US20090308274A1

US20090308274A1 - Integrated Pusher Plate for a Canister- or Gun-Launched Projectile and System Incorporating Same

Info

Publication number: US20090308274A1
Application number: US12/137,187
Authority: US
Inventors: Wayne K. Schroeder; Umang R. Patel; Johnny E. Banks
Original assignee: Lockheed Martin Corp
Current assignee: Lockheed Martin Corp
Priority date: 2008-06-11
Filing date: 2008-06-11
Publication date: 2009-12-17
Also published as: WO2010036424A1

Abstract

A pusher plate assembly for launching a projectile includes a pusher plate, a pressure seal circumferentially extending about the pusher plate, a cage extending from an aft side of the pusher plate, and a plurality of propellant portions disposed in the cage. A projectile system includes a launching tube, a projectile disposed in the launching tube, a pusher plate assembly disposed between an aft end of the projectile and the launching tube, a fuze, a charge igniter operatively associated with the fuze and the plurality of propellant portions, and a retainer disposed within the launching tube proximate a mouth of the launching tube. The pusher plate assembly includes a pusher plate, a pressure seal circumferentially extending about the pusher plate to seal an annulus between the pusher plate and the launching tube, a cage extending from an aft side of the pusher plate, and a plurality of propellant portions disposed in the cage.

Description

BACKGROUND

1. Field of the Invention
The present invention relates to projectile launching systems.
2. Description of Related Art
Many modern projectiles, such as missiles, rockets, and the like, are launched from canisters or guns. In some projectile systems, thrust from a projectile's motor is used to launch the projectile from a canister or gun. Using the projectile's thrust to launch the projectile, however, reduces the amount of propellant available to propel the projectile to its intended target.
In response to this problem, some projectile systems employ a launching propellant, which is separate from the projectile's propellant, to launch the projectile from the canister or gun and to provide an initial velocity to the projectile. For example, FIG. 1 depicts a projectile system 101 in a pre-launch configuration. Projectile system 101 includes a projectile 103 disposed in a canister 105. Disposed between an aft end 107 of projectile 103 and canister 105 is a propellant 109 and a pusher plate 111. When projectile 103 is to be launched from canister 105, a propellant igniter 113 is activated to ignite propellant 109. Expanding gases generated by the burning propellant 109 urges pusher plate 111, and thus projectile 103, generally in a direction corresponding to an arrow 115. Shortly before projectile 103 exits canister 105 or upon projectile 103 exiting canister 105, a projectile motor igniter 117 ignites a motor (not shown) of projectile 103. Thrust from the projectile motor propels projectile 103 toward its intended target.
It is desirable, however, for canister 105 to be as small as possible to minimize the size of the overall projectile system and to minimize cost. However, as shown in FIG. 2, the configuration of projectile system 101 accelerates projectile 103 very quickly, which often exceeds the acceleration rating of projectile 103. Moreover, the acceleration of projectile undesirably decreases substantially over distance.
To overcome this problem, as shown in FIG. 3, projectile 101 and pusher plate 111 are spaced away from propellant 109 to provide a space 301 for propellant gases to initially accumulate, thus decreasing the maximum acceleration, and particularly inhibiting an acceleration spike, of projectile 103, as shown in FIG. 4. Such a configuration, however, increases the overall length of canister 105 by a distance L, which is undesirable for at least the reasons set forth above.
There are many designs of projectile launching systems well known in the art, however, considerable shortcomings remain.

DESCRIPTION OF THE DRAWINGS

The novel features believed characteristic of the invention are set forth in the appended claims. However, the invention itself, as well as, a preferred mode of use, and further objectives and advantages thereof, will best be understood by reference to the following detailed description when read in conjunction with the accompanying drawings, in which the leftmost significant digit(s) in the reference numerals denote(s) the first figure in which the respective reference numerals appear, wherein:

FIG. 1 is a stylized, side, cross-sectional view of one particular conventional projectile system;

FIG. 2 is a graph illustrating a particular acceleration versus distance curve for the projectile of the conventional projectile system of FIG. 1;

FIG. 3 is a stylized, side, cross-sectional view of an alternative conventional projectile system;

FIG. 4 is a graph illustrating a particular acceleration versus distance curve for the projectile of the conventional projectile system of FIG. 3;

FIG. 5 is a stylized, side, cross-sectional view of an illustrative embodiment of a projectile system;

FIG. 6 is a stylized, side, elevational view of a pusher plate assembly of the projectile system of FIG. 5; and

FIGS. 7-9 depict one particular embodiment of a method for operating the projectile system of FIG. 5.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Illustrative embodiments of the invention are described below. In the interest of clarity, not all features of an actual implementation are described in this specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developer's specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure.
A pusher plate assembly for launching a projectile includes a pusher plate, a pressure seal circumferentially extending about the pusher plate, a cage extending from an aft side of the pusher plate, and a plurality of propellant portions disposed in the cage.
A projectile system includes a launching tube, a projectile disposed in the launching tube, a pusher plate assembly disposed between an aft end of the projectile and the launching tube, a fuze, a charge igniter operatively associated with the fuze and the plurality of propellant portions, and a retainer disposed within the launching tube proximate a mouth of the launching tube. The pusher plate assembly includes a pusher plate, a pressure seal circumferentially extending about the pusher plate to seal an annulus between the pusher plate and the launching tube, a cage extending from an aft side of the pusher plate, and a plurality of propellant portions disposed in the cage.
A method for launching a projectile from a launch tube includes providing a pusher plate assembly disposed between the projectile and the launch tube. The pressure plate assembly includes a pusher plate, a pressure seal circumferentially extending about the pusher plate to seal an annulus between the pusher plate and the launching tube, a cage extending from an aft side of the pusher plate, and a plurality of propellant portions disposed in the cage. The method further includes igniting the plurality of propellant portions, burning an opening in the cage with the ignited plurality of propellant portions, urging the projectile with expanding gases produced by the ignited plurality of propellant portions, and allowing a progressively larger fraction of the plurality of propellant portions to escape the cage as the pressure plate assembly traverses within the launch tube.
Referring to FIG. 5 in the drawings, an illustrative embodiment of a projectile system 501 comprises a projectile 503, a launching tube 505, a pusher plate assembly 507, a charge igniter 509, a fuze 511, and a retainer 513. It should be noted that launching tube 505 may be any tube from which a projectile, such as projectile 503, is launched, e.g., a projectile canister, a gun barrel, or the like. Projectile 503 is disposed in launching tube 505 and, in certain embodiments, may be positioned within launching tube 505 by conventional sabots or other such spacers, which are not shown. It should be noted that, while projectile system 501 is discussed herein as comprising launching tube 505, projectile system 501 may alternatively comprise a gun or gun barrel from which projectile 503 is launched. Pusher plate assembly 507 is disposed between an aft end 515 of projectile 503 and launching tube 505. Charge igniter 509 extends between fuze 511 and charge igniter 509. Generally, pusher plate assembly 507 urges projectile 503 from launching tube 505 upon activation of charge igniter 509 by fuze 511 and ignites a motor 517 of projectile 503, as is discussed in greater detail herein.
FIG. 6 depicts an enlarged view of one particular embodiment of pusher plate assembly 507. It should be noted that elements of projectile system 501 included in FIG. 6, with the exception of pusher plate assembly 507, are depicted in phantom to better illustrate pusher plate assembly 507. In the illustrated embodiment, pusher plate assembly 507 comprises a pusher plate 601, a pressure seal 603, a cage 605, a plurality of propellant portions 607, a projectile motor igniter 609, and a motor igniter controller 611. In one embodiment, however, projectile motor igniter 609 and motor igniter controller 611 are omitted. In use, projectile 503 rests on or abuts pressure 601 and pressure seal 603 extends between pusher plate 601 and launching tube 505, substantially sealing an annulus 613 between pusher plate 601 and launching tube 505. Preferably, pressure seal 603 comprises an elastomer, such as a silicone elastomer. Pusher plate 601, pressure seal 603, and launching tube 505 define a substantially closed chamber 519 in which the plurality of propellant portions 607 burns, as is described in greater detail herein.
Still referring to FIG. 6, cage 605 extends from an aft side 615 of pusher plate 601. Preferably, cage 605 is formed of wire mesh. Part of cage 605 is removed in FIG. 6 to better reveal the plurality of propellant portions 607 disposed therein. The plurality of propellant portions 607 comprises a solid propellant or a combination of solid propellants; however, the particular composition of propellant portions 607 is implementation specific. In some embodiments, propellant portions 607 comprise a nitrate-based solid propellant, while in other embodiments, propellant portions 607 comprise an aluminum-based solid propellant. For example, if the particular implementation lends itself to the use of a high-energy propellant, an aluminum-based propellant may be used. However, if smoke is not desirable at the launch of a projectile, such as projectile 503, a non-aluminum based propellant may be used. The plurality of propellant portions 607 may comprise any propellant material or combination of propellant materials that are suitable, when activated, for urging projectile 503 from launching tube 505. Preferably, the propellant portions of the plurality of propellant portions 607 are generally spherical in shape, but other shapes are contemplated by the present invention.
Still referring to FIG. 6, motor igniter controller 611 is attached to pusher plate 601 and is preferably disposed within pusher plate 601. Motor igniter controller 611 is coupled with projectile motor igniter 609, which extends into a nozzle 617 of projectile motor 517, to control the activation of projectile motor igniter 609, as is discussed in greater detail herein.
FIGS. 7-9 depict one particular embodiment of a method for using projectile system 501. In FIG. 7, fuze 511 (shown in FIG. 5) is initiated to activate, as represented by a graphic 701, charge igniter 509 (shown in FIG. 5). Charge igniter 509 ignites at least some of the plurality of propellant portions 607. At some point in time after ignition, however, substantially all of the plurality of propellant portions 607 are ignited. It should be noted that, at ignition, the plurality of propellant portions 607 are preferably packed in cage 605. Thus, initially, not all surfaces of the plurality of propellant portions 607 are available for burning, as some surfaces of the plurality of propellant portions 607 are in contact with other surfaces of the plurality of propellant portions 607.
Still referring to FIG. 7, charge igniter 509 and/or the ignited part of the plurality of propellant portions 607 burn through cage 605, allowing some of the plurality of propellant portions 607 to escape cage 605 into chamber 519. The burning propellant portions of the plurality of propellant portions 607 create expanding gases that pressurize chamber 519. When the force acting on pusher plate 601 and pressure seal 603 due to the pressure generated by the expanding gases in chamber 519 exceeds the force on pusher plate 601 and pressure seal 603 due to gravity and friction between pressure seal 603 and launching tube 505, pusher plate 601, pressure seal 603, projectile 503, the remaining portion of cage 605, and the portion of the plurality of propellant portions 607 remaining in cage 605 are urged in a direction generally corresponding to an arrow 703.
Referring now to FIG. 8, as pusher plate 601 and pressure seal 603 are urged in the direction generally corresponding to arrow 703, a volume of chamber 519 increases, a larger portion of cage 605 is burned away, and a greater fraction of the burning plurality of propellant portions 607 escapes cage 605 into chamber 519. As more of the burning plurality of propellant portions 607 escapes into chamber 519, more propellant surface area is exposed for burning, thus increasing the burning rate of the plurality of propellant portions 607 and creating a greater volume of expanding gases, which continue to pressurize chamber 519. As chamber 519 continues to be pressurized, pusher plate 601, pressure seal 603, projectile 503, the remaining portion of cage 605, and the portion of the plurality of propellant portions 607 remaining in cage 605 are further urged generally along arrow 703.
It should be noted that the burning surface area of the plurality of propellant portions 607, and thus the burn rate of the plurality of propellant portions 607, increases in relationship to the fraction of the plurality of propellant portions 607 that escape cage 605. Generally, chamber 519 increases in volume as a larger fraction of the plurality of propellant portions 607 escapes cage 605. This relationship provides a flatter acceleration curve for projectile 501 than that shown in FIG. 2 and, in one embodiment, provides an acceleration curve for projectile 501 corresponding to that shown in FIG. 4.
Referring now to FIG. 9, motor igniter controller 611 (shown in FIG. 6) ignites projectile motor igniter 609, as represented by a graphic 901, prior to projectile 503 fully exiting launching tube 505. Projectile motor igniter 609 extends into nozzle 617 of projectile motor 517 to start projectile motor 517 when activated by motor igniter controller 611. Motor igniter controller 611 may be operated to control projectile motor igniter 609 using a variety of sensed conditions. For example, in one particular embodiment, motor igniter controller 611 comprises an accelerometer, such that motor igniter controller 611 operates projectile motor igniter 609 when motor igniter controller 611 experiences acceleration at a predetermined level. The predetermined acceleration level can be a predetermined acceleration level in an upward trend of acceleration levels or a predetermined acceleration level in a downward trend of acceleration levels. In another embodiment, motor igniter controller 611 comprises a position sensor, such that motor igniter controller 611 operates when motor igniter controller 611 reaches a certain location within launching tube 505, corresponding to a desired location of projectile 503 with respect to launching tube 505. In one embodiment, the position sensor interacts with retainer 513, thus providing the sensory input to motor igniter controller 611 to operate projectile motor igniter 609. Alternatively, motor igniter controller 611 comprises a timer, such that motor igniter controller 611 operates projectile motor igniter 609 after a predetermined period of time has elapsed following activation of charge igniter 509. Other scenarios for operating motor igniter controller 611, however, are contemplated by the present invention.
Retainer 513 is fixedly disposed proximate a mouth 521 of launching tube 505. Pusher plate 601, pressure seal 603, the remaining portion of cage 605, and any portion of the plurality of propellant portions 607 remaining in cage 605 are captured within launching tube 505 by retainer 513 as projectile 503 exits launching tube 505, thus inhibiting damage to equipment and personnel about projectile system 501.
Advantages of the invention include, but are not limited to (1) providing a means for launching a projectile from a launching tube that manages the acceleration of the projectile without increasing the size of the launching tube; (2) providing a means for launching a projectile from a launching tube without requiring a high axial acceleration tolerance of the projectile; and (3) providing a means for launching a projectile that further includes a means for igniting a motor of the projectile.
The particular embodiments disclosed above are illustrative only, as the invention may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular embodiments disclosed above may be altered or modified and all such variations are considered within the scope and spirit of the invention. Accordingly, the protection sought herein is as set forth in the claims below. It is apparent that an invention with significant advantages has been described and illustrated. Although the present invention is shown in a limited number of forms, it is not limited to just these forms, but is amenable to various changes and modifications without departing from the spirit thereof.

Claims

1. A pusher plate assembly for launching a projectile, comprising:

a pusher plate;

a pressure seal circumferentially extending about the pusher plate;

a cage extending from an aft side of the pusher plate; and

a plurality of propellant portions disposed in the cage.

2. The pusher plate assembly, according to claim 1, wherein the cage is formed of wire mesh.

3. The pusher plate assembly, according to claim 1, wherein the pressure seal comprises:

an elastomer.

4. The pusher plate assembly, according to claim 1, wherein at least some of the plurality of propellant portions comprises one or more of a nitrate-based solid propellant and an aluminum-based solid propellant.

5. The pusher plate assembly, according to claim 1, further comprising:

a projectile motor igniter; and

a motor igniter controller operatively associated with the projectile motor igniter.

6. The pusher plate assembly, according to claim 5, wherein the motor igniter controller includes an accelerometer.

7. The pusher plate assembly, according to claim 5, wherein the motor igniter controller includes a position sensor.

8. The pusher plate assembly, according to claim 5, wherein the motor igniter controller includes a timer.

9. A projectile system, comprising:

a launching tube;

a projectile disposed in the launching tube;

a pusher plate assembly disposed between an aft end of the projectile and the launching tube, the pusher plate assembly comprising:

a pusher plate;

a pressure seal circumferentially extending about the pusher plate to seal an annulus between the pusher plate and the launching tube;

a cage extending from an aft side of the pusher plate; and

a plurality of propellant portions disposed in the cage;

a fuze;

a charge igniter operatively associated with the fuze and the plurality of propellant portions; and

a retainer disposed within the launching tube proximate a mouth of the launching tube.

10. The projectile system, according to claim 9, wherein the cage is formed of wire mesh.

11. The pusher plate assembly, according to claim 9, wherein the pressure seal comprises:

an elastomer.

12. The pusher plate assembly, according to claim 9, wherein at least some of the plurality of propellant portions comprises one or more of a nitrate-based solid propellant and an aluminum-based solid propellant.

13. The pusher plate assembly, according to claim 9, further comprising:

a projectile motor igniter; and

14. The pusher plate assembly, according to claim 13, wherein the motor igniter controller includes an accelerometer.

15. The pusher plate assembly, according to claim 13, wherein the motor igniter controller includes a position sensor.

16. The pusher plate assembly, according to claim 13, wherein the motor igniter controller includes a timer.

17. A method for launching a projectile from a launch tube, comprising:

providing a pusher plate assembly disposed between the projectile and the launch tube, the pressure plate assembly comprising:

a pusher plate;

a cage extending from an aft side of the pusher plate; and

a plurality of propellant portions disposed in the cage; igniting the plurality of propellant portions;

burning an opening in the cage with the ignited plurality of propellant portions;

urging the projectile with expanding gases produced by the ignited plurality of propellant portions; and

allowing a progressively larger fraction of the plurality of propellant portions to escape the cage as the pressure plate assembly traverses within the launch tube.

18. The method, according to claim 17, further comprising:

igniting a motor of the projectile with a projectile motor igniter of the pusher plate assembly.

19. The method, according to claim 18, further comprising:

operating the projectile motor igniter based on at least one of an acceleration of the pusher plate assembly, a position of the pusher plate assembly with respect to the launching tube, and an elapsed time from ignition of the plurality of propellant portions.