, comprising:

• • launching a first munition from a bore of a barrel of a launcher;
  • generating an amount of gas that is sufficient to clear the bore of water after the first munition launches, wherein the gas is generated in a bay that is external to the launcher;
  • exceeding a relief pressure of a pressure relief system that controls a flow of the gas from the bay;
  • delivering the gas to the bore of the barrel, thereby clearing the bore of water for a period of time; and
  • launching a second munition within the period of time.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a partial view of a multi-shot launcher in the prior art.

FIG. 2 depicts an embodiment of an underwater, multi-shot launcher in accordance with the illustrative embodiment of the present invention.

FIG. 3 depicts a longitudinal cross-section through the multi-shot launcher of FIG. 2.

FIG. 4 depicts a fragmentary view of the multi-shot launcher of FIG. 3, showing additional details of the external propellant bay.

FIG. 5 depicts a fire control system.

DETAILED DESCRIPTION

The terms appearing below are defined for use in this disclosure and the appended claims as follows:

• • “Operatively Coupled” means that a first object, which might be remote from a second object, can have some effect on the second object or have some effect on a third object through the second object, etc. For example, consider a rigid linkage having a first end and a second end. The first end attaches to a plate and the second end abuts a wall. The linkage is capable of transferring, to the wall, a force that is received at the plate. The linkage and the plate can therefore be considered to be operatively coupled for transmitting a force. Operatively-coupled objects need not be in direct contact with one another and, as appropriate, can be coupled through any medium (e.g., semiconductor, air, vacuum, water, copper, optical fiber, etc.). The coupling between operatively-coupled objects can transmit, as appropriate for the nature of the coupling and the objects, any type of force, signal, charge, electrical current, optical energy, etc. Consequently, operatively-coupled objects can be electrically-coupled, hydraulically-coupled, magnetically-coupled, mechanically-coupled, optically-coupled, pneumatically-coupled, thermally-coupled, fluidically-coupled, etc.
  • “Fluidically Coupled” means that, with respect to two regions, fluid (i.e., liquid, vapor, gas) can move between the two regions or that a change in pressure in one region can affect the pressure in the other region, etc.
  • “Projectile” means an object propelled by the exertion of a force that ceases after launch.
  • “Munition” means an object that is propelled by the exertion of a force that either ceases after launch or continues after launch.

The illustrative embodiment of the invention is directed to the launch of stacked projectiles underwater from a multi-shot launcher. FIG. 2 depicts a side view of multi-shot launcher 200 in accordance with the illustrative embodiment of the present invention. FIG. 3 depicts a longitudinal cross section of launcher 200.

Launcher 200 comprises barrel 201, which, in the illustrative embodiment, is composed of multiple flanged segments. In the illustrative embodiment, barrel 201 comprises four segments: forward segment 204, intermediate segments 206A and 206B, and aft segment 206C. Aft segment 206C is sealed by breech portion 208. Forward segment 204 is attached to segment 206A and sealed by water seal 202. In the illustrative embodiment, segments 206A, 206B, and 206C are identical.

Each segment 204, 206A, 206B, and 206C has a central bore that aligns with a long axis of the segment. When these segments are attached as in FIGS. 2 and 3, these bores transversely align to define bore 305 of the barrel.

Each segment 206A, 206B, and 206C includes a plurality of ignition primers 210-1, 210-2, and 210-3, respectively. In the illustrative embodiment, there are three primers 210-1 (only two of which are visible in FIG. 2). Each segment also includes at least one pressure transducer 212-1, 212-2, and 212-3, respectively. Segments 206A and 206B also include, in the illustrative embodiment, respective rupture discs 214-1 and 214-2. The ignition primers, pressure transducers, and rupture discs are discussed in further detail later in this specification with respect to FIGS. 3 and 5.

FIG. 3 depicts three projectiles 320-1, 320-2, and 320-3 disposed in bore 305 of barrel 201. Pusher plates 322 abut the tail each of these projectiles. The pusher plates are intended to distribute, across the tail of the projectile being fired, the static load that is generated (due to a rapid rise in pressure) when the propellant for the projectile is ignited. The pusher plates are not attached to the adjacent projectile, but when a projectile is launched, the associated pusher plate is ejected from the launcher as well.

In some embodiments, a load-redirecting pusher plate, such as is disclosed in co-pending application Ser. No. 12/571,966 (incorporated by reference herein), is used in conjunction with at least some of the projectiles. The load-redirecting pusher plate, which is different than the conventional pusher plates depicted in FIG. 3, redirects to the barrel the static load (due to propellant ignition) that would otherwise be borne by the projectiles that remain in the barrel.

Associated with each projectile is propellant cartridge 324. The cartridge is filled with a propellant, such as SHP831, available from General Dynamics—Ordnance and Tactical Systems. The propellant provides the motive force for launching the projectile. In the illustrative embodiment, propellant cartridges 324 have a cylindrical shape. Each cartridge 324 is disposed aft of its associated projectile. In the illustrative embodiment, the cartridge fits in an annular cavity that is created between mating portions of adjacent segments of launcher 200. Propellant gas ports 325 place bore 305 of the barrel in fluidic communication with propellant cartridge 324.

During launch of a projectile, initiation primers (e.g., 210-1, etc.) ignite the propellant in one of the propellant cartridges 324. Gas, which is generated upon propellant ignition, is conducted by propellant gas ports 325 to bore 305. In the illustrative embodiment, three propellant gas ports 325 are disposed in barrel at the axial position corresponding to the location of each propellant cartridge 324 (although only one gas port 325 is depicted at each such location as a consequence of the cross-sectional depiction). Pressure rapidly rises in the bore and serves as the motive force for launching the projectile. A pressure reading can be obtained via pressure transducer 212.

It is understood that, for the illustrative embodiment, a trio of initiation primers and a trio of propellant gas ports are located at each axial position corresponding to the location of a propellant cartridge. In the illustrative embodiment, there is one propellant cartridge per each projectile within the launcher. In some other embodiments, a greater or less number of initiation primers and propellant gas ports can be used in conjunction with each propellant cartridge. Also, in some embodiments, two or more propellant cartridges are used to launch each projectile.

Since launcher 200 is intended to fire projectiles at underwater and at high speed (such as is required to create a supercavitating mode of operation), several adaptations are required to the launcher. In particular, the launcher must include an adaptation that ensures that bore 305 is clear of water when a projectile is fired. To that end, water seal 202 is provided. In the illustrative embodiment, water seal 202 comprises a rupture disc 303. Prior to the first firing of launcher 200, rupture disc 303 seals the muzzle of the launcher, thereby preventing water from entering bore 305. As the pressure rises within bore 305 upon ignition of the propellant for projectile 320-1, the rupture disc 303 will eventually burst. Burst pressure is a function of the prevailing pressures within the bore upon ignition as well as the operating depth of the launcher. Those skilled in the art will be able to determine a suitable burst pressure for rupture disc 303.

Extreme pressures are generated upon propellant ignition. As such, the pressure within bore 305 persists above the external water pressure (at typical operating depth) for a brief period of time (e.g., 100 millisecs, etc.) as a function of pressure. Water is therefore prevented from entering bore 305 for this brief period of time following launch of a projectile. As a consequence, if launcher 200 is to be operated in a manner in which all projectiles in launcher 200 are fired in immediate succession, bore 305 will remain clear of water during the launch of all projectiles. For this type of operation, only water seal 202 is required.

It is appreciated that a rupture disc is a single-use device. In the present context, once rupture disc 303 bursts and projectile 320A is launched, water will be free to enter bore 305 when bore pressure subsides. As a consequence, to the extent that projectiles might not be fired in rapid succession, an adaptation is required to clear water from the barrel prior to firing each projectile (after the first projectile is fired).

To that end, and in accordance with the illustrative embodiment, launcher 200 comprises external propellant bay(s) 330-1 and 330-2, hereinafter collectively or generically referenced as “external propellant bay(s) 330.” Each external propellant bay 330 is disposed outside of launcher 200, but is placed in fluidic communication with bore 305 via conduits and/or passages, as discussed later in further detail. Each external propellant bay 330 includes propellant that, when ignited, generates a gas. The gas, which is conveyed to bore 305, raises the pressure in the bore to a level sufficient to expel water therefrom. This provides a brief window of time in which a projectile can be launched. Further discussion of external propellant bay 330 is provided in conjunction with FIG. 4.

With continuing reference to FIG. 3, launcher 200 includes (n−1) external propellant bays, wherein “n” is the maximum number of projectiles that can be contained in the launcher for firing. The reason for using (n−1) bays 330 is that, for the illustrative embodiment, bore 305 is initially sealed by water seal 202 and is therefore free of water. As a consequence, an external propellant bay is not required to clear water prior to launching the first projectile. For example, in the illustrative embodiment in which the capacity of launcher 200 is three projectiles, two external propellant bays 330 are included. External propellant bay 330-1 is used to clear the bore of water prior to firing projectile 320B and external propellant bay 330-2 is used to clear the bore before firing projectile 320C.

Operation of launcher 200 is controlled via fire control system 340. In some embodiments, fire control system 340 incorporates one or more processor(s), processor-accessible information storage, transceiver(s), appropriate drivers, and, in some cases, a power supply. In some embodiments, the fire control system can be attached to launcher 200. In the more typical situation in which launcher 200 is mounted on AUV, etc., the fire control system is located elsewhere on the AUV itself.

Fire control system 340 responds to a command to “launch” that typically originates from another weapons-related system (e.g., on board the AUV or other underwater vehicle). For example, the command can be issued from detection/ranging/targeting systems that have acquired a target and determined that a projectile should be launched. Further description of fire control system 340 is provided in conjunction with the discussion of FIG. 5.

FIG. 4 depicts further detail external propellant bay 330-1 and the region in FIG. 3 demarcated by dashed lines and referenced as “A.” This Figure depicts the launcher after the first projectile—projectile 320-1—has been launched. The associated pusher plate 322 has been ejected from bore 305 and propellant cartridge 324 is spent.

External propellant bay 330-1 includes, within housing 450, propellant 452, expansion chamber 454, initiation primer 456, and gas outlet passage 458. In some embodiments, propellant 452 is smokeless propellant, such as 20N29 propellant manufactured by Vihtavuori Oy of Finland. Initiation primer 456 is an electric ignition unit, well known in the art, for igniting propellant 452. Upon ignition, propellant expands as a gas into expansion chamber 454. In some embodiments, 50 grams of 20N29 propellant is used and expansion chamber 454 provides a volume of 50 cubic centimeters. In conjunction with the present disclosure, those skilled in the art will be able to select an amount of propellant for clearing the bore of water as a function of bore volume, operating depth, and like considerations.

External propellant bay 330-1 is placed in fluidic communication with bore 305 of the launcher through a pressure relief system, high pressure conduit 328, and channel 326 within the barrel. In the illustrative embodiment, the pressure relief system comprises two rupture discs 214-1 and 460. Rupture disc 460 couples to gas outlet passage 458. Rupture disc 460 ensures that substantially all propellant 452 is consumed. In other words, pressure builds in expansion chamber 454 as the propellant burns. To generate enough pressure to reach the burst pressure of rupture disc 460, substantially all propellant must be consumed.

High-pressure conduit 328 associated with external propellant bay 330-1 leads from rupture disc 460 to rupture disc 214-1. Rupture disc 214-1 is fitted to opening 440 in section 206A of the barrel. Opening 440 is one terminus of channel 326. This channel leads through the barrel terminating, at its other end, at bore 305. Rupture disc 214 is designed to burst when exposed to the pressure within high-pressure conduit 328, as caused by propellant ignition in external propellant bay 330-1 (after rupture disc 460 bursts). But it will not burst when exposed to the pressure in bore 305 during launch. Therefore, rupture disc 214-1 prevents propellant gas that is generated during launch of projectile 320-1 from entering high pressure conduit 328. It also prevents water that enters bore 305 after the launch of projectile 320-1 from entering high pressure conduit 328.

The pressure within bore 305 at launch is greater than the pressure in the bore during water expulsion. As a consequence, the operation of the rupture disc 214-1 is not symmetric. That is, this rupture disc is designed for “one-way” operation in that it can withstand more pressure on one side (i.e., the “bore side”) than the other side (i.e., the “high-pressure conduit side”). In some alternative embodiments, a one-way valve is used in place of rupture disc 214-1. A one-way valve (e.g., typically a ball valve) rated for a pressure that exceeds the maximum pressure experienced in the bore will not release at any pressure experienced in the bore. It will release, however, at some minimum pressure in the high-pressure conduit.

Thus, external propellant bay 330-1 is placed in fluidic communication with the bore of the barrel via channel 326, high pressure conduit 328, and a pressure relief system. The same is true for external propellant bay 330-2, which is disposed aft of projectile 320-2 and is used to clear water from the bore after the launch of projectile 320-2.

Referring now to FIG. 5, fire control system 340 is suitably connected (e.g., wire, etc.) to each triad of initiation primers 210-1, 210-2, and 210-3 and to the initiation primers 456 for external propellant bays 330-1 and 330-2 to deliver a control signal thereto to ignite propellant at an appropriate time. Furthermore, fire control system 340 is appropriately connected to pressure transducers 212-1, 212-2, and 212-3 for receiving signals therefrom indicative of the pressure at various locations within bore 305. Fire control system 340 also receives information concerning current depth (or ambient pressure).

Fire control system 340 keeps track of which, if any, projectiles have been fired to determine if water expulsion is required and, if so, which external propellant bay 330 is to be used. Having received a command to “launch,” and having determined that the next projectile to launch is projectile 320-2, fire control system 340 sends a signal to initiation primer 456 of bay 330-1. The initiation primer ignites propellant 452, which expands into chamber 454. Once sufficient pressure builds in chamber 454 (and gas outlet passage 458), rupture disc 460 bursts. Pressure then rises in high-pressure conduit 328, which causes rupture disc 214-1 to rupture. The gas generated by propellant 452 then pressurizes bore 305 and expels all water.

There is a brief window of time (from the time when the propellant in external propellant bay 330-1 is ignited) in which to launch projectile 320-2. Pressure transducer 212-1 monitors pressure in bore 305 and transmits pressure measurement data to fire control system 340. The data is used by algorithms running on fire-control system's processor(s) to determine when to send a signal to initiation primer 210-2 to ignite the propellant to launch projectile 320-2. In some other embodiments, launcher includes additional pressure transducers (i.e., in addition to 212-1, 212-2, and 212-3) to obtain pressure readings within bore 305.

In a typical scenario, there is approximately a 100-millisecond window for projectile launch from the time that bore 305 is clear of water. It will take a projectile about 10 milliseconds to egress from the barrel once it begins to move. It will take about 70 millisecs for the ignited propellant to generate the requisite pressure to launch the projectile. As a consequence, in such a scenario, fire control system 340 can send a signal to initiation primer 210-2 as late as about 20 milliseconds after water has cleared the barrel (as determined by pressure readings within the bore, which are relayed to fire control system 340 from pressure transducer 212-1).

In conjunction with the present disclosure, those skilled in the art will be able to develop algorithms that are capable of determining when to ignite the propellant that launches a projectile.

It is to be understood that the disclosure teaches just one example of the illustrative embodiment and that many variations of the invention can easily be devised by those skilled in the art after reading this disclosure and that the scope of the present invention is to be determined by the following claims.

Claims

1. A launcher for launching stacked munitions under water, comprising:

a barrel having a bore, wherein the bore is dimensioned to contain at least a first munition in a first position for launch, a second munition in a second position for launch, and a third munition in a third position for launch, and wherein the munitions are arranged one behind another;

a first channel leading from the bore to a first opening through the external surface of the barrel; and

a first external propellant bay that contains an amount of propellant that is sufficient for clearing water from the bore after the first munition is fired, wherein the first external propellant bay is in fluidic communication with the first opening and the bore through a first pressure relief system.

2. The launcher of claim 1 further comprising a water seal that seals a muzzle of the bore prior to the launching the first munition.

3. The launcher of claim 1 wherein the first channel is disposed aft of the first munition.

4. The launcher of claim 1 further comprising a high pressure conduit, wherein the high pressure conduit fluidically couples the first external propellant bay to the first opening.

5. The launcher of claim 1 wherein the first pressure relief system comprises a rupture disc, wherein the rupture disc is disposed at a gas outlet of the external propellant bay.

6. The launcher of claim 4 wherein the first pressure relief system comprises a rupture disc, wherein the rupture disc is disposed between the first opening and the high pressure conduit.

7. The launcher of claim 1 wherein the first pressure relief system comprises a rupture disc disposed at a gas outlet of the external propellant bay and a one-way pressure-relief device disposed between the first opening and the first rupture disc.

8. The launcher of claim 3 further comprising:

a second channel leading from the bore to a second opening through the external surface of the barrel; and

a second external propellant bay that contains an amount of propellant that is sufficient for clearing water from the bore after the second munition is fired, wherein the second external propellant bay is in fluidic communication with the second opening and the bore through a second pressure relief system.

9. The launcher of claim 8 wherein the second channel is disposed aft of the second munition.

10. A launcher for launching stacked munitions under water, comprising:

a barrel having a bore, wherein the bore is dimensioned to contain at least three munitions that are arranged one behind another; and

an external propellant bay that is fluidically coupled to the bore, wherein the external propellant bay comprises: (a) an amount of propellant sufficient for clearing water from the bore; (b) a chamber into which the propellant expands as a gas when ignited; and (c) a pressure relief system that is configured to permit the gas to egress from the external propellant bay when propellant contained therein is consumed.

11. The launcher of claim 10 further comprising a water seal that seals a muzzle of the bore prior to the launching the first munition.

12. The launcher of claim 9 wherein the launcher comprises a number, p, of external propellant bays, wherein p=n−1, wherein n is the maximum number of munitions that can be contained in the launcher.

13. A method for launching stacked munitions under water, comprising:

launching a first munition from a bore of a barrel of a launcher;

generating an amount of gas that is sufficient to clear the bore of water after the first munition launches, wherein the gas is generated in a bay that is external to the launcher;

exceeding a relief pressure of a pressure relief system that controls a flow of the gas from the bay;

delivering the gas to the bore of the barrel, thereby clearing the bore of water for a period of time; and

launching a second munition within the period of time.

14. The method of claim 13 wherein the operation of generating an amount of gas further comprises igniting a propellant that is stored in the bay.

15. The method of claim 14 wherein the operation of generating an amount of gas further comprises enabling the gas that is generated when the propellant is ignited to expand into a chamber within the bay.

16. The method of claim 13 wherein the operation of delivering the gas to the bore of the barrel further comprises conducting the gas through a high pressure conduit.

17. The method of claim 16 wherein the operation of delivering the gas to the bore of the barrel further comprises rupturing a seal disposed between the high pressure conduit and the bore of the barrel.