EP0802392B1 - Method and device for identifying a corrected desintegration time of a programmable and frangible projectile - Google Patents

Abstract

The disaggregation time determination involves performing a calculation based on an impact distance, RT, to a target determined from sensor data, a projectile velocity, Vm, at a muzzle and a given disaggregation distance, Dz. The disaggregation distance is kept constant by a correction of a disaggregation time using the equation: Tz(Vm) = Tz + K*(Vm-Vov) Tz(Vm) is the corrected disaggregation time. K is a correction factor. Vov is a lead velocity of a projectile. The correction factor is calculated based upon flying time of the projectile, air resistance and a value relating to a position of the gun barrel.

Description

The invention relates to a method for determining a corrected disassembly time a programmable dismountable projectile shot from a gun barrel according to the preamble of claim 1 and a device for performing of the method according to the preamble of claim 9.

With the European patent application 0 300 255 a device has become known which has a measuring device for the projectile velocity arranged at the mouth of a gun barrel. The measuring device consists of two ring coils arranged at a certain distance from one another. When a bullet passes through the two ring coils, a pulse is generated in short succession in each ring coil due to the change in magnetic flux that occurs. The pulses are fed to evaluation electronics, in which the projectile speed is calculated from the time interval between the pulses and the distance between the ring coils. In the direction of movement of the projectile, a transmitting coil is arranged behind the measuring device for the speed, which co-operates with a receiving coil provided in the projectile. The receiving coil is connected to a counter via a high-pass filter, which is connected on the output side to a timer. A disassembly time is formed from the calculated bullet speed and a target distance to a target object, which is transmitted inductively to the bullet immediately after the measuring device has flown through. With this disassembly time, the time fuse is set so that the projectile can be disassembled in the area of the target object.

If projectiles with sub-projectiles are used (ammunition with primary and secondary ballistics), an attacking target can be destroyed by multiple hits, as is known, for example, from a publication OC 2052 d 94 from the company Oerlikon-Contraves, Zurich, if, after the sub-projectiles have been ejected, Time of disassembly the expected area of the target is occupied by a cloud formed by the subprojectiles. When dismantling such a projectile, the part carrying the subprojectiles is separated and torn open at predetermined breaking points. The ejected subprojects describe a swirl-stabilized trajectory caused by the rotation of the projectile and lie evenly distributed on approximately semicircular curves of circular areas of a cone, so that a good chance of hitting can be achieved.

In the device described above, scattering in the disassembly distance, which, for example, by scattering the bullet speed and / or use not updated values are caused, not always a good meeting or Probability of being shot down. With larger disassembly distances the circular area would probably be larger, but the density of the subprojectiles would be smaller. The reverse occurs with smaller disassembly distances: the density of the subprojectiles would be larger, but the circular area would be smaller.

The invention is based on the object of a method and an apparatus To propose the preamble of claims 1 and 9, by means of which avoiding the aforementioned Disadvantages an optimal hit or shot probability is achievable.

This object is achieved by the invention specified in claims 1 and 9 solved. Here there is a given optimal disassembly distance between a disassembly point of the floor and a meeting point of the target by correcting the disassembly time of the projectile kept constant. The correction takes place at the disassembly time a correction factor multiplied by a speed difference is added becomes. The bullet speed difference is the difference of the current measured Projectile speed and a projectile speed of the projectile formed, the lead speed from the mean of a number of previous, successive floor speeds is calculated.

The advantages achieved with the invention can be seen in the fact that a given disassembly distance is independent of the current measured bullet speed, so that a permanent optimal hit or shot probability is achieved can. The proposed correction factor for correcting the disassembly time is based only on the shooting elements of the meeting point for the control of the weapon, namely the gun angles α, λ, the hit time Tf and the lead speed V0v des Storey. This makes it possible to have a simple, minimal effort Integration into existing weapon control systems.

Fig.1

eine schematische Darstellung eines Waffensteuerungs-Systems mit der er findungsgemässen Vorrichtung,

Fig.2

einen Längsschnitt durch eine Mess- und Programmiervorrichtung,

Fig.3

ein Diagramm der Verteilung von Subprojektilen in Abhängigkeit von der Zerlegungsdistanz, und

Fig.4

eine andere Darstellung des Waffensteuerungs-Systems gemäss Fig.1.

The invention is explained in more detail below using an exemplary embodiment in conjunction with the drawing. Show it.

Fig. 1

1 shows a schematic illustration of a weapon control system with the device according to the invention,

Fig. 2

a longitudinal section through a measuring and programming device,

Fig. 3

a diagram of the distribution of subprojectiles as a function of the disassembly distance, and

Fig. 4

another representation of the weapon control system according to Fig.1.

In Figure 1, 1 denotes a fire control and 2 a gun. The fire control system 1 consists of a search sensor 3 for the detection of a target 4 , a follow-up sensor 5 connected to the search radar 3 for target detection, 3-D target tracking and 3-D target measurement, and a fire control computer 6 . The fire control computer 6 has at least one main filter 7 and a lead computing unit 9 . The main filter 7 is connected on the input side to the follow sensor 5 and on the output side to the lead computing unit 9 , the main filter 7 receiving the 3-D target data received from the follow radar 5 in the form of estimated target data Z such as position, speed, acceleration, etc. Computing unit 9 forwards. Meteorological data can be supplied to the lead computing unit 9 via a further input Me. The meaning of the designations on the individual connections or connections is explained in more detail below on the basis of the functional description.

A computer of the gun 2 has an evaluation circuit 10 , an update computing unit 11 and a correction computing unit 12 . The evaluation circuit 10 is connected on the input side to a measuring device 14 for the projectile speed, which is arranged at the mouth of a gun barrel 13 and is described in greater detail below with reference to FIG . 2 , and is connected on the output side to the lead computing unit 9 and the update computing unit 11 . The update computing unit 11 is connected on the input side to the reserve and correction computing unit 9, 12 and is connected on the output side to a programming part integrated in the measuring device 14 . The correction computing unit 12 is connected on the input side to the lead computing unit 9 and on the output side to the updating computing unit 11 . A gun servo 15 and a triggering device 16 responding to a fire command are also connected to the lead computing unit 9 . The connections between the fire control 1 and the gun 2 are combined to form a data transmission, which is designated by 17 . The meaning of the designations on the individual connections between the computing units 10, 11, 12 and between the fire control system 1 and the gun 2 is explained in more detail below on the basis of the functional description. 18 and 18 ' designate a floor which is shown during a programming phase ( 18 ) and at the time of disassembly ( 18' ). The projectile 18 is a programmable projectile with primary and secondary ballistics, which is equipped with an ejection charge and a time fuse and is filled with sub-projectiles 19 .

According to FIG. 2 , a support tube 20 fastened to the muzzle of the gun barrel 13 consists of three parts 21, 22, 23. Between the first part 21 and the second or third part 22, 23 , ring coils 24, 25 are arranged for measuring the bullet speed . On the third part 23 — also called the programming part — a transmission coil 27 held in a coil body 26 is fastened. The type of attachment of the support tube 20 and the three parts 21, 22, 23 to each other is not shown and described. Lines 28, 29 are provided for supplying the ring coils. Soft iron bars 30 are arranged on the circumference of the support tube 20 for the purpose of shielding against magnetic fields which interfere with the measurement. The projectile 18 has a receiving coil 31 which is connected to a timer 34 via a filter 32 and a counter 33 . When the projectile 18 passes through the two ring coils 24, 25 , a pulse is generated in short succession in each ring coil. These pulses are fed to the evaluation circuit 10 ( FIG. 1 ), in which the projectile speed is calculated from the time interval between the pulses and a distance a between the ring coils 24, 25 . Taking the projectile speed into account, a disassembly time is calculated, as described in more detail below, which is transmitted inductively in digital form to the receiving coil 31 when the projectile 18 passes through the transmitting coil 27 for the purpose of setting the counter 32 .

In Figure 3 , Pz denotes a point of disassembly of the projectile 18 . The ejected subprojectiles are, depending on the distance from the point of decomposition Pz, evenly distributed on approximately semicircular curves of (in perspective) circular areas F1, F2, F3, F4 of a cone C. On a first abscissa 1, the distance from the point of decomposition Pz is plotted in meters m, while on a second abscissa II, the area sizes of the areas F1, F2, F3, F4 are plotted in square meters m ² and their diameter in meters m. In the case of a characteristic projectile with, for example, 152 subprojectiles and an apex angle of the cone C of initially 10 °, the values plotted on the abscissa II are obtained as a function of the distance. The density of the subprojectiles on the circular areas F1, F2, F3, F4 decreases with increasing distance and is 64, 16, 7 and 4 subprojectiles per square meter with the selected ratios. Given a predetermined disassembly distance Dz on which the disassembly time is based, as described below, for example 20 m, in the assumed example a target area of 3.5 m in diameter would be occupied with 16 subprojectiles per square meter.

In FIG. 4 , 4 and 4 ' denote the target to be defended, which is shown in a hit or shoot position ( 4 ) and in a position ( 4' ) preceding the hit or shoot position.

The device described above works as follows:

The lead computation unit 9 calculates a target distance RT from a lead speed VOv and the target data Z, taking meteorological data into account for storeys with primary and secondary ballistics.

The lead speed VOv is formed, for example, from the mean value of a number of measured projectile speeds Vm supplied via the data transmission 17 , which immediately precede the current measured projectile speed Vm. On the basis of a predetermined disassembly distance Dz and taking into account the projectile velocity Vg (Tf) which is dependent on a hit time Tf, a disassembly time Tz of the projectile can be determined according to the following relationships: Dz = Vg (Tf) * ts and Tz = Tf - ts where Vg (Tf) is determined by ballistic approximation and Tz is the flight time of the projectile to the disassembly time Pz, and ts is the flight time of a subprojectile flying in the projectile direction from the disassembly point Pz to the meeting point Pf ( Fig. 3, 4 )

The lead computing unit 9 also determines a gun angle α of the azimuth and a gun angle λ of the elevation. The quantities α, λ, Tz or Tf and VOv are referred to as shooting elements of the meeting point and are fed to the correction computing unit 12 via the data transmission 17 . The shooting elements α and λ are also fed to the gun servo 15 and the shooting elements VOv and Tz to the update computing unit 11 . If only primary ballistics is used, the hit time Tf = Tz + ts is transmitted instead of the disassembly time Tz ( Fig . 1, Fig . 4 ).

The calculations described above are repeated in cycles, so that in the current cycle i the latest data α, λ, Tz or Tf and VOv for one certain periods of validity are available.

Between the cycle values, the current (running) time (t) is interpolated or extrapolated.

The correction arithmetic unit 12 calculates a correction factor K according to the equation at the beginning of each cycle i with the latest set of shooting elements α, λ, Tz or Tf and VOv K = - (1 + δTG / δto) * TG * (1 + 0.25 * q * (VOv * Vn) 1/2 * TG) (1+ (TG * (1 + 0.5 * q * (VOv * Vn) 1/2 * TG) * ω 2nd )) * VOv

Vn

ist eine Normgeschwindigkeit der Ballistik.

q

ist eine den Luftwiderstand des Geschosses berücksichtigende Grösse, die sich nach der Beziehung q = (CWn * γ * Gq) / (2 * Gm),

errechnet, wobei die Bedeutung der einzelnen einzusetzenden Werte im Patentanspruch 9 aufgeführt ist. Herein δTG / δto is the derivative of the flight time TG of the projectile after the time, according to the equation δTG / δto = (TG i - TG i-1 ) / to is calculated, where i is the current measure, i-1 the previous measure and to the duration of a measure, and wherein the flight time TG of a projectile is equal to the time Tf. ω ² is a quantity relating to the position of the gun barrel 13 , which depends on the relationship ω 2nd = (rate α * cos λ) 2nd + (rate λ ) 2nd calculated where rate α = (α i - α i-1 ) / to and rate λ = (λ i - λ i-1 ) / to the gun barrel angular velocities in the direction α or in the direction λ mean.

Vn

is a standard speed of ballistics.

q

is a quantity taking into account the air resistance of the projectile, which depends on the relationship q = (CWn * γ * Gq) / (2 * Gm),

calculated, the meaning of the individual values to be used is listed in claim 9 .

Instead of a numerical (or, if necessary, a filtered) solution, as stated above The tachometer value ω can also be read directly from the gun and for the Invoice can be used.

The update arithmetic unit 11 calculates a corrected disassembly time Tz (Vm) from the correction factor K supplied by the correction arithmetic unit 12 , the current measured projectile speed Vm supplied by the evaluation circuit 10 and the lead speed Vov supplied by the lead computing unit 9 the relationship Tz (Vm) = Tz + K * (Vm-VOv).

The corrected decomposition time Tz (Vm) is interpolated or extrapolated depending on the validity for the current running time t. The newly calculated disassembly time Tz (Vm, t) is fed to the transmitter coil 27 of the programming part 23 of the measuring device 14 and, as already described above with reference to FIG. 2 , is transmitted inductively to a projectile 18 flying by.

With the correction of the disassembly time Tz, the disassembly distance Dz ( Fig. 3,4 ) can be kept constant irrespective of the scatter of the projectile speed , so that an optimal meeting or Probability of shooting can be achieved.

Claims (9)

1. Method for determining a corrected fragmentation time (Tz(Vm)) for a programmably fragmentable projectile (12) fired from a gun-barrel (13) with a view to maintaining constant a given fragmentation distance (Dz) between a point of fragmentation (Pz) of the projectile (12) and a point of collision (Pf) of the projectile (12) with a target travelling at speed, in which

   sensor data are measured from which a strike distance (RT) from the gun-barrel (13) to the target is computed,

   the velocity (Vm) of the fired projectile is measured at the muzzle of the gun-barrel (13), and

   determination of the corrected fragmentation time (Tz(Vm)) is based upon at least

   the said strike distance (RT),

   the said velocity (Vm) of the projectile (12), and

   the fragmentation distance (Dz),

   characterized in that

   a predicted velocity (VOv) of the projectile is also determined from the measured sensor data, and

   the corrected fragmentation time (Tz(Vm)) is determined from the originally defined fragmentation time (Tz) by the relation Tz(Vm) = Tz + K x (Vm - VOv)

   in which

   Tz(Vm)

   stands for the corrected fragmentation time,

   Tz

   is the originally defined fragmentation time,

   K

   is a correction factor,

   Vm

   is the presently measured muzzle velocity of the projectile and

   VOv

   is a predicted velocity of the projectile,

   where the correction factor (K) is calculated in accordance with the equation K = -(1+δTG/δto) x TG x (1+0.25 x q x (VOv x Vn)1/2 x TG) (1 + (TG x (1 + 0.5 x q x (VOv x Vn)1/2 x TG) x ω2 )) x VOv in which

   TG

   stands for a flight time of the projectile,

   δTG/δto

   is the derivative of the flight time with respect to time,

   q

   is a variable taking account of the projectile's aerodynamic drag,

   VOv

   is the predicted velocity of the projectile,

   Vn

   is a standard velocity of the ballistics and

   ω²

   is a variable relating to the position of the gun-barrel.

2. Method according to Claim 1, characterized in that the calculations are performed repeatedly in timed cycles.
3. Method according to Claim 2, characterized in that the derivative of the flight time (TG) with respect to time is calculated by the equation δTG/δto = (Tgi - TGi-1 )/to in which

   i

   is the current cycle,

   i-1

   the preceding cycle and

   to

   the duration of a cycle.

4. Method according to Claim 2, characterized in that the variable (ω²) relating to the position of the gun-barrel (13) is calculated by the relation ω2 = (rateα x cosλ)2 + (rateλ)2 where

   α

   stands for a gun azimuth angle,

   λ

   a gun elevation angle,

   rate_α

   a gun-barrel angular velocity in the α direction and

   rate_λ

   a gun-barrel angular velocity in the λ direction.

5. Method according to Claim 4, characterized in that the gun-barrel angular velocities in the α direction and in the λ direction are respectively calculated by the equations rateα = (αi - αi-1)/to rateλ = (λi - λi-1)/to in which

   i

   is the current cycle,

   i-1

   the preceding cycle and

   to

   the duration of a cycle.

6. Method according to Claim 2, characterized in that the variable (q) taking the aerodynamic drag of the projectile into account is calculated by the relation q = (CWn x γ x Gq) / (2 x Gm), in which

   CWn

   is an aerodynamic drag coefficient,

   γ

   stands for air density,

   Gq

   a projectile cross-section and

   Gm

   the mass of the projectile.

7. Method according to Claim 1, characterized in that the predicted velocity (VOv) is obtained from the mean value of a number of measured muzzle velocities immediately preceding the presently measured muzzle velocity (Vm).
8. Method according to Claim 1, characterized in that the corrected fragmentation time (Tz[Vm]) is interpolated or extrapolated according to time validity for the current time (t).
9. Apparatus for carrying out the method according to Claim 1, with a fire direction computer (6) connected via a data-transmission (17) to a gun computer, in which the fire direction computer (6) has at least a prediction unit (9) and the gun computer has at least an evaluation circuit (10) for determining the muzzle velocity (Vm) and an updating unit (11) whose input is connected to the evaluation circuit (10) to feed the muzzle velocity (Vm) and whose output is connected to a programming part (23) of a device (14) for measuring the muzzle velocity (Vm), characterized in that

   a correction unit (12) is provided for calculation of the correction factor (K),

   the correction unit (12) has its input connected via the data-transmission (17) to the prediction unit (9) for the purpose of feeding the firing data on which the calculation is based viz. gun angles (α, λ), predicted velocity (VOv), and fragmentation time and/or strike time (Tz, Tf),

   the updating unit (11) has its input connected via the data-transmission (17) to the prediction unit (9) for the purpose of feeding the predicted velocity (VOv) and fragmentation time and/or strike time (Tz, Tf) and has its input connected to the correction unit (11) for the purpose of feeding the correction factor (K),

   wherein the corrected fragmentation time (Tz(Vm)) determined in the updating unit (11) is fed via the output-connection of the updating unit (11) to the programming part (23).

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