Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
2197602
WMC-070 PATENT
NOISE ABATEMENT SYSTEM FOR LARGE CALIBER GUN
FIELD OF THE INVENTION
The present invention relates to a system for minimizing the noise
generated by the firing of a large caliber gun and, when desired, for stopping
a
projectile fired by the gun.
BACKGROUND OF THE INVENTION
Due to the increased population in the world, the noise generated by
the testing of large caliber weapon systems in communities located near
testing
facilities of such weapon systems is becoming an increasing problem. As a
result
of this concern, there has been a need for a gun muffler or system for
attenuating
the generated noise level. Preferably, such a system should be able to rapidly
and
CRL I:\WMC\070\PAT-001.DOC
2197b02
W M C-070 - 2 -
safely attenuate the noise generated by the firing of a projectile by a large
caliber
gun.
When a firing range has limited space, it is desirable to cause the
projectile fired by a gun to be stopped a short distance from the firing of
the gun.
Accordingly, a system for attenuating the generated noise level should also
preferably be capable of stopping a projectile fired by the gun.
SUMMARY OF THE INVENTION
The present invention is directed to a noise abatement system for a
large caliber gun having a gun tube. The system includes a horizontal concrete
to slab; a gun muffler, mounted on the concrete slab and having an end adapted
to be
coupled to the gun tube, for attenuating pressure waves caused by a firing of
a
projectile by the gun; and a projectile stop, mounted on the concrete slab and
longitudinally aligned with the gun muffler, for selectively stopping the
projectile
fired by the gun and for selectively permitting the projectile to pass.
Preferably, the projectile stop has an opened first end closest to the
gun muffler and a second end to which a door is mounted. The door is closed to
stop the projectile fired by the gun and is opened to permit the projectile to
pass
through the projectile stop unhindered. The projectile stop may be comprised
of
steel and may be substantially rectangular. When it is desired to aim for a
target
2u beyond the projectile stop, the doors are opened to permit the projectile
to pass
through the projectile stop unhindered. When the projectile stop is used to
stop
projectiles, the doors are closed and the projectile stop is filled with a
particulate
material, such as sand.
wMC-ono _ 3 _ 219 7 6 0 2
BRIEF DESCRIPTION OF THE DRAWINGS
The invention is best understood from the following detailed
description when read in connection with the accompanying drawings, in which:
Fig. 1 is a fragmentary longitudinal side elevational view of the left
portion of a first embodiment of a gun muffler used with the present
invention;
Fig. lA is a fragmentary longitudinal side elevational view of the
right portion of the gun muffler shown in Fig. 1;
Fig. 2 is an elevational view of the reinforced left-end plate of the
gun muffler;
1o Fig. 3 is an elevational view of the reinforced right-end plate of the
gun muffler;
Fig. 4 is a fragmentary transverse vertical sectional view, showing
the orifice plate, taken along the line 4-4 of Fig. lA;
Fig. 5 is a fragmentary side elevational view of a gun and gun
muffler, partly in section;
Fig. 6 is a fragmentary side elevational view of a gun, having a
longer tube than the gun shown in Fig. 5 and the gun muffler, partly in
section;
Fig. 7 is an enlarged fragmentary transverse sectional view, showing
a tube transporter used with the present invention;
2197602
WMC-070 - 4 -
Fig. 8 is an enlarged fragmentary horizontal sectional view of a
portion of the tube transporter of Fig. 7, taken along the line 8-8 of Fig. 7;
Fig. 9 is a fragmentary vertical sectional view of the tube transporter
of Fig. 7, taken along the line 9-9 of Fig. 8;
Fig. 10 is a fragmentary longitudinal side elevational view of the
right portion of a second embodiment of a gun muffler used with the present
invention;
Fig. l0A is a fragmentary longitudinal side elevational view of the
left portion of the gun muffler shown in Fig. 10;
1o Fig. 11 is an enlarged fragmentary sectional view of the first and
second orifice plates shown in Fig. 10A;
Fig. 12 is an enlarged fragmentary sectional view of the third orifice
plate shown in Fig. 10A;
Fig. 13 is a plan view of an orifice plate having a circular, off
1s centered orifice;
Fig. 14 is a plan view of an orifice plate having an elliptical orifice;
Fig. 15 is a longitudinal side elevational view of the noise abatement
system of the present invention:
2197b02
WMC-070 - 5 -
Fig. 16 is an enlarged transverse end view, showing an end of the
enclosure of a gun muffler used with the present invention, taken along the
line 16-
16 of Fig. 15;
Fig. 17 is an enlarged transverse view (with the end wall removed),
showing an end of a gun muffler used with the present invention, taken along
the
line 17-17 of Fig. 15;
Fig. 18 is an enlarged transverse end view, showing the other end of
the enclosure of a gun muffler used with the present invention, taken along
the line
18-18 of Fig. 15;
1o Fig. 19 is an enlarged transverse sectional view, showing the
connection between the projectile stop and the concrete slab, taken along the
line
19-19 of Fig. 22;
Fig. 20 is an enlarged transverse end view, showing the end of the
projectile stop closest to the gun muffler used with the present invention,
taken
along the line 20-20 of Fig. l~;
Fig. 21 is an enlarged transverse end view, showing the other end of
the projectile stop, taken along the line 21-21 of Fig. 15;
Fig. 22 is a side elevational view of the projectile stop shown in Fig.
15; and
2o Fig. 23 is a top plan view of the projectile stop shown in Fig. 15.
X197602
WMC-070 - 6 -
DETAILED DESCRIPTION OF THE INVENTION
Referring to Fig. 15, the noise abatement system of the present
invention generally includes a gun muffler 250, a projectile stop 200, and a
concrete slab 210. Gun muffler 250 can be selected from gun muffler 50
discussed
below in connection with Figs. 1-9 or gun muffler 150 discussed below in
connection with Figs. 10-14. Alternatively, gun muffler 250 can include some
features from both gun muffler 50 and gun muffler 150. As discussed in detail
below, gun muffler 250 serves to attenuate pressure waves caused by a firing
of a
projectile of a gun. Gun muffler 250 has a first end 252 which is adapted to
be
to coupled to the tube of a gun, as discussed in more detail below. Gun
muffler 250 is
mounted to concrete slab 210 in any known manner. For example, gun muffler 250
may be mounted to concrete slab 210 by using bolts in a similar manner as
discussed below in connection with the mounting of projectile stop 200 with
concrete slab 210.
is Concrete slab 210 may be prepared from any conventional poured
concrete. Concrete slab 210 should have a thickness sufficient to support gun
muffler 250 and projectile stop 200, including when the projectile stop is
loaded
with a particulate material such as sand. Preferably, concrete slab 210 may
have a
thickness of 2 to 6 feet, and more preferably 4 feet. As shown in Fig. 15,
concrete
2u slab 210 has a greater thickness near end 252 of gun muffler 250 than the
remainder
of concrete slab 210. Not shown in Fig. 15 is the gradual decrease in
thickness of
concrete slab 210 occurring between the first and second shown portions of gun
muftler 250 near end 252. As shown in Fig. 15, concrete slab is preferably
horizontal. Preferably, concrete slab 210 is anchored to the ground or earth.
For
25 example, a plurality of support piles 212 may extend downward from concrete
slab
210 to bedrock.
197602
WMC-070 - 7 -
Shown in Fig. 15 and more clearly in Figs. 16-18 is a housing or
arch (e.g., a "Quonset" arch) which serves to protect the gun muffler and the
related instrumentation, such as the valves, hatches, and electrical
instrumentation,
from the environment. Arch 220 may be any suitable material, such as light
weight
corrugated steel, sheet metal, or plastic. As shown in Figs. 16 and 18, arch
220 is
disposed over gun muffler 250 and has end walls 222 and 224 at each end with,
respectively, doors 223 and 225 for personnel to enter the interior of the
arch, as
shown in Fig. 17. Fig. 17 also shows end 252 of gun muffler 250. An opening
226 exists in arch 220 for permitting valve and blower assembly 228 to extend
1o through and to the exterior of arch 220.
Figs. 20-23 show the ends, sides, and top of projectile stop 200. As
shown, projectile stop 200 is substantially rectangular in shape. Each side,
wall,
and top of projectile stop 200 can be made of steel, preferably about 4 inches
thick.
As shown in Fig. 20, projectile stop 200 is comprised of first side wall 201,
second
side wall 202 (identical to first side wall 201), and top plate 203. In use,
side walls
201, 202 may be 10 feet high, and top plate 203 may be 12 feet wide. Fig. 19
shows how projectile stop 200 is mounted to concrete slab 210. More
specifically,
an "L-connector'' 205 is mounted to the base of side walls 201 and 202 and
then is
subsequently affixed to concrete slab 210 by bolt 206. L connector may be
2u connected to side wall 201 by a similar bolt (not shown).
Fig. 21 shows doors 204a and 204b which are respectively mounted
by conventional heavy duty hinges 206 to side walls 202 and 201, respectively.
Accordingly, doors 204a and 204b can swing open and closed as needed. To lock
the doors a closed position, latches 207 are aligned with recesses in the
doors (not
shown) and bolts are subsequently screwed through recesses 208 in the latches
and
into the recesses of the doors 204a and 204b to keep the doors closed.
2197602
WMC-070 - 8 -
Fig. 22 shows side wall 202 mounted on concrete slab 210. As
shown, side wall 202 can actually be comprised of a plurality of panels 232a,
232b,
232c, and 232d. Panels 232a-d can be connected to one another by connectors
233a-c.
Fig. 23 shows top plate 203. In the same manner as side walls 201
or 202, top plate can actually be comprised of a plurality of top panels 234a-
e,
which can be connected by connectors 235a-d. Top plate 203 is coupled to side
walls 201 and 202 in any known manner, such as by being bolted thereto, and
may
be removable by a crane, for repairs.
1o As shown in Fig. 15, projectile stop 200 is longitudinally spaced
from gun muffler 250. In operation, when it is desired to aim at a target
beyond
the projectile stop 200, doors 204x, b are opened and interior space 209 is
emptied
by a front end loader through the open end of projectile stop 200. When it is
desired to stop the projectile, doors 204x, b are shut and locked into place
by use of
latches 207. Subsequently, interior space 209 is filled with a particulate
material,
such as sand, through the open end of the projectile stop 200. Then the gun is
fired
and the projectile subsequently retrieved upon emptying of interior space 209.
It is desirable to build the projectile stop of a sufficient size such that
over 1 million foot-pounds of energy can be absorbed. In one embodiment, which
2o is 10 feet high. 12 feet deep, and 32 feet long, such a projectile stop can
absorb
over 40 million foot-pounds of energy when filled with sand. Thus, such a
system
can be used to stop 6.1 inch diameter projectiles.
The present invention uses a muffler for a large caliber gun having a
gun tube. As used herein, a "large caliber gun" refers to a gun having the
size of at
2197602
WMC-070 - 9 -
least 155 mm. Although a muffler used with the present invention could be made
for smaller guns, for example, as low as 30 mm, it is normally not needed to
muffle the noise generated from such smaller guns. With a gun muffler used
with
the present invention, the noise level is attenuated by 30% at 100 yards from
the
firing of the gun and by 95 % at 300 yards from firing of the gun.
Referring to Figs. 1 and lA, a gun muffler 50 in accordance with a
first embodiment of the present invention is shown. The gun muffler includes a
transition section 4 which fits around the gun tube 24 and engages the gun
tube for
preventing the escape of residual combustion gases caused by a firing of the
gun.
to At least one pressure vessel is attached to transition section 4. As shown
in Figs. 1
and lA, the pressure vessels include a main pressure vessel 2 defining a main
pressure chamber 32 and an extension pressure vessel 3 defining an extension
pressure chamber 33. Extension pressure vessel 3 is disposed in series with
and
connected to main pressure vessel 2. The two pressure vessels may be bolted
t5 together.
As shown, main pressure vessel 2 and extension pressure vessel 3 are
generally cylindrical. In one embodiment, the main pressure vessel is about
4,000
cubic feet (9 feet in diameter and 64 feet long) and the extension pressure
chamber
is approximately 1,000 cubic feet.
2o Main pressure vessel 2 includes a port 26. A vent stack 20 is
coupled to main pressure vessel 2 at port 26 and includes a lower vent stack
15 and
an upper vent stack 16. Lower vent stack 15 is in permanent fluid
communication
with main pressure chamber 32 by way of port 26. Disposed in upper vent stack
16
is an exhaust blower 17. Exhaust blower 17 should be capable of rapidly
creating a
25 vacuum in main pressure chamber 32 and extension pressure chamber 33 for
2197602
WMC-070 - 10 -
venting residual combustion gases from these chambers to the atmosphere by way
of port 26. Blower 17 may be a squirrel-cage blower having drum type blowers
or
vanes.
Disposed in vent stack 20 is a valve 18, which separates upper vent
stack 16 from lower vent stack 15. Accordingly, valve 18 is disposed between
main pressure chamber 32 and exhaust blower 17. Valve 18 is actuated by
actuator
19, which is air-operated. Valve 18 should be capable of withstanding high
pressure, for example, pressure above 600 psi.
According to an embodiment of the invention, valve 18 is a
1o commercially available butterfly valve having a twenty-four inch diameter
through
port and is capable of operating at 1,000 psig. Also, actuator 19 can be a
pneumatic actuator which operates at 100 psig and is controlled by an
electrically
operated solenoid valve. Valve 18 is operated to be closed during firings of
the gun
and opened between firings of the gun.
At the end of main pressure vessel 2 which is coupled to extension
pressure vessel 3 is an orifice plate 7. Orifice plate 7 is an annular disk
defining a
central circular hole through which the projectile passes. The size of the
hole is
dictated by the size of the projectile. Also, if the hole is too small, it is
difficult to
rapidly vent extension pressure chamber 33 through the hole and out through
port
26 by way of exhaust blower 17. On the other hand, if the hole of orifice
plate 7 is
too large, the muffling of sound is not sufficient. It has been found that for
a
projectile of 15~ mm, the orifice plate 7 should have a hole of about ten
inches in
diameter.
WMC-070 - 11 -
As shown in Fig. lA, two baffle and orifice assemblies are disposed
in series in extension pressure chamber 33. These energy-absorbing baffle and
orifice assemblies each comprise a baffle 5 and an orifice plate 6. Baffles 5
are
generally conical in shape, having a diameter which linearly decreases from
the
entry end of extension pressure chamber 3 to the exit end of extension
pressure
chamber 3. Baffle 5 abuts against orifice plate 6, which is also shown in Fig.
4. A
retaining wall 28 is coupled to extension pressure chamber 3, and orifice
plate 6 is
mounted to retaining wall 28 by way of straps 21 and nuts and bolts 30.
Similar to
orifice plate 7, orifice plate 6 defines a central hole 27 through which a
projectile
1o passes. The diameter of hole 27 is defined by similar functional
requirements as
the diameter of the hole of orifice plate 7.
Also shown in Fig. lA are vent/access stacks 8, 9, 10. Vent/access
stacks 8, 9, 10 include stack covers 22, which could be mounted by way of a
hinge
to the vent/access stacks. Each vent/access stack covers an access cover 23
which
is mounted over an access port 2~. 35. Access ports 25 are in communication
with
extension pressure chamber 33, and access port 35 is in communication with
main
pressure chamber 32. The purpose of these access stack assemblies is to permit
personnel to enter into main pressure chamber 32 or extension pressure chamber
33
for maintenance or repair.
2o Because of the size and weight of the parts of vent/access stacks 8, 9,
10 cranes 11, 12, each having crane arms 14, are used to remove and replace
stack
covers 22 and access covers 23. Furthermore, crane 13, having crane arm 14, is
used to remove and mount transition section 4.
Figs. 2 and 3 show respectively the left-end plate 40 and right-end
2~ plate 41 of the present invention. Each end plate includes individual
plates 42
wMC-o7o - I2 - 21 9 7 6 0 2
which are connected to one another by connector beams 43. Each end plate
defines
a central hole 44. Preferably, each end plate includes removable annular disks
45
so that the diameter of central hole 44 can be changed to accommodate various
sizes
of guns.
Left-end plate 40 is placed vertically at the entry end of transition
section 4. A gun tube is pushed through central hole 44 and into transition
section
4. Preferably, the innermost removable annular disk 45 sealingly engages the
gun
tube.
Right-end plate 41 is placed on the exit end of extension pressure
1o chamber 3. A supplemental tube is placed through central hole 44.
Preferably, the
innermost annular disk 45 sealingly engages the supplemental tube.
The purpose of left-end plate 40 and right-end plate 41 is to retain
sand so that the main pressure vessel 2 and extension pressure vessel 3 can be
entirely covered in sand during operation. By covering the muffler 50 in sand,
the
U muffling effect is increased, although the muffler need not be covered in
sand.
Figs. 5 and 6 show transition section 4 in detailed cross section. Fig.
5 shows a gun having a shorter gun tube than the gun tube of Fig. 6. In either
case, transition section 4 includes radially inward protruding flanges 52, 53
which
serve as seals for engaging gun tube 24 for preventing residual combustion
gases
2o caused by the firing of the gun from escaping back through transition
section 4.
Fig. 6 also shows a supplemental tube 55 having an enlarged portion 57 which
tits
over gun tube 24. The projectile passes through gun tube 24 and through
supplemental tube 55 through the entire muffler 50.
wMC-o7o -13 - 219 7 6 0 2
Fig. 7 shows a cross section of main pressure vessel 2 at a point
through which supplemental tube 5~ extends. A supplemental tube transporter
assembly 60 is shown. Supplemental tube transporter assembly 60 includes a
first
extendable arm 61a and a second extendable arm 61b. At one end of each
extendable arm is a coupling 63a,b respectively, for coupling each extendable
arm
to a respective pair of wheels 65a,b. As shown in Fig. 8, wheels 65a,b engage
and
move along respective tracks 67a,b, which extend parallel to one another and
longitudinally along the inner surface of main pressure vessel 2. Such a
transporter
tube assembly 60 could also be disposed in extension pressure chamber 33. The
to supplemental tube transporter assembly 60 also includes flanges 69a,b
respectively
coupled to the ends of extendable arms 6la,b opposite the ends attached to the
wheels. Flanges 69a,b are selectively attached to supplemental tube 55.
In operation, transporter tube assembly 60 is used to transport
supplemental tube 55 from the exit end of extension pressure chamber 3 to a
point
so that it engages with a gun tube 24. This is done by first rolling wheels
65a,b
along tracks 67a,b towards the exit end of the pressure vessel. Then.
supplemental
tube 55 is pushed through the exit hole of the extension pressure vessel 3 and
into
extension pressure chamber 33. Extendable arms 6la,b are extended so that
flanges
69A,B are in engagement with supplemental tube 55. Then, the entire assembly
60
2o is moved towards the entry end of the pressure vessel.
After placing the supplemental tube in engagement with the gun tube
and securing the transition section over the top of the gun tube, the gun is
ready for
tiring. Initially, valve 18 is closed when the gun is fired. As a consequence
of
firing, combustion gases fill main pressure chamber 32 and extension pressure
2> chamber 33. The pressure waves caused by the firing of the gun are
attenuated by
orifice plate 7 and the baffle and orifice plate assemblies disposed in series
in
2i~76~2
WMC-070 - 14 -
extension pressure chamber 33. Thus, both pressure vessels serve to contain
residual combustion gases and attenuate the pressure waves.
Immediately after firing and attenuation of the pressure waves, valve
18 is opened thereby permitting exhaust blower 17 to remove the residua(
combustion gases from the main pressure chamber. This process is repeated
rapidly. As mentioned above, main pressure vessel 2 and extension pressure
vessel
3 are preferably covered with sand, which is contained by left-end plate 40
and
right-end plate 41.
A gun muffler 1~0 in accordance with a second embodiment of the
1o present invention is shown in Figs. 10 and 10A. In the same manner as the
gun
muffler of the first embodiment, gun muffler 150 includes a transition section
104
and at least one pressure vessel. Preferably, gun muffler 150 includes a main
pressure vessel 102 defining a main pressure chamber 132 and an extension
pressure vessel 103, disposed in series with and connected to main pressure
vessel
102 and defining an extension pressure chamber 133. The volume and shape of
the
pressure vessels may be similar to the first embodiment. Also similar to the
first
embodiment, gun muffler 1~0 includes a vent stack 115 and an exhaust blower
and
valve assembly 120 connected to vent stack 115. As in the first embodiment,
the
valve of an exhaust blower and valve assembly 120, which preferably is a
butterfly
2o valve, closes during firings of the gun for preventing pressure waves
caused by
firing from escaping directly to the atmosphere during firing and opens
between
rirings for permitting said exhaust blower to remove residual combustion gases
from said pressure chamber.
wMC-o7o - is - 219 7 6 0
The second embodiment of the invention may also incorporate some
other features from the first embodiment. For example, the gun muffler of the
second embodiment may include a tube transporter system shown in Figs. 7-9.
Gun muffler 150 includes at least one orifice plate, which is
adjustable relative to the pressure vessels and disposed in a pressure
chamber, for
attenuating pressure waves. More specifically, Fig l0A shows three adjustable
orifice plates. A first orifice plate 106a is disposed in extension chamber
133 and
has a first orifice, through which the projectile passes and which is
adjustable
relative to the longitudinal axis of extension pressure vessel 103. A second
orifice
plate 106b is disposed in series with first orifice plate 106a in extension
pressure
chamber 133 and has a second orifice, through which the projectile passes and
which is adjustable relative to the longitudinal axis of extension pressure
vessel 103.
First orifice plate 106a and second orifice plate 106b are identical. A third
orifice
plate 107 is disposed within extension pressure chamber 133 near the
connection of
~s main pressure vessel 102 to extension pressure vessel 103 and has a third
orifice,
through which the projectile passes and which is adjustable relative to the
longitudinal axis of extension pressure vessel 103.
The orifice plates may be made adjustable in any known manner.
Fig. 11 shows one way to make first and second orifice plates 106a, 106b
2o adjustable. Fig. 11 shows either orifice plate and the surrounding elements
and is
discussed below with direct reference to first orifice plate 106a and
parenthetical
reference to second orifice plate 106b. A first (or second) mounting plate 151
is
connected (i.e., welded or bolted) to extension pressure vessel 103 and has a
first
(or third) bolt hole 153. As shown in Fig. 10A, energy-absorbing baffles lOSa,
z5 lOSb may be respectively mounted to first and second mounting plates 151a,
lSlb.
A first (or second) retaining ring 1~~ has a second (or fourth) bolt hole 155
aligned
wMC-o7o -16 - Z 19 l 6 0 2
with first (or third) bolt hole 153 and has a first (or second) recess 156
confined by
first (or second) mounting plate 151. First (or second) orifice plate 106 is
secured
to first (or second) mounting plate 151 and first (or second) retaining ring
154 at
first (or second) recess 156.
s A first (or second) bolt 158 extends through first bolt hole 153 and
second bolt hole 155 (or through third and fourth bolt holes). By loosening
first (or
third) bolt 158, first (or second) orifice plate 106 may be adjusted to alter
the
location of first (or second) orifice 159 relative to the longitudinal axis of
extension
pressure vessel 103. For example, first (or second) orifice plate 106 may be
rotated
to by rotating first (or second) handle 160, which is connected to first (or
second)
orifice plate 106. More than one handle may be used to rotate orifice plate
106 for
ease of rotation. Upon reaching a desired position of first (or second)
orifice, first
(or third) bolt 158 is tightened to prevent further rotation of first (or
second) orifice
plate 106.
15 Similarly, as shown in Fig. 12, a third mounting plate 161 is
connected (i.e., welded or bolted) to main pressure vessel 102 and has a third
recess 166 and a fifth bolt hole 163. A third retaining ring 164 has a sixth
bolt hole
165 aligned with fifth bolt hole 163 and confines third recess 166. Third
oritice
plate 107 is secured to third mounting plate 161 and third retaining ring 164
at third
2u recess 166. A third bolt 168 extends through fifth bolt hole 163 and sixth
bolt hole
165. By loosening third bolt 168, third orifice plate 102 may be adjusted to
alter
the location of third orifice 169 relative to the longitudinal axis of
extension
pressure vessel 103. For example, third orifice plate 107 may be rotated by
rotating third handle 170, which is connected to third orifice plate 107. More
than
z5 one handle may be used to rotate orifice plate 107 for ease of rotation.
Upon
2197602
WMC-070 - 17 -
reaching a desired position of third orifice, third bolt 168 is tightened to
prevent
further rotation of third orifice plate 107.
A first type of orifice plate is shown in Fig. 13. The orifice plate
174 as shown has an orifice 175 which is circular and disposed off centered
relative
to the orifice plate. Also shown in Fig. 13 is a retainer ring. An alternative
type of
orifice plate is shown in Fig. 14. There, the orifice plate 178 as shown has
an
orifice 179 which is elliptical. The orifice plates are adjustable in order to
accommodate varying trajectories. Also, orifice plate I78 having an elliptical
orifice 179 is particularly useful if a projectile undergoes a drop in
trajectory as it
1o travels along the gun muffler.
As shown in Fig. 10A, a plurality of side ports 182 may be disposed
along the sides of the pressure vessel. Side ports 182 may be used for a
variety of
purposes. For example, side ports 182 may be used for access, viewing,
photography and radar. Side ports 182 may be made of a transparent material if
used for viewing. According to this second embodiment of the invention, gun
muffler 150 is not covered with sand in operation.
As shown in Fig. 10A, a sabot catcher 185 is disposed within one of
the pressure vessels for entrapping particulates caused by the firing of a
gun.
Catcher 185 may be made of any suitable material for permitting gas to pass
2o through but for preventing the passage of particulates. For example, it is
known to
use cables woven together as a sabot catcher. Catcher 185 is mounted to main
pressure vessel 102, such as by being welded or bolted thereto. Catcher 185 is
preferably disposed in main pressure chamber 132 near the connection of main
pressure vessel 102 to extension pressure vessel 103.
wMC-ono - is - ~ 19 7 6 0 ?_
Although illustrated and described herein with reference to certain
specific embodiments, the claims of the present invention are nevertheless not
intended to be limited to the details illustrated and described. Rather, the
claims
are meant to cover various common modifications without departing from the
spirit
of the invention.
