Note: Descriptions are shown in the official language in which they were submitted.
Burkhalter and Peterson Case 1
This invention relatPs to a consolidated charge for
cased ammunition and a method of making said consolidated charge.
More particularly, thi~ invention relates to a round of cased
ammunition in which the propellant comprises a porous consoli- -
dated charge.
Standard cased ammunition utilizes a loose powder
charge, which is usually in granular or small ball form. The
loading density for charges prepared from propellant granules is
about 0.9 grams per cc. and loading density for charges prepared
from ball powder is about 0.95 grams per cc. In accordance with
this invention, the loading density of cased ammunition can be
substantially increased, thus making it possible-to increase the
propellant charge weight within the confines of the cartridge case
and thus substantially increase available energy for the charge. ~;~
I Consolidated charges are not new, in fact they have been
known for many years. For example, U.S. Patent 321,042 describes
` a propellant charge formed of powder compacted into a cake within
1, a cylindrical shell or case, the powcler cake is solid. U.S.
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Patent 392,922 relates to a charge for cased ammunition in which
the powder forming the charge is pressed practically into a solid
mass with a centrally situated conical or cylindrical cavity
~hrough the charge. U.S. Patent 846,612 relates to cartridge
cases loaded with charges comprised of sheets or strips of smoke- 1
less powder. V.S. Patent 1,010,430 describes a shell having an
explosive charge which consists of a main charge of explosive
material in the ~orm of a cast homogeneous solid.
The consolidated charge employed in the cased ammunition
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~¦ of this invention, however, represents a distinct improvement over
~, the consolidated charges employed in cased type ammunition such
as heretofore described. The consolidated charge employed in this
, invention comprisès a compaction of granules of smokeless powder
`~ having a multiplicity of interstitial spaces substantially uni-
;` formly distributed throughout the compacted mass. The intersti~
tial spaces are formed as a result of compacting randomly
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oriented7 cylindrically or ball shaped granules. In preparing
~hes~ porous consolidated charges, the surfaces of the individ
ual granules are first softened by exposure of the granules to
sol~ent vapors and then pressed together~ This consolidated
charge provides the advantages of the p~ior art consolidated
charges, iOe~, it is ~elf-supporting and has high density, but
retains the advantages of a loose granular charge in that the
consolidated charge will burn upon ignition by a primer as if it
were a loose granular charge. The consolidated charge must be
porous to pernit flame spread throughout the charge upon ignl-
tion~ While not bound by any theory, it is believed that the
consolidated charge breaks up into individual granules under the
influence of the ignited primer and/or chamber pressure to burn
similarly to a loose granular charge.
According to the present invention there is provided
in a round of cased amm~nition comprising a projectile and a
metal cartrldge case having an internal cavity for holding a
propellant charge, and a propellant charge held wi~hin said
cavity in the metal cartridge case, the improvement comprising
- 20 a self-supporting~ consolidated, porous propellant charge pre-
pared by a process comprising wettillg smokeless powder granules ~
with a solvent ~or the nitrocellulose component of said gra~ules, ;
said solvent being employed as a vapor, said wetting being Gon; -
tinued for a time sufficient ~or said smokeless powder granules
to contain from about 2~o to about ~ by weight of solvent, con-
solidating said solvent-wet granules at a pressure of from ~00
p~s.i. to 5000 p.s~i. whereby the granules are~`compacted to form
~` a self-supporting charge, said granules being compacted up to
; 6~ o~ their original nonco~pacted volume~ and heat curing the ~ -
resulting consolidated charge.
The cased ammunition of this invention is more ~ully
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described with reference to the drawings which follow. In the
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drawings like numbers refer to like parts where applicable.
Figure l is a schematic view partly broken away and
partly in section of a cartridge case loaded with loose granules
of smokeless powder, as is typically done in the prior art.
Figure 2 is a schematic view partly broken away and
partly in section of a cartridge case in which a propellant
charge equivalent in weight to the charge shown in Figure l is
loaded into a cartridge case and consolidated.
In Figure l, a cartridge case lO is shown loaded with
loose granules of smokeless powder 12. The granules are held -
in position in the cartridge case with packing 14.
Figure 2 illustrates an identical cartridge case loaded
with an equivalent weight of smokeless powder granules which ~ ~
have been consolidated. To ef~ect consolidation, the surfaces ~ ;
of the granules employed in the cartridge case in Figure 2 are ~;
wet with the vapor of a solvent for nitrocellulose~ and then ;
pressed into the cartridge case with a ram. The packing density
- of the propellant granules is thereby increased. Visual com- ,~
parison of the
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i space occupied by the smokeless powder granules held within the
cartridge cases in Figs. 1 and 2 clearly illustrates the improved
packing density, and the volume available for additional smoke-
less granules in the cartridge case of Fig. 2, the cased ammuni-
tion of this invention.
The consolidated propellant charge employed in the cased
ammunition of this invention is preferably prepared as follows.
- A desired amount of smokeless powder granules to be charged to the ~;
cartridge case of the round ammunition are brought to ambient tem- ;
! 10 perature. The smokeless powder granules are then exposed to sol-
vent vapor in which the solvent employed is a solvent for the
nitrocellulose component of the smokeless powder granules. The
exposure time of the smokeless powder granules to the solvent
vapor depends on the temperature and concentration of the solvent
vapor and the amount of solvation required. The smokeless powder ;
i granules should contain from about 2% to about 8% by weight of
solvent after vapor treatment. The solvent vapor can be employed
`1 alone or with a diluent gas such as nitrogen. Preferred condi-
tions for vapor treatment of the smokeless powder granules util-
izing nitrogen gas as a diluent in which the nitrogen is satur-
ated with acetone solvent are saturated nitrogen-acetone vapor
temperatures of about 80F. and an exposure time of about five
- minutes. A particularly suitable solvent which can be employed
in vapor form i9 acetone. Other solvents which can be employed
include ethyl acetate, butyl acetate, methyl alcohol, methyl
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~ ethyl ketone, methyl, ethyl, propyl or butyl nitrate, and the
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~`1 like.
After the surfaces of the smokeless powder granules are
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1 wet with solvent-vapor, the ~ranules are loaded into the cart- ~
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;i~ 30 ridge case and are compressed by any suitable means such as by
a--ram. Consolidation pressure is from about 500 p.s.i. to about
5000 p.s.i. and will vary depending on the rate of consolidation.
At low rates of consolidation, higher ram pressures are required
to produce a self-supporting charge. By the term ~Iself-supporting~
, . .
i5 meant the consolidated charge is unitary or in essence one
piece of propellant. The foregoing process o~ wetting smokeless
powder granules with solvent vapor, adding the solvent treated
granules to the cartridge case and pressing the charge is repeated -
until the cartridge case is suitably loaded with consolidated pro-
pellant.
: .
Following the subjecting of the smokeless powder gran-
ules to solvent vapor and pressing of the solvent wet smokeless
powder granules into the cartridge case, the resulting consoli- ~ `
10 dated charge is heat cured. Suitable curing conditions are curing ~-,
temperatures of from about 100F. to about 150F. for times of
about 18 hours to about 48 hours. Particularly suitable curing
` conditions are heating of the consolidated charge at a temperature `~
` of about 140F. for about 24 hours.
The following examples more fully illustrate this inven- -~
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` tion. In the examples parts and percentages are by weight unless
otherwise specified.
Examples 1 10
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, Ten standard 20 millimater M-102 cartridge cases are
filled with varying amounts of solvated smokeless powder granules `~
following the vapor treatment process heretofore described in
which the solvent employed is acetone. The treated granules-con- -
tain about 4% acetone. The solvent treated granules are compressed
within said cartridge case to a pressure of about 1000 p~ S o i ~ for
aboùt one minute. The weight of smokeless powder granules charged
~ in each case ir as specified in Table I. To achieve the degree
i" of loading required, two increments of granules are charged to
each case and each increment is pressed separately with the re-
` sult that the desired loadin~ is readil~ achieved. ~
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TABLE I
Smokel~ss
Powder Chamber Muzzle
~eight Pressure Velocity
Ex. ~ (P s.i.) (feet/sec.)
1 700 39,000 3740
2 750 ~8,000 3995
5,000 4128
4 775 49,000 4085
785 55,000 4114
6 785 50,000 40~7
7 785 55,000 4172
8 785 5~,000 4102
9 785 55,500 4135
785 54,000 409
The rounds of Examples 1-10 are fired. Each round is ~
assembled with a penetrator (projectile) having a nominal weight ``
of 1230 grains. Chamber pressure and muzzle velocities measured
for these examples are recorded in Table I. For comparison pur-
poses a standard 20 millimeter M~102 cartridge case was filled
to capacity with a loose charge of smokeless powder of the same
composition as that employed in Examples 1-10. The fully loaded
case held 630 grains of granules. The round was fired and the ~;-
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-~ chamber pressure was measured at 50,000 p.s.i. and the muzzle
;' velocity for the charge was 3760 feet per second. It can be seen
from review of firing data of rounds 2 through 10, listed in ;~
.... . . .
Table I, that the muz~le velocity of a round of ammunition pre- ;; ~
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pared employing the cased ammuniti~on of this invention, is about
4000`ft. per second employing a smokeless powder charge weighing ~ ;
from 750-785 grains.
In preparing the cased ammunition of this invention the
smokeless powder granules can be pressed up to about 65% of their
original-volume. It is preferable, however, only to press the
granules to ~rom about 70% to about 75% of the original volume.
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If the granules are compressed to more than about 65% of the
original volume, there is likely to be insufficient porosity
within the consolidated charge to permit the charge to break up
and burn similar to a loose charge o~ smokeless powder granules.
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; Such burning is required in order to obtain uniformity of ballis-
tic performance of the consolidated charge.
The term smokeless powder granules is used herein to
mean propellant granules of the single base, double base or
triple base type. The term cartridge case includes metal, plas~
tic or combustible type cartridge cases. . ~ :
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