Gravity-Deployed Double-Ended Anti-Tank Mine

The present inventions relates to an improved, high-explosive, anti-tank land mine containing a plurality of explosive charges, and fuze means for initiating the charges in a particular sequence, in response to a signal produced by the presence of a tank or other armored vehicle.

Bearce U.S. Pat. No. 3,216,354, granted Nov. 9, 1965, disclosed a land mine, intended to be placed underground, including a cylindrical housing containing a main high explosive shaped main charge having a lower flat surface and an upper dish-shaped surface which is lined with a metal plate or cover member of frangible or malleable material. An auxiliary clearing charge is carried by a removable top plate of the housing (above the shaped charge) together with a primer and an impact fuze mechanism adapted to be actuated by a vehicle to actuate the primer to initiate the clearing charge. Explosion of the clearing charge (1) blows the overburden and the top plate off the housing to expose the shaped charge and (2) actuates a firing mechanism which initiates a delay charge which, after a predetermined time interval, initiates the shaped charge.

An object of the present invention is to provide a new and improved high-explosive anti-tank, land mine.

In accordance with the present invention, the land mine of the Bearce patent is modified and improved by (1) substituting a hardened metal plate for the frangible or malleable liner of Bearce, to function as a hypervelocity projectile; (2) making the mine double-ended, with a concave surface on each end of the main charge lined with a hardened metal plate, a removable end plate or wall at each end of the housing, and a clearing charge at each end between the main charge and the end wall, whereby the mine can be carried into the air, e.g. by an artillery projectile, ejected over the target area, deployed and come to rest by gravity on either end, instead of being placed underground; and (3) providing the mine with means including a gravity-controlled switch for initiating the upper clearing charge only, thereby removing the upper end wall only and exposing the upper end of the main charge, in response to a firing signal, e.g. derived from a proximity fuze, prior to initiation of the main charge. The gravity-controlled switch may, for example, be a liquid mercury switch having at least three electrodes.

FIG. 1 is an axial section view, taken on line 1-1 of FIG. 2, of a land mine embodying the present invention.

FIG. 2 is a transverse section view, taken on line 2--2 of FIG. 1.

FIG. 3 is a fuze circuit diagram including a longitudinal section view of a liquid mercury switch.

FIGS. 1 and 2 show a generally symmetrical, double-ended, high explosive, anti-tank mine 1 capable of being deployed from the air and come to rest on the ground 2 by gravity on either end and producing an explosively launched projectile or missile from the upper end by selective initiation. The mine has an external housing 3, which includes a short cylindrical side wall 5 and two flat circular end walls or plates 7 and 8, on either of which the mine may come to rest, removably attached to the side wall 5. A typical housing would be about 5 inches in diameter and about 2.3 inches long.The diameter should be at least twice the length of minimize resting on the side. An annular charge 9 of high explosive material, such as pressed PBX, is fixed within the housing 3, as by casting, facing the end plates 7 and 8. The two ends of charge 9a, are dish-shaped or concave and lined with two similarly-shaped hardened metal annular plates 11 and 12, to form (with the charge) a double-ended Misnay-Schardin, or "plate", charge 13. The central opening 15 of the charge 9 is preferably lined with a tubular booster charge 17 of intermediate high explosive material capable of initiating the main charge 9.

Two clearing charges 19 and 20 of low explosive propellant are mounted, one at each end of the mine, in the end spaces 20 between the plates 11 and 12 and the end walls 7 and 8, for removing the upper end wall and exposing the upper plate of the mine. Each of the clearing charges 19 and 20 is adapted to be initiated electrically, and is connected by two conductors 21-22 and 23-24 to a fuze 25, which may be located within the booster charge 17. Parts of the fuze 25 may be located in the end spaces 20. The fuze 25 includes a gravity controlled switch, such as a liquid mercury switch 27 shown in FIG. 3, for selectively initiating the particular clearing charge that is at the top of the mine when the latter comes to rest, that is, the "upper" clearing charge.

The switch 27 shown as an example in FIG. 3 is identical to the mercury switch disclosed in Stewart U.S. Pat. No. 3,088,014, granted Apr. 30, 1963, and comprises an insulating housing 29 containing an elongated central electrode 31 and two annular end electrodes 33 forming an elongated space 35, containing a mercury globule 37. The switch 27 is oriented in the mine 1 parallel to the central axis A-A, so that when the mine comes to rest on the end plate 8, the mercury globule 37 will fall to the lower end of space 35 and connect electrodes 31 and 34 as shown in FIG. 3. The electric squib 39 of the upper clearing charge 19 is connected to a battery 41, by conductor 22, conductor 43 and a signal switch 45, and by conductor 21, central electrode 31, mercury globule 37, lower annular electrode 34 and conductors 45 and 47. At the same time, squib 40 of the lower clearing charge 20 is short-circuited by conductors 23, 24 and 45, electrodes 31 and 34 and the mercury globule 37. If the positions of the mine and switch were reversed, the squib 40 of clearing charge 20 would be connected to the battery 41 by conductors 24 and 47, and by conductor 23, central conductor 31, mercury globule 37, annular conductor 33, conductors 49 and 43, and switch 45. Therefore, closing of the switch 45, after the mine has come to rest on either end, automatically initiates the clearing charge that is at the top of the mine, thus removing the upper end plate, and any overburden if the mine has buried itself in soft earth, and exposing the upper plate charge.

The switch 45 may be actuated by a signal obtained by a conventional tank-sensing device, (not shown) such as the magnetometer of Odom et al. U.S. Pat. No. 3,239,754, dated Mar. 8, 1966, forming part of the fuze 25. The battery 41 and switch 45 may be replaced by a signal voltage obtained from the tank-sensing device. The fuze 25 also includes conventional means including a delay element and one or more firing trains (not shown) for initiating the booster charge 17 at a predetermined time after initiation of the upper clearing charge, to initiate the main charge 9 and explosively project the upper metal plate as a hypervelocity missile capable of penetrating several inches of armor, or severing the track of a tank. The total weight of a 5 inches x 2.3 inches mine, as described above, would be only about 5 to 7 pounds.

If the middle portion of the central electrode 31 in FIG. 3 were removed, to make a four electrode switch, it would be necessary to connect conductor 21 to the lower electrode 31, and conductor 23 to the upper electrode 31, to produce the same results.

The present invention is incorporated into a similar double-ended mine having a clearing charge at each end and a mechanical gravity-controlled switch for initiating the upper clearing charge only, disclosed and claimed in an application for Ferdinando V. Dukic (Ser. No. 627,175) filed concurrently herewith, assigned to the same assignee.

The invention is also incorporated into a similar double-ended mine having a clearing charge at each end, and fuze means, responsive to a firing signal, for simultaneously (1) initiating a fast firing train to initiate the upper clearing charge only, and (2) starting a slow firing train including a delay element to initiate the main charge after a predetermined time, disclosed and claimed in an application of Norman Regber, Ferdinando V. Dukic, and Frank Diorio (Ser. No. 627,176), filed concurrently herewith.