US2581355A - Optical aiming device for indirect artillery fire - Google Patents

Description

Jan. 8, 1952 H. BROWN 2,531,355

OPTICAL AIMING DEVICE FOR INDIRECT ARTILLERY FIRE Filed Oct. 11, 1949 4 Sheets-Sheet l TARGET PANORAMIC TELESCOPE DEVICE INVENTOR. LEO H. BROWN. BY

@@ iwwmw ATTORNEYS L. H. BROWN 2,581,355

OPTICAL AIMING DEVICE FOR INDIRECT ARTILLERY FIRE Jan. 8, 1952 4 Sheets-Sheet 2 Filed Oct. 11, 1949 INVENTOR. LEO H. BROWN.

L. H. BROWN 2,581,355

OPTICAL AIMING DEVICE FOR INDIRECT ARTILLERY FIRE Jan. 8, 1952 4 Sheets-Sheet 3 Filed Oct. 11, 1949 INVENTOR LEO H. BROWN. BY QW %M ATTORNEYS L. H. BROWN 2,581,355

OPTICAL AIMING DEVICE FOR INDIRECT ARTILLERY FIRE Jan. 8, 1952 4 Sheets-Sheet 4 Filed Oct. 11, 1949 INVENTOR. LEO H. BROWN FIGH BY /@1 mm 1 04W 1/ ATTORNEYS:

Patented Jan. 8, 1952 UNITED STATES OPTICAL AIMIN G DEVICE FOR INDIRECT ARTILLERY FIRE The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment of any royalty thereon.

My invention relates broadly to the art of indirect artillery fire aiming devices and more especially to the use of an optical device in the aiming of a cannon, artillery piece, or like weapon for indirect firing. A primary object is to provide an aiming device which will permit a relatively great displacement of the weapon due to recoil or other reason without the necessity of repositioning the aiming device or making time-consuming calculations to compensate for such displacement.

Another object of my invention is to provide an aiming device which can be positioned relatively close to the weapon with which it is used.

Still another object is to provide an aiming device which can be used on uneven terrain.

Yet another object is to provide an aiming device which can be used equally well at any time during the day or night.

One more object is to provide an aiming device which can be used with equal facility during all types of weather conditions such as rain, fog, snow, etc. as well as in a smoke-laden atmosphere.

A further object is to provide an aiming device which will maintain its efiectiveness and ac-- curacy Within very close limits.

A still further object is to provide an aiming device which is simple in design and construction, durable, light in weight, and easy to manufacture and use.

The foregoing and other objects of my invention will become apparent from an inspection of the following description and the accompanying drawings wherein:

Fig. 1 is a view from above schematically showing a typical operative relationship between my device, the weapon and attached sighting system (as for example a panoramic telescope) with which my device is employed, and a target.

Fig. 2 is a view, also from above, indicating some of the considerable number of possible conditions of weapon displacement in which the conventional need for repositioning the aiming device is eliminated by use of my invention.

Fig. 3 is another view from above depicting some of the large number of possible conditions of weapon displacements and how the weapon can be brought back onto the target without the necessity for repositioning the aiming device or making compensatory calculations.

amended April 30, 1928; 370 O. G. 757) Fig. 4 is a front view, partly in section, of my aiming device in the operating position, and shows the appearance of a distinctive line pattern as seen by a gunner when he looks into the weapons attached sighting system, provided a certain definite relationship exists between the weapons sighting system and my aiming device, as will be later described.

Fig. 5 is a top view, partly in section, taken from line 5-5 of Fig. 4, to show additional features of my novel device including a stake which is secured to brackets so as to act as a handle for transporting my device from place to place, but which also can serve as a means for supporting my aiming apparatus upright in the field.

Fig. 6 is an end View, partly in section, taken from line 6-6 of Fig. 4, the front cover having been moved to the closed position.

Fig. 7 is a vertical section taken from line 1-7 of Fig. 4.

Fig. 8 is a view taken from line 88 of Fig. 7.

Fig. 9 is a partial vertical section taken on line 9-9 of Fig. 4.

Fig. 10 is a partial section taken on line l0l!l of Fig. 7.

Fig. 11 is a front view of an alternate form of my aiming device.

Fig. 12 is a section taken from line I2I2 of Fig. 11 to show constructional details of the. alternate form of my device.

Prior to my invention, practically universal use was made of the well known barber pole type of aiming post in the operation of artillery for indirect firing. As is well known, these posts were used in pairs, and after a weapon was brought to bear on atarget, these posts were vertically positioned one behind the other at a considerable distance from the gun. The posts were so placed that, when viewed by a gunner through a sighting system attached to the gun, the nearer pole would completely obscure the farther one, thereby indicating that "the g-uns sight was aligned with both posts.

Unless the two posts were perfectly congruent, the near post would not completely hide the farther one, indicating that the gun had moved out of alignment with the two posts and that some correction for the displacement would have to be made in order to get the gun properly aimed at the target again. Since, for greatest accuracy, the posts had to be positioned at a considerable distance from the weapon with which they were used it was necessary many times for some soldier to expose himself to direct enemy fire in order the prior art aiming posts, made indirect firing.

a very hazardous, and often inefiectual operation because of the indicated numerousshortcomings;

With my new aiming device, however, the

many objectionable features of the prior art aiming posts have been overcome; smo device, without detracting from its accuracy,'-can Q between the weapons sighting system and :the

device may be as, much as 25. feet. Probably most important .of its features-is the .fact that. my device possesses a very;wide range of utility throughout whichits ..accuracy is. unchanged.

This wide rangemakes neediorrepositioning my 7' device a very infrequent occurrence.

I accomplish the foregoingandother objects of my invention by providing an apparatus having. in

unique relationship a .mirror, a,glass grating, and v a sighting system. (as. for examplea panoramic telescope) attached to a cannon, artillery. iece or like weapon;

My unique aiming deviceessentially consists of a long box-like structure having a substantially triangular cross-section. Itsbase consists of a strong, grooved bar I5 having end blocks 16 and H attached thereto (see Figs, 4 to 7 and by means of screws 18.

From end to end the, uppersurface of base bar I?) contains a W-like groove l9 whose sides and floors are in a certain, angular relationship'to each other, for reasons which will bemade more clear later (see Figs. '7 and 10) The inner surfaces of the end blocks l6 and il' each contain two grooves and 2! which emanate from the W-like groove .19 in base bar i5 and diverge as they progress upward (see Figs. v'7 and 10). Each of these same surfaces also has a pair of hinges 22 attached to it by screws 23. Joined to the other leaves of the hinges 22, as by welding, is a gate plate 24 (see Figs. 4, 5, 7,9, 10). f

Gate plates 24 are capable of two stable positions: open and closed. In the open position of Figs. 4, 5, 7, 9 and 10 they are parallel to the end blocks I6 and J1 and permit maximum range of usage of'my device: For best results, the gate plates 24 should always be in the open position whilethe device is being used. In'the closed position of Fig. 6 the gate plates 24'are perpendicular to the end blocks I6 and 11. More details about the gate plates will be given later.

End block H has projecting from its outer side a hollow lug 25 to which is threadedly attached a desiccator 257. An opening 2'! through end block 11 (see Fig. 7) between grooves Ztand 2t makes possible communication betweenhollow'lu'g 25 and the interior of the box-like principal portion of my device.

Attached to the foundation comprising the base bar I 5 and its attached end blocks 16 and I1, there isprovideda casingconsistingof an upper,

larger sheet metal member 28, and a lower, smaller, L-shaped sheet metal member 29 of the same length (see Figs. 4-7, 9 and 10).

The upper, larger sheet metal casing member 28, 'shaped as shown in Figs. 6 and 7, forms the back and top of the casing and is secured to the end blocks. 16 and I1 and to the base bar 45 by means of screws 30 (see Figs. 5, 6, 7, l9). Approximatelvmidway between the end blocks, on

casingmember 28, is a flat extruded portion 3l"'upon' which is mounted a conventional level vial 32; asby meanspf screws 33 (see Figs. 5, 6, 7).

The-lower..sheet metal member 29: forms the bottom and part of therfront of the devices casing and is secured to end blocks-1 6-H and. to base bar I5 bymeans of screws 55' (see Figs. 4, 6, 7, 9 and 10)..

Extending along the top front edge 34 of casing member 28, to which it is securedbetween end blocks l6 and Ill by means of hinges35, is a sheet metal cover 36'to'which isthreadedly attached a knob 31 (see Figs. 4,? )J The cover 35 is generally placed in oneof threadiffe'rent positions; fully open (not shown), halftopen as in Fig.."7,-and closed asin Fig. 6. V

In the fully open position the cover 36'is swung away from the top'front edge :34. of the casing member 28 to the fullamount allowed by the hinges 35. When placed'in that position, the cover may be prevented from moving by any one of a number of conventional means (not shown). My device is used with the coveriifi in the fully open position :(gate plates "24 also open) when a proper amount of'natural daylight exists.

In the half openposition the cover 36'rests upon "gate plates'2 l", which are'in their open position and which support the cover resting upon them as in Figs. 4, 5, 7. This'position of cover 36 and gate plates 24 is used when shading of the face of my'dcvice from-excessive sunlight or other causeyis necessary,"orwhen itf'iS desired to con fine illumination from 'a built-in lighting unit (later to be described) to the face of the device as would be necessaryforoperation during the night, inclement weather;'or other reason;

The cover 35 may be placed in the closed positiononly after gate'plates 24 have been swung to their-closed position; as shown in Fig; 6. The cover and gate plates areput in the'closed position for protecting the devices front surface or face as for storing, shippingandt'he like;

Stake brackets 38"and 39 are attachedto end blocks l6 and H by means of some of the same screws 3b which also hold the upper casing member 28 thereto, as illustrated in Fig. 5. Stake bracket 38has a lug 40 having an opening si- (see Figs. 5 and 6) which'slidably accommodates the hollow, cylindrical shank- 42 of a stake 43 (see Figs. 5 to 7') uponwhich my device is clamped during usage. Stake bracket 39 likewise has a lug 44 having an opening 15 of somewhat lesser diameter than opening 4! for slidably accommo dating the cylindrical end plug 560f stake 53 (see Figs. 5 to 7). Lug 441- in addition, has a circumferential groove 47, and also has an opening (not shown) which slidably receives-the shank 48 of a stake retaining pinfiQ.

Stake retaining pin 49-istransfixed by an arcuate' 'wirespringwhichffitsinto the circumferential groove 41 i'n-lu'g Q-KandWhich exerts sufiicient resilient pressure to cause the shank end 48 of the stake retaining pin to project part way into the opening 45 in lug 44 (see Figs. 5 to 7).

Earlier mention was made of the stake 43 upon which my inventive device was clamped during usage. That stake has attached to one end of its hollow, cylindrical shank 42, as by welding, a spade plate 5! (see Fig. 5). On its opposite extremity there is secured, by any conventional means, an end plug 46 of somewhat smaller diameter than shank 32 (see Fig. 7). The junction of the end plug and stake diameters form a shoulder 52. End plug 46 is provided with a circumferential groove 53 whose size is sufiicient slidably to accommodate the smaller or shank end 38 of the stake retaining pin 49 which projects into the.

end plugs opening 45 .in lug 44; and a tapered nose 55 which greatly facilitates engagement between end plug 45 and opening 45. For storing or transporting my device, the stake can serve as a convenient handle by fitting it into brackets 38 and 39, as shown in Fig. 5, and looking it in that position by means of the retaining pin 49. But when my novel apparatus is to be put in use, the stakeis removed and the spade plate plunged into the earth (not shown), following which my device is clamped to the other end of the stake as shown in Figs. 4, 6 and 7.

Secured to the upper inner reaches of casing member 28, as by welding or other means, and extending between end blocks 16 and H are troughs 56 and 51 (see Fig. 7). These troughs are in alignment with the grooves 26 and 2| in the end blocks, and in conjunction with them and the w-like groove IS in base bar [5 form two continuous, unbroken channels around the inside of the casing.

As shown in Figs. 7 and 10, there is seated in the W-like groove in base bar l5, end block grooves 28 and 2| and troughs 56 and 51 a continuous, preferably one-piece, channeled gasket 58 made of molded rubber. Fitted snugly in the front portion of this gasket, namely that which extends from trough 57 to the front half of the W-like groove l9 and in groove 2 i, is a rectangular glass grating 60. Similarly fitted in the rear portion of the gasket, namely that which extends from trough 56 to the rear half of the W- like groove l9 and in groove 29, is a somewhat smaller rectangular mirror 59.

The purpose of the channeled gasket is to cushion mirror 59 and glass grating 60 and to seal 01f the confined space 6| contained within those two members and end blocks l6 and l! in order to prevent dust, dirt, or other like contamination from entering thereinto. In order to prevent fogging in that confined space 6 l the previously mentioned desiccator 26, which is connected therewith through the opening 21 in end block ll, serves to remove any moisture which may be present therein.

Mirror 59 is preferably of good quality optical glass having its reflecting surface 62 facing the front of my device (toward the reader in Fig. 4 or to the readers right in Figs. 7 and 10) The glass grating 60 likewise should also preferably be good quality transparent optical glass upon whose inner surface 63 are etched, ruled, printed, or otherwise produced'a multiplicity of equally spaced, preferably fine, parallel lines 66. When grating 60 is assembled into my device these lines extend up and down and, when viewed from without, extend in a substantially true ver- 6 tical direction (as in Fig.8) when the level vial 32 atop casing member 28 is properly trued.

Concerning the inner, lineated surface 63 of grating 60, the object is to produc lines which will stand-out or be very conspicuous, to anyone using my device; If these lines be produced by printing or some like process, any desirable, satisfactorily colored opaque pigment can be used; If the lines be made by etching, ruling, or other similar process, it is desirable to apply some properly colored opaque material into the lines thus produced in order that sharp contrast will be obtained." The exact number of grating lines per inch is not critical, but a greater number per inch will give a more pronounced line pattern 55 of the type shown in Fig. 4.

As best shown in Fig. 7, it can be seen that the mirror 59, having reflecting surface 62 facing the front (at the reader's right), and the glass grating ill having its inner, lineated surface 63 (see Fig. 8) facing the rear (at the readers left) are positioned at an included angle of preferably about 30 to each other, converging at their lower ends. Other acute angles are suitable, of course, short of a right angle. However, this angle, like the number of grating lines per inch, is not critical since changing it would only change the shape of the line pattern 55 (later to be discussed) on each side of a single, substantially straight vertical reference line 66 (see Fig. 4) contained in the pattern.

A self-contained source of illumination for the line pattern is supplied in the form of a twopiece light reflecting trough 10 housing an electric light bulb 58. This trough 10 may be of sheet metal, or other like material, which has been shaped as shown in Figs. 4, 5, '7, 9 and 10 to contain an elongated opening 15 and an apron 76. The inner surface of the trough, as well as the apron surface 11 nearest glass grating Bil, have been treated in a conventional manner to reflect light rays issuing from light bulb l8.

Trough i0 is supported at each end by a support block 68. These blocks are secured by screws El to the inside of the bottom surface of lower casing member 29, adjacent base bar I5 and near each end block I6 and I1, as shown in Figs. 4, 5, 9 and 10. Each block contains a central opening 69 into which fits the. outer end of trough 10. Likewise secured to the inside of the bottom surface of lower casing member 29 by screws 7 I, adjacent the base bar 15 and approximately midway between the end blocks l6 and Il, is a central trough support block '12 shaped as shown in Figs. 4 and 7. This central block 72 serves to support the inner ends of the two-piece light-reflecting trough as Well as to house a bulb socket 13 which is retained therein by a thumb screw it.

In the ends of trough 'Hl resting in support blocks 68 are end plugs 19 which prevent the undesirable escape of light from the bulb '18 and into which trough retaining screws are threaded.

The purpose of the light-reflecting trough "Ill and lighting source contained therein is, of

course, to make possible the ready use of my invention during darkness as well as during daylight hours. To supply the energy for the electric light bulb 18 there is provided a lighting unit consisting of bulb socket l3, insulated wire 98 and a dry cell I62, the last named being contained in a'cell case I00 covered by a cap l0! (see Figs. 4, 6, 7).-

All that need be said concerning these parts is that the cell case I00 is accommodated'inthe mac ete 7 cylindrical recess-84 in a lug :83 whercit is' akeyed (not shown) inwell-known fashion toaeprevent rotation of the cell case-during rot'ation of a knob 99. Cell |02is housedin cell case I-OO'and is held thereby the case cap which -is'-: ioined to the case by any/convenient, well known means; When the case-cap isrproperlyjoined to the cell case, removal of the case-from i-lug 183' is impossible. At the end of cell case 100 onithe readers right is knob 99 :which can,-- by:means of a turning movement applied thereto, serve "the dual" function of operating a switch (not shown) and also a rheostat,- potentiometerfor .like' 616-.- ment (not shown) for controlling'fthedegree-of 7, bulb socket 13 is mounted"in"central-:"blocklm where it is fastened in place by thumb screw '14. Insulated wire carries ---ele'ctrical energy from cell I02 to the bulb 18.

Midway between the two 'end blo'cks' 16 and I1 the box-like portion of my .inventiveaiming .de'-' vice is mounted on a right-angled-seat portion 8| of-a saddle block 82 by means of conveniently located screws (not shown) which pass through the sheet metal casing members '28 "and 29 and thread into the base bar l (see'Figs'. '4 ton?) Projecting downward from the bottom of the right-angled seat-portion 8|-'of saddle block 82 is cylindrical lug 83 (see Figs; '4 to '7) which containsan axial dry-cell. case 1130889 84 to-which access is gained through a cleft 85'; and projecting outward from the rear of the right-angled seat portion 8| is another somewhatcylindrical lug .86. This lug 386 @has an: axial clamp'recess 8?, and in addition a vertical stake-opening 88 and a threaded clampopening 89, both of -'which communicate with the mainaxial openingtl, as shown in Figs. 5 to 7.

Slidably accommodated in axial: recess 81' 'of lug 86 is a split clamp composed of the two halves 99 and 9| (see Figs/. 5 and 7). The adjacent faces of each half of the clamp are cylindricallysre'e cessed to a size slightly .le'ssthan the radius of shank 42 of stake 43; and the twohalves'of'the' clamp are kept in proper alignment with each other by means of the pin 92* which=-is-=driven into clamp. member- BM and which is "slidably accommodated in a recess 93 in clamp member 9 In turn, as Fig. 7 shows, "the opening inclamp members 90 and 9| iskeptin' proper relationship with the larger stake opening .88"in"lug'.86"by means of "the pin 94 which is' drivenin'todug 8S and which projects into a'recess 99in clamp member 98. Recess 95 "isso made as to permit a certain amount of axialrotation of thetwopiece clamp member'so thatthe-stake shank re cess therein can, before cl'amping ,-;i floatbetween the limits of the larger stake opening 88 to facilitate setting-up my device. I

Clamping pressure is applied and-released by use of the clampscrewEQl which is threadedlyat tached to lug 86'. This pressure urgesc'lampe ing member 90 forwardly against the stake which is forced against clamp Jmember 9 I and there held rigidly because one-end 9610f member 9|"is backed up by sheet metal casing-member 29 reenfdrced bythe strongbase bar-1511 Before describing the operation of my invention, it would be wellnow to discussone of the most importantfeatures :of-"my aiming-.gdevlce, 5

that is I the line pattern v6 5-=sh0wn in Fig. :4.

The two elementsresponsible forthis pattern are the mirror 59 and the glass' grating fifl ably assisted by" either natural. or artificial light. '2 As was pointed-wilt*earlientlielreflectihgsdrface-F B 2" 8 ofthe mirror andthelineatedisurface 63 0f l the glassgrating are mounted facing Ebut at-an angle to each other (see Fig. 7)

As a result of this relationship between mirror- 59 and glass grating Bil, a distinctive linerpattern S5 is. seen by a gunner when he views 'the front face of my device through the weapons sighting system if his line of sight is perpendicular tothe' horizontal line of intersection of the plane 0f mirror 59 andthe plane of glass gr'ating 60. The line pattern depicted in Fig- 4 is seen 'to'consistof the single substantially straight reference line 66 flanked on either side by 'lines- 503' which gradually curve away with successively increas ing curvatures, and tend to becomealmostiperpendicular to the single substantially. straight reference line 66.

In' -the Figa l'showingof the-line-pattern the gunners line of sight is represented as being directed approximately -midway' between'the extremities of mirror 59 and glass grating 60, hence the similarity between both sides of the line pat.- tern on each side of the central reference line'fifi. However, if the gunners line of sight, still'remaining perpendicular to the line of intersection of the two planes; were to be moved either to the right or left, the substantially straight reference line 66 would move accordingly with a corre-* sponding change in the line pattern. That is, the curvilinear portions on one side of line 96 would be fewer and shorter than on the other side. Such movement of the reference line will alter slightly the position of the gun aimed thereby, but the amount of such variation will be negligible and of no consequence in affecting the guns accuracy, as will later become evident. In short,the"gun can undergo horizontal translation in any direc tion, without affecting the accuracy of aim so long as the line of sight to the device falls'between the ends of the sight pattern formed by the mirrorand grating.

It will be readily appreciated from the foregoing that my device makes possible accurate aiming-of the gun from anumber of different positions caused-by its displacement uponfiring. Movement of the gun in a linear direction perpendicularly away from the front face of my device is not a limiting factor so long asthe vguns sighting-mechanism is powerful enough to pick 7 up the line pattern 65. The only limitation is that when the gun moves laterally (with respect to-my device) from its original emplacemenfimy device is effective only if the guns sighting'm'echanism can be trained on a perpendicular to the intersection of the plane of the mirror and'the plane of the grating, as aforesaid. Thusyif the distance between end blockslfi and I1 "is con veniently made-to be two feet; the effective lat eral range through'which-the gun can be moved-,- and yet permit accurate aiming without the need forcompensatory calculations; is two 'feet.

In discussing the use-of my invention, recourse will be had to Figs. 1 to 3.

Fig.1 shows one desired relationship "between a target H14, a gun lil5 its attachedsightingsys tem-including a panoramic telescope -|fl6, and-a schematic representation of my "unique -aiming device whose principal elements 59- and '60 are shown. Line I0? is the "ideal line of fire (neglecting pertinent variables) between the gun I05 and the target I94 When the gunners eye ='|08' sights through the panoramictelescope; his-lineof'vision I09 which looks into mydevice is perpenclicular to the line of intersection between athe? planeeof mirrori59- and the plane-of .glassigrating ments due to recoil or other causes in which the gunners line of sight I09 into my device is still perpendicular to the line of intersection of the plane of mirror 59 and the plane of grating 60. Thus in each 'of these many cases, the gunner (not shown) is able to sight the substantially straight reference line 66 flanked on either side by the curved lines I03.

Lines H represent a large number of imaginary lines of vision, each parallel to the original line of vision I09 and therefore perpendicular to 1.

I01 and that the gun, for all practical purposes, '32:

is still on target.

Fig. 3 deals with displacement of the gun I05, duev to recoil or other cause, in which the. gunner can no longer see reference line 66 whenhe-looks into the guns sighting system. This is because the line of sight I09 is no longer perpendicular to the line of intersection between the plane of mirror 59 and the plane of glass grating 60. Only two of a considerable number of possible conditions of this nature are indicated.

In Fig. 3 the solid line drawing of the'gun I05 and its attached sighting system I06 indicates the gun firing on the target (not shown), because in each case the gunner is able to see the correct line pattern on my device. The dashed line drawings indicate that, after firing, the gun I05 has been displaced because of recoil or other cause and that as a result the gunner can no longer see the line pattern when he looks into thesighting system I06. Immediately, he knows the gun I05 is off target in azimuth. v

By traversing the gun and sight as a unit until the sight pattern as seen by the gunner in looking. through his sight, is symmetrical, the gun can be brought back on target quickly and effectively. As abovesaid, the only limitation to the use of my device would occur when the gun is displaced parallel with the line of intersection of the mirror and grating such a distance that the line of sight from the gun falls without the confines of the device. 3

For example, in using the prior art plain aiming posts, the post nearer the gunner would be seen by him, through the guns sighting system,

' to coincide with the farther post only if his line of sight fell in the imaginary vertical plane deterthe aiming posts or the extra step of making com- 'pensatory' calculations therefor would be neces- 'sary, Whereas no such maneuvering is required in i using my device.

In beginning to explain the use of my invention, it may be assumed that the aiming device is in the closed, inoperable position; that is, the gate plates 24 and cover 36 are facing the glass grating (see Fig. 6), and the stake 43 is secured between the brackets 36 and 39 (see Fig.

5). Although my device could be employed for indirect firing at a moving target, in the present illustration it may further be assumed that it will be employed for indirect firing at a stationary target.

By using one of the conventional techniques described in existing Armed Forces manuals, as for example F. M. 6-81, the weapon I05 with which my device is to be used is brought to bear on the target.

After releasing the stake 43 by pulling the stake retaining pin 49 sufficiently outward, the stake 43 is removed from the brackets 38 and 39, then thrust, spade end first, into the ground (not shown) in a substantially vertical position. Stake 43 is located in the ground on the same side of the weapon as its sighting system I06 (for example, a panoramic telescope), and may be located at any convenient place within a radius of, say, from five to one hundred feet from the weapons sighting system. One preferred relationship between target I04, weapon I05, its attached sighting system I06, and the principal elements 59 and 60 of my aiming device is shown in Fig. 1.

The cover 36 is next raised and the gate plates 24 are swung outward as far as they will go. If daylight conditions are not excessive, and the face of my device does not require shading, the cover 36 is raised upward as far as it will go to the fully opened position. If bright sunlight, reflections, or other causes require the face of my device to be shaded, or if the instruments builtin lighting unit is to be'used, the cover 36 is allowed to rest upon the gate plates 24 (see Figs. 4, 5, '7).

My device is then placed in a convenient location along the shank 42 of the stake 43 (see Fig. '7) facing in the general direction of the Weapons sighting system I06. It is preferable to have the box-like portion of my device horizontally level, and this can be done when mounting it on the stake with the aid of level vial 32. The gunner, represented in'Fig. 1 by the eye I06, endeavors by looking into the sighting system I06 visually to pick-up" the line pattern on the face of the aiming device. By coordination between the gunner and a second person (not shown) handling my aiming device, adjustments are made until the gunner sees the line pattern having its central straight reference line 66 approximately midway between gate plates 24.

It is not imperative that the reference line 66 be locatedapproximately midway between the gate plates, 24, since it can actually be located anywhere along that distance between the gate plates. The mid position is, however, preferable. Since the gun has been placed on target, by means earlier referred to, when the gunner sees the substantiallystraight reference line 66 in my aiming device he thereby establishes a fixed datum point for keeping the gun on target. Although my device could be used for the initial laying of the gun on the target, its best use 31 accrues from enabling the gunner to keepthe gun on target after an initial correct setting. This is so because my device is eiiectiveindealing only with the azimuth component of the aiming process.

It must be understood that'the disclosure here made is for illustrative purposes only, and that many diverse variations of my invention are possible without departing from the spirit and scope of my inventive concept. For that reason I do not wish tobe limited to thenarrow confines of this single practical application- One example of an alternate form of: my invention (see Figs. 11-12) is the use of asecond line grating I58 instead of mirror 59,.backed up by frosted glass I51 or other translucent member, if desired, instead of a mirror. (In Fig. 12, the glass-plate I! is shown only partially frosted, the remaining portions being unfrostedto-admit more'light; however, this is optional, as the whole plate may be frosted, if preferred.) Another modification consists in inverting" the box-like structure so that the included angle between-mirror 59 and grating: 6a is at the top (see- Fig; 11:) rather than at the bottom (as in Fig, '7), whereupon the line pattern of Fig. 4 likewise will appear inverted, taking the form shown in Fig. .11. Other obviousdesign modifications are shown in Figs. 11-12, such as the use of three support legs I52 instead of a stake 113, etch From'the foregoing, itwill be evident-tothos'e skilled in the art that I have provided an aiming device which will permit a relatively great displacement of the weapon without the necessityfor repositioning. the deviceor making timeconsuming compensatory calculations; that I have providedan aiming device which can. be positioned relatively close to the weapon with which it is used; that I have provided an aiming device which can be used on uneven terrain; that I have provided'an aiming device whichcan be: used equally well at any time during the day or night;that-I- have provided an aiming device which canbe used with equal facility during all types of weather and atmospheric conditions; thatI have provided an aiming device which will maintain its effectiveness and accuracy within very closelimits; and that I have provided an aiming device which is simple in design and construction, light in weight, and easy to manufacture and use.

I claim": 1

1. For use inthe indirect aiming; of a gun mounted for elevation about-a normally horizontalaxis upon a part trainable about a normally vertical axisthe combination with said gun of a sighting device mounted upon said part for movement therewith and angular movement relatively thereto, about normally vertical and horizontal axes; an aiming target comprising a transparent member having a multiplicity of parallel grating lines thereon and an opaque member having a refiecting s'ur'face, the planes of said opaque and said transparent members intersecting each other at an acute angle along the longitudinal axis of said aiming target "and with the said reflecting surface facing the said grating lines; and means mounting said aiming target adjacent to and independently of said gun remote from the plane of fire, with its longitudinal axis horizontal and its reflecting surface visible through said s'ight-. ing device;

2-. In a devicef'or indirect aiming of a gun having an aiming sight mounted. thereon, a trans: parent member having a mu tiplicity of parallel '12 grating lines, a planereflector member; and means uniting and supporting said members with the reflecting surface of said reflector member making an acute angle'with said grating lines,

said grating: lines being reflected from the refleeting surface of said reflectingmember toward the sight; to' thereby produce a sight pattern indicating th-e'prop'er aim of the sight with respect to the device;v

3. In an aiming device for indirect aimingv of a gun having an aiming-sight-mount'edthereon, a substantially box-like housing, a mirror, a grating, said mirror and grating being somountedin said housing that their planes: intersect at an acute-angle, the lines of said grating being refiected from the reflecting surface of said mirror toward the sight, to thereby produce a sight pattern: indicating the proper aim of the 'sight with respect-to the device.

4. A device as r re'cited'in claim 3, said acute angle beingabout 30.

5; In an aiming: device for indirect aimingxof a gun havingv an aiming sight thereon, a substantiallyboxelike housing, a" mirror; a grating, means mountingsaid mirror and grating fixedly in said housing withtheirflanges intersecting at an acute angle, a light-reflecting trough in said housing'and illuminating means secured within said trough to-illuminate said mirror and grat ing, the lines of said grating beingrefiectedby said mirror toward the gun to produce in the field of viewpfthe sight thereof, a distinctive pattern of lines which"iis-symmetrical only when the sight is properly aimed with'respect to the device;

6; ma device for the indirect aiming of a gun havingv an aiming sight mounted thereon and pivotall'y adjustable about a normally vertical axis relatively thereto, a housing, a grating, a mirror, means rr'iounting saidgrating and mirror within saidhou'sin'g with their planes intersecting at an acute angle and their line of inter-- section substantially horizontal, a pair of end plates hingedly attached to said housing to extend from the respective ends of said grating, and a cover for said housing, saidcover being hingedto the top front of said housing above said grating, said cover when in open position resting uponand being supported by said end plates extended, tothereby constitute a shade for said grating.

'7. In a device for the indirect aiming of a-gun having an aiming sight mounted thereon for training movement as a unit therewith about normallyyerticalaxis, and for pivotal adjust-- ment-relativelythereto about an axis parallel tos'a'id normally vertical axis, a housings. mirror; a grating, means mounting said mirror and grating said housing with their planes making an' acute angle and with said grating forwardly of said mirror, the lines of said grating being at right angles to the line of intersection of said planes, and means for mounting said housing independently of the gun with said line of intersection horizontal, said grating lines being reflected from said mirror to form in the field of viewof said sight a distinctive pattern of lines symmetrical only when the line of sight from gun to deviceis perpendicular to said lineof intersection.

8. In a device for the indirect aiming of a gun; having-an aiming sight mounted thereon for training "as a unit" with the' -gun and for adjust ment in azimuth relatively'thereto', a transparent ane member having a multiplicity of parallel.

grating lines, a plane reflector member, and means uniting and supporting said members independently of the gun with their planes intersecting at an acute angle, the grating lines of said transparent member being at right angles to the line of intersection of said members, said reflector member reflecting a distinctive symmetrical pattern of grating lines into the field of view of the aiming sight only when the line of sight is at right angles to said line of intersection.

9. In a device for the indirect aiming of a gun having an aiming sight mounted thereon, a substantially box-like housing, first and second gratings mounted within said housing so that their planes intersect at an acute angle, a translucent member covering the surface of said second grating outside of said included angle, and illuminating means secured to said housing to illuminate said gratings, said gratings when facing toward the gun, coacting to form a sight pattern in the field of view of said sight indicating the proper aim of the sight with respect to the device.

10. In a device for the indirect aiming of a gun having an aiming sight thereon, a substantially box-like housing, first and second gratings mounted within said housing so that their planes intersect at an acute angle, a reflecting member covering the surface of said second grating outside of said included angle, and illuminating means secured to said housing so as to cast light upon said gratings, said gratings when facing toward the gun forming a distinctive symmetrical image pattern in the field of view of the sight thereof which pattern is symmetrical only when the line of sight of the sight is normal to the line of intersection of said gratings.

11. An aiming device as recited in claim 10, said acute angle being about 30.

LEO H. BROWN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,546,687 Stutzer July 21, 1925 1,590,532 Lenouvel June 29, 1926 2,150,992 Scott Mar. 21, 1939 2,399,971 Wolfe May 7, 1946 2,491,476 Brown Dec. 20, 1949

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