EP0845098A2

EP0845098A2 - Asymmetric penetration warhead

Info

Publication number: EP0845098A2
Application number: EP96927859A
Authority: EP
Inventors: Zeev Tal
Original assignee: Rafael Advanced Defense Systems Ltd; State of Israel
Current assignee: Rafael Advanced Defense Systems Ltd; State of Israel
Priority date: 1995-08-17
Filing date: 1996-08-16
Publication date: 1998-06-03
Anticipated expiration: 2016-08-16
Also published as: DE69611273D1; ES2155196T3; WO1997007379A2; AU6753796A; IL114973A0; DE69611273T2; ATE199978T1; BR9610411A; EP0845098A4; EP0760458A1; EP0845098B1; EP0760458B1; WO1997007379A3; IL114973A

Abstract

The penetration warhead (14) for use in a position-controlled roll-stabilized missile (10) includes a nose section which is asymmetric with respect to the main axis of the warhead <IMAGE>

Description

ASYMMETRIC PENETRATION WARHEAD

FIELD AND BACKGROUND OF THE INVENTION

The present invention relates to projectiles and missiles and, more

particularly, to roll-stabilized guided missiles or "smart bombs" designed

to reach and penetrate specific hardened targets.

For ease of presentation, the present invention is described herein

in terms of a guided missile, it being understood that the present invention

is of far broader applicability.

A typical guided missile is commonly made up of a number of

sections, which are housed in, or connected to a generally cylindrical

housing of varying radius in the longitudinal direction.

At the front of the missile is the guidance section which typically

includes one or more sensors, such as a Forward Looking Infrared (FLIR)

or video camera, and the various electronic systems which control the

sensors, analyze and inteφret the signals received by the sensors, and

control the flight control system which determines the trajectory and the

roll position of the missile. The guidance section may also include means

for receiving signals from outside of the missile and may also includes

means for transmitting signals from the missile.

Behind the guidance section is the warhead which is typically a

hollow cylindrically shaped casing, typically made of a high strength steel. The function of a penetration warhead is to penetrate a hardened target and

place the explosive charge in the appropriate position, i.e., inside the

target, at the moment of explosion, thereby maximizing the effect of the

explosion on the target. Inside the hollow casing is placed the explosive

and the rear end of the warhead lies the ignition fuse which is designed to

be set off at the proper moment, typically, at some pre-determined time

after the warhead encounters the target. The warhead is typically made of

three sections: (1) a front section, or nose, which is usually in the shape

of an ogive or cone; (2) the main section which includes the explosive

charge and is usually cylindrical; and (3) the aft section which seals the

explosive charge within the casing and holds the fuse.

Behind the warhead typically lies the engine which provides thrust

to the missile.

Housed in and connected to the housing at the rear of the missile,

and in some cases also in other locations along the missile housing, is the

flight control section, including fins and foils, which are used to adjust and

stabilize the trajectory of the missile during its flight to the target and to

prevent the missile from rolling during flight.

For maximum penetration of the hardened target it is desirable to

have the missile impact the target directly, i.e., at a 90° to the target

surface. In most cases, however, the angle of impact is different,

sometimes significantly, from the optimal 90°. For example, a significant fraction of hardened targets, such as

command bunkers, and the like, are built into the ground and have an

outer wall which is substantially horizontal. A typical guided missile

would typically impact the outer wall at an angle which, in many cases,

may be in the range of from about 45 ° to about 65 ° , substantially different

from the optimal angle of 90°. The deviation of the impact from the

perpendicular greatly reduces the penetration depth of the warhead into the

target and significantly decreases the effectiveness of the explosion.

There is thus a widely recognized need for, and it would be highly

advantageous to have, a warhead which is configured so as to improve its

penetration when impacting the target at an angle which deviates from the

perpendicular.

SUMMARY OF THE INVENTION

According to the present invention there is provided a penetration

warhead for use in a position-controlled roll-stabilized missile, the warhead

having a main axis, the warhead comprising a nose section which is

asymmetric with respect to the main axis of the warhead.

Also according to the present invention, there is provided a roll-

stabilized position-controlled missile, comprising a warhead having a nose

section, the warhead being characterized in that the nose section is

asymmetric with respect to the axis of the warhead. According to further features in preferred embodiments of the

invention described below, the nose section includes a portion which

projects forward such that during impact of the missile with a target, the

portion of the nose is the first to make contact with the target.

The present invention successfully addresses the shortcomings of the

presently known configurations by providing a penetration warhead or

projectile which is shaped to include a nose section which is asymmetric

with respect to its longitudinal axis. The warhead is intended for use in

a roll-stabilized, position-controlled, guided missile or projectile designed

to penetrate a hardened concrete target or other highly resistant targets.

Roll-stabilization relates to the keeping of the angular position of the

missile about its axis roughly constant. Position control relates to ensuring

that the missile is oriented so that the top portion is pointing up while the

bottom portion is pointing down, i.e., to prevent the missile from flying

with the wrong roll angle.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is herein described, by way of example only, with

reference to the accompanying drawings, wherein:

FIG. 1 shows an illustrative guided missile according to the present

invention as it appears just prior to impact with a target;

FIG. 2 shows a warhead with a ogival nose; FIG. 3 shows a warhead with an conical nose;

FIG. 4 indicates the path of a projectile impacting a target at a very

low angle resulting in a ricochet;

FIG. 5 indicates the path of a^' projectile impacting a target at a

larger angle than in Figure 4 resulting in a J-shaped trajectory;

FIG. 6 indicates the path of a projectile impacting a target at a

larger angle than in Figure 5 resulting in an attenuated J-shaped trajectory;

FIG. 7 indicates the path of a projectile impacting a target at a 90°

angle;

FIG. 8 schematically depicts the forces experienced by a

conventional warhead upon impact;

FIG. 9 schematically depicts the forces experienced by a warhead

according to the present invention upon impact;

FIG. 10 shows a comparison between the paths taken by a

conventional warhead and a warhead according to the present invention

following impact with a target at an angle;

FIG. 11 shows a side view of one possible nose design of a

warhead according to the present invention;

FIG. 12 is a front view of the nose of Figure 11 ;

FIG. 13 shows a side view of a second possible nose design of a

warhead according to the present invention;

FIG. 14 is a front view of the nose of Figure 13; FIG. 15 shows a third possible nose design of a warhead according

to the present invention;

FIG. 16 is a top view of the nose of Figure 15;

FIG. 17 shows a side view of a fourth possible nose design of a

warhead according to the present invention;

FIG. 18 is a top view of the nose of Figure 17;

FIG. 19 shows a side view of a fifth possible nose design of a

warhead according to the present invention;

FIG. 20 is a front view of the nose of Figure 19;

FIG. 21 shows a side view of a sixth possible nose design of a

warhead according to the present invention;

FIG. 22 is a front view of the nose of Figure 21.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is of a penetration warhead assembled in a

roll-stabilized or non-rolling guided missile or smart bomb (herein referred

to collectively or singularly as "missile") body having a construction which

significantly improves the penetration of the warhead into a target which

is impacted at an angle which differs from the perpendicular.

The principles and operation of a warhead or missile according to

the present invention may be better understood with reference to the

drawings and the accompanying description. Shown in Figure 1 , is a schematic side cross-sectional view of a missile 10 which includes a

guidance section 12, a warhead 14 (which is described in greater detail

below), with an explosive charge 15, an engine section 16 and a flight

control section 18 and tail fins 20. Missile 10 is shown just prior to

impact with a target 22, at a certain angle, , between the plane of the

target and the main (longitudinal) axis of missile 10.

Presently, various warheads, bombs and projectiles are used for

penetrating armored vehicles, such as tanks and thick concrete or similar

other hard or hardened targets, typically made of concrete and further

protected by layers of rock, soil and/or steel.

Presently available warheads are symmetrical so that the

performance of the missile is independent of its roll angle at the moment

of impact between the missile and the target. The symmetry of the

warhead is critical in missiles, bombs, and the like, which roll during

flight so that it is not possible to predict the roll angle of the missile at the

instant of impact.

Typically, the nose of a conventional warhead has either an ogival

or a conical front section (Figures 2 and 3, respectively), both

configurations being completely symmetrical with respect to the main axis

of the warhead.

The purpose of a penetration warhead is to penetrate as deeply as

possible into the target in order to place the explosives in the targeted space, or as close to it as possible. The extent of penetration of the

warhead is greatly affected by the angle of impact, i.e., the angle between

the main axis of the missile or warhead and the plane of the target.

Most warheads strike their target at angles which are substantially

in the range of from about 45° to about 65°. At sufficiently small angles

there is a greater chance of a ricochet, i.e., the warhead is likely to fail to

penetrate the target and to bounce off the target (Figure 4).

At an impact angle of greater than about 45°, the warhead

penetrates the target but tends to form a J-shaped path (Figures 5). The

diversion of the warhead from a straight line path is causes by an

imbalance of forces on the nose of the warhead, as shown schematically

in Figure 8 which induces a moment tending to rotate the warhead about

its center of gravity in a direction away from the target. In some cases the

warhead comes to a stop with its nose pointing somewhat away from the

target (Figure 2) . The J-shaped path implies a decreased penetration of the

warhead into the target.

At somewhat larger impact angles, milder J-shaped paths are

encountered (Figure 6).

Finally, when the missile impacts the target perpendicularly, i.e.,

at 90°, the warhead moves directly into the target and maximum

penetration depth is achieved (Figure 7). In some cases the differences in

penetration achieved with a head-on impact (Figure 7) and angled impacts (Figures 5 and 6) could mean the difference between delivery of the

explosive charges direcdy into, or in close proximity to, the intended area,

with a resultant highly effective explosion, and allowing the explosives to

detonate in a location where little or no real damage is done to the

intended target.

The present invention relates to a kinetic energy penetrating

warhead which is designed to at least partly mitigate the negative effects

of an angled impact of a hardened target. A warhead according to the

present invention includes, in sharp contrast with known warheads, a front

section, or nose, which is asymmetric with respect to the main axis of the

warhead. A warhead according to the present invention is intended for

use with guided missiles, projectile or smart bombs which do not roll, or

are roll-stabilized, position-controlled and which are designed to penetrate

hard and high value targets. In such systems, the missile or bomb has

defmed up and down portions and impact takes place substantially with the

lower portion of the system (Figure 9).

As is shown schematically in Figure 9, the asymmetric

configuration of the warhead makes it possible for the warhead to dig into

the target by allowing the target counter forces to act on the warhead so

as to counter and correct the tendency of the warhead to take a J-shaped

path, as shown in Figures 8, 5 and 6. The forces acting on the nose of the

warhead thus tend to create a moment about the warhead's center of gravity which tends to direct the penetrating warhead in a direction which

is substantially toward the perpendicular, thereby increasing the warhead's

penetration depth.

The difference in path taken by two warheads, one symmetrical and

the other asymmetrical, is illustrated schematically in Figure 10. As can

be seen, the symmetrical warhead is diverted from its intended direction

while the path of an asymmetric warhead according to the present

invention is actually corrected so as to approach the perpendicular. The

resultant deeper penetration, and resultant enhanced explosion

effectiveness, can be seen in Figure 10.

Various and sundry asymmetric nose sections may be envisioned.

All of these are intended to be included within the scope of the present

invention. Illustrative of some of the various possibilities are the

configurations shown in Figures 11 to 22. The precise choice of nose

design and degree of asymmetry will depend on the parameters of intended

applications, perhaps including, but not limited to, the expected nature of

the target, the type of explosives used and the expected angle of impact.

Shown in Figures 11 and 12 are a side and a front view of a nose

design which includes a planar surface. The planar surface takes on the

shape of an ellipse.

Another possible configuration is shown in Figures 13 and 14.

Here, the nose section is in the shape of an oblique cone, i.e., a cone which is asymmetric with respect to its base or, more importantly with

respect to the main axis of the warhead whereas the cone tip can be at any

designed distance from the warhead main axis.

Shown in Figures 15 and 16 is a nose section which is

asymmetrically concave while the nose section in the embodiments of

Figures 17 and 18 are asymmetrically convex. Finally, shown in Figures

19 and 20 and in Figures 21 and 22 are two more configurations which are

asymmetrically concave and convex.

While the invention has been described with respect to a limited

number of embodiments, it will be appreciated that many variations,

modifications and other applications of the invention may be made.

Claims

WHAT IS CLAIMED IS:

1. A penetration warhead for use in a position-controlled roll-

stabilized missile, the warhead having a main axis, the warhead

comprising a nose section which is asymmetric with respect to said main

axis of the warhead.

2. The warhead of claim 1 , wherein said nose section includes

a planar configuration at its anterior end.

3. The warhead of claim 1, wherein said nose section includes

an oblique conical configuration at its anterior end.

4. The warhead of claim .1 , wherein said nose section includes

a convex configuration at its anterior end.

The warhead of claim 1 , wherein said nose section includes

a concave configuration at its anterior end.

6. A roll-stabilized position-controlled missile, comprising a

warhead having a nose section, said warhead being characterized in that

said nose section is asymmetric with respect to an axis of the warhead.

7. The missile of claim 6, wherein said nose section includes a

planar configuration at its anterior end.

8. The missile of claim 6, wherein said nose section includes an

oblique conical configuration at its anterior end.

9. The missile of claim 6, wherein said nose section includes a

convex configuration at its anterior end.

10. The missile of claim 6, wherein said nose section includes a

concave configuration at its anterior end.