U.S. patent number 3,563,177 [Application Number 04/737,128] was granted by the patent office on 1971-02-16 for caseless ammunition and ignition means therefor.
This patent grant is currently assigned to Thiokol Chemical corporation. Invention is credited to Harold W. Ritchey.
United States Patent |
3,563,177 |
Ritchey |
February 16, 1971 |
CASELESS AMMUNITION AND IGNITION MEANS THEREFOR
Abstract
A caseless charge for firearms and a firearm therefor, said
charge being porous and made from comminuted or particulated
combustible materials having the surface of each particle thereof
softened with a solvent. The softened material is consolidated in a
combustible pyroxylin tube and inserted in the firearm. Ignition is
provided from an electrical discharge between the end of an
ignition probe and the projectile attached to the charge.
Inventors: |
Ritchey; Harold W. (Langhorne,
PA) |
Assignee: |
Thiokol Chemical corporation
(Bristol, PA)
|
Family
ID: |
24962684 |
Appl.
No.: |
04/737,128 |
Filed: |
June 14, 1968 |
Current U.S.
Class: |
102/431;
42/84 |
Current CPC
Class: |
F41A
19/58 (20130101); F42B 5/18 (20130101) |
Current International
Class: |
F42B
5/00 (20060101); F41A 19/00 (20060101); F42B
5/18 (20060101); F41A 19/58 (20060101); F42b
009/16 () |
Field of
Search: |
;102/38,39,(CC),46,70.2,28,104,99 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Stahl; Robert F.
Claims
I claim:
1. A caseless ammunition round adapted for firing from a firearm
and the like comprising a projectile, a propellant charge having a
central core adhesively attached to said projectile, said charge
comprising a combustible mass formed from propellant particles
having their outer surfaces softened by contact with a solvent for
a period of time of up to 60 seconds and thereafter being
consolidated by a force of from 2 ounces to about 25 pounds whereby
said mass is sufficiently compacted to cause said particles to
become mutually impregnated, and form a unitary mass, a
combustible, pyroxylin protective tube containing said mass, and a
combustible, pierceable, pyroxylin end cover attached to said
tube.
2. The ammunition round of claim 1, wherein said charge is
porous.
3. The ammunition round of claim 1, wherein said solvent is
selected from the group consisting of acetone, alcohol, ether,
methyl ethyl ketone and mixtures thereof, methylene chloride and
halogenated fluorocarbon solvents.
4. The ammunition round of claim 1, wherein said solvent is a
vapor.
5. The ammunition round of claim 1, wherein said solvent is the
form of a mist.
6. The ammunition round of claim 1, wherein said solvent is a
liquid.
7. The ammunition round of claim 1, wherein a portion of said end
cover is electrically conductive.
8. The ammunition round of claim 1, wherein the material of said
protective tube and said end cover is pyroxylin.
9. The ammunition round of claim 1, wherein the propellant material
for said charge is selected from the group consisting of cellulose
nitrate, ballistite, guanadine nitrate and black powder.
10. The ammunition round of claim 1, wherein the propellant
particles are spherical.
11. The ammunition round of claim 1, wherein the propellant
particles are rodlike.
12. The ammunition round of claim 1, wherein the propellant
particles are flat plates.
13. The ammunition round of claim 1, wherein the propellant
material is a mixture of spherical, rodlike and flat plate
particles.
14. The ammunition round of claim 7, wherein said conductive
material is a metal selected from the group consisting of aluminum
magnesium, copper, zinc, iron and titanium.
15. The ammunition round of claim 7, wherein said conductive
material is carbon.
Description
This invention relates to ammunition and firearms. More
particularly this invention relates to caseless charges or
ammunition useful for firing projectiles or the like from firearms
or other ballistic launching devices.
Caseless ammunition has in the past proved feasible in caliber
sizes ranging from 22 caliber through large artillery rounds.
However, the use of caseless charges as ammunition in small arms
has not been entirely successful, particularly in rapid fire
applications. Reasons for this lack of success stem from many
factors, the chief one being improper, incomplete or otherwise
faulty burning of the propellant charge material and resulting lack
of sufficient gas generation to adequately propel the
projectile.
Prior art caseless ammunition has been prepared by molding
granules, powder or the like, of combustible oxygen bearing
substance mixed with a binder of nitrocellulose and dissolved in a
solution of ethanol or ethyl ether. The mixture is formulated to a
semisolid constituency and thereafter subjected to a pressure of
3,000-- 9,000 p.s.i. for short periods of about 15 seconds and
dried at about 50.degree. C. A nonporous substance results having
relatively poor burning characteristics because of unsatisfactory
flame propogation. Other workers in the art sought to overcome this
problem by preparing the charge by foaming the mixture to induce
porosity or by mechanically manipulating the charge by machining
cavities and channels therein to create larger burning surfaces.
These solutions while improving the burning quality of small arms
ammunition, still did not provide a fully satisfactory round
because, though porosity helped, the degree thereof and its control
to form a reproducible propellant surface and web thickness of the
particles were inadequate.
Another problem with prior art caseless ammunition was ignition,
which either was too time consuming for small arms ammunition or
relatively ineffective in accomplishing combustion. Ignition means
encompassed all known means including; hot electrical resistance
wire, exploding bridge wire, hot air blast, auxiliary charges and
spark gap electrical discharge. While success of varying degree has
been achieved, a completely satisfactory ammunition round
performing at least as well as metal cartridge type rounds has
eluded those concerned.
Accordingly it is an important object of this invention to provide
an improved round of caseless ammunition which performs at least as
well as ordinary ammunition and is capable of being reproduced in
large quantities with no appreciable performance deviations from
round to round.
It is still another object of this invention to provide an improved
round of caseless ammunition having a porous propellant wherein the
degree of porosity thereof is controlled reproducibly from round to
round to bring about improved burning characteristics.
It is still another object of this invention to provide a round of
caseless ammunition of the character above referred to wherein an
electrical ignition system is used to significantly enhance the
overall performance of the round.
It is a still further object of this invention to provide an
improved closed breech type firearm which accommodates the improved
propellant charge of this invention and also serves as an important
part of the ignition system therefor.
Other objects and advantages of this invention will be readily
apparent upon perusal and consideration of the following
description and the drawings annexed wherein;
FIG. 1 is a longitudinal section of a portion of a firearm
illustrating the position of the caseless ammunition round of the
invention therein at the time of initiation of combustion;
FIG. 2 is a magnified view of a portion of the charge of the
invention along Section 2-2 of FIG. 1;
FIG. 3 is a sectional view similar to FIG. 1 of another embodiment
of the invention;
FIG. 4 is a view of the invention taken along Section 4-4 of FIG.
3; and
FIG. 5 is a view similar to FIGS. 1 and 3 of still another
embodiment of the invention.
Referring now to the drawings, and in particular to FIG. 1 thereof,
there is shown the interior breech portion of a firearm 10 with a
round 11 in a preferred form of the invention. Round 11 includes a
projectile 12 attached to a hollow caseless charge 13 of propellant
by an adhesive 14 (heavy black line in this FIG.). Projectile 12
has a rearwardly projecting portion 15 which is provided to
increase the adhesive surface and for ignition purposes as will be
hereafter more fully explained. Round 11 is positioned in the bore
16 of firearm 10 with the forward edges of charge 13 abutting the
annular wall 17 of a recess 18 in bore 16.
Situated aftwardly of charge 13 in breech 20 is a reciprocating
bolt 21 of the type found in most firearms. However in this
instance bolt 21 is modified to include within its structure an
electrical conductor 22 together with its associated insulation 23.
Conductor 22 is a two-piece high tension line, one piece being
within bolt 21, the other piece leading from a power source 25. The
two pieces are electrically joined at a terminal head 22-a when
bolt 21 is in the position shown in FIG. 1. Insulation 23 (not
shown on the piece of conductor 22 leading from power source 25) is
selected to provide full insulation of electrical energy therein
from the surrounding metal of bolt 21. Conductor 22 terminates in
electrical contact with an ignition probe 24 which is transported
by and moves with bolt 21 in its reciprocating motion. As shown in
FIG. 1, bolt 21 and probe 24 are in their extreme forward positions
and in firing (breech 20 closed) mode. Conductor 22 is connected to
high tension electrical power source 25 by means of a switch 26
activated by a firearm trigger 27, shown in schematic form in the
various figures.
Charge 13, as shown in the drawings, is a cylindrically shaped
combustible mass composed of any of the usual substances well known
in the art of ammunition propellants but of modified form for the
purposes of this invention, being a porous combustible body made
from gun propellant, preferably a homogeneous, solvent type, which
is uniquely treated to induce and control porosity and to insure
reproducible burning surfaces and particle web thicknesses. This
treatment involves contacting the particles forming the charge mass
with a solvent, preferably acetone, to soften the surfaces thereof,
and thereafter consolidating them under a light load of a few
ounces to a few pounds, e.g. 2 ounces to about 25 pounds. The
sizes, i.e., diameters, thicknesses and the like are selected in
accordance with the desired end use and burning rate required. In
small arms ammunition spherical particles from 5 to about 100 mills
diameter are preferred. Other particle shapes also usable in this
invention are rods, both hollow and solid, flat plates and mixtures
of all of these. Since burning time is related to the so-called
"web thickness" or web, which in spherical particles is the
diameter thereof, contact time of the solvent and subsequent
consolidation load determines web thickness in the completed
charge. In hollow rod particle shapes burning on all surfaces, web
thickness is one-half the distance from the outer surface to the
inner surface. In solid rod particles it is one-half the diameter,
and in flat plate particles it is one-half the distance from one
side to the other. Thus it can be seen that the novel treatment of
this invention permits a predictable and reproducible web thickness
in the particles and therefore provides the means to produce a
charge having a degree of predictable combustion performance not
heretofore available.
FIG. 2 illustrates in a magnified view, a portion of charge 13, in
this instance the particles being selected from ball propellant and
therefore spherical. However, any particle shape above-mentioned
can be used. Referring to FIG. 2 the particles or spheres 28 have
been softened by, for example, passing them through a solvent for a
short period of a few seconds depending on the temperature thereof
and on the type of solvent. The particles are then collected in a
protective cylinder 18 and consolidated while still softened,
consolidation pressure on the other above referred to being
sufficient to result in the formation of mutual impregnations or
penetrations 29. In the consolidating step, excess material 30
flows into the interconnecting channels or interstices 31 between
particles 28, and by careful control thereof a mass having a
predictable and reproducible degree of porosity, and therefore
consistant burning characteristics, results. It should also be
evident that similar results can be obtained regardless, within the
above stated limitations, of the particle shape selected.
In practice charge 13 is contained (and consolidated) in protective
cylinder 32 cut from thin wall tubing of pyroxylin (low nitrogen
content cellulose nitrate with plasticizer) which is itself
consummable in the burning of charge 13. Charge 13 when
consolidated after softening in tube 32 can be in a hollow form
having a central perforation 33 of substantially the same diameter
as rearwardly projecting projectile portion 15 and can be attached
thereto by adhesive 14. An end cover 34 also of pyroxylin can be
adhesively attached to the rearward end of charge 13 to seal it
against moisture and damage due to handling.
Alternatively, charge 13 can be made separately in a mold or the
like, and protective tube 32 and end cover 34 formed on its outer
surface by spraying or dipping to obtain a skinlike covering
thereon. Other means for containing and protecting charge 13 will
no doubt occur to skilled artisans.
While the preparation of charge 13 has been disclosed as a porous
mold of propellant or power treated by contact therewith of
acetone, it should be understood that other solvents can be used
for applicant's purpose. For example, various alcohols, e.g. ethyl,
methyl, propyl and butyl alcohol ether, mixtures thereof and of
acetone therewith will also accomplish this end. Other solvents
include many of the ketones, e.g., methyl ethyl ketone and many of
the halogenated hydrocarbons such as methylene chloride,
fluorotrichloromethane difluorodichloromethane and the like. It is
preferred to pass the propellant particles through the solvent
which is in the vapor form, or in a mist, for sufficient time to
obtain the desired surface softening, this being determined by
choice of solvent. In the case of acetone, a single pass through
the vapor, recovering the particles through a metering valve at the
bottom will result in a contact time of at most a few seconds.
Temperature conditions during the softening period range from about
50.degree. C. to about 70.degree. although, depending on the
solvent used, may range from lower to higher temperatures. Warm air
passing through the softened propellant is used to dry the mass and
remove excess solvent to prevent over softening.
In other instances the solvent can be passed through the loose
propellant in tube 32 either under pressure or under a vacuum for
periods from a few seconds to several minutes depending on the
desired degree of surface softening (and therefore porosity of the
charge) desired. The softened powder is then subjected to warm air
for drying and to prevent over softening, and consolidated with any
suitable apparatus well known to the art such as a piston and the
like under a light compressing load ranging from several ounces to
about 25 pounds to obtain the result indicated in FIG. 2 and above
described. Softening of the particles can also be achieved by
spraying the solvent on the moving material or by flowing the
solvent over particles which remain stationary.
While this invention has been described with reference to cellulose
nitrate based propellant, other propellant materials are also
suitable for application herein. For example, the material known as
"Ballistite" or cellulose nitrate mixed with nitroglycerine also
can be used. Guanadine nitrate propellants and even black powder
are also acceptable candidates in achieving a reproducible charge
13 with the desired predictable porosity.
FIGS. 3 and 4 illustrate an additional embodiment wherein the
electrical ignition circuit is modified in that conductor 22
connects to and terminates in a round headed terminal 22-a, passing
through the lower part of an insulator collar 35 in breech 20.
Terminal 22-a electrically contacts an outer conductive ring cover
36 which is insulated from the surrounding firearm 10 members by
collar 35. Conductive ring 36 includes a radially extending central
portion 36-a which generally extends from cover 36 to the central
area of charge cover 34 over the end of perforation or core 33.
Probe 24 (in FIG. 3 and also FIG. 5) is electrically isolated from
power source 25 when in the position shown in FIG. 3, and from bolt
21 by insulator bushing 24-a. FIG. 4 shows the relative position of
cover 36 and center portion 36-a when viewed from breech 20. It
should be noted that regardless of the orientation of round 11 in
bore 16, electrical contact will be maintained between ring 36 and
conductor 22, and central portion 36-a will always extend over
perforation 33.
FIG. 5 illustrates still another embodiment of this invention
wherein charge 13 and cover 34 includes an outer sheath 37 of
conductive material. Materials selected for sheath 37 (and ring 36)
include any conductive material, preferably metal foil or the like
which is thin enough to be easily pierced by probe 24 and, as will
be later indicated, conductive of electric current and combustible.
Candidate materials are magnesium, aluminum, copper, zinc, iron and
titanium and the like. Ring 36 and sheath 37 can also be integral
with cover 34 by forming cover 34 with carbon or metal particles
within the pyroxylin whereby current will be conducted from power
source 25.
In operation of the invention charge 13 is prepared by softening
particles of commercial propellant with a solvent in vapor form by
passing the vapor through the loose powder 28 contained in cylinder
18, dropping the propellant particles into the solvent, or any of
the other methods above described. A mandrel (not shown) can be
used to form core 33, which can be hollow and integral with
cylinder 18 and of combustible pyroxylin, or removable. After a
time sufficient to soften the surfaces of particles 28, the solvent
vapor is removed and the particles dried and consolidated under
light pressure until charge 13 is of the desired porosity and
length. End cover 34 is preferably preattached to cylinder 18 and
the final length of charge 13 is determined by trimming the
opposite end. A projectile 12 is positioned on charge 13 with
projecting portion 15 in core 33 and adhesively attached thereto.
Round 11 thus prepared is inserted in bore 16 with bolt 21
retracted as shown in FIGS. 3 and 5. Bolt 21 is then moved
forwardly causing probe 24 to pierce end cover 24 in FIG. 1, coming
to rest at position shown in FIG. 1 to provide an electrical
discharge gap A between the ends of probe 24 and projectile portion
15. Firearm 10 is now armed and ready for firing. To ignite charge
13 and fire projectile 12 trigger 27 is pulled closing switch 26.
Current from power source 25 flows through lead 22 to ignition
probe 24 and discharges across gap A with high energy to ignite
charge 15 and fire projectile 12 by the pressurized gas generated
thereby.
In FIGS. 3 and 5, bolt 21 is shown in its retracted position, probe
24 being physically and electrically separated from power source 25
and electrically from bolt 21 by bushing 24-a. As bolt 21 is moved
forwardly probe 24 pierces end cover 34 and conductive central
portion 36-a of ring 36, coming to rest in the position shown by
the dotted lines in FIGS. 3 and 5, so as to again provide discharge
gap A. In piercing central portion 36-a, probe 24 becomes
electrically connected to power source 25 and activation of trigger
27 supplies energy thereto, and an electrical discharge across gap
A occurs igniting charge 13. Similarly in FIG. 5 probe 24 in
piercing shield 37 becomes electrically connected to energy source
25 and activation of trigger 27 causes a discharge across gap A to
ignite charge 13.
Thus what has been described and illustrated is a new form of
caseless ammunition wherein a porous charge is provided in a
combustible protective cylinder. By treating a commercially
obtainable propellant by the methods above described, controlled
and predictable porosity is obtained, and upon ignition, complete
combustion occurs, smoothly and with little or no residue. A
protective cylinder being similarly made from combustible, low
nitrogen content cellulose nitrate, wherein the nitrogen content is
in the 7 to 10 percent range and well known to the art also burns
completely and contains the porous charge. The means for ignition
of the propellant is a high tension electrical discharge system
which, in the preferred embodiment, is a part of the reciprocating
bolt common to most firearms. Arming of the projectile occurs when
the bolt is in its forward position, and though not shown, the
circuitry can easily be provided with safety switching means to
prevent premature firing, for example, conductor lead 22 can be
provided with a switch mounted at the power source or on the
firearm itself.
While only a preferred and several additional embodiments have been
presented, it should be understood that other variations and
modifications will become apparent to skilled artisans after
perusal hereof. Therefore no limitations should be placed upon the
scope of this invention except as indicated by the appended
claims.
* * * * *