US 3065695 A
Description (OCR text may contain errors)
Nov. 27, 1962 w. J. JARRETT 3,065,695
SHAPED-CHARGE CARTRIDGE Filed 001;. 14. 1960 United States Patent Ofifice 3,065,695 Parented No'v. 27,l 1962 3,065,695 SHAPED-CHARGE CARTRIDGE William J. 'arrett, Springfield, Mass., assignor to the United States of America as represented by the Secretary of the Army Filed Oct. 14, 1960, Ser. No. 62,806
4 Ciaims. (Cl. 102-38) (Granted under Title 35, U.S. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment of any royalty thereon.
This invention relates to ammunition and more particularly to cartridges in which the projectile is energized by the shaped-charge phenomenon.
With the conventional type of cartridges, the projectile is energized by the pressure of the gases produced by discharge of the propellant charge and, therefore, it is necessary that the cartridge be confined within a barrel to provide a space of time in which the gas pressure may be applied to the projectile as the propellant is relatively slow in burning. Because of this requirement for a barrel, weapons for discharging conventional type ammunition have considerable bulk and weight added to the firing mechanism.
In the conventional type of ammunition, such as rockets, in which the projectile is self-propelled and so does not require the confinement of a barrel for full utilization of the propellant, the initial acceleration of the projectile is relatively slow in comparison with that of the projectiles of cartridges fired in barreled weapons.
It is, therefore, the object of this invention to provide a cartridge type ammunition in which the propellant is energized by the shock Waves produced in the detonation of the propellant charge rather than by the pressure of the generated gases. Whereby, the cartridge does not need the confinement of a barrel to prolong the time during which the projectile is subjected to the forces produced by the detonation as the full period of the shock wave effect lasts only about 20 micro, or .000020, second.
It is a further object of this invention to provide for such a cartridge a buffer device disposed between the propellant and the projectile for reducing the approximate 16,000 f.p.s. Velocity of the shock Waves to workable limits so as to prevent deformation of the projectile thereby.
'It is another object of this invention to provide a kind of ammunition in which a fin-stabilized projectile is energized for flight by a Controlled utilization of the shapedcharge phenomenon.
The specific nature of the invention as well as other objects and advantages thereof Will clearly appear from a description of a preferred embodiment as shown in the accompanying drawings in which:
FIG. 1 is a cross-sectional view of the shaped-charge cartridge;
FIG. 2 is a view similar to FIG. 1 but showing the initiating charge detonated;
FIG. 3 is a view similar to FIG. 1 but showing the initiation of the jet stream phenomenon and the beginning of the disintegration of the skirt; and
PIG. 4 is a View similar to FIG. 3 but showing the projectile propelled in flight by the jet stream phenomenon.
Shown in the figures is a cartridge 12 comprised of a projectile 14, a skirt 16 and a base 13 fixed to the rear end thereof. Projectile 14 is provided with a plurality of radial fins 20 which extend longitudinally along the projectile to stabilize the flight thereof. A cylindrical cavity 22 extends concentrically into projectile 14 from the rear end thereof and such cavity is filled with a gas volume 24 comprised of a high density gas, such as Freon or uranium hexichloride, which has low compression Wave propagation of the order of about 500 feet per second. Gas
volume 24 is confined within cavity 22 by a spherical diaphragm 26 which is fixed to the end of projectile 14 so as to extend convexly therefrom. Diaphragm 26 is preferably fabricated from copper for a reason to be hereinafter explained.
Skirt 16 is of cylindrical configuration and has a diameter similar to that of the rear end of projectile 14. Skirt 16 is fixed to the rear end of projectile 14 so as to extend axially rearward therefrom and is fabricated from plastic material which is readily disintegrated responsive to shock Waves created Within the skirt. Extending axially forward into skirt 16 from the rear end thereof is a cylindrical bore 28 which flares outwardly at the front to form a concentric conical recess 30. Conical recess 30 is filled with a shaped charge 32 having in the front a concave recess 33 which matingly receives a diaphragm 26 to provide a lining therefor. Shaped charge 32 is composed of a detonating material of high order which is vdetonated by an initiating explosive charge 34 in bore 28.
Base 18 has a diameter similar to that of skirt 16 and is concentrically fixed to the rear end thereof. The rear end of skirt 16 is reduced in diameter to form forwardly, of base 13 an annular channel 36 which receives means 37 whereby cartridge 12 is supported for discharge. A conventional primer 38 is centrally disposed in base 18 to provide means for detonating initiating charge 34.
Thus, FIG. 1 shows cartridge 12 mounted on a supporting and direction pointing means 37 which may be of hand, shoulder, tripod or vehicle supported type, depending upon the size of the cartridge. When primer 38 is initiated, initiating charge 34 is exploded (FIG. 2) to cause detonation of shaped charge 32 which sets up a phenomenon discovered by Munroe in 1888 and is known in the art as the Munroe Effect? Munroe discovered that, when the front end of a detonating charge is shaped with a concave recess, the gases and the shock Waves produced by the detonation form a jet stream which ad- Vances along the axial line of the shaped recess at a terrifically high Velocity of the order of 16,000 f.p.s.
As shown in FlG. 3, the detonation of shaped charge 32 produces gases and shock Waves which assume a jet stream formation, as noted at 40, which advances along the axis of recess 33 at a Velocity of the order of 16,000 f.p.s. There are also lateral shock Waves produced which act to disintegrate skirt 16 as shown in FIG. 3. The disintegration of skirt 16, however, has no effect upon the continued formation of jet stream 40 as it has been demonstrated that the phenomenon is produced by a shaped charge even when unsupported.
When the forward end of jet stream 40 contacts diaphragm 26, the diaphragm is projected thereby into cavity 22 With the shock waves caused thereby initially accelerating projectile 14 forwardly. The interference of diaphragm 26 prevents the perfect formation of jet stream 40 until projectile 14 is initially accelerated. Thereafter, jet stream 40 assumes its shape, as shown in FIG. 4, and thrusts axially against projectile 14 at the Velocity of approximately 16,000 f.p.s.
Without the provision of gas Volume 24 with its relatively low compression wave propagation to act as a resilient buffer to the high Velocity of jet stream 40, the jet stream Would move axially through projectile 14 by plastically displacing the metal thereof so that the projectile would drop from lack of acceleration rather than be energized for flight. The entire jet stream phenomenon lasts a period of 20 micro-seconds but during that time projectile 14 is accelerated to a Velocity of more than 3000 f.p.s. which would be comparable to the muzzle Velocity of the projectile if energized by a conventional type cartridge in a barreled Weapon.
Diaphragm 26 is preferably fabricated from copper which shows unusual resistance to the effect of jet stream 40. After projectile 14 is no longer under the accelerating infiuence of jet stream 40, diaphragm 26 springs back towards its normal position to provide further acceleration to the projectile. With the forces applied by jet stream 40 against projectile 14 being ax'ial thereto, the flight of the projectile is readily aimed at a target and during fiight the projectile is stabilized by the fins 20.
From the foregoing it is readily apparent that there is provided herein a Cartridge which has the advantages of the conventional cartridges as to rapidity of acceleration of the projectile but which eliminates the need for a barrel on the supporting Weapon.
Although a particular embodiment of the invention has been described in detail herein, it is evident that many variations may be devised within the spirit and scope thereof and the following clairns are intended to include such variations.
1. A Cartridge comprising a projectile, a shaped charge for eifectng a jet stream from the gases and shock waves produced by detonation of said shaped charge, said shaped charge being disposed for directing said jet stream axially against said projectile, and means disposed as a buifer between said projectile and said jet stream to prevent plastic deformation of said projectile thereby.
2. The Cartridge as defined in claim 1 wherein said bufer means includes a volume of gas having low compression wave propagation trapped in a concentric cavity extending into said projectile from the rear end thereof.
3. The Cartridge as defined in claim 1 wherein said bufer means includes a cavity concentrically formed in 4. A Cartridge comprised of a projectile with radial fins disposed longitudinally therealong, a skirt for housing a charge of detonating material, said skirt being coaxially fixed to the rear end of said projectile and disposed for disintegration by said charge when detonated, a spherical recess formed in the front end of said charge coaxial to said projectile to produce a jet stream phenomenon di rected axially against said projectile from the gases and shock Waves created when said charge is detonated, a cylindrical cavity extending forwardly into said projectile from the rear end thereof, a volume of gas having low compression wave propagation filling said cavity, a spherically formed diaphragm fixed to the end of said projectile for trapping said volume of gas in said cavity and providing a lining for said recess in said charge, a base coaxially fixed to the rear end of said skirt and a primer disposed in said base for initating said charge.
References Cited in the file of this patent UNITED STATES PATENTS 2,440,568 Arter Apr. 27, 1948 2,603,155 Clarke July 15, 1952 2,869,825 Crawford Jan. 20, 1959