US2786415A - Mortar training device - Google Patents

Description

March 26, 1957 w. D. ALDERSON MORTAR TRAINING DEVICE Filed June 15, 1951 6 2 g Z m M 4 a Al za/476%? 5W i:

IN V EN TOR.- flak/50m United States Patent MORTAR TRAINING DEVICE William D. Alderson, Chicago, 11!.

Application June 15, 1951, Serial No. 231,823

5 Claims. (Cl. 102-41) The present invention pertains to an improved device for use in the training of military personnel in coordination aiming, and observation in firing the mortar.

Generally, it is an object of the invention to provide a mortar training or practice device of the foregoing description which in use simulates all of the conditions which obtain during the actual firing of a live, full size mortar projectile, enabling the practice by a team or unit of all of the manipulations and other duties involved in firing the piece under actual field conditions, but at a small fraction ofthe cost thereof, which device permits accurate observation of the result of the firing since it may be conducted in a company area, drill field or like restricted space, and also greatly stimulates the interest of the personnel partaking of the practice.

It is another object of the invention to provide a mortar training device of the above character, suitable for training personnel in observation and fire control for all types of mortar, 60 mm., 81 mm. or 4.2 inch, whether firing a high explosive missile or a chemical or smoke emitting round, which device employs a special dummy round fabricated from the casing and tail assembly of a standard mortar round of any of the above sizes, plus a miniature or subcaliber projectile fired from a subcaliber barrel fitted in the dummy round, and in which the dummy round is dropped into the bore of a conventional mortar tube to fire a blank cartridge associated with the subcaliber barrel and thereby expel the miniature projectile from the mortar tube.

Another and more specific object is to provide a mortar training device which includes a standard mortar shell modified in a simple and inexpensive manner to provide a subcaliber barrel whose bore, and a rear extension thereof, extend through the shell from nose to tail thereof, the bore extension being adapted to receive a small blank cartridge at its tail end which is fired by dropping the shell into a mortar tube in the usual fashion, together with .a subcaliber projectile simulating the appearance and flight characteristics of the shell and fitted into the subcaliber barrel bore with its tail assembly exposed to the aforesaid passage, whereby explosion of the blank cartridge by the mortar tube firing pin expels the subcaliber projectile from the bores of the subcaliber barrel and mortar tube.

.A still further object of the invention is to provide a device of the type described which, because it employs a subcaliber projectile projected by a small charge for a flight of small range, but otherwise closely simulates the appearance and flight characteristic of a live, full size projectile, enables the results of firing of the miniature .projectile to be observed clearly and interpreted proportionately, in terms of elevation, deflection or dispersion,

range or other flight characteristics of the full size missile.

Another specific object is to provide a mortar training device of the above description which is provided with 'ineans effective to release a visible spotting signal upon 'impact of its subcaliber projectile with the ground, target 2,786,415 Patented Mar. 26, 1957 'ice or other object, thereby to enable the firing crew, and particularly its observer, to judge the accuracy of the firing.

Still more specifically it is an object of the invention to provide a subcaliber projectile adapted to be fired from a built-in barrel of a dummy projectile or other firing tube, the subcaliber projectile being provided with a spotting charge, preferably in the form of a cartridge blank, and a relatively movable firing pin, which pin is impact-shifted to firing engagement with the blank cartridge to cause issuance of a visible spotting signal from the sub-caliber projectile.

Another object is to provide a subcaliber projectile of the sort referred to in the preceding paragraph which has improved provision to prevent pre-ignition of th spotting charge thereof.

The foregoing statements are indicative in a general way of the nature of the invention. Other and more specific objects will be apparent to those skilled in the art upon a full understanding of the construction and op eration of the device.

A single embodiment of the invention is presented herein for purpose of illustration, and it will be appreciated that the invention may be incorporated in other modified forms coming equally within the scope of the appended claims.

In the drawings:

Fig. 1 is a sectioned side elevational view showing the training device of the invention in operative firing relation to a standard mortar tube and its firing pin, the subcaliber projectile appearing in this view being a simple type lacking a spotting charge;

Figs. 2 and 3, are, respectively, views in vertical section through the longitudinal axes of two main components of the dummy projectile of the device, Fig. 3 indicating in dotted lines the operative relationship of these components when assembled;

Fig. 4 is a view in horizontal section along line 4-4 of Fig. 1, illustrating details of the tail assembly of the projectile in their relation to the subcaliber barrel and propellent cartridge of the dummy projectile; and

Fig. 5 is a view in axial section through a special and preferred embodiment of the miniature or subcaliber projectile for the device, which has provision for emitting a spotting charge upon impact.

The present invention provides a mortar training device for the training or practice of military personnel in the use of mortar, whether of the high explosive or chemical type, and in any existing or future caliber or bore. It uses a subcaliber or miniature projectile of low cost, so that there is no appreciable loss due to loss of projectiles in practice. Moreover, the limited range of the miniature projectile greatly reduces such loss and, what is more important, the effect of the practice firing may be accurately observed within a small area. The physical and flight characteristics of the miniature correspond in proportionate degree to those of an actual mortar projectile, whose appearance it also closely simulates, so that results of practice firing may be readily translated into terms of corresponding hypothetical results of firing full size, live ammunition. Training of the mortar crew, and especially .its observer, is cheapened, facilitated and made more effective, and interest of the crew is greatly stimulated because of the ability to actually observe results closely which the device makes possible. Needless to say, use of subcaliber charges practically eliminates danger from premature explosion or otherwise. Equally evident, the slight cost of production of the device, and of its day-to-day use, is an important item in relation to the military budget.

Referring to Fig. 1 of the drawing, the reference numeral 10 generally designates the cylindrical tube of a conventional mortar, which may be considered to represent-anyone of the standard mortars in pa st, present or future use by military personnel. The reference numeral 11 generally designates a full size dummy shell or projectile, which is fabricated to aconside rable extent from an actual casing and tail assembly er a standard mortar round of the appropriate caliber, and the-reference numeral 12 generally designates a miniature or subcaliber projectile or round, which is 'snuglyrec'eived in an [elongated subcaliber bore 13in and coaxial with projectile 11. Bore 13 has an elongated, smaller diameter rear extension or passage 14, and subcaliber projectile 12 is adapted to be fired from bore 13 by ignition of apowder charge in asmallblank cartridge '15, preferably a .22 caliber, rim fire type, inserted in rear bore extension 14,'just as the usual ignition'charge for a live mortar round is mounted thereon. v

7 When dummyprojectilelll is dropped into the bore '16 of mortar tube 10, the blank cartridge 15 is ignited by the usual firing pin 17 at the base of thetube. Subcaliber projectile 1'2 fits snugly in the subcaliber bore 13 so that the'expanding gas from the cartridge, indicated by stippling in Fig. 1, passes through bore extension 14 and expels'the projectile. The range is such that the miniature is readily observable by the observer or other personnel of the mortar crew. I

Dummy projectile 11 is equipped with an extractor ring 18in its nose portion, and this ring has an eye 19 thereon to which a rolled extractor chain 20 is attached. This enables the dummy projectile to be withdrawn upwardly through the tube bore without 'scarring the same,

for re-arming with another subcaliber projectile 12 after each firing. Thedropping of the dummy projectile and its subsequent withdrawal for reloading are the only movements of this element, hence the tail assembly 21 thereof functions solely as a guide to'maintain the projectile in proper axial relation to the tube bore. In all respects, other than the subcaliber bore construction 24 disposed rearwardly of and in alignment with ring 23 connects the forward casing space 25,which normally receives the explosive and other charges of the round, with a rear, counterbored cylindrical chamber 26. It is in this chamber that a projectile propellent charge or shotgun shell is usually disposed. Chamber 26 is axially threaded at 27 for a purpose to bedescribed. As stated above, the tail assembly 21 of dummy 11 is that of an actual mortar shell. I

The second component of the dummy projectile 11'is a two-piece unit comprising a forward member 2313f tubular shape defining the subcaliber bore 13 and a rear tubular'element 29 of elongated outline defining the bore extension or passage 14. Elements 28, 29 are machined to provide conical mating surfaces 31 at their junction. Hence, when they are assembled by axial movement in opposite directions, the surfaces 31 nest snugly and seal the subcaliber bore 13 and extension 14 against escape of ignited gas, without need for a permanent connection of the two parts 28, 29. This contributes to economy of manufacture and ease of assembly.

Forward bore defining element 28 is externally shaped at 32 to merge with the extractor" ring 19 and adjoining nose surface 33 ofdummy projectile 11, and the element is threaded at 34 immediately adjacentthis surface for downward threading assembly with adapter or insert 23, from the nose end of the projectile body. The second tubular element 29 has an enlarged, externally threaded rear end 35 for engagement with the internal thread 27 at the rear of cha i'nber 26 of 'the proje'ctile b'ody. Erniem 29 is screwed into the rear end of the dummy projectile and the two elements are thus threadingly approached into sealing engagement with one another at 'the conical sealing surface 31.

The cylindrical bore extension or passage 14 is of proper diameter to receive the small caliber blank cartridge 15 snugly, yet to allow the cartridge casing to be removed readily, after"du mmy'projeetile 11 is withdrawn by chain 2%, for replacementby another impelling charge.

As stated above, the subcaliber projectile 12 duplicates, in smaller scale, the shape, and flight characteristics of an actual mortar round. Details 'of construction of a special and preferred embodiment of such projectile, specially designated 12', are illustrated in Fig. 5 of the drawing. it comprises a shaped rear tail member 37 having fin elements 38 applied to a cylindrical rear extension thereof to constitute a miniature tail assembly. Tail 'ineinber37 is threadingly applied to the rear of an intermediate bodymember 39 which is provided with a cylindrical bore or chamber 40, and rearwardly and radially inclined passages 41 are drilled from the exterior into communication with this chamber at the forwardextremi'ty thereof. A smaller diameter bore 40', of a proper diameter to receive a .22 caliber blank cartridge 42, opens from the forward end of' member 39 into chamber '40,

thelength of bore 40 being such that when the rim of a cartridge therein rests against the forward surface of the body member 39 theshell of the cartridge will terminate short of the rear end' of the bore.

Member 39 is externally threaded at 43 for the reception of a shaped nose' 44, which nose is provided with an axially extending bore 45 snugly receiving a firing'pin 46. The stem of this pin'has a snug frictional fit in bore '45, sufficient-to prevent rearward displacement of the pin due to the'inertia of gas-propelledprojection of projectile I2 out' of subcaliber bore 13. Arear firing element 47 on pin 46'extends into a chamber 48 in nose member 44 forwardly of bore 40f, while the opposite, forward end of the pin is equipped with an enlarged contact member "49 of disk-like outline.

As will be appreciated by those skilled in the art, forcible contact of member 49 withthe earth or other target or object will cause pin 46 to be thrust rearwardly with violence to strike and firethe blank cartridge"42.

The resultant burning powder'issues in quantity through inclined passages 41 to afford a readily visiblespotting forward in intermediate b'ody member 39 'of subcaliber projectile '12 that gases enterin'g the same'upon'ex'plosion of the propellent blank cartridge 15 will not directly impinge'the rear of spotting blank. Instead the intense heat of this blast isdirected against an annular rearwardly facing surface 50 of chamber 40 which surrounds bore 40'. The shellportion of cartridge 42 is Well protected against the heat of a cone' shaped blast through passages 41. Thus accidental pre-ignition of the spotting charge, while projectile 12 is still in subcaliber bore 13, is prevented in a simple and inexpensive manner.

I claim:

1. A mortar training device comprising a dummy projectile provided with an-internal subcaliber barrel, and a subcaliberprojectile'snugly fitted in said'barrel said subcaliber projectile being provided with an internal chamber communicating with the exterior of the projectile and adapted to'fixedly receive a small caliber cartridgeblank and a bore opening from said chamber greens through the nose of the subcaliber projectile, and a firing pin frictionally received in said bore in aligned relation to said blank cartridge, whereby to explode the latter upon impact of the pin with an object.

2. A mortar training device comprising a dummy projectile provided with an internal subcaliber barrel, and a subcaliber projectile snugly fitted in said barrel, said subcaliber projectile comprising a pair of separately connected elements being provided with an internal chamber, an axial opening communicating with the exterior of the projectile and adapted to fixedly receive a small caliber cartridge blank and a bore opening from said chamber through the nose of the subcaliber projectile, and a firing pin frictionally received in said bore in aligned relation to said blank cartridge, whereby to explode the latter upon impact of the pin with an object and discharge burned powder through said axial opening to the exterior.

3. A mortar training device comprising a dummy projectile provided with an internal subcaliber barrel, and a subcaliber projectile snugly fitted in said barrel, said subcaliber projectile having an internal chamber, an axial opening communicating with the exterior of the projectile and adapted to fixedly receive a small caliber cartridge blank and a bore opening from said chamber through the nose of the subcaliber projectile, and a firing pin frictionally received in said bore in aligned relation to said blank cartridge, said dummy projectile barrel extending from end to end of the projectile to receive said subcaliber projectile at the nose end and a small caliber propellant at the tail end.

4. A subcaliber projectile for a weapon training device comprising a tubular body having an internal chamher and an axially extending forward bore opening rearwardly to said chamber, which bore is adapted to receive at spotting charge, said body having one or more passages non-axially through the wall thereof and communicating said chamber with the exterior, said passage being out of alignment with a spotting charge in said bore, whereby the charge is shielded from direct impingement by a blast from the exterior through said passage.

5. A subcaliber projectile for a Weapon training device comprising a tubular body having an internal chamber and an axially extending forward bore opening rear- Wardly to said chamber, which core is adapted to receive a spotting charge, said body having one or more passages non-axially through the Wall thereof and communicating said chamber with the exterior, said passage being out of alignment with a spotting charge in said bore, whereby the charge is shielded firorn direct impingement by a blast from the exterior through said passage, a nose removably applied to the forward end of said body, which nose has a bore in axial alignment with said body bore, and a firing pin frictionally received in said nose and extending externally of the nose.

References Cited in the file of this patent UNITED STATES PATENTS 1,357,927 Clarke Nov. 2, 1920 1,483,864 Borden et al. Feb. 19, 1924 1,489,165 Spencer Apr. 1, 1924 1,757,675 7 Methlin May 6, 1930 2,069,759 Hofstetter Feb. 9, 1937 2,322,212 Allen June 22, 1943 2,342,684 Nelson Feb. 29, 1944 2,541,025 Bluford et al Feb. 13, 1951 FOREIGN PATENTS 524,977 Great Britain Aug. 19, 1940 553,823 Great Britain June 7, 1943

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