US3339450A

US3339450A - Adjustable reflector sight for hightrajectory projectiles

Info

Publication number: US3339450A
Application number: US299439A
Authority: US
Inventors: Frederick P Reed
Original assignee: Individual
Current assignee: Individual
Priority date: 1963-08-01
Filing date: 1963-08-01
Publication date: 1967-09-05
Anticipated expiration: 1984-09-05

Description

UHUQQ HLI'LEKUWL wuuwu nuw F. P. REED Sept. 5, 1967 ADJUSTABLE REFLECTOR SIGHT FOR HIGH-TRAJECTORY PROJECTILES 5 Sheets-Sheet 1 Filed Aug. 1, 1963 INVENTOR. FI'EaET'iBk P REEa Sept. 5, 1967 F. P. REED 3,339,450

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Sept. 5, 1967 F. P. REED 3,339,450

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United States Patent 3 339,450 ADJUSTABLE REFLECTOR SIGHT FOR HIGH- TRAJECTORY PROJECTILES Frederick P. Reed, Ludlow, Mass., assignor to the United States of America as represented by the Secretary of the Army Filed Aug. 1, 1963, Ser. No. 299,439 4 Claims. (Cl. 88-1) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment to me of any royalty thereon.

This invention relates to sights for guns and more particulanly to a reflector sight to be used with shoulder-supported firearms for high-trajectory projectiles.

Included in the arsenal of modern weapons are shoulder-supported firearms which discharge grenades at a low velocity and with a high trajectory so that, when the target is some distance from the shooter, the firearm has to be elevated to a considerable angle for lobbing the grenade to the target. Considerable difiiculty has been encountered in providing a suitable sighting device for such firearms because the considerable angle of elevation requires that the conventional type of rear sight mounted on top of the barrel be adjustable up to a considerable height and, therefore, is bulky and inconvenient to use. Attempts have been made to overcome these problems by designing sighting devices which are mounted on one side of the weapon but these are not satisfactory as they are not interchangeable for right-hand and left-hand shooters. Also, sighting along a line different from that of the barrel is not satisfactory.

Moreover, the barrels of such high-trajectory grenade launching firearms are rifled to spin the grenade during travel down the barrel and, because of the low velocity of the grenade, this spin causes it to drift away from the target with the amount of drift increasing with the increase in the distance of the target. Previous sighting devices have not successfully solved the problem of automatically compensating for this drift.

It is, therefore, one object of this invention to provide for such firearms a reflector sighting device which utilizes an adjustable mirror for range finding and for automatically compensating for the known components of drift at the different range settings.

It is a further object of this invention to provide such a sighting device which is compact in size, rugged in construction and easy to use.

The specific nature of the invention as well as other objects and advantages thereof will clearly appear from a description of a preferred embodiment as shown in the accompanying drawings in which:

FIG. 1 is an elevational view of a grenade launcher with the sighting device of this invention mounted thereon;

FIG. 2 is an enlarged view taken along line 22 of FIG. 1;

FIG. 3 is a view taken along line 33 of FIG. 2 and shows the position of the adjustable mirror when adjusted for zero range;

FIG. 4 is a view similar to FIG. 3 but shows the position of the adjustable mirror, and the angle of elevation of the grenade launcher, when the sighting device is adjusted for the maximum 375-yard range;

FIG. 5 is a view taken along line 5-5 of FIG. 3;

FIG. 6 is a view taken along line 6-6 of FIG. 3;

FIG. 7 is a view taken along line 7-7 of FIG. 4;

FIG. 8 is a view taken along line 88 of FIG. 4;

FIG. 9 is a view taken along line 99 of FIG. 1;

FIG. 10 is a fragmentary perspective view of the front end of the shaft in the knob assembly to show the helically formed cam surface;

3,339,450 Patented Sept. 5, 1967 FIG. 11 is a schematic 'view showing, exaggerated, the relationship between the sight line and the bore axis of the firearm in the horizontal plane, with the drift of the grenade being compensated for at the -yard range adjustment;

FIG. 11a is a schematic view showing the relationship of the sight line and the optical path in the sighting device respective to the line axis of the firearm when the sighting device is adjusted to the IOO-yard range setting;

FIG. 12 is a view similar to FIG. 11a but shows the relationship of the sight line and bore axis when the sighting device is adjusted for the 250-yard range;

FIG. 12a is a view similar to FIG. 11a but shows the relationship of the sight line and the optical path respective to the bore axis when the sighting device is adjusted for the 250-yard range;

FIG. 13 is a view similar to FIGS. 11a and 12a but shows the relationship of the sight line and bore axis when the sighting device is adjusted for the 375-yard range; and

FIG. 13a is a view similar to FIGS. 11a and 12a but shows the relationship of the sight line and optical parts respective to the bore axis when the sighting device is adjusted for the 375-yard range.

Shown in the figures is a grenade launcher 12, such as the M79 Grenade Launcher, which is shoulder-supported for firing. Grenade launcher 12 includes a barrel 14 which is rifled to spin a grenade (not shown) during discharge therealong and which has a bore axis xx. A sighting device 16, mounted on barrel 14 by means of front bracket 18 and a rear bracket 20, includes a tube 22, an eyepiece 24 of approximately two-power magnification mounted on the rear end of the tube and an optical adjuster 26 with a mirror arrangement 27 mounted on the front end. Sighting device 16 is mounted on barrel 14 so that the front end of optical adjuster 26 is adjacent the muzzle end of the barrel, whereby the front end of the barrel will not block the front of the optical adjuster when sighting at a distant target when the elevation of grenade launcher 12 is consequently very high. Optical adjuster 26 includes a housing 28 of substantially rectangular configuration with a sleeve extending integrally rearward from the lower portion of the rear end thereof for receiving the front end of tube 22. Extending longitudinally through the upper portion of housing 28 is a stepped bore 32 which is interrupted by a clearance 34 which provides communication between the bore and a chamber 36 extending rearwardly into the housing from the front end thereof.

Adjuster assembly 38 includes a knob 40 disposed outside of bore 32 for manual turning and a shaft 42 which is slidingly and rotatingly received by the bore. Knob 43 is provided with a pintle 44 having an annular channel 46 which receives a pin 48 mounted laterally through housing 28 for holding knob 40 against axial displacement while permitting rotation thereof. A threaded hole 49 extends into pintle 44 from the front end thereof and is arranged to receive a matingly threaded portion 50 formed on the rear end of shaft 42, whereby rotation of knob 40 is converted to translational displacement of shaft 42 when the knob is rotated and the shaft is held against rotation respective thereto. The front end of shaft 42 is slabbed to form a curved cam surface 52 having a predetermined helix which will be further explained hereinafter. A pin 54 extends laterally through housing 28 so as to have sliding contact with surface 52, whereby, when knob 40 is turned and shaft 42 is moved longitudinally, a limited and predetermined angular displacement of the shaft around its longitudinal axis is effected. This angular displacement of shaft 42 is utilized to adjust the sight line of sighting device 16 laterally as will be explained hereinafter.

A pin 56 extends laterally through shaft 42 and projects from opposite sides thereof to form end portions 58 which pivotally support a first mirror 6t) in mirror arrangement 27. First mirror 66 is essentially rectangular in configuration with a reflecting surface 62 on the front face and is provided with an integral pair of hangers 64 which extend rearwardly from the top rear portion of the first mirror. Hangers 64 are each provided with a hole for receiving one of the ends 53 and, as is best shown in FIGS. 3 and 4, the hangers are also respectively provided with a planar side 66 and an arcuate corner 63 formed where each of such planar sides join the front face of first mirror 64 Corners 68 have sliding and pivotal contact with a front side 7!) of clearance 34 so that, when shaft 42 is forwardly displaced by knob 49, front mirror 60 is pivoted upwardly. Corners 68 are resiliently held in contact with front side 7% by a double coil spring '72 which is supported by a pin 74 mounted laterally through the hangers 64. Proper clearance is provided between the sides of first mirror 66 and the sides of housing 28 to permit sufiicient lateral displacement of the first mirror for the lateral adjustment of the sight line as hereinafter described.

Reflecting surface 62 is positioned directly rearward of an aperture 76 formed in the front end of housing 28 above a second mirror 78, in mirror arrangement 27, fixedly mounted in the housing. Second mirror 78 is located immediately in front of tube 22 so that a reflecting surface 80 on the second mirror faces the end of its tube and is disposed at a 45 angle relative to the center axis thereof to reflect the image transmitted thereto by first mirror 64 to eyepiece 24 along optical path z-z of sighting device 16.

The operation of sighting device 16 can best be understoOd by first referring to FIG. 3 wherein it is seen that, when reflecting surfaces 62 and iii) are parallel, a sight line yy, which is the forward projection of optical path zz, is parallel with the portion of the optical path within tube 22. Therefore, as the axis of tube 22 and bore axis xx are parallel, sighting device 16 is adjusted for zero range.

Now, referring to FIGS. 11a, 12a, and 13a, it is seen that, when first mirror 6t) is tilted about lateral pin 56 by the longitudinal displacement of shaft 42 through rotation of knob 40 the angle of reflection b, which is determined by the angular relationship of reflection surface 62 respective to optical path z-z, is decreased, angle of incidence a is similarly decreased and sight line yy is consequently inclined downwardly relative to bore axis xx. Therefore, in order to bring sight line yy back onto a target 52 so that the image thereof will be transmitted to eyepiece 24-, the elevation of grenade launcher 12 must be raised.

Provided on knob 40 are range distance markings 84 which are calibrated so that, when a selected one of the markings is properly indexed, the angular position of first mirror 6:? is adjusted to correctly elevate grenade launcher 12 for the range distance when sight line y-y is on target 82. Provided in eyepiece 24 are cross-hairs S6 for increasing the accuracy of sighting device 16 and the eyepiece is provided with a low magnification to improve the sight picture. Grenade launcher 12 is elevated 38, when aimed at target 82, which is 375 yards distant, but because a one degree change in the angular displacement of first mirror changes the inclination of sight line yy 2 with the angle of inclination a and the angle of reflection 12 being similarly effected, the angular change of first mirror is only 19. Thus, it is evident that sighting device 16 is compact with very little displacement required of the moving parts thereof.

As has been noted hereinbefore, the rotation of knob 40 displaces shaft 42 longitudinally and, through the sliding cooperation of surface 52 with pin 54, the longitudinal displacement effects an angular displacement of the shaft about its longitudinal axis and as first mirror 60 depends therefrom the angular displacement of the shaft swings the first mirror laterally according to the helical angle of the surface. As the angular relationship of first mirror 60 respective to the axis of shaft 42 is less than 90 and as the first mirror is displaced in an arcuate path when shaft 42 is angularly displaced the first mirror is tilted respective to reflecting surface of second mirror 73 to shift sight line y-y laterally. The helix of surface 52 is generated so that, when shaft 42 is positioned for correctly displacing first mirror 60 to the range distances, the shaft is angularly displaced to swing the first mirror laterally and thereby tilt it respective to second mirror 78 so as to change angle of incidence a laterally and shift sight line yy accordingly to correct the known component of grenade drift at the indexed range distances. The relationship between the elevation adjustment and drift compensation of sighting device 16 is graphically illustrated in FIGS. 11 through 130. A windage adjustment 88 is provided in rear bracket 20 for pivoting sighting device 16 laterally around a ball joint in front bracket 18.

Although a particular embodiment of the invention has been described in detail herein, it is evident that many variations may be devised within the spirit and scope thereof and the following claims are intended to include such variations.

I claim:

1. For shoulder-supported firearms firing high-trajectory projectiles with a predetermined component of lateral drift: a sighting device including a tube mounted on a barrel of the firearm so as to be parallel therewith, an eyepiece mounted on the rear end of said tube, and an optical adjuster mounted on the front end of said tube; said optical adjuster including a housing, a pair of mirrors respectively mounted in said housing so as to be vertically inclined respective to the axis of said tube and substantially in parallel relationship and so as to cooperate in effecting an adjustable sight line extending from an optical path determined by said eyepiece and said pair of mirrors, said pair of mirrors including a first mirror and a second mirror, said second mirror being fixedly mounted in said housing for reflecting an image transmitted thereto by said first mirror to said eyepiece; an adjuster assembly including a rotatable knob, sight line adjusting means operationally disposed between said knob and said first mirror including a shaft mounted in said housing for longitudinal and angular displacement, cooperating thread means on said knob and said shaft for converting rota tional displacement of said knob to longitudinal displacement of said shaft, a pin mounted laterally through said shaft for mounting said first mirror thereto for pivotal displacement respective thereto and for lateral swinging displacement therewith, abutting portions on said first mirror and said housing arranged in cooperation to convert longitudinal displacement of said shaft to pivotal displacement of said first mirror about said pin for elevational adjustment of the sight line to selected range distances, and cam means on said shaft cooperating with fixed means in said housing for converting longitudinal displacement of said shaft to angular displacement thereof to swing said first mirror laterally in an arcuate path while being pivotally displaced for elevational adjustment of the sight line to also adjust the sight line laterally.

2. The sighting device as defined in claim 1, wherein said fixed means is a pin mounted through said housing, and said cam means is a curved cam surface formed on said shaft for sliding contact with said pin.

3. The sighting device as defined in claim 1, wherein said cam means is a curved cam surface formed with a predetermined helix for displacing said first mirror to adjust the sight line laterally to compensate for the predetermined component of lateral drift of the projectiles at the selected range settings.

5 4. The sighting device as defined in claim 1, wherein said second mirror is mounted at a 45 angle to the axis of said tube.

References Cited UNITED STATES PATENTS 6 2,627,779 2/1953 Szelwach 88-2.4 3,145,248 8/1964 Shuping 882.4 X

DAVID H. RUBIN, Primary Examiner. 5 JEWELL H. PEDERSEN, Examiner.

T. KUSMER, Assistant Examiner.

Claims

1. FOR SHOULDER-SUPPORTED FIREARMS FIRING HIGH-TRAJECTORY PROJECTILES WITH A PREDETERMINED COMPONENT OF LATERAL DRIFT: A SIGHTING DEVICE INCLUDING A TUBE MOUNTED ON A BARREL OF THE FIREARM SO AS TO BE PARALLEL THEREWITH, AN EYEPIECE MOUNTED ON THE REAR END OF SAID TUBE, AND AN OPTICAL ADJUSTER MOUNTED ON THE FRONT END OF SAID TUBE; SAID OPTICAL ADJUSTER INCLUDING A HOUSING, A PAIR OF MIRRORS RESPECTIVELY MOUNTED IN SAID HOUSING SO AS TO BE VERTICALLY INCLINED RESPECTIVE TO THE AXIS OF SAID TUBE AND SUBSTANTIALLY IN A PARALLEL RELATIONSHIP AND SO AS TO COOPERATE IN EFFECTING AN ADJUSTABLE SIGHT LINE EXTENDING FROM AN OPTICAL PATH DETERMINED BY SAID EYEPIECES AND SAID PAIR OF MIRRORS, SAID PAIR OF MIRRORS INCLUDING A FIRST MIRROR AND A SECOND MIRRORS, SAID SECOND MIRROR BEING FIXEDLY MOUNTED IN SAID HOUSING FOR REFLECTING AN IMAGE TRANSMITTED THERETO BY SAID FIRST MIRROR TO SAID EYEPIECE; AN ADJUSTER ASSEMBLY INCLUDING A ROTATABLE KNOB, SIGHT LINE ADJUSTING MEANS OPERATIONALLY DISPOSED BETWEEN SAID KNOB AND SAID FIRST MIRROR INCLUDING A SHAFT MOUNTED IN SAID HOUSING FOR LONGITUDINAL AND ANGULAR DISPLACEMENT, COOPERATING THREAD MEANS ON SAID KNOB AND SAID SHAFT FOR CONVERTING ROTATIONAL DISPLACEMENT OF SAID KNOB TO LONGITUDINAL DISPLACEMENT OF SAID SHAFT, A PIN MOUNTED LATERALLY THROUGH SAID SHAFT FOR MOUNTING SAID FIRST MIRROR THERETO FOR PIVOTAL DISPLACEMENT RESPECTIVE THERETO AND FOR LATERAL SWINGING DISPLACEMENT THEREWITH, ABUTTING PORTIONS ON SAID FIRST MIRROR AND SAID HOUSING ARRANGED IN COOPERATION TO CONVERT LONGITUDINAL DISPLACEMENT OF SAID SHAFT TO PIVOTAL DISPLACEMENT OF SAID FIRST MIRROR ABOUT SAID PIN FOR ELEVATIONAL ADJUSTMENT OF THE SIGHT LINE SELECTED RANGE DISTANCES, AND CAM MEANS ON SAID SHAFT COOPERATING WITH FIXED MEANS IN SAID HOUSING FOR CONVERTING LONGITUDINAL DISPLACEMENT OF SAID SHAFT TO ANGULAR DISPLACEMENT THEREOF TO SWING SAID FIRST MIRROR LATERALLY IN AN ARCUTAE PATH WHILE BEING PIVOTALLY DISPLACED FOR ELEVATIONAL ADJUSTMENT OF THE SIGHT LINE TO ALSO ADJUST THE SIGHT LINE LATERALLY.