Patent Application
20070068374
This application claims priority under 35 USC ยง 119 to European patent application no. 05445016.8 filed on 21 Feb. 2006.
The present invention relates to a countermass for use in a weapon to balance the forces arising when a launchable unit, such as a rocket, a projectile, a shell or the like, is launched from a launcher tube of the weapon, the countermass comprising a first container enclosing a liquid. The invention also refers to a countermass weapon comprising a launcher tube open or openable in both ends, the launcher tube housing a launchable unit such as a rocket, a projectile, a shell or the like, a countermass comprising a first container enclosing a liquid, a pressure chamber, and a propellant charge that upon firing and combustion of the charge in cooperation with the pressure chamber and the countermass accelerates the launchable unit forwards in the tube at the same time as the countermass accelerates backwards in the tube.
An example of a countermass and a countermass weapon according to the above is previously known from SE patent 8205956-9 (publication number 444 722). According to said patent the liquid is enclosed in a shell construction in the shape of a plastic container. It is important that such a container cracks in a controlled manner. To this end measures have been done to improve the cracking procedure for instance by introducing fractural impressions. Nevertheless it is a problem that the container may crack in an uncontrolled way mainly due to non-cracking in the intended fragmentations. This may result in that fragments having a high velocity are ejected backwards from of the launcher tube resulting in that the requirements on the back blast area not are fulfilled.
The object of the invention is to obtain a countermass and a countermass weapon that fulfils the requirements concerning back blast area and thus preventing generation of harmful high velocity fragments reaching an area to be safe a distance behind the weapon. A considered safety distance behind is often about 20 meters.
The object of the invention is obtained in that the first container enclosing the liquid is made of a non-rigid material and that a second container is provided to cover or almost cover the first container, the second container being designed with damping characteristics.
When firing such a weapon, the countermass behaves in a favourable way. The second container designed with damping characteristics is rapidly split into pieces and slowed down behind the weapon. The first container of non-rigid material is also rapidly destroyed. Accordingly there is no harmful ejection of material behind the weapon beyond a standard safety distance. The use of a first container of a non-rigid material also makes it possible to keep down costs for manufacturing the countermass and the time to produce different variants of countermass containers. It is easy to adapt the first container to different shapes of the inner walls of the outer second container. A new mould for the outer second container designed with damping characteristics can also be prepared within a short period. Furthermore the weight of the countermass containers is low so that the total weight of the weapon can be reduced.
According to a favourable development of the countermass the first container is made of a plastic foil. Another favourable development proposes that the first container is made of a metal foil, such as aluminium foil. The proposed foils are easy to adapt to almost any shape of the inner walls of the second container and are easily torn up behind the weapon avoiding harmful effects.
According to another favourable development the second container designed with damping characteristics is made of foam plastic. Such a material has turned out to rapidly split into pieces and slow down behind the weapon.
According to still another development a liquid binding material is enclosed in the first container. A suitable liquid binding material specifically proposed in this connection is a material of Oasis type.
According to yet another development it is proposed that the first container is designed as a sealable bag. The bag can be provided with an inherent sealing which is sealed when the bag has been filled with liquid and if adequate a liquid binding material. The bag can also be sealed by means of the covering second outer container.
Preferably the second container consists of two essentially rotary symmetrical sections joint to each other after insertion of the first container. Such a designed second container facilitates the enclosure of the first container and also contributes to the sealing of the first container. Advantageously a peripheral part of the first container is clamped in between the sections of the second container.
According to one proposed embodiment the countermass of the weapon is fixed to the launcher tube by means of a clamping effect. According to another embodiment the countermass is fixed to the launcher tube by means of a screw joint. Both embodiments propose simple solutions how to arrange the countermass in the launcher tube.
In a particular embodiment the launchable unit is a rocket and in another embodiment the launchable unit is a projectile. The use of a countermass as claimed in these application fields enables a limitation of harmful fragments behind the weapon at the same time as the rocket or projectile is adequately launched from the launcher tube when firing.
The invention will now be described in more detail by means of an embodiment with reference to the accompanying drawings in which:
The countermass 1 shown in
The inner container 2 is made of a non-rigid material such as a plastic foil or metal foil. An example of a plastic foil that can be used is a foil of silicon. The proposed foils are very flexible and can easily be adapted to almost any desirable shape. In one embodiment the inner container 2 is designed as a sealable bag. The outer container 3 has damping characteristics and is suitably made of foam plastic, such as EPP (expanded polypropylene), Frigolit or other porous materials. In the proposed embodiment the outer container comprises two rotary symmetrical sections 6 and 7. The sections 6, 7 are provided with grooves 8 facilitating the split into pieces. Furthermore the periphery of the container sections 6 and 7 can be provided with recesses, not shown, intended for cooperation with raisings 9 in the launcher tube 11 enclosing the countermass 1. When assembling the countermass 1, the inner container 2 with its liquid is put into the cavity 17 of a first one of the sections 6 or 7. The other section is then pressed against the first one with the cavities of the two sections 6, 7 facing each other. To keep the sections pressed against each other a glue joint, a clamping joint or any other suitable joint could be used.
The liquid used could be of any kind of liquid known as a suitable countermass liquid and preferably liquids with high specific gravity could be used. Fire extinguishing liquids is often preferred. A suitable material for the liquid binder is material having characteristics of Oasis type or other sponge like materials.
The operation of the countermass weapon will now be described with references to
The embodiment described above refers to a rocket application. It is however easy and within the scope of the invention to modify the weapon for other types of launchable units such as projectiles or shells.
| Number | Date | Country | Kind |
|---|---|---|---|
| 05445016.8 | Feb 2005 | EA | regional |
