The present invention generally relates to stackable projectiles, and more particularly to an adaptor for coupling to a propulsion unit for a stackable projectile.
Stackable projectiles typically comprise a warhead coupled to a propulsion unit. The propulsion unit usually takes the form of a tailpiece containing a propellant burner, a primer and other components, and which is shaped to accommodate the nose of a similar projectile. Such projectiles can be stacked nose to tail in the barrel of a weapon and fired sequentially using a suitable firing mechanism.
A propulsion unit can be crimped or screw threaded amongst other methods onto a warhead in order to couple the two together. Both crimping and screw threading are direct approaches of joining the warhead to the propulsion unit. However, crimping and screw-threading are not suitable if the propulsion unit is made of different materials. For example, if the warhead is made of metal and the propulsion unit is made of plastic.
Furthermore, different manufacturing parties produce different profiles of warheads and propulsion units, so crimping and screw threading may not be the appropriate methods for joining different profiles of warheads and propulsion units. In order to couple the different profiles of warheads to propulsion units, the profile of the propulsion unit is usually redesigned to accommodate the profile of the warhead. Alternatively, the profile of the warhead can be redesigned to accommodate the profile of the propulsion unit. However, redesigning the profile of the warhead or propulsion unit can be time consuming and costly.
It is an object of the invention to provide for improved coupling between a warhead and a propulsion unit when forming a stackable projectile, or at least to provide an alternative to existing projectiles. Another object of the invention is to provide an improved propulsion unit for stacking projectiles. A further object of the invention is to provide for adapting existing warheads for stacking.
Accordingly, in one aspect, the present invention provides a stackable projectile comprising: a warhead having a head section and a base section; an adaptor having a top surface, a bottom surface and a side surface, wherein the top surface is configured to accommodate the base section of the warhead; and a propulsion unit having a base, and a cylindrical wall extending from the base to form a receptacle, wherein the receptacle is configured to accommodate the adaptor and the base section of the warhead, wherein the side surface of the adaptor is configured to fit into the receptacle, thereby when the projectile is assembled, the top surface of the adaptor is coupled to the base section of the warhead, and the side surface of the adaptor is coupled to the cylindrical wall of the propulsion unit.
In another aspect, the present invention provides a method for assembling a stackable projectile, comprising the steps of: providing a warhead having a head section and a base section; providing a propulsion unit having a base, and a cylindrical wall extending from the base to form a receptacle; providing an adaptor for coupling the warhead to the propulsion unit, wherein the adaptor has a top surface, a bottom surface and a side surface, the top surface of the adaptor is configured to accommodate the base section of the warhead, and the side surface of the adaptor is configured to fit into the receptacle of the propulsion unit; coupling the top surface of the adaptor to the base section of the warhead; and coupling the side surface of the adaptor to the cylindrical wall of the propulsion unit.
In another aspect the present invention provides a stackable projectile comprising: a warhead having a head section and a base section; and a propulsion unit having a base including an interchangeable trailing surface portion having a trailing surface for engaging with a trailing projectile.
Preferred embodiments according to the present invention will now be described with reference to the Figures, in which:
a shows the assembled projectile with a further alternative adapter and a stacking adaptor,
b shows more detail of the forward end of the projectile of
c shows more detail of the rearward end of the projectile of
a shows the assembled projectile with another further alternative adapter and stacking adaptor, and
b shows more detail of the rearward end of the projectile of
It will be appreciated that the invention may be implemented in various ways for a range of stacked projectile weapons and a range of projectile calibers. The embodiments described here are given by way of example only.
The adaptor 30 includes a top surface 32, a side surface 33 and a bottom surface 34. The top surface 32 is configured to accommodate the base section 24 of the warhead 20. In particular, the top surface 32 is preferably coupled to the base section 24 using adhesives, wherein the top surface 32 provides additional surface area for adhering the warhead 20 to the adaptor 30. The adaptor 30 is typically solid structure and can be made from a range of materials such as plastics, metal, metal alloys, or the like. It may also be coupled to the warhead and/or the propulsion unit by screw threads or press fit structures for example. Other surfaces of the warhead, adaptor and propulsion unit may also be fastened together if required. In a more complex form described below the adaptor may include components which operate with the propulsion unit.
The propulsion unit 40 comprises a base 41, and a cylindrical wall 43 extending from the base to form a receptacle 42, wherein the receptacle 42 is configured to accommodate the adaptor 30 and base section 24 of the warhead 20. In particular, the side surface 33 of the adaptor 30 is configured to fit into the receptacle 42. The side surface 33 of the adaptor 30 can be coupled to the cylindrical wall 43 of the propulsion unit 40 using screw thread or adhesives for example. The propulsion unit 40 can be made from metal materials, plastic materials, or the like. A primer 52 and a propellant 54 can be centrally disposed at the base 41 of the propulsion unit 40. The base 41 may have a high pressure chamber 46 that houses the propellant 54 for stackable munitions.
The base 41 includes a surface 47 which is shaped to accommodate the head section 22 of another warhead so that the projectile can be stacked with other projectiles in the barrel of a weapon. The surface 47 may take a range of shapes depending on the shape of the head section of the trailing projectile, and preferably forms a seal with the head section and/or with the barrel of the weapon. The seal is typically formed by contact of surface 47 with the trailing head section and an outwards deformation of edge portions 48. A seal of this kind acts to reduce the possible effect of ignition gases on the propellant 54 in successive projectiles and also the passage of ignition gases down the barrel when the leading projectile in a stack is fired. The chamber 46 and propellant 54 may take many forms including self-sealed systems which are not dependent on sealing between adjacent projectiles or between projectiles and the barrel. A wide range of sealing systems may be used in the propulsion unit.
In
The primer 52 is seated in a primer pocket which extends into the high pressure chamber 46. The chamber 46 and inductor 51 are concentric and capped by the electronics stage 53. These arrangements reduce the overall length of the propulsion unit for a set volume of propellant and pressure chamber.
The firing and propulsion components of the propulsion unit 40 such as the electronics stage 52, inductor 51 and pressure chamber 46 may be housed in respective chambers in the propulsion unit 40. This arrangement allows for easy assembly. The components may be dropped into position in their respective chambers. Or when necessary, press fit into position or fixed in position with an adhesive where necessary.
The electronics stage 53, inductor 51 or even the high pressure chamber 46 can be selected from a range of such components to vary the safety, authorization or even the propulsion characteristic of the propulsion unit. For example, a higher level of safety is required for high explosive warheads than for kinetic warheads comprising resilient synthetic materials used for crowd control or for sand filled projectiles. Safety is a feature of the propellant, primer and inductor as well as the electronics stage or a combination thereof. The inductor can be selected as a function of the energy required by a particular primer 52 or alternatively, depending on the energy available from the projectile launcher. Furthermore, the electronics stage 53 and/or inductor 51 can be readily substituted where a different level, particularly a higher level, of qualification such as military specification is required or if such specifications change. For example, the electronics stage 53 can be selected to provide for different EM filtering requirements that are currently specified or that may be specified in the future. Similarly the inductor 51 can be selected to operate at a specified level of safety in all currently known and future EM environments.
The forward portion 74 is typically solid structure and can be made from a range of materials such as plastics, metal, metal alloys, or the like.
In
In
Other coupling arrangements may be used as required to suit the particular adaptor 30 and forward portion 74 required for a particular warhead. For example, a forward portion for a 37 mm warhead fired from a 40 mm barrel may not have sufficient wall thickness for certain wall materials to provide a coupling with concentric cylindrical walls which is strong enough to withstand the very high forces exerted on the projectile during firing.
The coupling of the stacking adaptor 98 to the remainder of the propulsion unit 70 is preferably a sealing coupling so that propulsion gases do not escape forward up the barrel with the consequent loss of projectile velocity and will still force edge portion 48 into sealing contact with the bore of the barrel as designed. In the illustrated example of
The type of coupling and dimensions and materials of the coupling which can provide sufficient sealing will depend on the relative movement of the stacking adaptor 98 and the remainder of the propulsion unit 70 adjacent the coupling. This will determine, for example, the location of any sealing rings. Relative movement near the coupling can occur from expansion of the high pressure chamber 46 as well as gases acting directly on the surfaces of the stacking adaptor 98 and the remainder of the propulsion unit 70. Movement is a function of the forces applied as well as the relative geometries. Where the high pressure chamber 46 is substantially rigid and hence undergoes little radial expansion, only forces from the expanding gases need be considered for design of the sealing coupling.
In the example in
Annular surfaces 112 and 114 may be angled relative to the longitudinal axis, not shown, of the projectile to provide a frusto-conical annular surface if required to provide sufficient sealing for a given geometry and gas pressure. Angled surfaces provide better seals as described in published PCT patent application WO2003/089871 by the present applicant.
Some warheads require either or both spin speed and spin count to arm the warhead. The leading end of the cylindrical portion 76 may include one or more driving bands 86 and keys to engage with the flats 84. The keys and flats 84 provide rotational coupling between the warheads and the driving band 86 whereby relative rotation there between is prevented. Rotational coupling is provided by the coupling between the adapter 30 and the base section 24 as described above. The coupling between the adapter 30 and the forward portion 74 may also be keyed to provide rotational coupling.
Stacked projectile launchers such those described in the applicant's prior patents WO94/20809A1 and more recently in WO2003/089871A1 have multiple firing positions along the length of the barrel. Firing of a lead projectile in a stack exerts longitudinal forces, along the length of the barrel, to the remaining projectiles. When the longitudinal force is removed as the pressure in the barrel from the lead projectile drops the remaining projectiles may separate and move out of alignment with their respective initiation mechanisms. To prevent such misalignment projectiles are preferably fastened together. Preferred methods include screw fastening and clip fastening. Fastening projectiles together allows a sliding fit between projectiles and the bore of the barrel of a launcher whereby the projectiles can be individually loaded directly into the barrel in the field over the life span of the launcher and throughout a practical service interval. To fasten adjoining projectiles, the forward portion 74 and preferably the leading end 94 of the examples of the embodiments of
As discussed above, the adaptor couples different profiles of warheads and propulsion units without any need for design modifications. Furthermore, the adaptor allows the warhead to be coupled to propulsion units made of different materials. This facilitates the testing of the warhead by coupling it to different propulsion units without any need of redesigning the profile of the warhead. In addition, different types of propulsion units can be coupled to the projectile to enable the projectile to be fired mechanically or electronically. Also, the current production process need not be modified too drastically for producing stackable projectiles. Similarly the interchangeable trailing surface portion of the propulsion unit provides for the convenient and low cost stacking of existing known and yet to be developed warheads and particularly warheads not originally designed for stacking.
While the present invention has been described with reference to particular embodiments, it will be understood that the embodiments are illustrative and that the invention scope is not so limited. Alternative embodiments of the present invention will become apparent to those having ordinary skill in the art to which the present invention pertains. Such alternate embodiments are considered to be encompassed within the spirit and scope of the present invention. Accordingly, the scope of the present invention is described by the appended claims and is supported by the foregoing description.
Number | Date | Country | Kind |
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2006907006 | Dec 2006 | AU | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/AU07/01928 | 12/14/2007 | WO | 00 | 12/15/2009 |