Piston/rocket projectile with separable casing

A piston/rocket projectile for use within a launcher system having a barrel and method of firing such are presented herein. The projectile comprises a projectile body having a combustion chamber for propellant, a piston moveable to extend out a base of the projectile as a result of ignition of propellant in the combustion chamber, and vents for expulsion of combustion products from the ignition of propellant out of the projectile base after initial movement of the piston. A casing is secured to the base of the projectile body, enclosing the piston and vents prior to the ignition of propellant, and a separable joint is disposed between the casing and the base of the projectile body. Upon ignition of propellant in the combustion chamber, the projectile piston is forced down and the separable joint is caused to separate, leaving the casing in the barrel. After the piston completes exertion of propulsion force, combustion products of the ignition of propellant are expelled through the vents out of a lower end of the projectile and solid combustion byproducts from the ignition of the propellant are collected in the casing.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention pertains to the field of weaponry and, more particularly, to a piston/rocket projectile sed for non-lethal applications.

2. Description of the Related Art

The use of non-lethal projectiles in weapon systems include the use of frangible projectiles, which are designed to disintegrate upon target impact thereby minimizing penetration of the target. The use of these non-lethal projectiles can often require specialized equipment, meaning that a non-lethal weapon system cannot be used for lethal applications. Weapon launcher systems that are used for lethal applications may employ non-lethal ballistics such as beanbags or rubber projections, but lack the accuracy.

A launcher system employing a caseless piston/rocket projectile is described in U.S. Pat. No. 8,342,097 titled “CASELESS PROJECTILE AND LAUNCHING SYSTEM” and issued Jan. 1, 2013 presents a launcher having a barrel adapted to receive a projectile with a charge of propellant and a magazine adapted to hold additional projectiles. Each caseless projectile includes a piston shiftably mounted for movement relative to a main body. When propellant in the projectile is ignited, either mechanically or electrically, the propellant forces the piston forward from a retracted position during a period of initial thrust. After the piston moves to a fully extended position, the propellant exits through vent holes to provide an additional thrust for the projectile, while safely discharging pressure from within the projectile. When an electric current is used to initiate a primer and gas-generating solid propellant inside the projectile, electric current passes through the surfaces on the launcher barrel breech or bolt face into the projectile base and then to the primer and propellant. Once the projectile has been launched, no casing is left in the barrel that must be ejected, and the patent describes that reloading an additional projectile becomes relatively easy and the magazine simply pushes an addition projectile into firing position under the influence of a spring. The launcher system of U.S. Pat. No. 8,342,097 describes no means of extraction of the projectile from the barrel, even in the event of a misfire or if the launcher barrel needs to be emptied.

Furthermore, upon multiple firings of the launcher system described in U.S. Pat. No. 8,342,097, it has been discovered that carbon fouling occurs in the barrel bolt face. Since the propellant in the projectile is ignited electrically, such fouling reduces the conductivity of the surfaces contacting the projectile base and significantly limits the total number of projectile firings that may occur before the weapon will not have a sufficient electrical path to ignite the primer and propellant. The carbon deposit residue from repeated ignitions cakes onto the bolt face to a thickness of up to 0.020 in. (0.5 mm) and is extremely difficult to clean. While not being limited by theory, it is believed that such reside also includes aluminum either from the piston or lower combustion chamber melting and adding a plasma or other byproduct layer with the carbon deposited. As a result, cleaning is difficult under laboratory conditions, and is even more cumbersome in the field.

SUMMARY OF THE INVENTION

Bearing in mind the problems and deficiencies of the prior art, it is therefore an object of the present invention to provide a non-lethal projectile that may be fired within a launching system which reduces and/or eliminates fouling residue on a bolt face electrode inside the barrel chamber.

It is another object of the present invention to provide a non-lethal projectile that may be fired within a launcher system with improved accuracy.

A further object of the invention is to provide an apparatus and method of use directed to an electrically energized two stage piston/rocket projectile that captures the majority of ignition debris which may be readily evacuated with each round.

It is yet another object of the present invention to provide a method and apparatus that increases the duty cycle and fired projectile round count before operational field cleaning is needed.

The above and other objects, which will be apparent to those skilled in the art, are achieved in the present invention which is directed to a projectile for use with a launcher system having a barrel comprising a projectile body having a combustion chamber for propellant, a piston moveable to extend out of a base of the projectile as a result of ignition of propellant in the combustion chamber, and vents for expulsion of combustion products from the ignition of propellant out of the projectile base after initial movement of the piston. A casing is secured to the base of the projectile body, enclosing the piston and vents prior to the ignition of the propellant. A frangible joint is located between the casing and the base of the projectile body such that upon ignition of propellant within the combustion chamber, the piston is forced against the casing and causes the frangible joint to break. The casing is left in the barrel so that after the piston completes exertion of propulsion force against the casing, combustion products of the ignition of the propellant are expelled through the vents out of a lower end of the projectile and solid combustion byproducts from the ignition of the propellant are collected in the casing.

The projectile vents may be noncircular and formed in part by wall of an inner surface of the projectile body and in part by an outer surface of the piston. The projectile body may be formed of an electrically non-conductive material and propellant in the combustion chamber may be ignited electrically. The projectile may further include an electrode extending through the projectile body and into the combustion chamber. The projectile may include a gel-type propellant in the combustion chamber, and the electrode may extend into the gel-type propellant within the combustion chamber.

In addition, the projectile may include a nose portion at an end opposite the projectile base, the nose portion may have a rupture capsule disposed in an interior surface of the nose portion. The nose portion may be configured to open the rupture capsule upon contact with a target. The nose portion may include tear joints on an exterior surface to facilitate opening of the rupture capsule. The diameter of the nose portion may be smaller than the projectile body. The projectile may also include a sticky chip on the projectile body so that the sticky chip can adhere to a target upon impact with the projectile.

In a related aspect the present invention is directed to a method of launching a projectile from a launcher system having a barrel and a breech comprising providing a projectile body having a combustion chamber for propellant, a piston moveable to extend out a base of the projectile as a result of ignition of propellant in the combustion chamber, and vents for expulsion of combustion products from the ignition of propellant out of the projectile base after initial movement of the piston, as well as providing a casing secured to the base of the projectile body by a frangible joint between the casing and the projectile body base so that the casing encloses the piston and vents prior to the ignition of propellant. The method includes igniting propellant in the combustion chamber, causing the piston to be forced against the casing and causing the joint to break, thereby leaving the casing in the barrel such that after the piston completes exertion of propulsion force against the casing, combustion products of the ignition of propellant are expelled through the vents out of a lower end of the projectile and solid combustion products from the ignition of propellant are collected in the casing.

The frangible joint may comprise a flange in one of either the casing or projectile base, secured in a groove in the other of the casing and or projectile base, and wherein the flange may be sheared upon a predetermined force by the piston to separate the casing from the projectile body upon ignition of propellant in the combustion chamber and extension of the piston out of the projectile base.

In another aspect the present invention is directed to a projectile for use with a launcher system having a barrel comprising a projectile body having a combustion chamber for propellant, a piston moveable to extend out a base of the projectile as a result of ignition of propellant in the combustion chamber, and vents for expulsion of combustion products from the ignition of propellant out of the projectile base after initial movement of the piston, the vents being formed in part by walls of an inner surface of the projectile body and in part by an outer surface of the piston. The projectile further comprises a casing secured to the base of the projectile body by a joint between the casing and the base of the projectile body, so that the casing encloses the piston and vents prior to the ignition of propellant. Upon ignition of propellant in the combustion chamber, the piston extends such that the vents are exposed before the piston reaches the limit of its travel within the projectile body, whereupon combustion products of the ignition of propellant are expelled through the vents out of the lower end of the projectile.

Yet another aspect of the present invention is directed to a method of launching a projectile from a launcher system having a barrel comprising providing a projectile body having a combustion chamber for propellant, a piston moveable to extend out a base of the projectile as a result of igniting of propellant in the combustion chamber, and vents for expelling combustion products from the ignition of propellant out of the projectile base after initial movement of the piston, the vents being formed in part by walls of an inner surface of the projectile body and in part by an outer surface of the piston. The method includes providing a casing secured to the base of the projectile body by a joint between the casing and the base of the projectile body, so that the casing encloses the piston and vents prior to the ignition of propellant. The method further comprises igniting propellant in the combustion chamber, causing the piston to extend, exposing the vents the piston reaches the limit of its travel within the projectile, and expelling combustion products of the ignition of propellant through the vents out of the lower end of the projectile.

A further aspect of the present invention is directed to a projectile for use with a launcher system having a barrel comprising a projectile body formed of an electrically non-conductive material having a combustion chamber for propellant, the combustion chamber having a gel-type propellant therein and an electrode extending through the projectile body and into the combustion chamber for electrically igniting the gel-type propellant, a piston moveable to extend out a base of the projectile as a result of ignition of said gel-type propellant in the combustion chamber, and vents for expulsion of combustion products from the ignition of said gel-type propellant out of the projectile base after initial movement of the piston. A casing is secured to the base of the projectile body, which encloses the piston and vents prior to the ignition of the gel-type propellant. A frangible joint is located between the casing and the base of the projectile body such that upon ignition of the gel-type propellant by the electrode in the combustion chamber, the piston is forced against the casing and causes the joint to break, leaving the casing in the barrel. After the piston completes exertion of propulsion force against the casing, combustion products of the ignition of the propellant are expelled through the vents out of the lower end of the projectile and solid combustion byproducts from the ignition of the propellant are collected in the casing.

Still another aspect of the present invention is directed to a method of launching a projectile from a launcher system having a barrel comprising providing a projectile body formed of an electrically non-conductive material having a combustion chamber for propellant, the combustion chamber having a gel-type propellant therein and an electrode extending through the projectile body and into the combustion chamber for electrically igniting the gel-type propellant, a piston moveable to extend out a base of the projectile as a result of igniting the gel-type propellant in the combustion chamber, and vents for expelling combustion products from the ignition of the gel-type propellant out of the projectile base after initial movement of the piston. The method includes providing a casing secured to the base of the projectile body, thereby enclosing the piston and vents prior to the ignition of the gel-type propellant. The method further comprises providing a frangible joint between the casing and the base of the projectile body, and igniting the gel-type propellant by use of the electrode in the combustion chamber, thereby forcing the piston against the casing as a result of propulsion force and causing the frangible joint to break, leaving the casing in the barrel such that after the piston completes exerting propulsion force against the casing, expelling combustion products of the ignition of the propellant through the vents out of the lower end of the projectile such that solid combustion byproducts from the ignition of the propellant are collected in the casing.

In another aspect the present invention is directed to a projectile for use with a launcher system having a barrel comprising a projectile body formed of an electrically non-conductive material having a combustion chamber for propellant, the combustion chamber having a gel-type propellant therein and an electrode extending through the projectile body and into the combustion chamber for electrically igniting the gel-type propellant, a piston moveable to extend out a base of the projectile as a result of ignition of the gel-type propellant in the combustion chamber, and vents for expulsion of combustion products from the ignition of the gel-type propellant out of the projectile base after initial movement of the piston. A non-electrically conductive layer is located between the gel-type propellant and the end of the chamber opposite the piston, the non-electrically conductive layer covering at least a portion of a width of the combustion chamber. The non-electrically conductive layer has an opening therein through which extends the electrode. An electrically conductive layer covering at least a portion of the width of the combustion chamber is also included, and is disposed between the non-electrically conductive layer and the gel-type propellant so that the electrically conductive layer is in electrical contact with an end of the electrode. Upon ignition of the gel-type propellant by the electrode and electrically conductive layer in the combustion chamber, the piston is forced outward from the lower end of the projectile and subsequently combustion products of the ignition of the gel-type propellant are expelled through the vents out of the lower end of the projectile.

The non-electrically conductive layer may cover the entire width of the combustion chamber, or may include projections extending along the sidewalls of the combustion chamber. The electrically conductive layer may cover the entire width of the combustion chamber, or may include a projection extending therefrom in contact with the end of the electrode.

A further aspect of the present invention is directed to a method of launching a projectile from a launcher system having a barrel comprising providing a projectile body formed of an electrically non-conductive material having a combustion chamber for propellant, the combustion chamber includes a gel-type propellant therein and an electrode extending through the projectile body and into the combustion chamber for electrically igniting the gel-type propellant, a piston moveable to extend out a base of the projectile as a result of igniting the gel-type propellant in the combustion chamber, and vents for expulsion of combustion products from the ignition of the gel-type propellant out of the projectile base after initial movement of the piston. The method includes providing a non-electrically conductive layer between the gel-type propellant and the end of the chamber opposite the piston, the non-electrically conductive layer covering at least a portion of a width of the combustion chamber, the non-electrically conductive layer having an opening therein through which extends the electrode. The method further comprises providing an electrically conductive layer covering at least a portion of the width of the combustion chamber, the electrically conductive layer disposed between the non-electrically conductive layer and the gel-type propellant in electrical contact with an end of the electrode. The method further includes igniting the gel-type propellant by use of the electrode and electrically conductive layer in the combustion chamber, forcing the piston outward from the lower end of the projectile and subsequently expelling combustion products of the ignition of the gel-type propellant through the vents out of the lower end of the projectile.

The invention in another aspect is directed to a projectile for use with a launcher system having a barrel comprising a projectile body having a combustion chamber for propellant, a piston moveable in one direction to ignite the propellant in the combustion chamber and in an opposite direction to extend out a base of the projectile as a result of ignition of propellant in the combustion chamber, and vents for expulsion of combustion products from the ignition of propellant out of the projectile base after initial movement of the piston. A casing is secured to the base of the projectile body enclosing the piston and vents prior to the ignition of propellant, and a separable joint is between the casing and the base of the projectile body. Upon ignition of propellant in the combustion chamber by movement of the piston in the one direction, the piston is forced in the opposite direction and causes the separable joint to separate, leaving the casing in the barrel such that after the piston completes exertion of propulsion force, combustion products of the ignition of propellant are expelled through the vents out of a lower end of the projectile and solid combustion byproducts from the ignition of the propellant are collected in the casing. The propellant in the combustion chamber may be ignited mechanically.

In a corresponding aspect, the present invention is directed to a method of launching a projectile from a launcher system having a barrel and a breech comprising providing a projectile body having a combustion chamber for propellant, a piston moveable in one direction to ignite the propellant in the combustion chamber and in an opposite direction to extend out a base of the projectile as a result of ignition of propellant in the combustion chamber, and vents for expulsion of combustion products from the ignition of propellant out of the projectile base after initial movement of the piston. A casing is secured to the base of the projectile body by a separable joint between the casing and the projectile body base, the casing enclosing the piston and vents prior to the ignition of propellant. The method includes moving the piston in the one direction to ignite propellant in the combustion chamber, causing the piston to be forced in the opposite direction and causing the joint to separate, thereby leaving the casing in the barrel. After the piston completes exertion of propulsion force, combustion products of the ignition of propellant are expelled through the vents out of a lower end of the projectile and solid combustion products from the ignition of propellant are collected in the casing.

In both the apparatus and method aspects of the invention as described above, the propellant in the combustion chamber may be ignited by an electrically- or mechanically-initiated primer. The separable joint may be separated upon a predetermined force by the piston to separate the casing from the projectile body upon ignition of propellant in the combustion chamber and extension of the piston out of the projectile base. The separable joint may comprise a flange in one of the casing or projectile base secured in a groove in the other of the casing or projectile base, or may comprise a reverse or conical joint flange between the casing and projectile base.

DESCRIPTION OF AN EMBODIMENT OF THE INVENTION

In describing the embodiment of the present invention, reference will be made herein toFIGS.1-21of the drawings in which like numerals refer to like features of the invention.

Certain terminology is used herein for convenience only and is not to be taken as a limitation of the invention. For example, words such as “upper,” “lower,” “left,” “right,” “horizontal,” “upward,” “downward,” or the like, merely describe the configuration shown in the drawings. Indeed, the referenced components may be oriented in any direction and the terminology, therefore, should be understood as encompassing such variations unless specified otherwise. For purposes of clarity, the same reference numbers will be used in the drawings to identify similar elements.

Additionally, in the subject description, the words “exemplary,” “illustrative,” or the like, are used to mean serving as an example, instance, or illustration. Any aspect or design described herein as “exemplary” or “illustrative” is not necessarily intended to be construed as preferred or advantageous over other aspects or design. Rather, the use of the words “exemplary” or “illustrative” is merely intended to present concepts in a concrete fashion.

The exemplary piston/rocket projectile40of the present invention as shown inFIGS.1and2includes a cylindrically shaped outer body60having an ogive or blunt shaped dome62at its nose or front end and a casing50secured to body60at its opposite, lower or base end to seal the projectile base61. Casing50has a flat base59and on its periphery above the base, an extractor groove58and an outer cylindrical extension54above the groove. Inserted within body60are lower inner sleeve70and upper inner sleeve80, which each have cylindrically shaped inner surfaces that slidingly receive piston90, which may slide therein with a slight interference. Body60may be made from any suitable material such as a composite or polymer. Lower inner sleeve70may be made from a metal or alloy such as extrudable 6061-T6 aluminum. Upper inner sleeve80may be made from a metal or alloy such as steel. Piston90may be made from a metal or alloy such as 7075-T6 aluminum. Casing50may be made from a metal or alloy such as aluminum or may have a composite construction of a polymer with a metallic insert molded into a plastic casing body with annular ring, as discussed further below.

The connection or joint between projectile body60and casing50is achieved by an interlocking, annular structure comprising a cylindrical extension64extending from the lower or rear end of body60within an outer cylindrical extension54extending up or forward from casing50, with the outer diameter of extension54being comparable to the outer diameter of projectile body60, as shown inFIGS.2and8. Outwardly extending body flange66and inwardly extending casing flange56fit snugly within complimentarily shaped grooves in casing extension54and body extension64, respectively. The flanges and grooves, positioned adjacent the outer diameter of casing50and body60, are configured to be able to have a snap fit as they are pushed together during assembly of the casing to the projectile body. While the above flange and groove configuration are preferred, other configurations are not precluded, for example, having the body flange extending inwardly and casing flange extending outwardly. It should be understood by a person skilled in the art that any configuration sealing the casing50and the body60could be permissible, including acceptance of a flange within an annular channel.

Lower inner sleeve70is received in a tight fit within the lower portion of outer body60. Upper inner sleeve80is likewise received in a tight fit within the upper portion of the outer body60, and the lower end of sleeve80is stepped in with a smaller diameter to fit within the upper end of sleeve70. In some embodiments, upper sleeve80and lower sleeve70may be of a single construction within body60. Piston90has a cylindrical elongated body sized to slide freely within the inner bore of lower inner sleeve70and a cylindrical head96of larger diameter sized to slide freely within the inner bore of upper inner sleeve80. The cylindrical construction of piston90and head96is exemplary only, and may be of any construction so that sliding within the inner bore of sleeve80is permitted. As depicted inFIGS.3and4, channels72are formed in the inner surface of lower inner sleeve70, for example by extrusion along the entire inner bore thereof, and are enclosed along their length at the upper end in part by the stepped-in portion of upper inner sleeve80and at the lower end in part by the outer surface of the elongated body of piston90. The channels72in the lower portion of sleeve70form in cross-section non-circular passageways along approximately one-half of the length of the sleeve70. Three of these channels72are shown in the example as a “Y” shape equally spaced around the periphery of piston90. These lower end channels72and the mating portions of the outer wall of the piston90elongated body form gas vents, as will be described further below.

Combustion chamber100as shown inFIGS.2and5is formed between the upper end of the interior of upper inner sleeve80and the upper end94of piston head96. Propellant101in combustion chamber100may be electrically ignited by applying a current from a battery132and capacitor134power source via a circuit extending along or through the launcher barrel (FIG.5). As shown in the schematic, one leg of the circuit in the launcher barrel connects via contact126with an upper portion of projectile body60. A metal electrode110or any other suitable conductive means is provided with an exposed outer end portion adjacent ogive62that connects to contact126and extends inwardly and has a 90-degree turned contact tab that travels through an opening in the forward end of upper inner sleeve80. The opposite inner end portion112of electrode110makes contact with an electronic primer at the forward end of combustion chamber100. Electrode110may be inserted or molded into body60. The other ground leg of the circuit in the launcher barrel includes contact128that connects with casing50, which is in contact with the lower end92of piston90. If casing50is not made from a metal or alloy, it may have a composite construction of a polymer or similarly non-conductive material with a metallic electrode slug or terminal bridge insert forming contact128molded therein and extending from the outer surface of casing base59to the casing inner surface52for conductivity with the lower end of piston90. Because of the use of electrode110as the first circuit leg, no electrically insulating coating is needed on piston90as part of the ground leg.

When projectile40is loaded into launcher120, ignition of the propellant is achieved by closing switch130and discharging the ignition circuit which travels in one leg from a contact126in the launcher barrel through electrode110and in the other ground leg from a contact128in the launcher barrel breech through the casing50and piston90. For example, a 150V capacitor134may be discharged to supply current to energize a primer, such as the Remington ETRONX primer, and ignite the propellant charge in the combustion chamber100. It should be understood by those skilled in the art that the use of 150V capacitors to energize Remington ETRONX primers are only one example of providing ignition of a propellant charge within a combustion, and that other ways of providing a propellant charge within a combustion chamber are not precluded.

FIG.6depicts the initial piston thrust portion of the launch of projectile40from launcher120. As the propellant explodes, the hot combustion gases102force piston90downward. Instead of directly contacting the barrel breech face as in U.S. Pat. No. 8,342,097, piston lower end92instead contacts casing inner surface52and applies force against the casing50structure to propel the remainder of the projectile forward. The joint between the projectile body60and casing50provides a type of shear flange in which column thickness of the joint materials regulates shear strength to control the release of the projectile from the casing at optimal internal pressures. In the embodiment shown inFIG.9, the casing flange56is configured to be frangible, i.e., to shear at a desired force substantially along line S, for example, 5 to 8 lbs. of linear force in the direction along the axis of the projectile. The joint may be configured via selection of materials and shape and thickness to achieve any desired separation force. Alternatively, the projectile body flange66may be configured to be frangible to shear along line S′. Other frangible geometrical configurations may be used in place of the joint configuration shown herein. For example, the shear flange may be interrupted and extend around only a portion of the circumference of the casing and projectile body, to reduce the force needed to separate the joint. The length of casing50relative to the length of projectile body60may be increased beyond that shown, so that the height of casing extension54may be greater than that depicted in the drawings. Thus, it will be understood by a person skilled in the art that other configurations of releasing a casing from a projectile are not precluded, and the above cited configurations are exemplary. A shear flange might be obsoleted because of retention within the base cap; or might be minimized in elevation to just hold the piston in assembly.

After the shear flange S of the joint between casing50and projectile body60is broken, projectile40is free to move forward by virtue of the force applied by piston90out of the projectile base61against casing50, the latter being thrust against and remaining in the breech of the launcher barrel. As the piston initially travels downward and rearward, mechanical force of the piston thrust alone propels the projectile40, which initially carries with it the sheared-off casing flange portion56of casing extension54. As shown inFIG.6, before the piston reaches the limit of its travel, at approximately 90% of the total distance of travel of the piston, the upper or forward end94of the piston passes the lower end of upper inner sleeve80and reaches the forward end of gas channels or vents72formed in lower inner sleeve70, which extend to the lower end of projectile body60. The exposure of the three channels72shown in the “Y” shape around the periphery of piston90as the top of piston passes by act as valves for the second stage propulsion of the projectile. Once channels and vents72begin to open to the exploding propellant, the combustion products102expel out of the lower end of the vents72of the projectile, and further expel rocket energy from the ignition charge. Piston90continues to move downward until it is fully extended, as shown inFIG.7. Once the piston90is fully extended and the piston base92lifts off and separates from contact with the casing50, the force of the combustion gases102out of the base91of projectile40alone add further force to propel the projectile from the launcher barrel124, as shown inFIG.7. For non-lethal rounds, the projectile speed may be in the range of about 300-400 ft./sec. The barrel may have a rifled interior surface to impart twist to the projectile as it moves through during the rocket propulsion stage of launch.

With a typical charge of 35 mg of gunpowder, and even if the composition is high in nitrogen-based compounds, there still is produced considerable carbon and other solid combustion residue104, which is captured in the defined contained area inside the internal cup shape of broken-off casing50as shown inFIG.7. The casing50remaining in the launcher barrel breech122provides the means to contain and hold the burnt, expelled gunpowder residue104of each projectile round, thereby keeping the barrel120chamber relatively clean and greatly extending the duty/cleaning cycle of the launcher.

As an alternative to the ETRONX primer and propellant system described above, a gel-type explosive may be employed, which combines the primer and main charge of the propellant. In such case, as shown inFIG.2, the primer may be eliminated, the electrode may be surrounded by annular insulator114, and the electrode end112in combustion chamber100may be extended into a gel-type propellant itself to ignite the propellant101.

In a further modification shown inFIG.10, an electrically non-conductive layer115(see alsoFIGS.11and12) is disposed between the gel-type propellant101and the upper end of combustion chamber100opposite upper end94of piston90, and has a central opening116for receiving electrode end112. Electrically non-conductive layer115may be made of a polymer with a thickness of approximately 0.15 in. (0.4 mm) and may form a layer within combustion chamber100extending up to the entire width of combustion chamber100, and may further extend117in a cup shape (FIGS.11and12) along the side walls of combustion chamber100. An electrically conductive layer118is disposed adjacent electrically non-conductive layer115and may similarly extend up to the entire width of the combustion chamber to form a layer between the electrically non-conductive layer and the gel-type propellant101. Electrically conductive layer118, shown in the form of a metal disk or plate of stainless steel or aluminum of approximately 0.3 in. (0.8 mm) thickness (FIGS.13and14), may have a stamped or otherwise formed projection119extending from the center of the surface opposite the propellant to facilitate good electrical contact with end112of electrode110. Electrically non-conductive layer115and side walls117form an insulative liner to ensure that the igniting electrical current is transferred directly to the gel-type propellant101and not dissipated into the metal walls of the upper portion of inner sleeve80surrounding the combustion chamber100. Electrically conductive layer or plate118ensures that the igniting electrical current is transferred uniformly along the end of the gel-type propellant within the upper end of the combustion chamber and further acts as a pressure-directing shutoff, to ensure that the force of the ignited combustion products is in the direction of piston90.

The gel-type explosive provides an improvement over gunpowder-type primer and propellant systems because the pressure vs. time curve is flatter. For low velocity projectiles, the ignition thrusts the projectile into the rifling of the barrel with a slower, more uniform combustion rate. As a result of the elimination of the ETRONX primer ignition and the direct contact of the electrode110or the electrically conductive disk118with the gel propellant101, the energy is transferred more rapidly to the piston, thereby increasing efficiency of the piston propulsion stage and increased velocity with less propellant. Additionally, the combustion byproducts are water vapor, hydrogen and reduced solids, so that less residue remains in the barrel and weapon duty cycles is increased.

The domed ogive of projectile40shown may be further modified in accordance with the intended use of the projectile. While the projectile shown inFIGS.1-14may be employed as a non-lethal projectile with the blunt trauma ogive62and body60, further modifications may include the additions of a die marker round, as shown inFIGS.15and16. Ogive62′ of projectile40′ may house, for example, a ⅜ in. diameter rupture capsule140that can hold various marker/paint formulation, as shown inFIG.16in cross-section. As best shown inFIG.15, the nose62′ cover may also be pre-molded with tear joints142extending from the tip of the nose down a portion of the side, to aid in opening of capsule140upon contact with the intended target. In some embodiments, the die marker nose62′ may have a smaller diameter than that of the body60′ so that the rifling of the launcher barrel does not disturb the perforations142during loading and firing of round40′. The die marker round40′ has the same headspace as the blunt trauma jacket40, thus permitting interchangeability of rounds40,40′ within a single launching system. The different use body jackets60,60′ may be configured to fit over a common combustion assembly of upper inner sleeve80, lower inner sleeve70and the combustion chamber100and piston90therein, and to connect the lower end to a common casing50. Additionally, other variant body jackets60,60′ may include a sticky chip that will have some electronics with an adhesive to stick to a target, to monitor location thereof.

The casing may be headstamped with identifying information such as caliber, round type, manufacturing date and/or other data. The casing also hermetically seals the projectile round from air or water invasive contamination, thus extending the shelf life significantly.

Upon activation of a bolt handle, slide, charging handle, or other similar device known in the art, the casing may be extracted at the end of the bolt stroke via a knockout rod and extractor system engaging casing extractor groove58. Casing groove58or another extractor groove molded or formed into the projectile body or jacket60may be used to enable mechanical means to eject a live cartridge that has malfunctioned.

A mechanically-initiated percussion primer may be used in place of the ETRONX primer described previously. In this embodiment of the projectile40′ of the present invention as shown inFIG.17, the piston90′ has a striker feature152extending away from piston upper end94, and the primer150in the primer cup is rotated around to face the rear of the projectile40′. Casing50′ includes a central opening55to receive a cylindrical transfer button154, slideably captured and moveable linearly along the projectile longitudinal axis, which may be struck in the direction of arrow160on transfer button base158by an otherwise conventional striker mechanism in the launcher breech (not shown) and move forward to cause the top face156to strike the base92of piston90′. A transfer button shoulder or flange157extends outwardly to a larger diameter than a casing step57of casing central opening55to prevent the transfer button from moving downward out of the casing50′. The impact of transfer button154then causes piston90′ to move forward toward primer150, so that the piston striker152may contact the surface of the primer cup to crush and ignite the primer fulminate (i.e., a moderately insensitive explosive) and mechanically ignite the propellant101in combustion chamber100, whereby the combustion gasses force the primer cup against piston90′ and consequently the piston downward against transfer button154and casing50′. The structure and operation of the projectile lower extension64and cylindrical extension54of casing50′ to hold and then separate the projectile body and casing upon ignition of the propellant are described further below, but may also be otherwise as described above in connection with the electronic primer version of projectile40, for example as shown inFIGS.8and9.

Another embodiment of the alternate mechanically-initiated primer mechanism in projectile40′ is shown inFIG.18. Casing50′ includes transfer button154in opening55as shown inFIG.17, but with a smaller diameter top surface156′. Transfer button top surface156′ is forced by impact of the striker in direction160to contact the base172of a cylindrical transfer-striker pin170slideable within a central opening91in the body of piston90″. Striker-transfer pin170is then projected forward within piston90″ until striker-transfer head172strikes and ignites primer150. Transfer-striker170has a lower mass than piston90′ inFIG.17, and likely lower friction in the striker column. The ignition of the propellant in chamber100then forces striker-transfer170downward back into piston90″ and piston90″ downward so that piston base92″ contacts and forces against transfer button154and casing50′. Casing step57prevents the transfer button from moving downward out of the casing opening55and shoulder176at the base of transfer-striker head172prevents the striker-transfer pin from sliding downward and out of piston90″. Again, the structure and operation of the projectile lower extension64and casing extension54to hold and then separate the projectile body and casing upon ignition of the propellant is described further below, but may also be otherwise as described above in connection with the electronic primer version of projectile40.

FIGS.19and20depict further alternate mechanically-initiated primer embodiments of projectile40′ wherein the transfer button shown inFIGS.17and18is removed, and the base92′ of piston striker90′ is extended to occupy the space once occupied by the transfer button. As shown inFIG.19, casing50′ central opening55is sized to receive and permit access to base92′ of piston90′ by movement in the direction of arrow160of an otherwise conventional striker mechanism168in the launcher162barrel breech. This configuration removes one joint, transfer button154, whereby the impact of the striker directly causes piston90′ to move forward toward mechanical primer150, thereby simplifying the energy transfer from the striker to the primer150. InFIG.19, piston striker152has a constant radius, and inFIG.20(showing casing50′ and projectile outer body60removed), piston striker152′ has a smaller radius at the tip and a taper to the piston upper end94. Also, inFIG.20the cup for primer150is wider and has a larger shelf in projectile upper inner sleeve80supporting it. Upon explosion of propellant101, the combustion gases forces piston90′ downward so that piston lower end92′ moves through and out of the opening55in casing50′ and applies force against the launcher barrel breech face164(instead of against the casing base or transfer button) to propel the projectile forward. The launcher's extractor system portion166engages casing extractor groove58to hold casing50′ in place as the projectile is fired. As before, the joint between extension64of projectile body60and extension54of casing50′ controls the release of the projectile from the casing at optimal internal pressures. Although casing50′ in the embodiment ofFIG.19has the opening55through which piston90′ moves, still a significant amount of solid combustion byproducts from the ignition of the propellant are collected in the casing.

Instead of the stepped frangible shear flange between projectile body extension64and casing extension54as shown inFIGS.2,8and9, the piston/rocket projectile40,40′ of the present invention may utilize a separable joint between the two, such as a conical tapered joint. As shown inFIG.21, casing50′ has casing upper extension54having outer and inner surfaces53a,53b, respectively, which mates with projectile lower extension64extending from the base of the projectile body60and having outer and inner surfaces63a,63b, respectively. The projectile outer body60and casing upper extension outer surface53ahave the same diameter A. The inner surface53bof casing upper extension54has a diameter less than A, and is not parallel to the outer surface53a, such that diameter B2at the casing upper extension distal end is less than the diameter B3of the casing upper extension closer to base59. This produces an angle α, for example 2°, between the casing50′ longitudinal centerline and upper extension inner surface53b. When the casing upper extension54and/or projectile body lower extension64are made of a polymer or other material with suitable flexibility, the diameter B1of the distal end of projectile body lower extension64may be slightly greater than diameter B2at the distal end of casing upper extension54, so that the extensions54and/or64flex and change in diameter sufficiently with moderate force as the male projectile body lower extension64is inserted into the female casing upper extension54to make the joint. The diameter of the projectile body lower extension64closer to nose62is less than diameter B1, so that the outer surface63aof the projectile body lower extension may have the same or different taper angle β with the projectile longitudinal centerline than angle α of the casing upper extension inner surface53b. This results in an interference fit in cross-sectional view between two frustum-shaped extensions54,64, using a reverse or dovetail-type conical joint, that requires a predetermined force threshold to achieve separation, which may be set by the extension angles α, β, the dimensions of the extensions, and the materials used, similar to the manner in which the predetermined force is set to shear the frangible joint described above. A slightly less taper angle β of the projectile body lower extension outer surface63ais believed to result in a more self-tightening joint to better control the overall length of the projectile and provide a better seal against intrusion of contaminants such as water, moisture and oils.

The present invention advantageously reduces and/or significantly eliminates fouling residue on a bolt face electrode inside the barrel chamber. The present invention provides the advantage of a method and apparatus that may be used with an electrically or mechanically energized two stage piston/rocket projectile that captures the majority of the ignition debris and further may be readily evacuated with each round, thereby leaving the chamber with little to no propellant residue. This method and apparatus increases the duty cycle and fired projectile round count before operational field cleaning is needed. In addition, due to the larger diameter of shearing between the base cap and projectile joint, the present invention offers a more accurate release of the projectile within the launching system.