Propellant charge module

Details Propellant charge module Propellant charge module

2000-03-14

2001-10-23

Nelson, Peter A. (Department: 3641)

Ammunition and explosives

Powder form

Composite type

C102S478000, C102S490000

Reexamination Certificate

active

06305288

ABSTRACT:

The present invention relates to a propellant charge module for artillery guns which is provided with a specially designed initiating charge.
The propellant charge module is of the type which consists of a predetermined quantity of propellant powder enclosed in a preferably rigid cylindrical container made of a combustible material, outwardly delimited by an outer cylinder wall adapted to the calibre dimensions of the relevant artillery gun, two essentially plane and parallel gable walls defining its ends, and a centrally arranged inner cylinder wall which extends axially through the propellant charge module and in turn defines a central ignition channel delimited from the propellant powder and which is itself made of a pyrophoric, i.e. easily combustible, material.
Propellant charge modules of this type are primarily to be regarded as unit charges since, almost without exception, several of them are used together to form propellant powder charges of a charge strength adapted for each range of fire. A general designation for these propellant charge modules or unit charges is “modular charges”.
A common feature of the modular charges is that they have an external diameter specific for each weapon and that they all have the abovementioned central axial ignition channel which, when several modular charges are arranged in succession, for adaptation to a predetermined longer range of fire, will form a common and continuous ignition channel through all the modular charges included therein. However, the modular charges can have different lengths and contain different types and quantities of powder and can thus be of a different charge strength. Among the advantages of these propellant charge modules that may be mentioned, they are easy to combine into propellant charges of different charge strength and are thus easily adapted to different ranges of fire, and, by virtue so their rigid configuration, they are simple to automatically load, something which was not true of the soft, so-called bag charges, which they have been developed to replace.
In the case of propellant charges consisting of a plurality of propellant charge modules of the modular charge type, in order to achieve an instant flash-over along the entire central ignition channel common to all the propellant charge modules, it has already been proposed to arrange special firing charges inside these ignition channels. Some earlier variants of such firing charges have consisted of continuous powder tubes or a number of powder rings bearing tightly against one another. The most common material in these older firing charges has been conventional black powder.
Older variants of propellant charge modules of the modular charge type in question here are described in more detail in U.S. Pat. Nos. 4,702,167, 4,864,932, 4,922,823 and WO 89/04453.
As has already been mentioned, the present invention relates to a propellant charge module for artillery guns of the modular charge type which has been provided with a specially designed initiating charge.
The problem which it has been possible to solve by means of the present invention is that of being able to eliminate the tendencies towards uneven initiation of the propellant powder, principally in those propellant powder charges which consist of a plurality of unit charge modules arranged one after another in a row, and which in earlier variants of firing systems often gave rise to turbulent internal ballistics and hazardous pendulum pressures in the launching barrels.
The present invention thus relates, in summary, to a propellant charge module for artillery guns, comprising a predetermined quantity of propellant powder enclosed in a preferably rigid cylindrical container made of a combustible material, outwardly delimited by an outer cylinder wall adapted to the calibre dimensions of the relevant artillery gun, two essentially plane gable walls defining its ends, and a centrally arranged inner cylinder wall which extends axially through the propellant charge module. This inner cylinder wall in turn defines a central ignition channel which is delimited from the propellant powder and whose boundary wall is made up of a preferably cylindrical relay tube of pyrophoric, i.e. easily inflammable material. Arranged inside the ignition channel, in the central part thereof, as seen in its longitudinal direction, at an equal distance from the ends of the charge, there is also a firing charge in the form of a number of firing charge rings which are arranged one after the other in succession and bear against one another. Their external dimensions match the internal dimensions of the relay tube, while their internal dimensions form a common inner ignition channel.
A distinguishing feature of the invention is now, principally, that the firing charge rings which together form the complete firing charge have, at their gable ends directed towards each other, distancing members in the form of bosses, nibs or radial waves made in one piece with, and of the same material as, the firing charge rings themselves. These distancing members have a small height and provide very narrow gaps of preferably 0.5-2 mm between the different firing charge rings, but this is quite sufficient to afford a number of ignition gaps in towards the abovementioned relay tube, from which the flash-over, as soon as it has burnt through, spreads to the propellant powder charges in each propellant charge module. Practical tests have shown that the quicker flash-over obtained in this way means that the turbulent internal ballistics often occurring in earlier initiating systems, and the consequent pendulum pressures, have been able to be more or less completely eliminated. With this type of firing charge, it is ensured that the firing of the propellant powder in the main charge always takes place via the central channel, which in turn makes it possible to use the same charges in similar guns, even if these have slightly different chamber dimensions. The initiating is thus so quick that a flash-over from outside never has time to take place, even if there were a sufficient gap between the chamber wall and the propellant charge so that this could theoretically have happened.
In a further development of the invention, the relay tube surrounding the firing charge, and delimiting the space intended for the actual propellant powder charge from the central ignition channel, is provided with a number of through-slots or holes in order to accelerate the actual burning-through.
The invention also includes the variant in which the central firing ring of the firing charge is replaced by a firing pill which is made of the same or equivalent material and which differs from the firing rings in that it completely lacks the centre holes which these have. However, it has proven advantageous if this firing pill has its smallest material thickness in line with the centre axis of the ignition channel. The variant with ignition pill is especially suitable for initiating with laser, which will probably become more and more common since one is then no longer dependent on initiating cartridges for firing the actual artillery gun.
In addition, the relay tube will preferably consist of at least 70% nitrocellulose while the firing charge, i.e. the firing rings and the alternative firing pill, will expediently consist of a pyrotechnic charge which is prepared by wet mixing and which includes 60-70% potassium nitrate, 20-30% boron and 10-15% zinc stearate and, finally, 4-10% of an acrylic binder.


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