Ammunition and explosives – Cartridges – Having divided propelling charge
Reexamination Certificate
2000-08-09
2001-04-03
Carone, Michael J. (Department: 3643)
Ammunition and explosives
Cartridges
Having divided propelling charge
C102S288000
Reexamination Certificate
active
06209460
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to propellant charges in medium and large caliber cased or caseless gun systems. More specifically the invention is directed to the configuration of the charge that is loaded into the cartridge case assembly. The configuration, in this case, generally the shape, density and placement of the propellant charge is a departure from contemporary configurations.
Munitions that use solid propellants carried in the cartridge casing typically relied on spherical or cylindrical grain geometry for ease of processing. Burn rates, the speed that a flame front is propagated through the propellant, were controlled through geometry (i.e. grain perforations) or through chemical (i.e. deterrents) means. Burn rate modification and progressivity tuning are important considerations in designing charge loads. Another technique to provide a propellant in the cartridge is to use what are known as co-layered propellants in a disk or rolled scroll. Co-layered propellants being a descriptive term describing the use of layers of precut propellant elements cut from a sheet of propellant material. It is known to use co-layered propellants in the shape of rings or appertured disks of different propellants stacked in a sandwich configuration. In co-layered propellants so called “fast burn” propellant sheet stock, cut in the appropriate appertured disk or ring shape, is sandwiched between two layers of slower burning propellant sheet stock. The source of co-layered propellant sheets is Alliant Tech Systems who can provide the co-layered propellant in die-cut annular ring shapes or in uncut sheets.
Another use of co-layered propellants is in a rolled scroll form. In this configuration the propellant sheet is rolled to form a scroll. The scroll form is aligned longitudially with the boom of the projectile and if ignited from the end of the scroll, the normal technique, the flame propagation will be more difficult to control than the flame propagation of this invention. In the scroll form of propellant it is difficult to control burn propagation and there is a risk that waves of pressure may build to the point of weapon destruction. Therefore the scroll form of propellant is more difficult to specify than is the strip embodiment presented here.
One of the disadvantages of co-layered propellants is that the stacked disks provide, having only limited natural ullage, a barrier to gas flow which can lead to detrimental pressure waves in the gun. These detrimental waves are caused in part by the blockage presented by the disks. The invention presented in this specification avoids or minimizes the barrier to the gas flow as the strips of propellant allow sufficient ullage between the strips.
Another disadvantage of co-layered propellants in disk form, as is used in the prior designs, is that the manufacture of the rings creates a large amount of scrap propellant. It is known that to cut a circular disc from a rectangular sheet of propellant material will cause significant selvage or waste of material. The sheets of propellant are expensive and anytime you can save on material the cost of a loaded cartridge case will be commensurately lower.
SUMMARY OF THE INVENTION
One aspect of this invention is the use of strips of material which are placed in a shell casing in a direction that is aligned with the longitudial axis of the shell. The strips of material, the material being a propellant compound that is pressed and formed into sheets, are arranged to be vertical when the shell, for reference purpose, is stood on its end. One advantage of the strip contour, as contrasted to the disk shaped propellant, is that the strips are more economical to produce and produce less waste in the production cycle. In the scroll form of propellant packaging the sheets of propellant are well utilized. However, the burn characteristics of the scroll form are not as predictable as the disk embodiments or of the embodiments presented here.
In the development of this invention the inventors have found that the strip type of propellant will produce a better combustion event in a gun chamber. Therefore it is an object of this invention to provide a propellant charge in the form of a strip of propellant material such that a better, more complete and more uniform burn rate of the propellant is realized. The strips of propellant will burn more efficiently than known embodiments of either disk, scroll or solid rod type fuel charges.
It is another object of the invention to provide a propellant charge that is cut from a sheet of propellant material in an efficient way to minimize the amount of wasted propellant scrap.
It is also an advantage of this invention that the strips used will be self-supporting. The configuration and arrangement of the propellant strips will comprise a self-supporting column. This is beneficial as the column arrangement will not buckle or shift during transport or handling.
Another advantage of the arrangement of the strips verses the disk arrangement is that with the embodiment incorporating the strips there will be a channel to accommodate the fins of the projectile.
One further advantage of the invention is that the position of the strips in a generally vertical column shape will allow the cartridge case to be slipped over the column of propellant material in the assembly phase. This is advantageous as the assembly of the cartridge and the propellant can be done cleanly and swiftly as there will be less potential interference between the edge of the shell and the column of propellant.
It is another object of the invention to provide a propellant charge which provides passageways and has an adequate percentage of ullage in the propellant charge to provide effective axial and radial flame propagation and flame spread paths.
One further advantage of the invention over the disks of the known art is that the strips can straddle the fins of the projectile boom whereas in the disk embodiment the disks are limited to being large in interior diameter to accommodate the fins extending radially outwardly from the boom of the projectile.
Another advantage of this invention is that the propellant strips can be contoured to follow the ramp angle of the boom allowing the use of more propellant in the cartridge or the same amount of propellant in a better distribution when compared to a conventional disk style embodiment.
One further advantage of the invention is that it lends itself well to the use in a modular charge. That is, the strips are easily contoured to a shape appropriate to a large number of possible uses, for instance in different gun systems.
Basically the invention set forth herein has as its object the improvement in the burn propagation of a flame in a large munition. This is to be accomplished while at the same time making the cost to produce the propellant charge less expensive through the elimination of waste in the production of usable propellant inserts.
These and other objects and advantages of the invention will be apparent to a person of skill in the munitions field as the following specification is comprehended and the accompanying drawing figures are studied.
The preferred embodiments of the invention presented here are described below in the drawing figures and Detailed Description of the Drawings. Unless specifically noted, it is intended that the words and phrases in the specification and the claims are given the ordinary and accustomed meaning to those of ordinary skill in the applicable arts. If any other special meaning is intended for any word or phrase, the specification will clearly state and define the special meaning.
Likewise, the use of the words “function” or “means” in the Detailed Description of the Drawings is not intended to indicate a desire to invoke the special provisions of 35 U.S.C. 112, Paragraph 6, to define the invention. To the contrary, if the provisions of 35 U.S.C. 112, Paragraph 6 are sought to be invoked to define the inventions, the claims will specifically state the phrases “means for” or “step for” and a func
Chaboki Amir
Isle Brian J.
Zelenak Steven R.
Bergin James S.
Carone Michael J.
Kamp Ronald C.
United Defense L.P.
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