US2355920A - Gun sight - Google Patents

Description

OR 293555992X) Aug. 15, 1944.

o. F. MARsToN GUN SIGHT Filed Feb. 27, 1942 3 Sheets-Sheet 1 Mmmm Aug' 15, 1944. o. F. MARsToN 2,355,920

` GUN SIGHT Filed Feb. 271942 5 Sheets-Sheet 2 //Z/ef' E Mans fol/7,

mmm mmummm Il, Aug. l5, 1944., o. F. MARsToN 2,355,920 GUN SIGHT Filed Feb. 27, 1942 3 Sheets-Sheet 3 O//Vek E Manjom www 33. GEOMTWCM, WSTRUWM Patented Aug. 15, 1944 UNITED STATES yPATENT OFFICE 22 Claims.

This invention relates to improvements in gun sights for direct fire of guns on both stationary and moving targets; the term guns being used to mean riiles, machine guns, cannons, hovvitzers, torpedo tubes and the like. While designed for gun firing at ranges up to about a thousand yards,

such\as anti-tankgunshwa gun sight in accordf principal object a simple and effective gun sight of the above stated character, which automatically predicts the point of impact of the projectile on the target by computing the proper angle of lead in accordance With the speed of the target while at the same time adjusting automatically \within itself to correct for all necessary laying variations in order to obtain target hits.

A further object is to provide a sight which is capable of performing this prediction regardless of the direction of movement and speed of the target, and irrespective of whether the gun on which the sight is mounted is stationary or movable and irrespective also of the speed and direction of the gun if the latter is movable.

Moreover, the invention seeks to provide a sight which is adjustable for the direct iiring of any type or calibre of gun and for the different muzzle velocities of the different types of ammunition used therewith.

It is also an aim of the invention to provide a sight of simplified operation, by Which one operator may control the firing piece for range, deection or angular lead and also elevation. As an example, in a test firing of an American 75 mm. cannon (Model M'2-A3) by a two-man gun crew, only one operator was required to eiectively control the piece, i. e. establish the range, y i

Fig. 1 is a plan view of the gun sight of the present invention;

Fig. 2 is a side elevation of the sight illustrated in Fig. 1;

Fig. 3 is a section taken along line 3 3 of Fig. 2;

Fig. 4 is a detail illustrating the manner of closing the scope tube slot; and

Fig. 5 represents a section taken along line 5-5 of Fig. 2.

As conducive to a clearer understanding of the invention, the improved sight operates on the principle that a moving target traveling directly across the field of iire requires the same angular lead for any uniform given speed of the target, regardless of the range. This principle is directly applicable only at the relatively short ranges Within Which there is no appreciable change in the ratio of unit time of iiight to unit of range. However, it is also applicable at the greater ranges provided suitable correction is applied to the angle of lead to compensate for factors such as initial muzzle velocity and trajectory characteristics which result in substantial change in the aforesaid ratio.

According to the present invention, there is provided a vertical index or indicator at the target end of the sight, the angular deviation of Which from an at rest position is proportional to the speed of traverse of the gun muzzle as the latter is tracked on a target moving across the line of fire. Accordingly, the position of the vertical index is a direct function of the rate of traverse of the gun and hence of the speed and direction of travel of the moving target. For ranges up to about a thousand yards, the sight of the present invention incorporates a range finding device operating on the principle of stadia, and whose operation results in the introduction of the necessary correction or modifying factor automatically within the sight itself, with the result that the position of the vertical index, i. e., the lead angle computed thereby, is modied to correct for appreciable change in the unit of time of flight to unit of range ratio. Moreover the stadia ranging result at any range is also applied to provide a line of sight on the target which effects the necessary correction for trajectory characteristics. Thus, the sight of the invention automatically adjusts itself to correct all necessary laying variations in order to obtain target hits in direct lire.

Considering now a sight operating in accordance with the foregoing principle, reference is made to the drawings wherein like reference characters designate like parts through the several views. The sight is carried by a metal base I which supports means for properly actuating the vertical index 8, such as a suspended, magnetic-drag two-direction type tachometer 2, i. e. a Stewart-Warner type automobile speedometer modified to indicate linear speed both to left and right of a zero. It will of course be understood that other functionally equivalent devices of suitable nature and design may be substituted for the tachometer of the type referred to. A cover 9 is provided to protect the vertical index 8 which is operated by the tachometer. The base l also carries a tubular scope 3 with necessary appurtenances which is held to the base by brackets 4 and 5. By reference to Fig. 2, it will be seen that bracket 4 at the target end of the scope is higher than bracket 5 at the sighting end thereof, whereby the tube 3 is maintained non-parallel to base I, being sloped downwardly from its target to its sighting end for the purpose of correcting for trajectory characteristics, as will hereinafter be explained. Bracket 4 can be raised or lowered by longitudinal movement of wedge 6, thus allowing the target end of the scope tube to be further raised and lowered. Wedge 6 is movable along a scale 1 provided on the top of base I which is calculated and marked for the different types of ammunition available for the particular calibre of gun, for example, shrapnel, M-l shell high explosive shell, and armor piercing shell, according to the relationship of the lower the muzzle velocity of the ammunition selected for use, the longer the time of flight, and hence the higher the bracket 4 and the target end of the tube must be raised by wedge 6. The scale 1 may show the same relationships by other markings, i. e. 1750 f/s, 2000 f/s, 2600 f/s, 2800 f/s, or by both. At its breech sighting end the scope 3 is equipped with a rubber eye piece I3.

By reference to Figs. 3, 4 and 5, it will be seen that the scope tube 3 is longitudinally slotted along its side from substantially end to end thereof, as indicated by the points I8, I9, the latter representing the range limits of the sight. A slide handle 2l] travels longitudinally along the slot I4 and carries a stem extending through the slot to which is secured a lens holding tube or ring 2l which travels with handle 20 inside the scope tube. The slot I4 is closed by a springmetal tape I 1 held in place by spaced guide strips I5, I6, the tape functioning to seal the interior of the scope tube from light which would otherwise pass thereinto through slot I4. Circular housings 22 and 23 arranged at the opposite ends of the scope tube cause the tape I1 to coil upon itself at one end and to uncoil at its other end when the handle 20 is operated to move the lens holding ring 2l along the scope tube, as more clearly illustrated in Fig. 5. The length of the tape I1 is such that the tape maintains the slot closed on both sides of the handle regardless of the position of the handle 20 along the slot.

The slide handle 20 carries a standard 26, to the upper end of which is secured a disc 25 arranged in a. plane transverse to the axis of the scope tube. The disc is provided with a central peep-sight hole 24 and may also be further provided with large diameter openings, as indicated in Fig. 3, to provide more complete visibility than would a solid disc.

The lens holding ring 2l carries a lens 21 which is etched with stadia lines 28 and 29 which are spaced apart a calculated distance in accordance with principles of stadia ranging, and in the present device, proportionally to a known, observable dimension of an enemy target.

With the construction so far described, it will be observed that lens 21 and disc 25 can be actuated along the scope tube slot I4 by the slide handle 20, the metal tape I1 also moving along the slot with the handle for the purpose of maintaining the tube light-tight. The spring action of the tape I1 holds the lens ring 2l with its lens 21, and the handle 20 and disc 25 carried thereby, in place when the gun is fired.

The cover 9 above referred to is provided for the purpose of protecting the Vertical index 8 from the influence of air currents which might otherwise affect the same. The cover proper is preferably provided by a sheet of metal bent to U-shape and stiffened by a reinforcing rib 30. Grooves 3|, 32, 33 and 34 are provided along the side corners of the open ends of the cover for the purpose of holding glass ends or windows 35, 39 in place, as indicated in Fig. 3, while at the same time allowing the windows to be slid out of the tops of the grooves. The cover as shown is removably held in place on base I by a metal plate 31 welded to the base I along one edge thereof and beneath which one bottom edge of the cover may be slid. The other bottom edge of the cover is screwed to the base I as by bolts 38 and 39. The cover 9 also acts as a holder for a stationary horizontal index 40 (Figs. 2 and 3) arranged in a plane which is parallel to base I.

Considering now the mechanism for imparting to the vertical index 8 a position which corresponds to the speed of traverse of the gun as the latter is tracked on the target, the input to tachometer 2 (or the magnetic-drag instrument earlier referred to) is derived from the gun travers-ing hand wheel 4I the wheel shaft carrying an actuating drum 42. Arranged in frictional engagement with the drum is a wheel 43 which may be of rubber, the latter being supported from bracket 44 and carried by a flexible shaft 45 revolving within a exible shaft housing 46. Thus, when hand wheel 4I is turned by the gunner, rotation thereof is transmitted to the flexible shaft 45. The latter turns the primary side of the magnetic-drag tachometer 2. The output of the secondary side of the tachometer 2 acts upon a vertical spindle 52 carrying the metal arm 41. Thus, arm 41 is deflected from the zero position and is rotated to a position which is a direct function of the speed of rotation of hand wheel 4I, account being taken of the drum and wheel ratios required to impart the proper angular deflection to said arm.

Normally, arm 41 is at its position of rest indicated in full lines in Fig. 3 when there is no input to the tachometer, a condition which obtains, for example, when both the gun and target are stationary. The direction of rotation of arm 41 from its at rest position is determined by the direction of rotation of hand wheel 4I, reversing gears being included in the transmission system, if necessary, to cause arm 41 to rotate in the proper direction for the accomplishment of the purpose of the invention.

Arm 41 is marked for the different types of ammunition, i. e., initial muzzle velocities, and supports slides 48, 49 which are mounted for free sliding movement along arm 41 except when xed in place by set screws 50, 5I. Slide 48 constitutes the base for the vertical index 8, slide 49 functioning as a Counterweight to balance arm 41 do. utUlvlt. l HIUAL His l Humm lo,-

for free pivoting movement about the axis of the tachometer output spindle 52 in accordance with the setting of the slide 48.

The sight as shown is mounted in a convenient place on the gun or cannon with which it is to be used, by means of brackets (not shown). These brackets position the sight in proper alignment with t-he tube of the gun.

Describing the mode of operation of the sight, it will be assumed that the type of ammunition to be used, its muzzle velocity, and its time of flight for each of the various ranges are known. Wedge 6 is first adjusted to the proper type of ammunition marking on scale 1, thus to raise or lower the target end of the scope tube 3, this setting obtaining until a different type of arnmunition is to be used. This adjustment varios the relative heighth of brackets 4 and `5 according to the muzzle velocity of the selected ammunition. Slide 48 is also adjusted along arm 41 to the marking to correspond with the selected type of ammunition, being moved closer to axis of spindle 52 for types having the greater muzzle velocities and the arm is thereuponcounterbalanced by slide 49, the slides 48 and 49 being then xed in position by set screws 50 and 5l., The setting of slide 48 thus sets the length of the radius of turn of the index 8 to correspond with the initial muzzle velocity of the ammunition being fired. Windows 35 and 36, which were removed to permit the adjustment of the sides 48 and 49, are then slid into proper position, whereupon the sight is ready for use.

When the target appears, the gunner sights the same through scope tube 3. adjusting handle 2|] until stadia lines 28 and 29 just include the height of the target, the dimensions of which are known or can be estimated. It will be observed here that handle 20 and hence lens 21 are moved towards the target end -of the scope tube with increase in range, the points I8 and I9 correspending to the maximum and minimum ranges determined by stadia of the device illustrated. Since the height of the target is known, or can beestimated, and since the gunners eye "s a regulated apex of two similar triangles, the position of handle 20, lens 21, and disc 25 along the length of the scope 3 provides a determination of the range of the target in terms of stadia ranging, and the linear positon of the rear sight, i. e. disc 25 and its peep hole, wth reference to the vertical index 8 is thereby established.

The range having been determined, the gunner next sights on the target through peep-hole 24 by bringing the target on to the intersecton of the vertical index 8 and horizontal index 41, such latter constituting the front indicator of the sight illustrated. Due to the sloping of the scope tube 3, the peep-sight 24 has a relative elevaton to horizontal index 40 which varies with the stadia ranging of the target, and which is determined by the position of disc 25 along the slot I4 of scope 3. Obviously, in order to keep peep-hole 24 and horizontal index 40 aligned on the target at any range, the muzzle of the gun must be elevated by the gunner in initially sighting the target, this elevation correcting for the trajectory characteristics of the projectile. Further elevation or lowering of the gun muzzle adjusts for the- Search liscia eiect the necessary compensation, although its curvature is too slight to be apparent from an inspection of the drawings.

As the gunner traverses the piece in tracking the target, arm 41 is displaced from its at rest position and the vertical index 8 carried thereby, and whose radius of turn is adjusted to the type of ammunition being red, moves along an arc in proper direction to a position which is a function both of the rate of traverse of the piece and of the initial muzzle velocity of the particular type ammunition. This arcuate movement of index 8 is necessary inasmuch as the proper lead angle is an angle which is dependent upon the target speed at the range as measured by stadia, on which latter the position of peep-hole 24 depends.

Since the position of peep-hole 24 from position I9 is relative to the range to the target directly as the angular height of the target diminishes with increase of range, and since the angular speed of the target varies inversely proportional to the range, the trigonometric result of index 8 moving on an arc, as regards the position of peep-hole 24 between positions I8 and I9, is a resultant deflection angle which is the proper lead angle required to hit the target.

It will be seen, from the above description, that the sighting device as above described is adaptable for direct re upon targets, both moving and stationary, and that it predicts the point of impact in relation to the range and speed and direction of travel of the target, adjusting within itself to correct and compensate for all necessary laying variations in order to obtain target hits in direct fire.

While the above described sighting device combines in a single instrument all of the necessary factors for determining the proper angle of lead for direct ring, it is of course possible to cornbine an independently obtained value of range applied in terms of peep-hole (rear sight) position, with a measurement of the deflection or angular displacement of the movable indicator of the front sight as provided by the present instrument, and thus obtain the same results as explained above in connection with the described sighting device. Moreover, although the sighting device illustrated and described in the foregoing is of the type employing a transversely movable Vertical indicator combined with a xed horizontal indicator for measuring displacement in azimuth of moving targets, and a stationary telescope, variations in and even reversals of the described arrangement, such as would suggest themselves to those skilled in the particular art, are intended to be included within the purview of the invention. It will be observed also that a sight according to the invention, which in the illustrated embodiment uses optics of a ratio of 1:1, lends itself without substantial modification or variation from the disclosed principles of operation to the use of optics with a power of greater than or less than 1:1.

Hence, as many changes could be made in carrying out the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

I claim:

1. In a gun sight, the combination of a stadia ranging scope, a rear sighting element position- :able longitudinally of the scope by and in accordance with the'range of the target as determined by said scope, a vertical index providing a front sighting element, said sighting elements cooperating to establish a line of sight on the target, and means for moving one of said elements transversely of the gun tube with reference to the other element to a position which is a function both of the apparent angular velocity of the target and of the initial muzzle velocity of the ammunition being red, whereby at the instant of firing the line of sight has the proper lead angle relatively to the gun bore required to cause the projectile being fired to hit the target.

2f. A gun sight as set forth in claim 1, Wherein the vertical index is movable to the position which is the function both of the apparent angular velocity of the target and of the initial muzzle velocity of the ammunition being fired.

3. A gun sight as set forth in claim 1, wherein the movable element moves in an arcuate path and on a radius of turn whose length is dependent on the muzzzle velocity of the ammunition being fired.

4. A gun sight as set forth in claim 1, wherein the vertical index is movable as aforesaid and moves in an arcuate path and on a radius of turn whose length is dependent on the muzzle velocity of the ammunition being red.

5. In a gun sight, the combination of a base determining a planenilglggingwtelescope including a scope tube mounted on saidbase, means for/'s'lcpgd the scope tube downwardly from target to sighting end thereof with reference to the plane of the base, a rearsightposi tionable longitudinally of the scope tube by and `in accordance with the range of the target as determined by the telescope, afronta-indicator including intersecting vertical and horizontal indexes cooperating with the rear sight to establish a line of sight on the target, means mounting the vertical index for movement about an axis on a radius of turn whose length is dependent on the initial muzzle velocity of the type of ammunition being fired, and means responsive to the rate of angular movement of gun and sight in following the target for moving said vertical index about said axis to a position which is a direct function of the rate of traverse of the gun as it is tracked on the target.

6. A gun sight as set forth in claim 1, wherein means are provided for adjusting the slope of the scope tube relatively to its normal plane parallel to the gun bore in accordance with the initial muzzle velocities of the various types of ammunition available for use with the gun being red.

'7. In a gun sight for the direct firing of guns, the combination of sights, means for varying the relative elevation of said sights proportionally to the range of the target and the linear distance between said sights in inverse proportion to said range, one of said sights including an index movable transversely of the gun bore from an at rest position to a deflected position which is a function of the rate of angular movement of gun and sight in following the target and of the muzzle velocity of the ammunition selected for firing, said sights coacting to establish a line of sight on the target which is angularly related to the gun bore by the angle of lead required to cause a projectile being fired to hit the target.

8. In a gun sight for the direct firing of guns, the combination of front and rear sights whose positions establish a line of sight on a target which is angularly related to the gun bore by the iangle of lead required to cause a projectile being fired to hit the target, means mounting said rear sight for movement toward and from the front sight in accordance with the range of the target, said front sight including an index movable transversely of the gun, and means controlled by the rate of traverse of gun and sight in following the target for moving said front sight from an at rest position to a position which is a function both of the speed and direction of travel of the target and of the initial muzzle velocity of the ammunition selected for firing.

9. In a sight for the direct firing of guns, the combination of means adjustable axially relative to the gun bore in accordance with the range of a target, an index movable transversely relative to the gun bore, and means controlled by and in accordance with the angular rate of movement of gun and sight in following the target for effecting movement of the index transversely as aforesaid to a position which is a function both of the apparent angular velocity of the target and of the muzzle velocity of the ammunition being fired, said adjustable means and said index coacting to establish at the instant of firing a line of sight which is angularly deflected relatively of the gun bore to provide the proper lead angle required to cause the projectile being red to hit the target.

10. In a sight for the direct firing of guns, the combination of a movable index, a rear sight which is adjustable axially relative to the gun bore and toward and from the index in accordance with the range of the target, means controlled by and in accordance with the angular rate of movement of gun and sight in following the target for effecting movement of the index transversely of the gun bore to a position which is a function both of the apparent angular velocity of the target and of the muzzle velocity of the ammunition being red, said rear sight and index coacting to establish at the instant of firing a line of sight which is angularly deflected relatively of the gun bore to provide the proper lead angle required to cause the projectile being red to hit the target.

11. In a sight for the direct firing of guns, the combination of right angularly related indexes, means controlled by and in accordance with the angular rate of movement of gun and sight in following the target for effecting movement of one of said indexes transversely of the gun bore to a position which is a function both of the apparent angular velocity of the target and of the muzzle velocity of the ammunition being fired, means adjustable axially relative to the gun bore in accordance with the range of the target, said last means and said indexes coacting to establish at the instant of firing a line of sight which is angularly deflected relatively of the gun bore to providey the proper lead angle required to cause the projectile being fired to hit the target.

l2. In a sight for the direct firing of guns, the combination of right angularly related indexes, means adjustable for muzzle velocity and controlled by and in accordance with the angular rate of movement of gun and sight in following the target for effecting movement of one of said indexes transversely of the gun bore to a position which is a function of the apparent angular velocity of the target, and a rear sight movable toward and away from said indexes in accordance with the range of the target, the rear sight and indexes coacting to establish at the instant of firing a line of sight which is angularly deflected relatively of the gun bore to provide the proper lead angle required to cause the projectile being fired to hit the target.

13. In a sight for the direct firing of guns, the combination of an index mounted to turn transversely relative to the gun bore about an axis and on a radius of turn whose length is dependent on the muzzle velocity of the type of ammunition being fired, means controlled by and in accordance with the angular rate of traverse of gun and sight in following the target for turning said index about said axis as aforesaid to a position which is a function of the apparent angular velocity of the target, and means adjustable axially relative to the gun bore in accordance with the range of the target and coacting with the so positioned index to establish at the instant of firing a line of sight which is angularly deected relatively of the gun bore to provide the proper lead angle required to cause the projectile being fired to hit the target.

14. In a sight for the direct firing of guns, the combination of an index mounted to turn transversely relative to the gun bore about an axis and on a radius of turn whose length is dependent on the muzzle velocity of the ammunition being fired, means linearly and vertically adjustable relative to said index in accordance with the range of the target, and means controlled by and in accordance with the angular rate of traverse of gun and sight in following the target for turning said index about said axis as aforesaid to a position which is a function of the apparent angular velocity of the target, said first means coacting with the so positioned index to establish at the instant of firing a line of sight which is angularly deflected relatively of the gun bore to provide the proper lead angle required to cause the projectile being flred to hit the target.

15. In a sight for the direct firing of guns, the combination of an index mounted to turn transversely relative to the gun bore about an axis and on a radius of turn whose length is dependent on the muzzle velocity of the ammunition being fired, a rear sight adjustable toward and away from the index in accordance with the range of the target, and means controlled by and in accordance with the angular rate of traverse of gun and sight in following the target for turning said index about said axis as aforesaid to a position which is a function of the apparent angular velocity of the target, said rear sight and the so positioned index coacting to establish at the instant of firing a line of sight which is angularly deected relatively 0f the gun bore to provide the proper lead angle required to cause the projectile being fired to hit the target.

16. In a sight for the direct firing of guns, the combination of a sighting element including horizontal and vertical indexes, one of said indexes being mounted to turn transversely relative to the gun bore about an axis and on a radius of Cil Search licei turn Whose length is dependent on the muzzle velocity of the ammunition being fired, a second sighting element movable toward and away from said indexes and vertically relative to the horizontal index in accordance with the range of the target, and means controlled by and in accordance with the angular rate of traverse of gun and sight in following the target for turning said one index about said axis as aforesaid to a position which is a function of the apparent angular velocity of the target, said sighting elements coacting to establish at the instant of firing a line of sight which is angularly deflected relatively of the gun bore to provide the proper lead angle required to cause the projectile being fired to hit the target.

17. In a sight for the direct ring of guns, the combination of a front sight including horizontal and vertical indexes, the vertical index being mounted to turn transversely relative to the gun bore about an axis and on a radius of turn whose length is dependent on the muzzle velocity of the ammunition being fired, a rear sight which is movable toward and away from said indexes and vertically relative to said horizontal index in accordance with the range of the target, means controlled by and in accordance with the angular rate of traverse of gun and sight in following the target for turning said vertical index on its axis to a position which is a function of the apparent angular velocity of the target, the front and rear sights coacting to establish at the instant of liring a line of sight which is angularly deflected relatively of the gun bore to provide the proper lead angle required to cause the projectile being fired to hit the target.

18. A sight as set forth in claim 9, wherein the means adjustable in accordance with the range of the target includes a stadia ranging device for measuring the range of the target.

19. A sight as set forth in claim 10, including a stadia ranging telescope having a movable lens, and wherein the rear sight is movable with said ens.

20. A sight as set forth in claim 13, wherein the radius of turn of the index is adjustable in accordance with the initial muzzle velocities of the various types of ammunition available for use with the gun being red.

21. A sight as set forth in claim 14, wherein the means adjustable in accordance with the range of the target includes a stadia ranging device for measuring the range of the target.

22. A sight as set forth in claim 17, including a stadia ranging telescope having a movable lens, wherein the rear sight is movable with said lens, and wherein means are provided to effect vertical adjustment of the rear sight relative to the horizontal index in accordance with the various types of ammunition available for use with the gun being fired.

OLIVER F. MARSTON.

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