WO1995033176A1 - Practice land mine simulating detonation by harmless discharge - Google Patents

Abstract

Intendedly harmless discharge device (10, 70, 80, 100, 110) for simulating effects of other explosive devices, has a casing with two chambers. One chamber (10, etc.) holds material to be discharged intendedly harmlessly through associated venting provision (20/26A, B; 77; 87; 102; 120/124; 222A, B, C) of that one chamber. The other chamber (12, 74, 84, 104) holds releasable propellant with associated triggering means (46, 65, 72, 82, 90, 94, 95) for initiating sudden propellant release. The two chambers inter-communicate at least after initiation of propellant release to drive and discharge said material through said venting provision. The venting provision (20/26A, B, etc.) contributes by size shape and location of exit orifices (20, 78, 88, 102, 120, 220A, B, C) and/or by configuration of venting ducts (26A, B; 124, 222A, B, C) to achieving desired pattern of discharged material.

Description

PRATICE LAND MINE SIMULATING DETONATION BY HARMLESS DISCHARGE

DESCRIPTION

TECHNICAL FIELD This invention relates to devices of an intendedly harmless sudden-discharge nature for producing spurts of spray and/or audible noise and/or visible flash.

BACKGROUND ART

Hand-held devices, often called "paint-ball guns", are well known for discharging small well-defined discrete quantities of marker paint or dye with an intendedly high degree of directional accuracy; and find various uses, such as in so-called war-games where participants have need to simulate shooting each other. We believe there is unfulfilled utility for other devices that can discharge much larger quantities of paint etc without requirements for being aimed to achieve momentary directional accuracy.

DISCLOSURE OF THE INVENTION

It is an object of this invention to provide such devices, particularly, but not exclusively, for simulating mines or other explosive devices, and preferably with capability for simulating or substantially matching with range and pattern of particular types and/or sizes of such mines etc in terms of destructive effects.

According to one aspect of this invention, there is provided a discharge device comprising a casing having two chambers, one for material to be discharged through associated venting provision of that one chamber, and the other for releasable propellant with associated triggering means for initiating sudden propellant release, the two chambers being intercommunicating at least after initiation of propellant release to drive and discharge said material through said venting provision.

The propellant could be of compressed gas type with very rapid release or as a very rapidly vaporising liquid. However, it is preferred that the propellant be of rapid burn and/or explosive nature, typically a low order explosive, though other regular even high order explosives might be used for particular or special requirements or effects, say as for film or television work. Pyrotechnic effects can be desirable, and might be provided by such as magnesium powder, say as used for theatrical maroons, or by suitably small sized charges of various grades of gunpowder, or nitrocellulose or so-called synthetic black powder (Pyrodex) , even perchlorate rocket type fuel, could be used. Whatever the nature of the propellant, but particularly where it is of an explosive nature, the amount of the propellant and its effect need not, and preferably does not, significantly exceed desired material discharge etc requirements, for example being carefully matched as to characteristic range or spread of such discharged material relative to destructive effects of what is being simulated. Such range or spread is thus itself conveniently limited to that required to indicate serious consequences for anyone within that range or spread for a weapon-type device that would, of course (unlike devices hereof) be of intentionally damaging nature, but can be simulated as to its potentially damaging effects by a discharge device embodying this invention.

The triggering means can be of any suitable type, usually electrically or mechanically operated. Electrical control can be manual by way of a switch, usually remote via wiring, or remote by way of radio or infra-red or ultrasonic signals, or from proximity sensing such as by passive infra-red presence detectors. Mechanical control could also be manual and local or remote, but will more usually be on a proximity basis, typically using trip wires and/or pressure pads. For preferred low order explosives, electrical control will usually involve a spark detonator, and mechanical control will usually involve a percussion cap detonator with a spring-driven firing pin. Miniaturised detonators such as so-called "microdets", or squib igniters, could also be used, as could two-pin pyro cartridges. Suitable such detonator provisions and devices are, of course, well known and readily available, though special versions could be designed for use in and with this invention.

It is advantageous for the propellant to be in a suitable container and for that container to be associated with the triggering means, preferably as a single sub- assembly or unit then associatable as a whole with said casing in or as said other chamber thereof.

At least (but not exclusively) for a device simulating a directionally indiscriminate land-mine, it is convenient and preferred for said one chamber of the casing to surround said other chamber. At least then, a unit combining propellant container and triggering means can readily fit into the overall casing, say substantially centrally, conveniently from above. Fixing could be by a screw-fitting cap of such unit, or a slot-in cap with a latch, conveniently of spring-action type. Such a unit, perhaps particularly of cap-fitting type and for a re¬ usable device, can be readily replaced, say after removal of a spent unit, even re-charging the casing with material to be discharged.

Suitable venting provisions can be provided as plural orifices in the casing, say through the thickness sideways and/or through its top, and preferably using discrete ducting going from the orifices inwards of the casing to below the level of the material, normally liquid paint or dye, to be discharged. Such venting will be sized, shaped and located relative to a size and shape of casing in accordance with achieving a desired pattern and extent of discharged material. The ducting can assist by its length or depth and cross-sectional shape, including variation thereof along its length or depth. Suitable ducting can be generally tubular, including of circular section or flattened, or multi-sided usually then with rounded corners. Tapering at some stage or all along length or depth of such generally tubular ducting may be from smaller entry to larger exit orifices, or the opposite, or even be waisted say to produce or enhance Venturi effects. A casing that is circular in plan can have an outer ring of generally radial ventings about central accommodation of its triggering and propellant unit, and can have directionally indiscriminate or omnidirectional discharge characteristics. A casing that is generally elongated could have narrow rows of vents to each side of an also elongated propellant chamber, and wider arrays of vents at each end beyond the propellant chamber, as could produce a dumb-bell or figure-of-eight shape of discharge pattern.

At least for a casing to be discharged at least partially if not mainly through its top surface, the bottom of the casing can be configured to assist flow of contents, say outwardly by contribution from downwardly sloping surfaces as can be provided by insetting of the bottom of the casing, say as a central dome or cone for a device that is generally circular in plan. Additionally or alternatively, bottom wells may be adapted to serve in feeding discharge ducting, say spaced in an outer ring location that may conveniently be about a central inset formation as above. The wells may have selected extents and degrees of heights, widths, tapers of bottoms and tops, slopes of sides, spacings of bottoms from entries to ducting, and relationships with surrounded inset formation that serve as parameters for desired flow-aiding characteristics, such as Venturi effects.

On triggering, the propellant will release and exert high pressure against the material to be discharged, which will pass through the venting provisions to spurt and fly therefrom to desired extents, relative to which detail design including venting, propellant quantity and expansion characteristics, and ducting will be directed to achieving.

It is not necessary for the propellant to do more than end up occupying the whole of the space formerly occupied by the discharged material, and to rely on rate of propellant expansion from triggering to achieve desired discharge. For a magnesium powder propellant, about two grams load will usually be enough to simulate with paint the personal damage range of a land-mine of average size (about 24cm diameter by about 8cm height reducing towards its outer periphery) . Suitable casings for devices embodying this invention can be moulded from various synthetic plastics materials, for example polycarbonate, polypyromellitimi.de, or other conveniently copolymer materials. Polycarbonate is particularly preferred for its qualities in terms of electrical characteristics, dimensional stability, high impact resistance, non-toxicity, and being inherently self- extinguishing - say with a wall thickness of two to three millimetres. Preferred caps can also be moulded from synthetic plastics materials, most conveniently complete with slots, holes and ledgings for mounting and connections to electrical and/or mechanical components of the triggering means.

Rather than being omnidirectional as just indicated in relation to what can be a "flying saucer" shape of its casing, devices hereof can be of other shapes, including for mimicking damage range of an inherently directional type of mine.

A generally tubular structure with directional discharge characteristics will also be specifically described. Typical features can include an outer tubular casing part with one open end and an aperture in its otherwise closed other end to take a necked down hollow extension from an otherwise closed end of an inner tubular propellant holder part with an open end facing the open end of the outer casing part. Both open ends can be sealed off by displaceable webs, say of wax, that will retain respective contents but not obstruct desired discharge operation. Triggering can be by wires or other detonating actuators, such as of impact sensitive or friction types, through the hollow necked down extension of the propellant holder.

At least (but not exclusively) such directional devices are readily made from bio-degradable materials, such as strong cardboard.

BRIEF DESCRIPTION OF THE DRAWINGS Specific implementation for this invention will now be indicated and described relative to the accompanying diagrammatic drawings, in which:-

Figures 1A and IB are outline top plan and half sectional views of a casing for a substantially omnidirectional device; Figures 2A and 2B are outline top plan and cross- sectional views of a cap with a mechanical detonator; Figures 3A and 3B are outline top plan and cross- sectional views of a cap with electrical detonator; Figures 4A and 4B are outline diagrams for electrical detonator circuit and spark plug;

Figures 5A and 5B are outline diagrams for a two-pin pyro-cartridge type igniter;

Figures 6 and 7A, 7B are outline diagrams for so- called microdet miniaturised detonators of standard and non-fragmenting types, respectively;

Figures 8A and 8B are top plan and partly broken away side/sectional views showing more detail of a complete omnidirectional device; Figures 9A, 9B and 9C are central sectional, reduced internal plan and perspective detail views of a particular developed and operationally tested omnidirectional device;

Figures 10A,B and 11A,B are outline side and bottom views for directional devices having electrical and mechanical triggering, respectively;

Figure 12 is a perspective view of a device intendedly with a dumb-bell or figure-of-eight discharge pattern; Figures 13A, 13B and 13C are detail perspective views os preferred simple tubular, flattened tubular and waisted types of vent ducting.

BEST MODE FOR CARRYING OUT THE INVENTION Referring first to Figures 1A and IB, casing 10 is hollow and generally circular in plan with a central aperture 12 in its top wall 14, and an unapertured bottom wall 16, shown both extending to a short peripheral side wall 18. The top and bottom walls 14 and 16 are shown with annular portions 14A and 16A sloping convergently towards the side wall 18, virtually the whole of the top wall 14 being shown as annular and so sloping, features that are to be understood as preferred, including in assisting contents clearance at discharge, but perhaps not essential. Outwardly of the aperture 12, the top wall 14 has orifices 20 to serve as exit orifices for material to be discharged. The exit orifices 20 are shown elongated and extending generally radially of the top, further actually also sloped downwardly in and with the outer annular top wall portion 14A. Duct formations 22 extend inwardly of the casing 10 from each of the orifices 20 to smaller but also radially elongated entrance orifices at 24 for the material to be discharged, and will serve as guiding exits for that material. The illustrated duct formations 22 have spaced parallel main side walls 26A,B connected together at 28A by their radially inner and substantially axially extending edges and at 28B by their radially outer and outwardly sloping edges. Edges of the entrance orifices 24 are shown extending substantially at right angles to the central axis of the casing 10, but could be inclined if desired, say as may be found to assist desired material discharge.

Inset inwardly extending walling 30 from the aperture 12 can have thread or other formations to aid fitting of a cap carrying a minor chamber to fit within a major chamber constituted by the then remaining volume of the interior of the casing 10.

Figures 2A and 2B show such a cap 40 with an outer skirt 41 and provision for mechanical detonation by way of a firing pin 42 shown spring loaded at 43 in a central inner walled formation 44 within inner guide fins 45. The firing pin 42 has a head 46 protruding through a central aperture 47 in the cap 40 with the spring 43 seating about that aperture 47 and acting against pin shoulder 48. An exterior well formation 49 serves to house other provisions such as for arming the device and/or some suitable release mechanism for the firing pin 42.

Figures 3A and 3B show another such cap 50 with an outer skirt 51 and provision for electrical detonation by way of a spark plug (not shown) to be housed in a central well 52 with a bottom aperture 53 for the sparking contacts of the spark plug. Another well 54 will serve to house an electrical battery and related circuitry and wiring (none shown) via grooving 55 to the spark plug. A third well 56 can serve to accommodate arming and/or proximity sensing means or other desired operating provisions. Figures 4A and 4B show, respectively, an electrical circuit 60 including a battery 61, a detonation switch 62 and socket contacts 63; and a plug-in spark plug detonator 65 to engage in the contacts 63.

Figures 5A and 5B show a pyro-cartridge igniter device 90 having two externally projecting pins 91A,B and internal spring 92 and striker 93. Figure 6 shows a miniaturised detonator or micro-det 94 of standard elongated form, and Figures 7A and 7B show a non-fragmenting type 95 of button or top-hat shaped configuration. In Figures 8A and 8B, more detail is shown of a complete land-mine mimicking device 110. Reference numerals are generally as for Figures 1A and IB, etc for equivalent parts, but advanced by one hundred. Main differences are more formation and exterior ornamentation of the casing, to increase realism; and somewhat greater depth of the device than in Figures 1A and IB. The latter leads to somewhat increased extent of the duct formations 122, particularly by way of extensions at 129 to their entrance orifices 124, and a degree of tapering from the exit orifices 120 to the now-deeper extending entrance orifices 124. Also, whilst its cap 180 will be generally as in Figures 2A,B or 3A,B, there is an accompanying blind outer cover 182. Screw threading is indicated at 184 for affixment, and reduced inward extension by way of container 186 (shown dashed) serves to house the propellant, but not to obstruct its driving out the material to be discharged. Effectively, then, the container 186 is the "other" chamber first referred to above.

The whole of the casing 110 could be filled with material to be discharged after displacement at fitting the propellent container 186, but it is not usually necessary or desirable to fill beyond the bottom of the threaded neck, or even up to there so long as the entrance orifices 124 of the ducts 122 are well covered.

Figures 9A,B,C show further details of one device 200 developed and operationally tested, specifically top and bottom casing parts 210A,B joined (211) at mutually engaged rebating. Exit orifices 220 for flowable material, usually liquid, are here in radially extending rows or lines (say as dashed in Figure 1) through annular sloping top wall part 214 about central aperture 212 for the discharge drive system (not shown) . Discharge ducts 222 can be integrally moulded with the top casing part 210A in extending away from the sets of exit orifices 222.

Aids to efficient discharge are shown, particularly as bottom formations of the lower casing part 210B. One such formation comprises an inwardly directed central cone formation 223 slightly stepped at 223S in its slope from annular ledge 223L stepped radially in from a short cylindrical inset 223C. Other such formations concern wells 225 communicating with free ends of the discharge ducts 222, respectively, shown spaced from bottoms 225B of the wells but below tops 225T of those wells 225 further shown level with the annular ledging 223L.

Sloping sides 225S extend from tops 225T down to bottoms 225B of the wells, the tops 225T being shown tapering inwards more than the bottoms 225B, actually the former significantly more and the latter significantly less than strictly radial. These tapers, along with other relevant actual and relative shapes and dimensions, such as widths and radial extents of the discharge ducts 222 and the wells 225, heights of the wells 225 including relative to the ledging 223L and any outward sloping of the well tops 225T and slopes of the well sides 225S, are all parameters to be determined and selected according to desired discharge flow characteristics, such as desired Venturi effects and maximising completeness of discharge. Relevant actual and relative shapes and dimensions of the inset base cone 223, including height and width along with steepness and variation of its rise (as by doming or a top flat) , width ledging 223L (even possible radial slope thereof) , and step or other side contouring, are all parameters in themselves and/or along with parameters of the wells 225 that further contribute to effective discharge, perhaps particularly as to reducing resistance to flow under highly expansive drive gas pressures.

Turning to Figures 10A,B and 11A,B, devices 70 and 80 that mimic directional mines are shown, and differ only as to the nature of propellent triggering, either electrically over leads 71 to a spark plug 72 or by a cord 81 of friction device 82 as used in the well-known "Party Popper" devices.

Each directional device otherwise comprises two generally tubular parts 73, 74 (83, 84) that nest, and have open ends 73A, 74A (83A, 84A) and other ends 73B, 74B (83B, 84B) that are closed save for aperturing 75 (85) of the outer part 73 (83) to take a necked down hollow extension 76(86) of the inner part 74 (84). The inner part 74 (84) houses propellant and has a seal 77 (87) at its otherwise open end 74A (84A), conveniently of wax. The outer part 73 (83) houses material to be discharged and also has a seal 78 (88) across its otherwise open end 73A (83A) .

Figure 12 shows a device 100 to simulate a so-called bar mine, which is normally a large device of elongated flattish form a metre and a half or more in length. As shown, a main chamber part 101 will contain paint or dye to be discharged through orifices 102 in its upper surface 103 about the top of an elongate medial propellant chamber 104. The orifices 102 are in narrow rows immediately about, particularly to sides of, the propellant chamber 104; and further in clusters at each end of the lower chamber surface 103, thus assisting in obtaining a desired dumb¬ bell or figure-of-eight shape of discharged paint or dye pattern.

Figures 13A, 13B and 13C show variant forms of vent ducting 322A,B,C. That 322A of Figure 13A is closest to previous Figures, being of generally flattened generally tubular form, though with an exit orifice 320A that is smaller than its entrance orifice 324A, i.e. tapering between them oppositely from earlier Figures. Also, entry protection bars are shown at 325, and may be provided in similar or other form for other embodiments of venting for use herein, i.e. to offer some safe-guard against entry of unwanted foreign bodies, but always in a manner not adversely to affect discharge of paint or dye material, perhaps even a highly comminuted or powdrous material, it would, of course, be alternatively or additionally feasible to have removable covers, perhaps of peel-off type, over the exit orifices until installation or even after installation and until desired use. In addition to the bottom-to-top taper, the vent ducting 322A also tapers from one edge 321A (front as shown) to the other edge 323B (rear as shown) . Figure 13B shows another generally flattened tubular venting structure, this time with a taper from an exit orifice 320B in to a smaller waist 3226, and another taper out to a larger entrance orifice 324B, which may be greater or smaller than the exit orifice 320B and with a longer or shorter or steeper or shallower taper from the waist formation 326. Equality of these factors would allow economical fabrication using two identical tapered parts, whether or not like that of Figure 13A in having a taper also along its cross-section. Figure 13C shows a simple circular section venting duct 322C, but again with a taper out from its exit orifice 320C down (into a device casing not shown) to its entrance orifice 324C.

It will be appreciated that production of noise, even flash, can be achieved or enhanced by a small excess of explosive propellent and/or omitting part or all of material to be discharged.

INDUSTRIAL APPLICABILITY Thus the invention provides devices, particularly, but not exclusively, for simulating mines or other explosive devices.

Claims

1. Intendedly harmless discharge device for simulating effects of other explosive devices, comprising a casing having two chambers, one for material to be discharged intendedly harmlessly through associated venting provision of that one chamber, and the other for releasable propellant with associated triggering means for initiating sudden propellant release, the two chambers intercommunicating at least after initiation of propellant release to drive and discharge said material through said venting provision.

2. Device according to claim 1, wherein the propellant is of a rapid burn type, such as manganese powder, with a pyrotechnic effect.

3. Device according to claim 1, wherein the propellant is a small charge of explosive selected from gunpowder, nitro¬ cellulose, and synthetic black powder.

4. Device according to claim 1, wherein the propellant is rapid-burn rocket fuel type, such as perchlorate.

5. Device according to any preceding claim, wherein the triggering means is of electrically operated type.

6. Device according to any one of claims 1 to 4, wherein the triggering means is of mechanically operated type.

7. Device according to any preceding claim, wherein the triggering means is remotely operated.

8. Device according to any preceding claim, wherein the propellant is in a container complete with the triggering means, and the container comprises a sub-assembly readily associatable with the casing in or affording said other chamber.

9. Device according to claim 8, wherein the triggering means is a ready fit to the propellant container.

10. Device according to any preceding claim, wherein said venting provision includes exit orifices for said material from said one chamber, said exit orifices being located so as to contribute to a pattern of discharged material that assists simulation of said other device in terms of covering its region of characteristic destructive effect.

11. device according to claim 10, wherein the exit orifices are shaped further to contribute to said pattern.

12. Device according to claim 10 or claim 11, wherein the exit orifices are distributed about a position at which said other chamber is accessible.

13. Device according to claim 10, 11 or 12, wherein the exit orifices are elongated.

14. Device according to claim 13, wherein the elongated exit orifices are disposed directed away from or a or said position of access to said other chamber.

15. Device according to claim 13 or claim 14, wherein the elongated exit orifices wider at one end than the other.

16. Device according to any one of claims 10 to 15, wherein individual venting ducts extend inwardly from said exit orifices.

17. Device according to claim 16, wherein the venting ducts extend to entrance orifices thereto that are below normal undischarged level for said material in said one chamber.

18. Device according to claim 16 or claim 17, wherein the cross-sections of at least some of the venting ducts vary along their extents between the exit and entrance orifices.

19. Device according to claim 16, wherein the exit orifices are smaller than the entrance orifices.

20. Device according to claim 16, wherein the exit orifices are larger than the entrance orifices.

21. Device according to any one of claims 16 to 20, wherein at least some of the venting ducts are medially reduced in cross-section.

22. Device according to any one of claims 16 to 21, wherein said casing has well formations into which said venting ducts extend and through which said material will discharge into the ducts.

23. Device according to claim 22, wherein said casing is configured and contoured at said well formations to serve in assisting discharge of said material.

24. Device according to any preceding claim, wherein said casing has an inset into the material accommodating chamber configured to assist discharge of said material over and past said inset.

25. Intendedly harmless discharge device for simulating or demonstrating effects of other explosive devices, such as mines, arranged and adapted to operate as herein described with reference to and as shown in the accompanying drawings.