BACKGROUND AND SUMMARY

The present invention relates to a projectile with selectable angle of attack for increased impact on a target.

Mortars are used for indirect fire against targets which very often are not visible from the gun position. Likewise, mortars are a suitable choice if a target is in some way protected/blocked from the sides, or for various reasons is not penetrable from the side, but is more accessible from above. For instance, targets within an enclosure/wall, sunken targets, etc., can be cited.

Mortars exist in a large number of designs and with different calibers, most common being mortars in the calibers 8 or 12 cm, which are manually handled by a crew. Mortars can also be mounted on a stand or vehicle. The projectile which is launched from a mortar, for instance a shell-action shell (mortar shell), hits its target from above with tip first substantially perpendicular to the target. Most mortar shells are naturally fragmenting and have an all-round strike capability, which means that, upon detonation, splinters are mainly thrown out sideways, which does not have any major effect on, for instance vehicle roofs, concealed or lying targets.

The strength of mortars lies in their simple construction, low price and low weight. The weak aspects are primarily short firing range and little effect of the individual shot.

The projectiles which are today designed to solve to some extent the problems which are described above are significantly more technically advanced, significantly more costly and are usually used for a different type of situation and target.

For instance, there are projectiles with forward-directed ball plates, which eject balls/projectiles in the direction of travel of the shell, i.e. down toward the ground.

A further example is fin-stabilized artillery shells. They have control surfaces and fins and are guided with GPS technology, which makes them extremely accurate.

The shell is usually discharged with a howitzer and flies very high, maximally to about 15,000 meters, and at this height the wings are then deployed and the shell begins to glide toward the target. In the last bit, the shell falls almost vertically, which in this case optimizes the effect. In the case of long firing ranges, the maneuverability (diving capability) is, however, limited, which means that the angle of the shell upon detonation is not optimal.

In summary, there is a need for a method for being able to choose and control an angle of attack of a projectile in order to increase the effect. There is also a need for less costly projectiles, for instance mortar shells, with better impact on targets which are poorly accessible with balls/splinters having an all-round strike capability.

It is desirable to provide a projectile having increased impact on semi-hard targets compared with the projectiles which are used today.

The present projectile, according to an aspect thereof comprises a nose portion, a casing portion and a fin portion. The projectile further comprises an active part, a first initiation device, a sensor, at least one nozzle, a control computer, at least one impulse motor and a second initiation device.

The first initiation device initiates said at least one impulse motor. The second initiation device initiates an active part.

In a further embodiment, the projectile comprises a sensor in the form of a distance sensor. The distance sensor is used to measure the distance between the projectile and the target. The distance sensor can be, for instance, a height sensor.

The side-acting impulse motor tilts the projectile from one position into another position. For instance, the projectile is tilted substantially from a vertical position, in which the front face of the projectile is directed toward the target, into a substantially horizontal position, in which the outer surface is directed toward the target.

In one embodiment, the first initiation device can be initiated via the distance sensor.

In a further embodiment, the at least one side-acting impulse motor of the projectile is disposed on that side of the projectile which is adjacent to the front of the projectile.

In another embodiment, said at least one side-acting impulse motor is driven, for instance, by a powder charge.

In a further embodiment of the projectile, the impulse motor is pyrotechnical.

In one embodiment, the projectile also comprises at least one gyro.

In a further embodiment, the projectile comprises a single-axis gyro. The single-axis gyro is used to determine the angle of rotation of the projectile.

In another embodiment, said gyro is multi-axis.

In one embodiment, the active part is prefragmented with balls. In another embodiment, the active charge part is prefragmented with cubes, hexagons or disks.

The fragments of the active part can be disposed on one side of the outer surface of the projectile, preferably on the same side as the at least one nozzle.

In a further embodiment, the second initiation device can be initiated, for instance, via the single-axis gyro. In another embodiment, the second initiation device is initiated by a multi-axis gyro.

In another embodiment of the projectile, the active part of the second initiation device is initiated when the gyro signals a second angle relative to the first angle of around 90°. In another embodiment of the projectile, the active part is initiated when the gyro signals a second angle relative to the first angle within a range of 60-120°.

In another embodiment, the active part can be configured as a projectile-forming, directional explosive action.

The active part of the projectile can in another embodiment be prefragmented with balls, cubes, hexagons or disks made of heavy metal or steel.

In another embodiment, the projectile comprises a GPS unit.

In a further embodiment, the first initiation device can be initiated via the GPS unit.

In fin-stabilized projectiles, a multi-axis gyro can be used in combination with a plurality of impulse motors to orient the projectile relative to the vertical line/horizontal plane, so that the projectile acquires a, from the effect aspect, advantageous position at the moment of detonation. If the angle of descent of the projectile is shallow, the impulse motors on one side of the projectile are activated, so that the projectile assumes a more vertical position. One embodiment of fin-stabilized projectiles therefore comprises a plurality of impulse motors.

Another example is fin-stabilized projectiles of medium-caliber or greater caliber for direct fire. One or more impulse motors can then be utilized to rotate the projectile into any chosen angle prior to detonation.

In a further embodiment, the projectile comprises two selectable active parts for action according to two action modes, via a smaller active part disposed behind the front face of the shell and/or via a larger active part disposed behind the outer surface of the shell.

A further object of the present invention is to provide a method for tilting or choosing the angle of attack of a projectile as described above in connection with a target.

A method for choosing the angle of attack of a projectile, as is defined above, over a target comprises, for instance:

measuring the distance to the target with a height sensor,

starting a chosen impulse motor, wherein the projectile rotates in relation to its path, andinitiating the active part.

Other sensors or means can be used to initiate the first impulse motor.

In another embodiment, the method comprises:

setting the first angle signal of a gyro (5) to 0° at a predetermined distance to the target, and a second angle signal to the desired change of angle over a target,

measuring the distance to the target with a height sensor (4),

starting a chosen impulse motor (3), wherein the projectile rotates in relation to its path, and

initiating the active part (1) when the gyro signals the second, predetermined angle.

The second, predetermined angle depends on the projectile type.

In a further embodiment for choosing the angle of attack of a projectile over a desired target, comprises:

setting the first angle signal of a gyro to 0° at a predetermined distance to the target, and a second angle signal to the desired change of angle over a target,

measuring the distance to the target with a height sensor,

starting the impulse motor, wherein a first force direction results in rotation of the projectile in relation to its trajectory,

initiating the active part when the gyro signals the second, predetermined angle, at which point the outer surface of the projectile is exposed to the target.

The active part is initiated, for example, when the gyro signals a second angle relative to the first angle of around 90°.

The second, predetermined angle relative to the first angle can be freely chosen in other embodiments.

The second, predetermined angle varies relative to the first angle within a range of 1-120°.

The second, predetermined angle varies relative to the first angle within a range of 1-60°.

The second, predetermined angle varies relative to the first angle within a range of 60-120°.

In order that a mortar projectile in 120 mm caliber shall be able to rotate sufficiently far and expose the outer surface to a target according to the above, an impulse within the range 20-150 Ns is required.

For lesser rotations in the lateral direction, a smaller impulse is required.

In other embodiments, the nose of the projectile is exposed to the target.

Further advantages and effects of the invention will emerge from the detailed description of the invention.

