U.S. patent number 3,824,699 [Application Number 05/264,213] was granted by the patent office on 1974-07-23 for aiming device for indirect fire guns.
This patent grant is currently assigned to The United States of America as represented by the Secretary of the Army. Invention is credited to Ludwig J. Lenz, Robert Stanley Thompson.
United States Patent |
3,824,699 |
Lenz , et al. |
July 23, 1974 |
AIMING DEVICE FOR INDIRECT FIRE GUNS
Abstract
In firearms which must be aimed at elevated firing angles in
order to proe the fired projectile with an arcuate trajectory
capable of hitting a hidden target, the attainment of the proper
firing angle is automatically signaled by the return to zero
inclination of a gravity sensing electrolytic switch which had been
set at an angle corresponding to the degree of rotation required to
position a range indicator at the estimated or known range of the
target. A second gravity sensing switch may also be utilized to
signal the absence of any transverse canting of the firearm when
the required firing angle is attained.
Inventors: |
Lenz; Ludwig J. (Muscatine,
IA), Thompson; Robert Stanley (Bennett, IA) |
Assignee: |
The United States of America as
represented by the Secretary of the Army (Washington,
DC)
|
Family
ID: |
23005068 |
Appl.
No.: |
05/264,213 |
Filed: |
June 19, 1972 |
Current U.S.
Class: |
33/334; 42/111;
89/41.17; 89/41.11; 33/366.11 |
Current CPC
Class: |
F41G
3/14 (20130101) |
Current International
Class: |
F41G
3/00 (20060101); F41G 3/14 (20060101); G01c
009/34 (); F41g 003/14 () |
Field of
Search: |
;33/334,366
;89/1F,1J,37C,41B,41D,41T,41CE ;340/267C ;42/7G |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Prince; Louis R.
Assistant Examiner: Phillips; Charles E.
Attorney, Agent or Firm: Kelly; Edward J. Berl; Herbert
Claims
We claim:
1. An aiming device for guns from which projectiles are fired at
elevated firing angles in order to provide an arcuate trajectory
capable of effecting a hit on a hidden target comprising,
a housing fixed to the gun in parallel relation to the firing axis
thereof,
a first tilt plate vertically mounted in said housing for rotation
about a transverse axis therethrough,
a pair of gravity sensing units secured to one side of said first
tilt plate and oppositely inclined relative to each other to
provide an included angle therebetween,
an electrical circuit containing means for producing an audible
signal during the interval in which the included angle between said
pair of units intersects a line parallel to true ground level,
adjusting means rotatably mounted in said housing for selective
adjustment to a desired reading,
cam means rotatably supported in said housing for converting the
rotation of said adjusting means to corresponding rotation of said
first tilt plate whereby said units are preset to the angle at
which the subsequent return thereof to the horizontal during the
elevation of the firearm will sound said audible signal to indicate
the attainment of the desired firing angle,
a second tilt plate pivotally mounted at right angles to said first
tilt plate for fore and aft swinging movement designed to maintain
a vertical position during the elevation of the firearm, and
at least one gravity sensing unit secured to one side of said
second tilt plate in electrical connection with said signal circuit
for producing an additional signal in the event the gun is canted
relative to the horizontal during the elevation thereof to a firing
position.
2. The aiming device defined in claim 1 including means for
adjusting the size of said included angle between said sensing
units on said first tilt plate to vary the duration of said audible
signal upon attainment of the desired firing angle.
3. An aiming device for firearms from which projectiles are fired
at elevated firing angles in order to provide an arcuate trajectory
capable of effecting a hit on a hidden target, comprising,
a gravity sensing switch mounted for rotation about an axis
disposed at right angles to the firing axis of the firearm,
cam means for rotating said switch to a predetermined tilted
position corresponding to the firing angle required of the firearm
in order to impart a given range to the projectile,
means for pivotally mounting said switch for swinging movement at
right angles to the firing axis of the firearm to maintain said
switch in a true vertical position relative to the ground despite
any transverse canting of the firearm during the elevation thereof
to the required firing angle, and
means for providing an audible signal when the firearm has been
sufficiently elevated to return said switch to a position of zero
tilt thereby informing the operator that the required firing angle
has been attained.
4. An aiming device for firearms from which projectiles are fired
at elevated firing angles in order to provide an arcuate trajectory
capable of effecting a hit on a hidden target, comprising,
a first gravity sensing switch mounted for rotation about an axis
disposed at right angles to the firing axis of the firearm,
cam means for rotating said first switch to a predetermined tilted
position corresponding to the firing angle required of the firearm
in order to impart a given range to the projectile,
a plate pivotally mounted for swinging movement about an axis
disposed at right angles to said first switch,
a second gravity sensing switch fixedly mounted on said plate at
right angles to said first switch,
means for providing a first audible signal when the firearm has
been sufficiently elevated to return said first switch to a
position of zero tilt thereby informing the operator that the
required firing angle has been attained, and
means responsive to said second switch for providing a second
audible signal in the event the firearm is canted relative to the
horizontal during the elevation thereof to the required firing
angle.
Description
BACKGROUND OF THE INVENTION
This invention relates to aiming devices for firearms which must be
fired at elevated firing angles in order to provide the projectile
with a trajectory capable of hitting a hidden target and is more
particularly directed to improved means for signaling the operator
when the firearm is correctly oriented to hit the target at the
estimated range.
Many of the firearms in current military use are designed to fire
grenade type ammunition in addition to the standard cartridges with
single projectiles. Since the ballistic trajectory of the much
heavier grenade projectiles is considerably different than that
imparted to a small caliber round fired from a rifled barrel,
separate sights are generally provided for each type of fire. The
grenade sight is ordinarily pivoted to the firearm so that it can
be readily preset, in accordance with the information provided by
any suitable range indicating means, to the particular angle at
which the firearm must be elevated in order for the grenade
projectile to hit the desired target area. The attainment of the
proper firing angle has heretofore been determined by such various
expedients as a gunner's quadrant, a spirit level, or a pendulum
indicator. However, the proper utilization of these prior art
devices requires repeated visual checking by the operator during
the elevation of the firearm to the desired firing angle and
consequently interferes with his ability to keep his attention
focused on the target area. Moreover, the necessary correlation
between the sighting of the target and the determination of the
proper firearm elevation is further complicated in the event of
poor visibility due to fog, rain or approaching nightfall.
Another problem frequently encountered in elevating the firearm to
the desired firing angle lies in the difficulty of avoiding some
degree of transverse cant thereof at the instant of firing.
Obviously, if the firearm is in a canted position at the instant
the tip of the grenade sight is aligned with the target, the firing
axis of the projectile will be transversely misaligned relative to
the target to an extent determined by the degree of cant and the
height of the sighting element above the firing axis of the
projectile.
SUMMARY OF THE INVENTION
Accordingly, it is an object of this invention to provide an aiming
device for grenade launching firearms which will automatically
signal the operator upon the attainment of the proper firing angle
required to hit a target at the estimated range thereof.
It is a further object of the present invention to provide an
aiming device as aforesaid, wherein the point at which the signal
is energized is readily controlled by the presetting of a
calibrated range indicator.
It is another object of this invention to provide a grenade
launching aiming device, as aforesaid, with the added capacity for
signalling the absence of any transverse cant in the orientation of
the firearm once the required firing angle has been attained.
Still another object of the invention lies in the provision of an
aiming device, as aforesaid, which will automatically nullify the
effect of any transverse cant in the firearm during the elevation
thereof to the desired firing angle.
It has been found that these objects can be readily accomplished by
an aiming device containing a gravity sensing switch which, upon
passage through a zero inclination relative to the ground, will
automatically signal the attainment of the proper firing angle at
which the grenade-launching firearm must be elevated to provide a
target hit. A preferred switch of this type is one in which an
electrolytic medium such as mercury, is contained in a capsule
provided with an electrical contact designed to close a circuit and
energize an audible signal when gravity forces cause the mercury to
contact both of the electrodes in the capsule. A rotatable range
indicator, calibrated in accordance with the maximum range to which
the grenade projectile can be fired, is utilized to cam the member
on which the switch is mounted to the particular angle at which the
firearm will be correctly elevated to produce a target hit when the
sensor is returned to a zero inclination. In order to avoid or
correct any transverse canting of the firearm, the aiming device
may also be provided with a second switch, identical to the first,
but mounted at right angles thereto for pivotal fore and aft
swinging movement. Both switch mechanisms are preferably arranged
to operate independently of one another and provide recognizably
different signals, or they can be connected in series so that the
audible signal will only be heard upon the gun being oriented
correctly in elevation and not canted. In the event increased
simplicity and compactness is required of the aiming device, the
transversely mounted switch may be eliminated from the assembly and
the function thereof retained by mounting the entire aiming device
so as to freely swing in a plane transverse to the firing axis of
the firearm. As a result, the tilt plate on which the elevation
switch is mounted will remain in a true vertical plane at all times
despite any canting of the entire firearm.
BRIEF DESCRIPTION OF THE DRAWINGS
The exact nature of the invention as well as other objects and
advantages thereof, will be readily apparent from consideration of
the following specification relating to the annexed drawings
wherein:
FIG. 1 is a perspective view of a grenade launching rifle equipped
with the orientation sensing unit of the present invention;
FIG. 2 is an enlarged partial top view of the sensing unit with the
cover and portions of the interior framework removed to show the
connection between the range selector and the cam means utilized to
pivot the follower mechanism containing the gravity sensing
switches;
FIG. 3 is a sectional view taken along line 3--3 of FIG. 2 to show
the configuration of the cam and follower mechanism utilized to
orient the switches to the angle corresponding to the range at
which the selector dial is set;
FIG. 4 is a sectional view taken along line 4--4 of FIG. 2 to show
additional structural detail of the carriers in which the switches
are mounted;
FIG. 5 is a cross-sectional view taken along line 5--5 in FIG. 2 to
show the manner in which the cam follower and the switch carriers
are mounted in adjacent relationship;
FIG. 6 is a schematic diagram of the electrical circuit utilized to
connect the gravity sensing switches to the buzzer elements in the
battery pack;
FIG. 7 is a side view of an alternate sensing unit similar to that
shown in FIGS. 2-5 and is partially cut away to schematically show
the additional gravity sensing switch utilized to signal the
absence of any transverse canting of the firearm during the
elevation thereof to the predetermined firing angle; and
FIG. 8 shows an alternate arrangement for providing the same
function as the sensing unit of FIG. 7 without the need for the
additional switch and swinging tilt plate therefor.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
As best shown in FIG. 1, the aiming device of the present invention
is contained within a rectangular housing 12 which is preferably
secured to the top of the carrying handle 14 of the rifle in
parallel relation to the barrel 16 thereof and the grenade
launching attachment 18 mounted therebeneath. A cover 17 is
removably secured to the top of housing 12 by screws 19 to permit
access to the interior thereof for a purpose to be hereinafter
shown. Power for the operation of the aiming device is provided by
a portable generator unit or battery pack 24 electrically connected
by a cable 26 to a suitable socket 27 in the side of housing
12.
As best shown in FIGS. 2 and 4, a range dial 28, calibrated in
increments of 25 meters to a maximum range of 500 meters, is fixed
to the lower end of a rotatable shaft 30 which extends vertically
upward through housing 12. Shaft 30 is supported by a flanged
bearing 31 rotatably seated in a bushing 32 which is, in turn,
fixed to a framework 34 extending along the interior wall surfaces
of housing 12. A portion of dial 28 protrudes sufficiently from the
side of housing 12 to permit a clear view of the range indicia
thereon. The upper end of shaft 30 is journaled in a right-angled
bracket 36 fixed at each end thereof to framework 34. A bevel gear
38 secured to the upper portion of shaft 30 is arranged to mesh
with a similar gear 40 oriented at right angles thereto for
imparting the rotation of range dial 28 to a horizontally disposed
shaft 42 journaled at one end in bracket 36 and at the other end
thereof in a suitable bushing 44 fixed between an inturned portion
of framework 34 and the sidewall of housing 12.
Fixedly secured to shaft 42 by a setscrew 45 is a cam 46 whose
exterior periphery is contoured, as indicated at 48 in FIG. 3, in
accordance with the ballistic ratio between any given elevation of
the firearm from which the grenade projectile is launched and the
range which will be imparted to the projectile at that particular
elevation of the firearm. Cam 46 is positioned on shaft 42 so that
the periphery 48 thereof bears against a pin 50 projecting
outwardly from the free end of an arm 51 depending from a cam
follower 52. In order to maintain pin 50 in continuous contact with
periphery 48 during the rotation of cam 46, a tension spring 54 is
extended between a projecting lug 55 disposed on the base of
framework 34 and a corresponding projection 56 disposed on follower
arm 51.
Cam follower 52 is a generally T-shaped member with a quadrant
portion 57 on one side of follower arm 51 and a rectangular portion
58 on the opposite side thereof. As best shown in FIG. 5, a shaft
60 secured at one end to bracket 36 and at the other end thereof to
framework 34 serves to rotatably support cam follower 52 in
adjacent and spaced relation to cam 46. The desired spacing between
cam 46 and cam follower 52 is provided by a hub 61 which projects
outwardly from quadrant portion 57 into bearing contact with a
suitable pad 62 fixed to bracket 36. Shaft 60 also serves to
rotatably support an upper and a lower switch carrier, 63 and 64
respectively, between cam follower 52 and a suitable bearing pad 65
affixed to framework 34.
The underside of upper carrier 63 is formed with a depending
mounting lug 66 for passage therethrough of shaft 60 while the top
of carrier 63 is provided with an upwardly extending lug 67
disposed between a pair of adjusting screws 68 threadably mounted,
as shown in FIG. 3, in spaced support blocks 70 projecting
outwardly from the end of rectangular portion 58. When screws 68
are advanced to contact the opposite sides of lug 67, carrier 63 is
adjustably secured to cam follower 52 for joint rotation therewith.
Lower carrier 64 is provided with a mounting lug 71 extending
upwardly into adjacent axial alignment with lug 66 on carrier 63
whereby the passage of shaft 60 therethrough positions both
carriers in spaced relation, as best shown in FIG. 3. A second pair
of adjusting screws 72 are threadably secured in opposite end
portions of carrier 63 to project therefrom into contact with the
corresponding end portions of lower carrier 64 which like carrier
63 is thereby adjustably secured to cam follower 52 for joint
rotation therewith. Screws 68 are utilized to position carrier 63
so that the long axis thereof is slightly inclined relative to the
corresponding axis of follower arm 51. Similarly, screws 72 serve
to position lower carrier 64 so that the long axis thereof is also
inclined in the opposite direction relative to follower arm 51.
Thus, carriers 63 and 64 can be individually adjusted to provide a
given included angle therebetween for a purpose to be hereinafter
shown. Such angle may be increased or decreased by rotating both
screws in each set in corresponding opposite directions.
Carriers 63 and 64 are each centrally bored, as shown at 75 and 76
in FIG. 5, to respectively seat gravity sensing switches 77 and 78
formed by at least one gravity responsive unit or capsule 80
partially filled with a quantity of mercury or other equivalent
electrolytic medium 81. A pair of spaced apart electrodes 86, 88
extend into capsule 80 from one end thereof. As shown particularly
in FIG. 6 of the drawings, the upper switch 77 is disposed with its
electrodes toward the butt stock end of the gun and the lower
switch 78 is disposed with its electrodes toward the muzzle end of
the gun. The two switches are connected in series and the upper
electrode 86 of the upper switch 77 is connected with a tone
generator or buzzer 89 by a lead 104. The lower electrode 88 of
lower switch 78 is connected with a source of electrical energy,
such as a battery 108. Both tone generator 89 and battery 108 are
conveniently mounted in the generator housing unit 24. As
heretofore described, the upper and lower switches 77 and 78 are
adjustably disposed for angular relation to each other, whereby the
bubbles in each switch will be disposed adjacent to the electrodes
incident to the switch being disposed at the proper horizontal
position governed by the angle of elevation of the gun. In such
position, the bubbles permit the mercury to establish contact
between the electrodes in each switch. Thus, as shown in FIG. 6,
the gun having been directed to the proper elevation angle, both
mercury switches 77 and 78 are conductive. If the gun should be
tilted upward, as indicated by the arrow A in FIG. 6, the lower
switch 78 becomes non-conductive. If the gun should be tilted
downward, as indicated by the arrow A in FIG. 6, the upper switch
77 becomes non-conductive. In order to render the signal producing
elements inoperative except upon demand, a mechanical switch 90 is
disposed in the circuit. The switch 90 may be conveniently provided
on the housing 12 for use by the user of the gun and it may be
connected in circuit with either lead 104 or 106 to activate the
unit. The tone generator 89 is activated by electrical energy
passing through switches 77 and 78 when disposed in a zero-gravity
position during the elevation of the firearm, the signal then being
transmitted to at least one earphone 91 connected to generator unit
24 by a flexible cable 92.
In operation, once a specific target has been located and the
position coordinates thereof established by any suitable fire
control method, range dial 28 is rotated to the determined range
thereby actuating bevel gears 38 and 40 to impart equivalent
rotation to cam 46. Since cam periphery 48 is in contact with pin
50 on follower arm 51, rotation of cam 46 will impart a
corresponding pivotal movement to cam follower 52 thereby tilting
switches 77 and 78 relative to the zero-gravity position thereof.
The new orientation imparted to switches 77 and 78 results in a
displacement of the mercury 81 and associated air bubble 84 which
interrupts the electrical continuity of the circuit. Thereafter,
switch 90 is manually actuated to activate buzzer 89 and as the
firearm is elevated in line with the desired target, the passage of
switch 77 in upper carrier 63 through a zero-gravity position
parallel to true ground level will energize buzzer 89 and alert the
operator of the firearm that the gun is at proper elevation and
firing may be initiated. However, if the elevating movement of the
firearm is not immediately halted and switch 78 in lower carrier 64
is moved through the zero-gravity position thereof, the
energization of the latter will terminate the buzzer signal thereby
informing the operator of the necessity for lowering the firearm
until the buzzer signal is again established. The energization
period of the buzzer can be appropriately increased or decreased by
the selective rotation of adjusting screws 68 and 72 as previously
explained.
While the foregoing arrangement will generally provide adequate
firing accuracy for rifle-launched grenade projectiles, this is, of
course, contingent on the ability of the operator to elevate the
firearm to the required firing angle without any appreciable
transverse canting thereof. In the event the firearm is canted
either to the right or left relative to the true ground level, the
resulting misalignment between switches 77 and 78 and the vertical
plane perpendicular to the true ground level will affect the
gravity flow of the mercury along the arcuate wall surface of glass
capsule 80 and thereby produce a false indication of the attainment
of a zero-gravity position. Thus, the firearm may not be elevated
to the exact firing angle which will permit the grenade projectile
to reach the range for which dial 28 was set.
In order to avoid such inaccuracy in the response of the pair of
switches 77 and 78, a similar gravity sensing switch 79 is included
in housing 12 in position to sense any tilting or canting of the
firearm in a transverse direction. As indicated at 93 in FIG. 7,
such switch 79 may be fixedly strapped on a tilt plate 94 disposed
rearwardly of cam 46 and provided with outwardly extending pivot
pins 96 at the opposite upper ends thereof arranged to rotatably
engage in the corresponding sidewalls of housing 12. Thus, tilt
plate 94 will remain in the same vertical plane and position switch
79 at right angles to switches 77 and 78, regardless of the extent
to which the firearm is being elevated and consequently be
accurately responsive to the introduction of any transverse cant in
the firearm. Additional switch 79 is preferably in electrical
connection with a second buzzer element (not shown) having a tone
which is clearly distinguishable from that of the buzzer element
arranged to be energized by the switches 77 and 78 contained in
carriers 63 and 64. Accordingly, whenever both buzzers are
simultaneously sounded, the operator of the firearm will be
automatically informed that the elevation thereof to the required
firing angle has been accomplished without any undesirable cant in
the transverse direction. If, on the other hand, only one of the
buzzers is sounded, the operator will realize the need for further
manipulation of the firearm in the direction required to energize
the silent buzzer. On the other hand, this additional switch 79 may
be connected in serie with the elevation switches 77 and 78 so that
energization of the buzzer will take place only when the gun is
properly elevated and not canted.
It has also been found that the adverse effect of canting the
firearm in the transverse direction during the elevation thereof to
the firing position can also be avoided without the necessity for
the additional switch arrangement shown in FIG. 7. This can be
accomplished simply by mounting housing 12 between opposing pivots
98 provided at the upper ends of upright posts 100 and 102 which
are, in turn, fixedly secured to the forward and rear portions of
the firearm carrying handle 14 as shown in FIG. 8. Thus, even if
the firearm should be transversely canted, housing 12 will still
maintain the true vertical position required to keep switches 77
and 78 therein accurately responsive to the changing orientation of
the firearm during the elevation thereof to the required firing
angle.
Accordingly, the present invention provides a unique aiming device
for automatically determining the attainment of the required firing
angle for a grenade-launching firearm and, thereupon notifying the
operator of the existence or absence of any cant in the transverse
direction. The device is readily adaptable to any firearm for which
a source of electricity is available and, provides the required
accuracy of fire even though the target is not visible at the time
of firing.
The foregoing disclosure and description of the invention is
illustrative only. Various changes may be made within the scope of
the appended claims without departing from the spirit of the
invention.
* * * * *