FORMING TEMPORARY AIRBORNE IMAGES

Abstract: Barrel assembly (10) includes rifled barrel (11) loaded with several pyrotechnic projectiles (12) for selective firing by an electronically controlled system. Each projectile (12) includes body (14), housing (15) containing pyrotechnic material (16), and trailing collar (17) supported on trailing hub (18) of body (14) for limited axial movement. Collar (17) includes leading wall (20) abutting trailing wall (21) of housing (15) and an internally tapered thickened rear part (24) engaging nose (25) of trailing projectile (12) to wedge into sealing engagement with barrel (11). Hub (18) supports propellant capsule (30) connected by electrical leads (31) to contacts (32) on outer cylindrical wall (33) of housing (12). Complementary contacts (34) are supported in barrel (11). Alignment of contacts (34) with contacts (32) occurs during the loading process. Fuse (35) extends between capsule (30) and primer (36) so that material (16) explodes a set time after firing projectile (12) from barrel (11).

Description: FORMING TEMPORARY AIRBORNE IMAGES The present invention relates to forming temporary airborne images and has particular application to forming temporary airborne images for entertainment purposes or advertising purposes. Such airborne images may be produced with fireworks or other projectiles that deploy a medium in the sky for display. Pyrotechnic displays for entertainment purposes have become very popular at events with organisations spending large sums of money in order to provide new and/or interesting airborne displays. To provide individuality, such displays must be custom made or organised. Further the displays are limited by the deployment systems for projecting the fireworks into the sky. This results in the variations being limited and/or expensive to produce. Many displays require large quantities of high explosives to be accumulated at the display site. Thus displays are often staged from a moored barge or pontoon. However the transport of the fireworks to the barge often entails transport through heavily populated areas and this poses a potential danger. Also the fireworks need to be set-up on site and this is generally labour intensive and time consuming. The set-up of fireworks is also very complex in the fusing in order to ensure that the timing of the firing is correct. We have now found an improved apparatus and method suitable for use in forming temporary airborne images such as pyrotechnic displays. The improved apparatus and method employ barrel assemblies from which projectiles for deploying media for creating temporary airborne images such as pyrotechnic projectiles may be launched from a barrel having a plurality of such projectiles axially disposed within the barrel and which are associated with discrete selectively ignitable propellant charges for propelling the projectiles sequentially through the muzzle of the barrel. A sealing engagement is provided between projectiles and barrel so as to prevent rearward travel of an ignited propellant charge to the trailing propellant charge. According to the present invention there is provided a projectile for deployment from a barrel assembly including a barrel having a plurality of said projectiles axially disposed within the barrel and which are associated with discrete selectively ignitable propellant charges for propelling the projectiles sequentially through the muzzle of the barrel, said projectile including:- a housing portion containing material for forming temporary airborne images; an initiator; a propellant capsule associated with the rear end of the housing whereby the propellant charge is ignited by activating the initiator; a fuse link to provide delayed ignition of the pyrotechnic material; a expandable collar wherein said collar is engaged with the housing for support and in operative sealing engagement with the bore of the barrel in an engaged condition and wherein said collar is relocatable relative to the housing whereby said collar is disengaged from operative sealing engagement with bore of the barrel in a relaxed condition for trailing movement with the housing, and wherein the expandable collar provides an open trailing end which engages about the nose of a following projectile or the breech end of the barrel in the case of the last projectile, and a pressure pad mounted on the housing inwardly of the open trailing end wherein said collar is relocated from the engaged condition upon ignition of the propellant and is retained in a relaxed condition by the pressure pad for passage through the barrel and out the muzzle of the barrel. The projectile of the present invention contains material for forming temporary air-borne images. The image forming material may include, for example, explosive matter, incendiary matter, incandescent or luminous matter or other matter to provide a highly visible temporary image. Alternatively, the image forming matter may include smoke, gas, particles or sheets or strips, such as in the nature of chaff, or other material capable of being dispersed to form, an image. The image forming matter may also include means for slowing its descent from its dispersed position, such as a parachute and the like. The projectiles may be arranged in the barrel assemblies such that once fired and the image forming matter deployed, the desired temporary airborne image is formed. Projectiles containing different image forming matter, either differing in colour or form, may be sequentially loaded into each barrel assembly. The image forming matter may be deployed, for example, by explosive means, by stored energy or by separation of separable parts of the projectile to expose the image forming matter or by any other suitable dispersing means. The projectiles of the present invention are fired from barrel assemblies of the type that include a barrel having a plurality of projectiles axially disposed within the barrel and which projectiles are associated with discrete selectively ignitable propellant charges for propelling the projectiles sequentially through the muzzle of the barrel. This invention may utilise barrel assemblies capable of firing a controlled rapid fire sequence of mortar like projectiles and being of the general type described and/or illustrated in our earlier International Patent Applications such as PCT/AU94/00124, PCT/AU96/00379, PCT/AU00/00296 and PCT/AU00/00297. In at least some of these earlier applications, including the earliest filed International Application No PCT/AU94/00124 and PCT/AU96/00379 there are described arrangements for grouping barrels each containing a plurality of projectiles so that a large number of projectiles can be fired in rapid-fire succession. In such arrangements barrels may be formed from a cylindrical shell having a plurality of projectiles axially disposed within the shell for operative sealing engagement with the bore of the shell and discrete propellant charges for propelling respective projectiles. Suitably the barrel assemblies may be of the low-pressure type which fire grenade-like projectiles although high muzzle pressure barrel assemblies may be used. Respective barrel assemblies may be loaded with different projectiles and the barrel assemblies may have different size bores for accommodating different size projectiles. Suitably each projectile includes a trailing collar captively mounted to the projectile body and when stored in the barrel, extends rearwardly to wedge against the nose portion of a trailing projectile body. Suitably the wedging action is provided by a shallow wedge whereby, in use, the trailing end of the collar is expanded into operative sealing engagement with the barrel. The trailing collar may be mounted for limited axial movement relative to the projectile body and the leading end of the collar formed with an annular sealing face engageable with a complementary face formed on the projectile body whereby rearward movement of the projectile body resulting from the reaction of propellant gases thereon forces the its complementary face into sealing engagement with the annular sealing face at the leading end of the collar. The complementary face and the annular sealing face may extend substantially radially and be formed with complementary sealing features thereon. However it is preferred that these faces are complementary part-conical sealing faces which wedge into tight sealing engagement with one another. The leading end part may also be expandable into operative sealing engagement with the barrel. Suitably however the wedging between the part-conical faces are relatively steep faces whereby the leading end of the collar is not expanded into operative sealing engagement with the barrel by the wedging action. Preferably, each projectile is associated with a high-pressure propellant chamber that exhausts to respective low pressure propulsion chambers formed between the adjacent projectiles for efficient low muzzle velocity operation. The high-pressure propellant chambers may be formed integrally with the projectile body or the trailing collar or be provided at the exterior of the barrel to communicate therewith through ports provided through the barrel wall. The housing may be of any suitable configuration that provides for the containment of the pyrotechnic material and is suitably configured for engagement with the trailing end of the expandable collar of the preceding projectile. Preferably the housing is of the type employed with grenade-like projectiles, having relatively squat shape although projectiles having elongate housings could also be employed. The housing may suitably be formed from biodegradable material and/or combustible material. This material may be based on a natural product such as woodchip or a synthetic material, such as a biodegradable polymer. The selection of materials for use in forming temporary airborne images may be any suitable materials and preferable may include pyrotechnic material. The selection of suitable pyrotechnic material is not narrowly critical and the person skilled in the art will be readily able to select appropriate pyrotechnic materials. The initiator may preferably be an electronic initiator whereby the projectiles may be electronically fired at an infinitely variable frequency up to the maximum rate of fire. For firing from a barrel assembly according to an aspect of this invention and arranged for low pressure, low muzzle velocity, the rate of firing may be limited by the time taken for each projectile to leave the barrel and by the time necessary for the gas pressure in the barrel to drop sufficiently to enable the firing of the next projectile. The electronic initiation may be effected by providing exposed contacts on the housing whereby a propellant capsule associated with the rear end of the housing is ignited by enlivening the electrical circuit made through the contacts. In order to mate the contacts with complementary contacts in the barrel there may be provided rifling which is configured for aligned-only insertion of the projectile into the barrel. Insertion may be performed with the collar mated with the housing in its engaged condition or alternatively in its relaxed condition. The propellant capsule may be of a convenient form and include a suitable propellant. The selection of suitable propellants is not narrowly critical the person skilled in the art will be readily able to select appropriate propellants. The propellant capsule is associated with the rear end of the housing. The propellant capsule may be engaged with the end of the housing of located proximate to the end of the housing in the space between the adjacent projectiles, such as within the trailing end of the expandable collar. The propellant is ignited by activating the initiator such that the ignited propellant produces combustion products. The combustion products typically include a gas and the generation of and expansion of the gas propels the projectile through the barrel and out the muzzle of the barrel. The combustion products also activate the fuse link. The combustion products may also include burning or hot materials that can activate the fuse link such as by causing the fuse to ignite. The fuse link may be any convenient fusing such as will be apparent to those skilled in the art of manufacture of fireworks and the like. The fusing may be selected such that the combustion products of the propellant capsule activate the fuse link and cause the fuse link to ignite the pyrotechnic material at the desired time after the projectile has been fire from the barrel assembly. The delayed ignition of the pyrotechnic material may be selected to form the desired images in the sky by igniting the pyrotechnic material of the multiplicity of projectiles at selected times. The fuse link may include other fuses or delay means for igniting the pyrotechnic material. For example timing systems such as electronic timers, twist could systems and the like may be used. Alternatively the fuse link may be in the form of a laser initiation of the pyrotechnic material. The expandable collar may suitably be formed from biodegradable material and/or combustible material. This material may be based on a natural product such as woodchip or a synthetic material, such as biodegradable polymers. The collar is engaged with the housing for support and is in operative sealing engagement with the bore of the barrel in an engaged condition. The expandable collar may be supported on the housing through a fusible body part or by a diaphragm type wall or spider having a central boss which is expanded when engaged over a hub portion of the housing and which relaxes upon removal from the hub portion. The expandable collar suitably has a rearward cylindrical extension from its support on the housing and suitably the outer periphery of the pressure pad extends adjacent the inner surface of the cylindrical extension. The collar is relocatable relative to the housing whereby said collar is disengaged from operative sealing engagement with bore of the barrel in a relaxed condition. The collar is retained by the projectile for trailing movement with the housing. The expandable collar provides an open trailing end that engages about the nose of a following projectile or the breech end of the barrel in the case of the last projectile. Suitably the collar extends rearwardly to wedge about the nose portion of a trailing projectile body. Suitably the wedging action is provided by a shallow wedge whereby, in use, the trailing end of the collar may be expanded into operative sealing engagement with the bore of the barrel. Suitably the configuration of the space into which the ignited propellant propagates and the propellant properties are such that only low barrel pressures occur in use, such as in the order of 2,000psi to 5,000psi. Typically the collar is such that in its relaxed attitude it does not prevent free movement of the projectile through the barrel either for loading purposes or during firing. A pressure pad is mounted on the housing inwardly of the open trailing end. The collar is relocated from the engaged condition upon ignition of the propellant and is retained in a relaxed condition by the pressure pad for passage through the barrel and out the muzzle of the barrel. A direction control means may be provided in a bank of barrel assemblies and may permit uniform pivoting of the barrel assemblies so that the inclination of the axis of the barrel assemblies relative to the axis of a pod containing the bank of barrel assemblies may be selectively varied to enable a target position relative to the pod to be varied. The direction control means may permit individual pivoting of each barrel assembly so that the inclination of each barrel axis relative to a pod axis may be individually varied to enable a target position or individual target positions relative to the pod to be varied. Such individual control may be associated with individual firing control of each barrel assembly if desired. The direction control means may alternatively permit a controlled splaying of all barrel assemblies so that the area covered at the target zone may be selectively varied. Alternatively the direction control means may permit all or some of the above variations to be achieved individually or collectively as required. The pod housing may be of any suitably configuration and may taper towards its base to enable barrel assemblies to be supported in a splayed attitude. The support means may be fold out legs that may be adjustable if desired. In one form the pod has a rectangular pod housing for economy or ease of storage and/or transport and the base thereof constitutes the support means. A pod of barrel assemblies may be fired from a marine platform. The pod may also be fired from an aircraft or from a number of aircraft flying in formation and if desired, with the firing coordinated between the aircraft by a suitable electronic link. Other aspects of this invention relate to methods of loading a barrel with projectiles and methods of delivering a pyrotechnic display as will hereinafter become apparent. In order that this invention may be more readily understood and put into practical effect, reference will now be made to the accompanying drawings which illustrate a typical embodiment of the invention and wherein:- FIG. 1 Is a diagrammatic sectional view of one form of barrel assembly loaded with two projectiles only; FIG. 2 illustrates the construction of a projectile; FIG. 3 illustrates the housing and collar of a projectile separated for loading purposes; FIG. 4 illustrates the final step in the loading process, and FIGS. 5 and 6 illustrate typical cross-sections through the projectile as illustrated at 5-5 and 6-6 in Fig. 2. The barrel assembly 10 illustrated has a rifled barrel 11 loaded with pyrotechnic projectiles 12 which may be selectively fired through electronically controlled ignition in known manner. Each projectile 12 includes a main body part 14 having a housing 15 containing pyrotechnic material 16 and a trailing collar 17 supported on a trailing hub 18 of the body part 14 for limited relative axial movement. The collar 17 has a leading wall 20 which abuts the trailing wall 21 of the housing 15 and an internally tapered thickened rear end part 24 which engages about a correspondingly tapered nose part 25 of a trailing projectile 12 to wedge into sealing engagement with the barrel 11. The hub 18 also supports a propellant capsule 30 connected by electrical leads 31 to contacts 32 on the outer cylindrical wall portion 33 of the housing 12. Complementary contacts 34, which may be spring loaded ball contacts as illustrated or brush type contacts, are supported in the barrel 11. Alignment of these contacts 34 with the projectile contacts 32 is achieved during the loading process through use of non-uniform rifling as described below. In a non-rifled design, the use of longitudinally separated annular contacts in the barrel wall and on the projectile can achieve a similar result. The hub 18 has a fuse 35 therethrough which extends between the propellant capsule 30 to a primer 36 in the pyrotechnic material 16 such that the material 16 will be exploded a set time after firing the projectile from the barrel 11 , this time being set by the fuse 35. Referring to Fig. 2 it will be seen that hub 18 is built up from a leading part 40 integral with the housing 15 and a trailing part 41 which supports the capsule 30 and provides a pressure wall 42 which extends outwardly to terminate adjacent the inner face 43 of the collar 17. These parts 40 and 42 are assembled together, such as by gluing after the collar 17 has been located loosely about a necked portion 44 of the leading part 40. This configuration is illustrated in Fig. 3. The forward portion 46 of the hub 18 in front of the necked portion 44 is dimensioned as an interference fit with the central aperture 47 of the leading wall 20. Thus when the wall 20, and the collar 17 which it supports, is forced onto the hub portion 46 the collar is expanded outwardly into tight engagement with the wall of the barrel 11. This expansion is effected once the collar has been inserted into the barrel in abutment with a previously located projectile so as to positively locate and hold each projectile in place and in operative engagement with the respective contacts 34. Referring to Figs. 3 to 6 it will be seen that the rifling 49 in the barrel 11 is relatively deep and it is arranged in a non-symmetrical manner whereby the projectiles 12 must be aligned in a unique manner before they can be engaged and fed to their fully home position. For loading purpose opposing ones of the rifling beads 48 in the housing 15 have diametrically opposed gaps 53 therein which are not present in the corresponding bead 52 on the collar 17 as shown at 53a. Thus a loading tool 50 having two spiral prongs 51 , and which is insertable through the gaps 53 about the housing 15 to abut the beads 52 at 48b, is used to load the projectile 12, with the collar 17 supported about the necked portion 44, into the rifled barrel 11. Initially the collar 17 is forced rearwardly through the barrel, spiralling into tight engagement with the previously loaded projectile 12. Thereafter as shown in Fig. 4, a load is applied to the nose of the projectile 12 using pushing tool 53 so as to force the hub 18 through the aperture 47 in the collar 17 which passes over the forward portion 46 of the hub 18, expanding the collar 17 and locking the projectile in position with the contacts 32, 34 in engagement with one another and enabling ignition of the propellant in the capsule 30. In use when the propellant in a leading capsule 30 is ignited the gas pressures act directly on the pressure wall 42 forcing the housing 12 forwardly and through the wall 20 until the aperture 47 sits over the necked portion 44. This initial movement releases the collar for free travel with the housing 12 from the barrel 11. At the same time the released collar provides sufficient gas containment behind the projectile for propulsion of the projectile to the desired height before the activated fuse 35 ignites the pyrotechnic material 16 through the primer 36. Further in the above embodiments the collar provides a relatively broad cylindrical surface which engages closely with the bore of the barrel so as to assist in preventing passage of ignited gases between the sleeve and the barrel to the propellant of a trailing projectile. This seal is enhanced in use through expansion of the thickened trailing end upon rearward movement of the following projectile as a result of being subject to propulsion pressures in the barrel from discharge of the leading projectile. In this embodiment the housing and the collar are formed from compressed wood particles so that they will burn up with ignition of the pyrotechnic material.. Any material that does not burn will fall to the ground and degrade. For this purposes the wood particles are suitably bonded with a water-soluble glue to accelerate their degradation. The barrel assemblies 10 of this invention may be set up and fired from a fixed launch pad such as an on-ground pad or a moored vessel. Preferably however the projectiles are fired from barrel assemblies supported on an aircraft which may carry the fireworks to a display site across minimally occupied terrain such as by following a river to a river display site. This will minimise the risk of transporting large quantities of high explosive into a densely populated area. Use of an aircraft as the launch pad also provides the advantage that projectiles may be launched in rapid succession with lateral separation therebetween so as to facilitate accurate formation of images spread across the sky, much in the manner of a printer head firing dots onto a page to produce a printed image It will of course be realised that the foregoing description has been given only by way of illustrative example of this invention and that all such and other modifications and variations thereto as would be apparent to persons skilled in the art are deemed to fall within the broad scope and ambit of this invention as is herein set forth.

Claims: CLAIMS 1. A projectile for deployment from a barrel assembly including a barrel having a plurality of said projectiles axially disposed within the barrel and which are associated with discrete selectively ignitable propellant charges for propelling the projectiles sequentially through the muzzle of the barrel, said projectile including :- a housing portion containing material for forming temporary airborne images; an initiator; a propellant capsule associated with the rear end of the housing whereby the propellant charge is ignited by activating the initiator; a fuse link to provide delayed ignition of the pyrotechnic material; a expandable collar wherein said collar is engaged with the housing for support and in operative sealing engagement with the bore of the barrel in an engaged condition and wherein said collar is relocatable relative to the housing whereby said collar is disengaged from operative sealing engagement with bore of the barrel in a relaxed condition for trailing movement with the housing, and wherein the expandable collar provides an open trailing end which engages about the nose of a following projectile or the breech end of the barrel in the case of the last projectile, and a pressure pad mounted on the housing inwardly of the open trailing end wherein said collar is relocated from the engaged condition upon ignition of the propellant and is retained in a relaxed condition by the pressure pad for passage through the barrel and out the muzzle of the barrel. 2. A projectile according to claim 1 wherein the image forming material is selected from the group consisting of explosive matter, incendiary matter, incandescent and luminous matter. 3. A projectile according to either claim 1 or claim 2 wherein the projectile includes an explosive means for deploying the image forming material. 4. A projectile according to either claim 1 or claim 2 wherein the housing is formed from seperable parts for deploying the image forming material. 5. A projectile according to any one of claims 1 to 4 wherein the housing is formed from materials selected from the group consisting of biogradable materials and combustible materials. 6. A projectile according to any one of claims 1 to 5 wherein the initiator is an electronic initiator whereby the projectiles are selectively electronically fired at a variable rate of fire. 7. A projectile according to any one of claims 1 to 6 wherein the propellant capsule is engaged with the end of the housing of located proximate to the end of the housing in the space between the adjacent projectiles. 8. A projectile according to any one of claims 1 to 7 wherein fusing is selected such that the combustion products of the propellant capsule activate the fuse link and cause the fuse link to ignite the pyrotechnic material at the desired time after the projectile has been fire from the barrel assembly. 9. A projectile according to any one of claims 1 to 7 wherein the fuse link is selected from the group consisting electronic timers, twist count fuses, and laser initiation. 10. A projectile according to any one of claims 1 to 9 wherein the expandable collar is formed from biodegradable material and/or combustible material. 11. A projectile according to any one of claims 1 to 10 wherein the expandable collar has a rearward cylindrical extension from its support on the housing and the outer periphery of the pressure pad extends adjacent the inner surface of the cylindrical extension. 12. A projectile according to any one of claims 1 to 11 wherein the collar extends rearwardly to wedge about the nose portion of a trailing projectile body. 13. A projectile according to claim 12 wherein wedging action is provided by a shallow wedge whereby, in use, the trailing end of the collar may be expanded into operative sealing engagement with the bore of the barrel. 14. A projectile according to any one of claims 7 1o 13 wherein the barrel assemblies are of the low-pressure type which fire grenade-like projectiles. 15. A projectile according to any one of claims 1 to 14 wherein projectile is associated with a high-pressure propellant chamber that exhausts to respective low pressure propulsion chambers formed between the adjacent projectiles for efficient low muzzle velocity operation. 16. A projectile according to claim 15 wherein the high-pressure propellant chamber is formed integrally with the projectile body. 17. A barrel assembly including a plurality of projectiles according to any one of claims 1 to 16 wherein said barrel assembly includes a barrel having a plurality of said projectiles axially disposed within the barrel and which are associated with discrete selectively ignitable propellant charges for propelling the projectiles sequentially through the muzzle of the barrel. 18. A barrel assembly according to claim 17 wherein including a direction control means for pivoting of the barrel assembly so that the inclination of the axis of the barrel assemblies relative to the axis of a pod containing a bank of barrel assemblies may be selectively varied to enable a target position relative to the pod to be varied. 19. A barrel assembly according to claim 18 wherein direction control means permits individual pivoting of each barrel assembly so that the inclination of each barrel axis relative to a pod axis may be individually varied to enable a target position or individual target positions relative to the pod to be varied.

Inventors: O'DWYER JAMES MICHAEL, O'DWYER, JAMES, MICHAEL
Applicants: DWYER JAMES MICHAEL O, METAL STORM LTD, METAL STORM LIMITED, O'DWYER, JAMES, MICHAEL
Application year: 2001
Main classification: F42B4
IPC codes: F42B4, F42B5, G09F13