U.S. patent application number 11/551688 was filed with the patent office on 2007-07-05 for aerodynamic rotational stabilization techniques for projectiles.
Invention is credited to Charles D. Widener.
Application Number | 20070151474 11/551688 |
Document ID | / |
Family ID | 38223046 |
Filed Date | 2007-07-05 |
United States Patent
Application |
20070151474 |
Kind Code |
A1 |
Widener; Charles D. |
July 5, 2007 |
AERODYNAMIC ROTATIONAL STABILIZATION TECHNIQUES FOR PROJECTILES
Abstract
A pliant projectile is provided with a plurality of 1-shaped
grooves in the circumference thereof. The grooves are at an angle
with the axis of the projectile and, in flight, will, through
interaction with the air, cause the projectile to rotate about its
axis, thereby stabilizing the flight path. The projectile may be
provided with an additional stabilizing member extending from its
tail which member includes a plurality of tabs each having a fin
that can interact with the air, in flight, to add additional
rotational forces to the projectile.
Inventors: |
Widener; Charles D.;
(SEARCY, AR) |
Correspondence
Address: |
KLEINBERG & LERNER, LLP
2049 CENTURY PARK EAST
SUITE 1080
LOS ANGELES
CA
90067
US
|
Family ID: |
38223046 |
Appl. No.: |
11/551688 |
Filed: |
October 20, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60730345 |
Oct 27, 2005 |
|
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|
Current U.S.
Class: |
102/501 ;
102/439; 244/3.23 |
Current CPC
Class: |
F42B 10/24 20130101;
F42B 10/26 20130101; F42B 14/064 20130101 |
Class at
Publication: |
102/501 ;
102/439; 244/003.23 |
International
Class: |
F42B 10/24 20060101
F42B010/24 |
Claims
1. A pliant projectile to be deployed from a weapon comprising: a.
A nose portion; b. A tail portion; and c. A substantially
cylindrical body portion having a plurality of substantially
L-shaped grooves formed therein, said grooves generally paralleling
the cylindrical axis of said body portion but at a slight angle
thereto.
2. The pliant projectile of claim 1 wherein each of said L-shaped
grooves includes a substantially radial surface and a substantially
circumferential surface, said radial surface being inclined at an
angle with respect to a radius of said cylindrical body
portion.
3. The pliant projectile of 1 wherein each of said L-shaped grooves
includes a substantially radial surface and a substantially
circumferential surface, said circumferential surface being
inclined at an angle with respect to the circumference of said
cylindrical body portion.
4. The pliant projectile of 3 wherein said radial surface is
inclined at an angle with respect to a radius of said cylindrical
body portion.
5. The pliant projectile of 1 further including a stabilizing
member extending from said tail portion, said stabilizing member
having a plurality of axially extending tabs each with a tapered
fin orthogonally extending therefrom.
6. The pliant projectile of 1 further including a stabilizing
member extending from said tail portion, said stabilizing member
having a plurality of axially extending tabs each with a tapered
fin extending therefrom at an acute angle.
7. A projectile comprising: a. A nose portion; b. A tail portion;
and c. A substantially cylindrical body portion having a plurality
of substantially L-shaped grooves formed therein, said grooves
generally paralleling the cylindrical axis of said body portion but
at a slight angle thereto.
8. The projectile of claim 7 wherein each of said L-shaped grooves
includes a substantially radial surface and a substantially
circumferential surface, said radial surface being substantially
aligned with a radius of said cylindrical body portion.
9. The projectile of claim 7 wherein each of said L-shaped grooves
includes a substantially radial surface and a substantially
circumferential surface, said radial surface being inclined at an
angle with respect to a radius of said cylindrical body
portion.
10. The projectile of claim 7 wherein each of said L-shaped grooves
includes a substantially radial surface and a substantially
circumferential surface, said circumferential surface is
substantially orthogonal to a radius of said cylindrical body
portion.
11. The projectile of claim 7 wherein each of said L-shaped grooves
includes a substantially radial surface and a substantially
circumferential surface, said circumferential surface is inclined
at an angle to a radius of said cylindrical body portion.
12. The projectile of claim 11 wherein said radial surface is
inclined at an angle with respect to a radius of said cylindrical
body portion.
13. The projectile of claim 7 further including a stabilizing
member extending from said tail portion, said stabilizing member
having a plurality of axially extending tabs.
14. The projectile of claim 7 further including a stabilizing
member extending from said tail portion, said stabilizing member
having a plurality of axially extending tabs each with a tapered
fin orthogonally extending therefrom.
15. The projectile of claim 7 further including a stabilizing
member extending from said tail portion, said stabilizing member
having a plurality of axially extending tabs each with a tapered
fin extending therefrom at an acute angle.
Description
[0001] This is a continuation-in-part of my provisional application
for letters patent Ser. No. 60/730,345, filed Oct. 27, 2005.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to special purpose
projectiles, and, more specifically to novel techniques to
significantly improve the accuracy and consistency of projectiles
fired from smooth bore weapons, such as shot guns and mortar
launchers.
[0004] 2. Description of the Related Art
[0005] U.S. Pat. No. 6,782,828 B2, issued to the present inventor,
discloses novel techniques for discharging elastomeric projectiles
from fire arms without risk of the soft projectiles jamming or
lodging in the barrel of the weapon. Although these unique
cartridges have been widely acclaimed by both law enforcement and
various branches of the government and the Department of Defense,
better accuracy and consistency, particularly at extended range,
were sought after by some of these same users. Border patrol,
prison guards, wildlife management and control and riot control
officers in particular, require rounds that they could use at
distances from 50 to 100 yards, for successfully engaging a human
or animal sized target consistently and meaningfully, without
lethality.
[0006] As a result of several years of development and testing of
this type of less lethal, very soft projectile, it was recognized
that to achieve that range with consistent accuracy, some
additional in-flight stabilization techniques would have to be
developed. Extensive development effort has resulted in a preferred
embodiment for a technique and design for what will now be referred
to as aerodynamic rotational stabilization or "aerodynamic
rifling".
SUMMARY OF THE INVENTION
[0007] A significant reason that rifle and pistol ammunition is
extremely accurate at close range as well as extended range is the
presence of rifling in the bore of the weapon. Rifling is a series
of alternate "lands" and "grooves" that are machined longitudinally
into the bore of the barrel in a helical pattern. This slight
"twist" imparts a spin to the solid lead or copper projectile as it
is forced through the bore of the weapon and subsequently provides
a remarkable stability to the projectile in flight.
[0008] Because shot guns and mortar launchers, for example, are not
provided normally with rifled barrels and the soft, less lethal
projectile of the aforementioned and present invention, require
minimum contact with a smooth bore for their best performance, it
became the challenge to impart some slight rotation or "spin" to
the projectile during flight giving rise to the term "aerodynamic
rifling".
[0009] During the compression or injection molding process of the
soft elastomeric projectile, a multiplicity of generally "L" shaped
grooves are placed at a slight angle to the horizontal axis, around
the periphery of the projectile. As the projectile passes through
the air at high velocity, the raised "lands" which are positioned
at a slight angle with respect to the air stream, cause the
projectile to rotate around its horizontal axis from the influence
of the air stream through which the projectile passes.
[0010] How and why the projectile rotates is a function of a
combination of many interrelated factors such as the initial muzzle
velocity, the number of "lands" and "grooves" on the projectile,
the depth of the grooves and equally important, the angle of the
"lands" with respect to the horizontal axis of the projectile. The
optimum angle, however, can only be determined and is affected by,
the values of the other aforementioned parameters, which may also
vary themselves, depending upon the range required of the round and
even the durometer of the elastomeric projectile.
[0011] However, the novel feature that contributes most to the
aerodynamic rotational performance of the design is the
configuration of the rifling profile itself. In order to allow the
air stream maximum access to the angled vertical surfaces of the
"lands", the profile must take more of an "L" shaped configuration
with one surface of the vertical leg of the "L" radiating from the
center axis of the projectile and the other leg surface positioned
at up to a 90 degree angle with respect to the first vertical leg
surface. This configuration provides maximum access of the air
stream to the vertical angled surface of each "land".
[0012] There exists an additional novel feature incumbent with
aerodynamic rifling that is only possible with a very soft
projectile that is disclosed in the aforementioned patent and in
the present invention. As stated earlier, the interrelationship of
many variables combined in numerous ways, all contribute to the
rotation of the projectile as it passes through the air. One
difficulty encountered, especially in the longer range versions
(which require a higher initial velocity), was the increased
aerodynamic drag, resulting from the elevated rotational speed
produced at these higher initial velocities.
[0013] With reference to the structure described and shown in the
patent, by extending the length of the transfer rod, or by the
addition of one or two more buffer pads in front of the transfer
rod (effecting the same result), the projectile, during the initial
acceleration phase, is permitted to elongate even further than
normal before its rear portion is contacted by the accelerating
front surface of the piston. By this additional stretching of the
projectile, the original angle of the surface of the rifling
"lands" on the projectile is decreased slightly during the
projectile's exit from the barrel of the weapon and for a period of
time during its initial flight to the target, thus reducing its
rotational velocity.
[0014] During flight, the elastic memory of the projectile causes
it to retract, assuming a configuration close to the original angle
of the rifling. During this same period of time, the projectile's
speed is deteriorating from its original muzzle velocity. Within
certain limits, the rotational velocity of the projectile is
inversely proportional to the forward velocity of the projectile.
Therefore, as the projectile slows as it approaches target, the
more unstable it would become were it not for the greater stability
provided by the increased rotational velocity resulting from the
restored angle of the rifling.
[0015] This unique self compensating feature, although it exists to
some extent in all aerodynamic rifling versions, is particularly
beneficial, if not required, in all extended range configurations
of aerodynamic rifling rounds. The unique configuration of the
"aerodynamic rifling" provides an additional significant
enhancement pertaining to the manufacturability of the
projectile.
[0016] Normally the design of an injection or rubber compression
mold to produce a sophisticated part such as this would require the
incorporation of "slides" in to the mold cavities to facilitate the
release prior to ejection of the finished part from the mold.
Slides are complicated and expensive and decrease the mold cavity
density. This projectile, due in part to the low durometer of the
elastomer and in part due to the modest angle of the rifling, but
mostly due to the substantial included angle between the two
surfaces of the "L", may be removed easily from the mold cavity
without the aid of slides. This moldability significantly increases
the production rate and lowers the initial cost of the molds.
[0017] Testing this design in a 12 gauge shotgun with an initial
muzzle velocity of approximately 700 f.p.s. at a range of 75 yards,
resulted in most all projectiles impacting within a man sized
target profile--unheard of for a soft elastomeric less lethal
shotgun projectile.
[0018] An additional feature of this configuration is that the
multiplicity of "aerodynamic rifling" grooves around the periphery
of the projectile, which, in the preferred embodiment, are
approximately 8 or more and, on average, 0.040 to 0.060 of an inch
or more deep, tend to weaken the cross section of the projectile,
allowing it to more readily expand radially upon impact with the
target to deliver, at higher velocity, more kinetic energy onto the
target body surface while remaining within acceptable kinetic
energy density limits of approximately 100 to 125 ft. lb/sq.
in.
[0019] While considering additional stabilizing techniques for this
projectile, which would further complement the aerodynamic rifling
feature, a design for an improved transfer member for shotguns and
other smooth bore weapons evolved. The new design consists of a one
piece assembly including the transfer rod, the piston or wad and a
multiplicity of tabs added around the periphery of the rear of the
piston.
[0020] Affixed to the outer surface of each tab may be vertical
fins. The tabs contribute additional in-flight stability to the
projectile assembly by effectively improving the ratio of the
length to the diameter (the L/D ratio), which ideally should be
approximately 3 to 1. The optional tapered vertical fins which may
be affixed to the top surface of the tabs contribute additional
stability. More importantly, these fins can provide a slight amount
of drag stabilization, if needed, for a more aerodynamically stable
projectile.
[0021] Also contemplated, but not included in the preferred
embodiment, is the concept of substituting an angled fin for the
straight vertical fin. This angled fin can be in lieu of, or in
addition to, the "aerodynamic rifling" on the projectile. For
example, at very slow projectile velocities, as in a less lethal
mortar round, the additional rotational force provided by the
angled fins, might optimize its performance as well as that of
small caliber hand gun projectiles where aerodynamic rifling molded
into the projectile might not be practical. Again, mold release
consideration and airstream aerodynamics dictate the shape of the
solid angled fin.
[0022] It should be noted that although all of the aforementioned
concepts are primarily directed toward launching soft projectiles
from smooth bore weapons, nothing stated herein precludes launching
these type of projectiles from rifled bores. It would be highly
advantageous, however, to have the induced rotational motion from
the aerodynamic rifling compatible with the twist of the rifled
bore.
[0023] Forward of the piston section, an annular cup was added to
receive the rear section of the projectile, which was also
lengthened, in a manner that more properly contains the back of the
projectile during the initial rapid forward acceleration of the
transfer member. This feature reduces the friction between the soft
projectile and the shell casing and also provides an improved, less
disruptive air flow between the lengthened rear portion of the
projectile and the transfer member during flight. A rim or collar
was added around the rear perimeter of the rifling on the
projectile to provide a more substantial surface with which the
forward rim portion of the annular cup interfaces during the
initial acceleration phase of the transfer member.
[0024] We now have an improved projectile and transfer member,
which working in concert with the novel aerodynamic rifling feature
provides a less lethal 12 gauge point round for law enforcement and
the military, capable of both pinpoint accuracy at close range and
the ability to engage a man sized target at ranges of from 50 to
100 yards, simply by adjusting the initial muzzle velocity and
possibly the durometer of the projectile.
[0025] Although the aerodynamic rifling disclosures in the present
invention were developed and mainly directed towards applications
involving very soft (25 to 35 Shore "A") projectiles, it should be
noted that the same technology might well be applied to the so
called "rubber bullets", that, of necessity, are much harder, being
in the range of 60 to 90 shore "A" in order to safely transit the
barrel of the weapon.
[0026] Although the concepts disclosed herein have been primarily
directed to less lethal applications, they are all directly
applicable to various other aerodynamic objects, either self
propelled or inertia devices, which may benefit from the disclosed
methods of aerodynamic stabilization. Applications as widely
diversified as toys to less lethal and malodorant mortar rounds are
all potential candidates that could benefit from this
technology.
[0027] An additional specific application for this present
technology exists in an area referred to as shotgun "slugs" which
are single projectiles for shotguns. These heavy projectiles are
usually made of lead and are used for hunting big game animals and
dangerous game such as wild boar and bear. Many states require by
law, the use of shotguns and slugs or buckshot for hunting deer and
other seasonal game animals.
[0028] Most attempts to improve the accuracy of shotgun slug type
projectiles at extended range, has been directed towards inducing
some limited rotational velocity into the projectile prior to its
exiting the bore of the weapon. The preferred and most pervasive
method has been to cast or mold the lead projectile with angular
"lands and grooves" around its periphery. These rectangular cross
sectional shaped "lands" are basically a mirror image of the
rifling on the inside of a rifled gun barrel. The outside diameter
of these "lands" is typically slightly larger than the inside
diameter of a smooth bore of a shot gun barrel, so in transiting
the bore, the projectile supposedly is caused to rotate. The
effectiveness of this approach is questionable because there is
very little improvement in the accuracy of "rifled slugs" over most
non-rifled slugs in actual practise.
[0029] All of the aforementioned technology and design pertaining
to less lethal projectiles is applicable to solid projectiles. The
design and specifications, however, incorporated in a preferred
embodiment of a solid projectile will differ from those selected
for a low durometer (soft) less lethal projectile. The initial
muzzle velocity can be almost three times that of a less lethal
projectile and the number of "grooves", their depth and angle, will
be consequently be affected.
[0030] However the technical challenges associated with the
successful design of a soft lead or copper slug incorporating
"aerodynamic rifling" for smooth bore shot guns or mortars or the
like is much less demanding if the techniques disclosed in the
present invention are used. A great many of the overlapping and
variable parameters associated with low durometor projectiles are
minimized or completely eliminated with a solid projectile
design.
[0031] Accordingly, it is an object of the present invention to
provide a less lethal projectile with improved stability in flight.
It is an additional object of the invention to provide a soft (low
durometer) projectile that can transit the bore of a weapon without
contact and have improved accuracy over ranges up to 100 yards. It
is a still further object of the invention to apply the same
principles to metal projectiles for smooth bore weapons that will
exhibit improved in flight stability and greater accuracy at
greater ranges.
[0032] The novel features which are characteristic of the
invention, both as to structure and method of operation thereof,
together with further objects and advantages thereof, will be
understood from the following description, considered in connection
with the accompanying drawings, in which the preferred embodiment
of the invention is illustrated by way of example. It is to be
expressly understood, however, that the drawings are for the
purpose of illustration and description only, and they are not
intended as a definition of the limits of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0033] FIG. 1 is a side view of a projectile according to the
present invention;
[0034] FIG. 2 is a front view of the projectile of FIG. 1;
[0035] FIG. 3 is a sectional view of the projectile of FIG. 1 taken
along the line 3-3 in the direction of the appended arrows;
[0036] FIG. 4 is a transfer rod, suitable for use with the
projectile of FIG. 1;
[0037] FIG. 5 is sectional view of a fin of the transfer rod of
FIG. 4, taken along line 5-5 in the direction of the appended
arrows;
[0038] FIG. 6 is an alternative embodiment of a transfer rod;
[0039] FIG. 7 is a sectional view of a fin of the transfer rod of
FIG. 6, taken along line 7-7 in the direction of the appended
arrows; and
[0040] FIG. 8 is a partial view of an alternate embodiment of
transfer rod fins.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0041] Turning first to FIG. 1, there is shown a projectile 10
according to a preferred embodiment of the present invention.
Molded into the body of the projectile 10 are a plurality of L
shaped grooves 12 which create a plurality of raised lands 14
around the outer circumference of the projectile 10. As shown, the
grooves 12 and associated lands 14 are at an angle to the axis of
the projectile 10.
[0042] FIGS. 2 and 3 give a better view of the grooves 12 and the
lands 14 created when the grooves 12 are formed in the outer
surface of the projectile 10. In flight, the wall of the land 14
provides aerodynamic resistance to the flow of air and causes the
projectile 10 to rotate in flight.
[0043] Turning next to FIG. 4, there is shown an improved transfer
member 20 which combines a transfer rod 22 with a piston element
24. Extending from the rear of the piston element 24 is a plurality
of tabs 26, each with a stabilizing fin 28. FIG. 5 shows the shape
of the fin 28 relative to the tab 26.
[0044] FIG. 6 shows an alternative embodiment of an improved
transfer member 40. In this embodiment, the tabs 42 are provided
with angled stabilizing fins 44 that are as wide as the tab 42 at
the base of the tab 42 but taper to a point at the outer end of the
tab 42. A cross section of the tab 42, showing the fin 44 is shown
in FIG. 7. Yet another embodiment of a transfer member 50 is shown
in FIG. 8. In this embodiment, a plurality of tabs 52 are provided.
Each tab 52 has a fin 54 of uniform width, but which angles,
diagonally across the width of the tab 52.
[0045] Thus there has been shown an improved projectile with a
grooved surface that can rotate in the flight to a target. The
rotation stabilizes the projectile and increases its accuracy. As
part of the improved projectile, an improved transfer member is
provided which combines a transfer rod with a piston and which can
remain with the projectile throughout the flight. For added
stabilization, the piston is provided with a plurality of
stabilizing tabs, each with a fin. The net effect is rotating
projectile with finned tabs that help resist pitch and yaw.
[0046] The scope of protection of my invention should be limited
only by the scope of the claims appended hereto.
* * * * *