EP1293751B1 - Method for adjusting the ignition time of a projectile, programming device and time fuse used in such a method - Google Patents

Description

The technical field of the invention is that of the methods for determining the moment of firing of a projectile using a chronometric rocket.

Chronometric flares are well known to those skilled in the art. They make it possible to control the initiation of an explosive projectile on trajectory or the ejection of a payload out of the shell of the projectile.

The projectile is fired by a weapon system that generally includes a firing line incorporating a rangefinder to measure the distance to which the target is located.

Means are provided in the weapon to ensure the programming of the rocket, that is to say the introduction into the latter of digital data relating to the moment at which the trigger must be controlled according to the different parameters of the shot: distance where is the target, meteorological data ......

Patent US4955279 and describes a time rocket for a projectile medium caliber (20 to 45 mm caliber). This electronic rocket is programmed in the weapon and it receives at the exit of the tube a correction of its programming to take into account the real initial velocity of the projectile (which depends on the conditions of temperatures and pressure).

Such a rocket is complex and is associated with very complex programming means.

The patent WO9932847, which serves as a basis for the preamble of the main claim, describes a device using permanent magnets arranged in the vicinity of the mouth of the barrel of the weapon. The projectile rocket detects the passage in front of the magnets and uses information such as the number, the field strength or the distance between two magnets to modify a program. This device does not allow to implement in a simple way a programming of a trigger moment. The distances are in fact frozen at the dimensional values defined during the construction of the magnets.

The known concepts (rocket and programming means) can be implemented in weapons systems such as anti-aircraft guns or anti-missile close defense systems. However, they are poorly suited to an inexpensive weapon system such as the one that should equip the infantrymen.

Nowadays, there is a need to equip the infantrymen with a weapon system capable of firing missiles equipped with a time rocket.

There is also a need to simplify and reduce the cost of the programming systems provided for medium (20 to 50mm) or even large (105 to 140mm) weapon systems.

It is the object of the invention to provide a method for determining a moment of triggering a projectile does not have such drawbacks.

The method according to the invention can thus easily be adapted to a portable weapon system.

According to another embodiment, the method according to the invention also makes it possible to considerably simplify the means for programming rockets for medium or large caliber projectiles without reducing the reliability and precision of the programming.

The invention also relates to the programming device and the rocket that are designed to implement such a method.

Thus the method according to the invention is simple to implement. It makes it possible to lead to the definition of a programming device that is also extremely simple to produce and inexpensive. This device is also very easy to use.

The method according to the invention also leads to a simple and rustic timing rocket that can be produced in quantity and low cost.

• on détermine la distance Rf à laquelle on souhaite déclencher le projectile, ou bien le temps Tf à l'issue duquel on souhaite réaliser ce déclenchement, le temps Tf étant déduit le cas échéant à partir de la distance Rf et à l'aide d'une table de tir,
• on détermine une distance de base Lb telle que le temps Tb nécessaire au projectile pour parcourir cette distance de base soit égal à Tf/K, K étant une constante donnée,
• on positionne les deux marqueurs, solidaires du système d'arme et devant lesquels doit passer le projectile, à une distance l'un de l'autre égale à la distance de base Lb, les dits marqueurs étant conçus de façon à pouvoir coopérer avec la fusée du projectile pour que cette dernière soit informée de son passage devant eux,
• on compte un nombre dit de référence (N_ref), qui est le nombre d'oscillations produites par un oscillateur intégré au projectile lors de son passage entre les deux marqueurs, c'est à dire lors du parcours de la distance Lb,
• on calcule un nombre d'oscillations théorique N_th en multipliant le nombre de référence N_ref par la constante K $$({\mathrm{N}}_{\mathrm{th}}={\mathrm{KN}}_{\mathrm{ref}}),$$
  
• on déclenche le projectile quand le nombre d'oscillations réel N_R compté à partir du tir du projectile est égal au nombre d'oscillations théorique ainsi calculé $$({\mathrm{N}}_{\mathrm{R}}={\mathrm{N}}_{\mathrm{th}}={\mathrm{KN}}_{\mathrm{ref}})\mathrm{.}$$
  

Thus, according to a first embodiment of the invention more particularly adapted to a short range weapon system (less than 300 m), for example for infantry equipment, the subject of the invention is a method for determining the an instant of firing of a projectile using a time rocket, a projectile fired from a weapon system, in which two markers are positioned, integral with the weapon system and in front of which the projectile, said markers being designed so as to cooperate with the rocket of the projectile so that the latter is informed of its passage in front of them, characterized by the following steps:

• the distance Rf to which the projectile is to be triggered is determined, or the time Tf at the end of which it is desired to carry out this triggering, the time Tf being deduced, if necessary, from the distance Rf and with the aid of a firing table,
• a base distance Lb is determined such that the time Tb necessary for the projectile to travel this basic distance is equal to Tf / K, K being a given constant,
• positioning the two markers, integral with the weapon system and in front of which the projectile must pass, at a distance from one another equal to the base distance Lb, said markers being designed so as to cooperate with the rocket of the projectile so that the latter is informed of its passage in front of them,
• there is a so-called reference number (N _ref ), which is the number of oscillations produced by an oscillator integrated into the projectile during its passage between the two markers, that is to say during the course of the distance Lb,
• a theoretical number of oscillations N _th is calculated by multiplying the reference number N _ref by the constant K $$({\mathrm{NOT}}_{\mathrm{th}}={\mathrm{KN}}_{\mathrm{ref}}),$$
  
• the projectile is triggered when the number of real oscillations N _R counted from the firing of the projectile is equal to the theoretical number of oscillations thus calculated $$({\mathrm{NOT}}_{\mathrm{R}}={\mathrm{NOT}}_{\mathrm{th}}={\mathrm{KN}}_{\mathrm{ref}})\mathrm{.}$$
  

• on détermine la distance Rf à laquelle on souhaite déclencher le projectile (4), ou bien le temps Tf à l'issue duquel on souhaite réaliser ce déclenchement, le temps Tf étant déduit le cas échéant à partir de la distance Rf et à l'aide d'une table de tir,
• on détermine au moins deux distances de base Lb1 et Lb2 telles que le temps Tf soit une combinaison linéaire des temps Tb1 et Tb2 nécessaires au projectile (4) pour parcourir ces distances de base, Tf = K1 Tb1 + K2 Tb2, K1 et K2 étant deux constantes données,
• on positionne les trois marqueurs (8a,8b,8c,8d) de façon à déterminer entre eux les deux distances Lb1 et Lb2,
• on compte au moins deux nombres, dits de référence (N_ref1,N_ref2), qui correspondent aux nombres d'oscillations produites par un oscillateur (15) intégré au projectile et décomptées entre deux marqueurs donnés déterminant une des distances de base Lb1, Lb2,
• on calcule un nombre d'oscillations théorique N_th en effectuant une combinaison linéaire des nombres de référence avec les constantes K1 et K2 (N_th = K1 N_ref1 + K2 N_ref2),
• on déclenche le projectile (4) quand le nombre d'oscillations réel N_R compté à partir du tir du projectile est égal au nombre d'oscillations théorique ainsi calculé $$\left({\mathrm{N}}_{\mathrm{R}}={\mathrm{N}}_{\mathrm{th}}={\mathrm{Kl\; N}}_{\mathrm{ref}1}+\mathrm{K}2{\mathrm{N}}_{\mathrm{ref}2}\right)\mathrm{.}$$
  

According to another embodiment of the invention, more particularly adapted to a medium or large caliber weapon system with a range greater than 300 m, the method for determining a moment of triggering a projectile with the aid of a chronometric rocket, a method in which at least three markers are positioned, integral with the weapon system and in front of which the projectile must pass, said markers being designed so as to cooperate with the rocket of the projectile so that the latter is informed of its passage in front of them, this process is characterized by the following steps:

• the distance Rf to which the projectile (4) is to be triggered is determined, or the time Tf at the end of which it is desired to carry out this triggering, the time Tf being deduced, if necessary, from the distance Rf and to the using a firing table,
• at least two basic distances Lb1 and Lb2 are determined such that the time Tf is a linear combination of the times Tb1 and Tb2 necessary for the projectile (4) to travel these basic distances, Tf = K1 Tb1 + K2 Tb2, K1 and K2 being two constant data,
• the three markers (8a, 8b, 8c, 8d) are positioned so as to determine between them the two distances Lb1 and Lb2,
• there are at least two numbers, called reference numbers (N _ref1 , N _ref2 ), which correspond to the number of oscillations produced by an oscillator (15) integrated into the projectile and counted between two given markers determining one of the base distances Lb1, Lb2,
• a theoretical number of oscillations N _th is calculated by performing a linear combination of the reference numbers with the constants K1 and K2 (N _th = _{K1N ref1} + _{K2N ref2} ),
• the projectile (4) is triggered when the actual number of oscillations N _R counted from the firing of the projectile is equal to the theoretical number of oscillations thus calculated $$\left({\mathrm{NOT}}_{\mathrm{R}}={\mathrm{NOT}}_{\mathrm{th}}={\mathrm{Kl\; N}}_{\mathrm{ref}1}+\mathrm{K}2{\mathrm{NOT}}_{\mathrm{ref}2}\right)\mathrm{.}$$
  

In either case we can determine the distance Rf using a range finder.

The base distance (s) Lb can be determined by means of a ruler or abacus which will be graduated according to the ballistic characteristics of the projectile.

We can alternatively determine the base distance (s) (Lb) automatically from a digital shooting table to which we will apply the measured or chosen distance Rf.

In this case, after determining the base distance (s) Lb, using a motorization, the relative displacement of the markers will be controlled to mutually separate them from the distance or distances Lb.

The subject of the invention is also a device for programming a chronometric rocket ensuring the triggering of a projectile fired from a weapon system and allowing the implementation of such a method.

This device comprises at least two reference markers, integral with the weapon system and separated by a distance Lb, markers in front of which must pass the projectile and intended to cooperate with detection means integrated into the rocket of the projectile, characterized in that at least one of the reference markers is movable relative to the second marker so as to allow a modification of the distance separating the markers.

According to another embodiment, the device comprises at least three reference markers, integral with the weapon system and determining between them at least two distances Lb1 and Lb2, at least two of the reference markers being movable relative to the third marker of to allow a modification of the distances separating the markers.

The marker or markers may be mobile relative to a ruler graduated in distance or time.

Alternatively, the device may comprise at least one motorization means ensuring the displacement of at least one of the markers relative to another.

The device may comprise a telemetry means connected to the means (s) of motorization via a control means, thus ensuring an automatic modification of the distance or distances separating the markers as a function of the distance measured up to 'to a targeted target.

According to a particular embodiment, one of the markers may be constituted by an end of a tube of the weapon system.

According to another embodiment, at least one of the markers may be annular.

According to another embodiment, at least one of the markers may be constituted by a metal element.

According to another embodiment, at least one of the markers may be an active marker comprising at least one electromagnetic field generating coil powered by an electric generator.

According to another embodiment, at least one of the markers may be constituted by a sensor of the passage of the projectile, transmission means being provided for transmitting the projectile passage information to the rocket of the projectile.

The invention finally relates to a programmable time rocket for a projectile and intended to be programmed by such a device for implementing the method according to the invention. This rocket comprises at least one oscillator and at least one oscillations counter delivered by the oscillator.

• des moyens permettant de détecter le passage du projectile au droit d'au moins deux marqueurs solidaires du système d'arme,
• au moins un compteur permettant de compter les oscillations délivrées par l'oscillateur entre les deux marqueurs ainsi que sur trajectoire,
• des moyens permettant de comparer le nombre d'oscillations réel N_R compté à partir du tir du projectile avec un nombre d'oscillations théorique (N_th) qui est proportionnel à un nombre d'oscillations dit de référence (N_ref), qui est le nombre oscillations comptées entre les deux marqueurs (N_th = K N_ref),
• les moyens de comparaison commandant le déclenchement du projectile quand le nombre d'oscillations réel est égal au nombre d'oscillations théorique ainsi calculé (N_R = N_th).

According to a first embodiment of the invention more particularly adapted to a short range weapon system (less than 300m), for example for infantry equipment, the rocket is characterized in that it comprises:

• means for detecting the passage of the projectile to the right of at least two markers integral with the weapon system,
• at least one counter for counting the oscillations delivered by the oscillator between the two markers as well as on the trajectory,
• means for comparing the actual number of oscillations N _R counted from the firing of the projectile with a theoretical number of oscillations (N _th ) which is proportional to a reference number of oscillations (N _ref ), which is the number of oscillations counted between the two markers (N _th = KN _ref ),
• the comparison means controlling the triggering of the projectile when the actual number of oscillations is equal to the theoretical number of oscillations thus calculated (N _R = N _th ).

• des moyens permettant de détecter le passage du projectile au droit d'au moins trois marqueurs solidaires du système d'arme,
• au moins un compteur permettant de compter les oscillations délivrées par l'oscillateur entre les différents marqueurs ainsi que sur trajectoire,
• des moyens permettant de comparer le nombre d'oscillations réel N_R compté à partir du tir du projectile avec un nombre d'oscillations théorique (N_th) qui est calculé par la fusée sous la forme d'une combinaison linéaire d'au moins deux nombres de référence (N_ref1,N_ref2)avec au moins deux constantes K1 et K2 (N_th = K1 N_ref1 + K2 N_ref2), les deux nombres de référence correspondant aux nombres d'oscillations délivrées par l'oscillateur entre deux des marqueurs détectés,
• les moyens de comparaison commandant le déclenchement du projectile quand le nombre d'oscillations réel est égal au nombre d'oscillations théorique ainsi calculé (N_R = N_th).

According to another embodiment of the invention, more particularly adapted to a medium or large caliber weapon system with a range greater than 300 m, the programmable time rocket further comprises at least one oscillator and at least one counter of the oscillations delivered by the oscillator and is characterized in that it comprises:

• means for detecting the passage of the projectile in the vicinity of at least three markers integral with the weapon system,
• at least one counter for counting the oscillations delivered by the oscillator between the different markers as well as on the trajectory,
• means for comparing the actual number of oscillations N _R counted from the firing of the projectile with a theoretical number of oscillations (N _th ) which is calculated by the rocket in the form of a linear combination of at least two reference numbers (N _ref1 , N _ref2 ) with at least two constants K1 and K2 (N _th = _{K1N ref1} + _{K2N ref2} ), the two reference numbers corresponding to the number of oscillations delivered by the oscillator between two of detected markers,
• the comparison means controlling the triggering of the projectile when the actual number of oscillations is equal to the theoretical number of oscillations thus calculated (N _R = N _th ).

In either case, the rocket may include a contact ensuring the power of the rocket when firing the projectile.

According to one embodiment, the detection means may comprise at least one proximity sensor ensuring the detection of a metal marker element or an electromagnetic field generated by a marker.

The proximity sensor may have a symmetry of revolution.

According to another embodiment, the detection means may comprise a signal receiver emitted by a programming device integral with the weapon system.

• la figure 1 est un schéma général décrivant la mise en oeuvre du procédé selon l'invention ainsi qu'un premier mode de réalisation d'un dispositif de programmation,
• la figure 2 est un schéma bloc diagramme d'une fusée chronométrique selon l'invention,
• la figure 3 montre une caractéristique temps / distance pour un projectile tiré par le système d'arme,
• la figure 4 est un synoptique décrivant les différentes étapes du procédé selon l'invention,
• la figure 5 montre un deuxième mode de réalisation d'un dispositif de programmation selon l'invention,
• la figure 6 montre un troisième mode de réalisation d'un dispositif de programmation selon l'invention,
• la figure 7 montre un quatrième mode de réalisation d'un dispositif de programmation selon l'invention,
• la figure 8 montre un cinquième mode de réalisation d'un dispositif de programmation selon l'invention,
• la figure 9 propose une variante de réalisation d'un dispositif de programmation selon l'invention,
• la figure 10 est un schéma bloc diagramme d'un dispositif de programmation suivant un sixième mode de réalisation,
• la figure 11 montre un dispositif de programmation suivant un septième mode de réalisation de l'invention,
• la figure 12 montre une variante de réalisation de ce dernier mode.

The invention will be better understood on reading the following description of various embodiments, a description given with reference to the accompanying drawings and in which:

• FIG. 1 is a general diagram describing the implementation of the method according to the invention as well as a first embodiment of a programming device,
• FIG. 2 is a diagram block diagram of a chronometric rocket according to the invention,
• FIG. 3 shows a time / distance characteristic for a projectile fired by the weapon system,
• FIG. 4 is a block diagram describing the various steps of the method according to the invention,
• FIG. 5 shows a second embodiment of a programming device according to the invention,
• FIG. 6 shows a third embodiment of a programming device according to the invention,
• FIG. 7 shows a fourth embodiment of a programming device according to the invention,
• FIG. 8 shows a fifth embodiment of a programming device according to the invention,
• FIG. 9 proposes an alternative embodiment of a programming device according to the invention,
• FIG. 10 is a block diagram diagram of a programming device according to a sixth embodiment,
• FIG. 11 shows a programming device according to a seventh embodiment of the invention,
• Figure 12 shows an alternative embodiment of the latter mode.

Figure 1 shows a weapon system 1 which is here a small caliber rifle for infantryman (caliber between 5.56mm and 12.7mm) having a first tube 2 of small caliber and a second tube 3 of a higher caliber (for example from 20 mm to 45 mm). The second tube is intended to fire a projectile 4 equipped with a time rocket 5. Such a projectile will for example be an explosive projectile which will explode on trajectory (explosion zone 6) at a distance Rf from the second tube 3.

According to the invention the weapon system 1 carries a programming device 7 for the chronometric rocket 5.

This device comprises here two reference markers 8a, 8b, which are integral with a lower portion of the first tube 2 of the weapon system, and which are separated by a distance Lb.

Each marker 8a, 8b is here annular and is constituted by a metal ring, for example steel.

The trajectory 9 of the projectile 4 passes through the markers 8a, 8b which are designed so as to cooperate with the rocket 5 of the projectile so that the latter is informed of its passage in front of them.

Means are therefore provided in the rocket to allow to take into account the passage of the markers and thus calculate a mathematical image of the time required for the projectile to travel the distance Lb.

Such means will be described later.

According to an essential characteristic of the invention, one of the markers is mobile with respect to the second marker, so as to allow a modification of the distance Lb separating the markers.

According to the embodiment shown in Figure 1, it is the first marker 8a is movable. For this purpose, it comprises a base 10 slidable relative to a rack 11. The sliding is controlled manually by a knob 12 which is connected to a pinion (not shown) integral with the base 10.

The base 10 carries a mark 13 which is thus displaced with respect to a graduated ruler 14 integral with the weapon system 1.

It will be possible according to the needs to use a scale graduated in distances (Rf) or in time (time Tf necessary to travel the distance Rf).

A simple movement of one marker relative to the other will be sufficient to ensure the programming of the rocket following the method which will now be described with reference to Figures 2 to 4.

Figure 2 schematically shows the internal structure of the rocket 5.

This comprises an electronic module comprising an oscillator 15 and at least one counter 16 of the oscillations 17 delivered by the oscillator 15.

According to a first embodiment, the rocket incorporates a proximity detector 18.

This one has the function of detecting the passage of the projectile to the right markers 8a, 8b integral with the weapon system.

For the simplification of the diagram only a rectangle is shown for the detector 18, connected to the counter 16.

This rectangle corresponds, of course, not only to the detector itself, but also to its associated driving and signal processing circuits which make it possible to recognize the passage of a marker and to deliver a calibrated pulse for controlling the start of the counter. 16 (passage of the first marker 8a) and its stop (passage of the second marker 8b).

From the point of view of technology, different types of detectors can be adopted depending on the nature of the markers used.

For example, an active magnetic proximity detector may be used. The magnetic field of the detector will be disturbed by the passage of the markers. This disturbance will be detected by the control circuits of the proximity detector and shaped to control the counter 16.

The first counter 16 therefore delivers at its output S1 the number of reference oscillations (N _ref ) which is counted between the two markers.

A multiplier circuit 20 makes it possible to multiply this number N _ref by a constant K to calculate a theoretical number N _th = KN _ref .

Parallel to the first counter 16, a second counter 19 also continuously counts the oscillations delivered by the oscillator 15 and delivers at all times at its output S2 the number of oscillations actually counted since the firing of the projectile (N _R ) .

A comparator 21 receives the calculated theoretical number (N _th ) as well as, in a continuous manner, the real number (N _R ) provided by the counter 19 and compares these two numbers. It delivers a trigger signal Sd when these two numbers are equal. This signal is applied to a trigger actuator 22 which will be, for example, a primer controlling the detonation of the projectile 4.

The different circuits of the electronic module will be made in the form of one or more integrated circuits. In particular, it will be possible to produce a specific integrated circuit (ASIC). The power supply of these circuits will be provided by a source 23 such as a bootable battery. An inertia contactor 24 will be actuated when firing the projectile and connect the circuits of the rocket to the source 23.

The structure of this rocket is given here as an indication. It is of course possible to give the rocket a different structure, provided that the described functions are met: counting, multiplication, comparison.

It will thus be possible to use only one counter instead of the two counters 16 and 19. In this case, a memory or a register will be provided which will be fed by the result of the counting performed by the counter between the two markers.

In a manner well known to those skilled in the art, the memorization may be controlled by the application to the counter of the second pulse emitted by detector 18.

In a preferred manner it will be possible to make the electronic circuit of the rocket in the form of a microprocessor with appropriate programming to perform the previously described functions.

FIG. 3 shows a firing curve of a projectile to which the method according to the invention will be applied.

The distance Rf at which the trigger is desired is reached for this projectile after a time Tf. The origin O corresponds to the moment of firing of the projectile. T1 corresponds to the passage of the projectile at the first marker 8a, T2 corresponds to the passage of the projectile at the second marker 8b. The duration Tb is that necessary for the projectile to travel the distance Lb separating the two markers.

The number of pulses Nref delivered by the counter during the duration Tb depends on both the initial velocity of the projectile (Vi), the frequency F of the oscillator and the distance Lb.

The ballistic characteristics of the projectile are therefore known by the curve 25, or by a network of curves (firing table) giving different characteristic curves 25 as a function of the firing conditions (such as temperature).

It is then possible to determine the distance Lb corresponding to a duration Tb which is such that Tf = K.Tb (K being a given constant for the weapon system and the projectiles considered).

The oscillator will supply N _R (Tf) trajectory pulses until the trigger time Tf. Moreover he provided N _ref pulses on the length Tb. The oscillator being chosen sufficiently stable in frequency, the equality chosen before shooting Tf = K.Tb will result in the equality N _R (Tf) = KN _ref , and this whatever the frequency of the oscillator.

A simple adjustment of the distance Lb between the two markers 8a, 8b thus makes it possible to program in an extremely simple manner the triggering time Tf of the rocket.

FIG. 4 is a logic diagram schematizing the various steps of the method according to the invention.

Step A corresponds to the determination of the distance Rf at which the trigger is desired (or the instant Tf from the firing at which this triggering must occur).

This step can be done manually. It will be conducted advantageously using a rangefinder that will provide the distance information. The corresponding tempering information will then be determined from the firing table 25 (Rf -> Tf).

puis $$\mathrm{Tb}\to \mathrm{Lb}$$

Step B corresponds to the calculation of the distance Lb which ensures Tf = K.Tb. This distance is also obtained from the firing table 25: $$\mathrm{Tf}\mathrm{\to }\mathrm{Tb}\mathrm{=}\mathrm{Tf}\mathrm{/}\mathrm{K},$$

then $$\mathrm{Tb}\to \mathrm{lb}$$

Step C corresponds to the setting on the weapon system of the distance Lb.

Steps B and C can be performed as previously described (Figure 1) from a graduated scale on the weapon system. In this case the firing table is simply integrated into the weapon system in the form of one or more graduated abacuses with respect to which the marker 8a is moved with a marker.

They can also be conducted automatically as will be described later with reference to Figure 10.

Step D corresponds to the firing of the projectile, which energizes rocket 5.

The test T1 corresponds to the waiting by the rocket of the passage of the first marker 8a.

Step E corresponds to counting the number of reference pulses N _ref . This count is stopped when the T2 test is positive (passage of the projectile at the second marker 8b).

Step F is the calculation of the product KN _ref = N _th .

Step G corresponds to counting the actual number of pulses N _R (whether made by another counter or by the same counter).

The test T3 corresponds to the comparison between the calculated theoretical number of pulses (N _th ) and the real number counted on trajectory (N _R ). When the test is positive (N _th = N _R ) the triggering of the projectile is controlled (step H).

• Vo la vitesse initiale nominale théorique et Vi la vitesse initiale réelle,
• Tb' et Tf' les durées de vol correspondant à Vi et
• Tb et Tf les durées correspondant à Vo.

The method according to the invention leads to a correct programming even if the actual initial velocity Vi of the projectile is slightly different from the theoretical nominal initial velocity. Indeed if we note:

• Vo the theoretical nominal initial velocity and Vi the actual initial velocity,
• Tb 'and Tf' the flight times corresponding to Vi and
• Tb and Tf the durations corresponding to Vo.

$$\mathrm{Tfʹ}\mathrm{=}\mathrm{KTbʹ}\mathrm{=}\mathrm{KLb}\mathrm{/}\mathrm{\left(}\mathrm{\right(}\mathrm{1}\mathrm{+}\mathrm{\epsilon }\mathrm{)}\mathrm{/}\mathrm{Vo}\mathrm{=}\left(\mathrm{1}-\mathrm{\epsilon }\right)\mathrm{KTb}/\mathrm{Vo}\mathrm{=}\mathrm{KLb}\mathrm{(}\mathrm{1}-\mathrm{\epsilon }\mathrm{)}=\mathrm{Tf}\left(\mathrm{1}\mathrm{-}\mathrm{\epsilon }\right)$$

$$\mathrm{Tfʹ}=\mathrm{Tf}\left(1-\mathrm{\epsilon }\right)$$

We have : $$\mathrm{Tb\text{'}}=\mathrm{lb}/\mathrm{Vi}=\mathrm{lb}/\left(\left(1+\mathrm{\epsilon }\right)\mathrm{Vo}\right)$$

$$\mathrm{Tf\text{'}}\mathrm{=}\mathrm{KTb\text{'}}\mathrm{=}\mathrm{KLB}\mathrm{/}\mathrm{\left(}\mathrm{\right(}\mathrm{1}\mathrm{+}\mathrm{\epsilon }\mathrm{)}\mathrm{/}\mathrm{Vo}\mathrm{=}\left(\mathrm{1}-\mathrm{\epsilon }\right)\mathrm{KTb}/\mathrm{Vo}\mathrm{=}\mathrm{KLB}\mathrm{(}\mathrm{1}-\mathrm{\epsilon }\mathrm{)}=\mathrm{Tf}\left(\mathrm{1}\mathrm{-}\mathrm{\epsilon }\right)$$

$$\mathrm{Tf\text{'}}=\mathrm{Tf}\left(1-\mathrm{\epsilon }\right)$$

Numeric example.

The example is based on a 25mm weapon system firing an explosive projectile of mass 0.12 kg. The Cx (aerodynamic coefficient) of the projectile is 0.3.

The frequency of the oscillator is 200 KHz, the multiplier K chosen is equal to 1400. The firing range varies between 30 m and 200m, the distance Lb varies between 20mm and 200mm.

The following two tables give the values of the range errors obtained for initial speed variations of +/- 10% and + 30% for the minimum (30m) and maximum (200m) ranges. Maximum range (200m) Vi rated Vi-10% Vi + 10% Vi + 30% Initial speed Vi (m / s) 270 243 297 351 Time Tf (s) 1.0156 1.1285 .9232 .7812 Lbase (m) 0.196 0.196 0.196 0.196 Error in range (m) -0.3645 .2376 .9828 Error in scope (%) -0.18 0.12 0.49

For the maximum range of 200m we see that the range error is less than 1 m (Vi + 30%). Minimum range (30m) Vi rated Vi-10% Vi + 10% Vi + 30% Initial speed Vi (m / s) 270 243 297 351 Time Tf (s) .1163 .1292 .1057 .0895 Lbase (m) 0,022 0,022 0,022 0,022 Error in range (m) -0.7776 -0.2079 .5265 Error in scope (%) -2.59 -0.69 1.76

For the minimum range of 30m we see that the range error is less than 0.8m (Vi-10%).

It will be noted that the range errors are essentially due to the time quantization error that is made by the oscillator. Indeed, the time Tb required to travel the distance Lb does not generally correspond to a finite number of pulses N _ref of the oscillator.

A simple way to reduce this quantization error, so the range error, is to choose a higher frequency oscillator.

If we adopt a frequency of the order of 500 KHz, the error in scope becomes negligible.

The table below gives for this same projectile the different values of the length Lb for adjusting the desired firing range Rf or the associated tempering Tf. Initial speed Vi = 270m / s Rf Range (m) 30 32 198 200 Time Tf (s) .1163 .1245 1.0021 1.0156 Lbase (m) 0,022 0,024 0,193 0.196

We see that the length Lb varies between 22mm and 200mm for a difference in range of 30m to 200m. Such values are fully compatible with a portable infantry weapon system.

Various variants are possible without departing from the scope of the claims.

FIG. 5 thus shows a second embodiment of a programming device according to the invention which differs from the first in that it is the second marker 8b which is mobile. This figure also shows a detection device 18 in the form of an active magnetic detector which is located on a peripheral zone of the rocket.

The rocket may also be a rocket disposed at the base of the projectile.

Figure 6 shows a third embodiment of a programming device according to the invention. In this mode the markers 8a, 8b are no longer annular but are formed by metal elements salient. The markers being devoid of symmetry of revolution, it is the proximity detector 18 of the rocket which is then annular. Thus the detector 18 can detect the markers regardless of the angular orientation of the projectile 4.

Figure 7 shows a fourth embodiment of a programming device according to the invention. This mode differs from the previous ones in that the markers 8a and 8b are active markers each constituted by a coil generating a magnetic field. The coils are connected to a generator 26 integral with the weapon system.

In this case the detector linked to the rocket 5 of the projectile may be a passive detector. For example, a detector 18 of the passive magnetic type may be used.

FIG. 9 proposes an alternative embodiment of a programming device according to the invention. According to this variant the first marker 8a is constituted by an end of the second tube 3 of the weapon. The second marker 8b is movable relative to the first tube 2. The active magnetic sensor carried by the projectile 4 will detect the exit of the weapon tube and the passage of the projectile in front of the metal element 8b forming the second marker.

According to this variant, the second marker comprises a base 10 that can slide relative to a rack 11. The sliding is controlled manually by a knob 12 which is connected to a pinion (not shown) integral with the base 10. The base 10 carries a reference 13 which moves relative to a graduated strip 14 integral with the weapon system 1.

FIG. 8 schematizes a fifth embodiment of a programming device according to the invention.

According to this mode, the markers 8a and 8b are constituted by magnetic sensors for detecting the passage of the projectile. These markers are connected to a processing electronics 27 integral with the programming device 7 carried by the weapon system.

This electronics will generate at each detection of passage of the projectile a signal (Sa, Sb) which will be transmitted to the rocket 5 of the projectile by a transmission means 28 (for example a coil in which or in which the projectile will pass).

The detection means 18 of the rocket 5 of the projectile 4 then comprise a receiver 29 of the signals emitted by the transmission means 28. The receiver is connected for this purpose to an annular antenna 30. The rest of the internal structure of the rocket is analogous to that described above with reference to FIG.

Advantageously, the transmission means will be constituted by the markers 8a / 8b themselves whose winding can act as transmitting antenna. The processing electronics 27 will then transmit to each marker a particular signal which will be superimposed on the magnetic field generated by each marker.

Such an embodiment simplifies the electronics of the rocket.

This embodiment can advantageously be associated with a projectile equipped with a base rocket.

The receiving antenna 30 will then be practically at the level of each marker when the signal Sa, Sb will be transmitted towards the projectile by the marker in question. The quality of the transmission is improved.

Fig. 10 is a block diagram diagram of a programming device according to a sixth embodiment.

According to this embodiment, the programming device 7 comprises a rangefinder 31 which determines the distance Rf between the weapon system and the target.

This rangefinder is connected to a processing electronics 32 which incorporates the firing table (s) 33 of the projectile with the weapon system considered.

As has been described previously with reference to FIGS. 3 and 4, the processing electronics determine the theoretical duration of the flight Tf from the measurement of the distance Rf and the firing table 33.

It also calculates the value Tb = Tf / K (K being the constant of the system according to the invention) and it deduces automatically from Tb and the firing table 33 the value of the distance Lb to separate the two markers.

The processing electronics 32 comprises control means which will then actuate a motor 34 (such as a stepper motor) which will ensure the relative displacement of at least one of the markers 8a, 8b to distance them from the distance Lb.

This embodiment makes it possible to automate almost completely the tasks of the shooter who only has to aim at a desired point to see the programming device adopt the desired position.

Advantageously, an input interface 35 and display will be provided which will make it possible to know the values of the measured distances Rf and the calculated times Tf and which will also make it possible to manually program the values of Tf or Rf.

The various embodiments described above are perfectly suitable for a short-range weapon system intended for infantrymen (range of less than 300m).

On the other hand, they are poorly suited to a medium-caliber weapon system (from 20 to 45mm) or a large caliber weapon (from 90 to 155mm) having a greater range (of the order of 1000m).

Indeed the distance Lb required between the two markers then becomes too important and can not be achieved for such a weapon system.

If to reduce this distance we chose a higher value for the multiplier coefficient K, then there would be a loss of accuracy of programming.

Another embodiment is shown in Figures 11 and 12 which overcomes such a disadvantage.

In this mode, at least three reference markers 8a, 8b and 8c are made integral with the weapon system 1.

These three markers thus make it possible to determine between them two distances Lb1 and Lb2. The distance Lb1 is that separating the first two markers (8a and 8b), the distance Lb2 is that separating the second marker (8b) from the third marker (8c).

Two of the reference markers (8b and 8c) are movably mounted relative to the third marker 8a so as to allow a modification of the distances Lb1 and Lb2 separating the markers.

For example, it is possible to make the markers 8b and 8c integral with the weapon system 1 by means of bases 10b, 10c each of which can slide independently relative to a slideway 36b, 36c. Each slide will advantageously be controlled by a motor M1, M2.

This embodiment is implemented with a variant of the method according to the invention.

According to this variant, the distance Rf to which the projectile is to be triggered is further determined, or the time Tf at the end of which it is desired to effect this triggering.

The two basic distances Lb1 and Lb2 are then determined such that the time Tf is a linear combination of the times Tb1 and Tb2 necessary for the projectile to travel these basic distances.

We will note thus: Tf = K1 Tb1 + K2 Tb2, expression in which K1 and K2 are two given constants.

As in the previous embodiments, the lengths Lb1 and Lb2 will be determined from the values Tb1 and Tb2 using the firing tables of the projectile considered.

In order to avoid any ambiguity in the interpretation of the signals at the level of the rocket, the possibility of giving a zero value for one of the two base lengths (preferably that associated with the largest coefficient K, by example here Lb1). So if the rocket sees only two markers (ie if one of the two lengths Lb1 or Lb2 is zero), it will interpret this as the choice of a null value for the length for which the null value is not forbidden (for example Lb2 if we have forbidden Lb1 = 0).

For a projectile having a range greater than 1000m and an initial speed of the order of 1200 m / s, the flight times are of the order of one second.

The two constants K1 and K2 make it possible to have two measurement bases: one with a large coefficient K1 making it possible to perform a rough adjustment of Tf (of the order of a few hundred milliseconds) and the other with a lower coefficient K2. allowing a finer adjustment of Tf (of the order of a few milliseconds).

As in the previous embodiments, the projectile 4 passes in front of the markers 8a, 8b and 8c. The rocket 5 of the projectile cooperates with the markers and can then count two numbers, referred to as reference numbers (N _ref1 , N _ref2 ).

N _ref1 corresponds to the number of oscillations produced by the oscillator integrated in the rocket between the markers 8a and 8b, thus along the base distance Lb1.

N _ref2 corresponds to the number of oscillations produced by the oscillator integrated in the rocket between the markers 8b and 8c, thus along the base distance Lb2.

The rocket will be programmed or designed to calculate a theoretical number of oscillations N _th which is the linear combination of the reference numbers with the same constants K1 and K2 (N _th = K1 N _ref1 + K2 N _ref2 ),

As in the previous embodiments, the rocket will trigger the launching of the projectile when the actual number of oscillations N _R counted from the firing of the projectile will be equal to the theoretical number of oscillations thus calculated. $$({\mathrm{NOT}}_{\mathrm{R}}={\mathrm{NOT}}_{\mathrm{th}}=\mathrm{K}1{\mathrm{NOT}}_{\mathrm{ref}1}+\mathrm{K}2{\mathrm{NOT}}_{\mathrm{ref}2})\mathrm{.}$$

Figure 12 shows an alternative embodiment in which four markers are provided (8a, 8b, 8c and 8d). Two markers are fixed (8a and 8c) and two markers are movable 8b and 8d. These can be moved relative to the fixed markers thanks to two engines M1 and M2.

Here again the different markers determine between them two basic lengths Lb1 and Lb2 which will be used by the rocket to calculate the theoretical number N _th . We will also refrain from giving a value of zero for one of the two lengths, for example Lb1, to avoid any ambiguity of interpretation by the rocket.

The simplified numerical example below is given with reference to a system made according to one or the other of the two variants (3 or 4 markers). It aims to highlight a method of programming the rocket using a linear combination of reference numbers.

Numeric example.

This example is again based on a 25mm weapon system firing an explosive projectile. The Cx (aerodynamic coefficient) of the projectile is assumed to be zero for the simplification of the example (projectile at constant speed on trajectory).

The initial velocity of the projectile is 1200 m / s the maximum desired range Rfmax is less than 2000m.

The setting of the first base (Lb1) is done step by step over a maximum distance Lb1 of 120mm, with 25 possible setting positions. The selected projectile travels the maximum distance Lb1 in about 0.1 millisecond. The coefficient K1 is chosen equal to 25000. This results in an incrementation of 100 milliseconds per adjustment step.

The adjustment of the second base (Lb2) is also done step by step on a maximum distance Lb2 of 120mm, with 50 possible setting positions. The selected projectile travels the maximum distance Lb2 in about 0.1 millisecond. The coefficient K2 is chosen equal to 1000. This results in an incrementation of 2 milliseconds per adjustment step.

The frequency of the oscillator will be chosen greater than 4 Mega Hz (in this case of the order of 4.8 Mega Hz) in order to minimize the quantization errors which are all the greater as the initial velocity of the projectile is important. Desired range Rf (m) 324 660 1380 2850 Desired Tf time (millisecond) 270 550 1150 2375 Lb1 (mm) 9.6 24 52.8 110.4 Lb2 (mm) 84 60 60 88.8 Tf time realized (millisecond) 267.92 550 1148.96 2,370.83 Time error Tf (ms) 2.08 0 1.04 4.17 Error in Rf range (m) 2.5 0 1.25 5

The quantization error in range (due to the discrete measurement of time) is of the order of 6 m. It leads to a standard deviation of about 2 m on the range which is quite acceptable.

The error due to a wrong adjustment of the distance (Lb1 or Lb2) is 0.3mm or less, resulting in a standard deviation on the range of about 2.25m.

It is of course possible for a given weapon system to minimize errors by varying the frequency of the oscillator and the increment values associated with each measurement base Lb1 or Lb2.

Different variants are possible without departing from the scope of the claims.

It is thus possible to use the different marker technologies previously described in a device using three or four markers. The displacement of two mobile markers can also be carried out manually or automatically by means of actuators connected to a control means associated with a range finder.

Claims (22)

1. A process to determine a trigger time for a projectile (4) using a timer fuse (5), such projectile (4) being fired by a weapon system (1), such process in which two markers (8a, 8b) are positioned, integral with the weapon system (1) and in front of which the projectile (4) shall pass, said markers being designed so as to be able to cooperate with the projectile fuse (5) so that the latter is informed of its passage in front of them, such process wherein it incorporates the following steps:

   - the distance Rf at which the projectile (4) should be triggered is determined, or else the time Tf after which such triggering is to be made, time Tf being deduced if need be from the distance Rf and by using a firing table,

   - a base distance Lb is determined such that the time Tb required for the projectile to cover this base distance is equal to Tf/K, K being a given constant,

   - the two markers (8a, 8b) are positioned at a distance from one another equal to the base distance Lb,

   - a so-called reference number (N_ref) is counted, which is the number of oscillations produced by an oscillator (15) integrated into the projectile during its passage between the two markers (8a, 8b), in other words, as it covers distance Lb,

   - a theoretical number of oscillations N_th is calculated by multiplying the reference number N_ref by constant K (N_th = K N_ref),

   - the projectile (4) is triggered when the actual number of oscillations N_R counted from the projectile being fired is equal to the theoretical number of oscillations calculated $$({\mathrm{N}}_{\mathrm{R}}={\mathrm{N}}_{\mathrm{th}}={\mathrm{K\; N}}_{\mathrm{ref}})\mathrm{.}$$

   
2. A process to determine a trigger time for a projectile (4) using a timer fuse (5), such projectile (4) being fired by a weapon system (1), such process in which at least three markers (8a, 8b, 8c, 8d) are positioned, integral with the weapon system (1) and in front of which the projectile (4) shall pass, said markers being designed so as to be able to cooperate with the projectile fuse (5) so that the latter is informed of its passage in front of them, such process wherein it incorporates the following steps::

   - the distance Rf at which the projectile (4) should be triggered, or else the time Tf after which triggering is to be made, is determined, time Tf being deduced if need be from
   the distance Rf and by using a firing table,

   - at least two base distances Lb1 and Lb2 are determined such that the time Tf is a linear combination of times Tb1 and Tb2 required for the projectile (4) to cover these base distances, Tf = K1 Tb1 + K2 Tb2, K1 and K2 being two given constants,

   - the three markers (8a, 8b, 8c, 8d) are positioned so as to determine between each other the two distances Lb1 and Lb2,

   - at least two so-called reference numbers (N_ref1, N_ref2) are counted, which correspond to the number of oscillations produced by an oscillator (15) integrated into the projectile and counted between two given markers determining one of the base distances Lb1, Lb2,

   - a theoretical number of oscillations N_th is calculated by performing a linear combination of the reference numbers with the constants K1 and K2 (N_th = K1N_ref1 + K₂N_ref2),

   - the projectile (4) is triggered when the actual number of oscillations N_R counted from the projectile being fired is equal to the theoretical number of oscillations calculated $$({\mathrm{N}}_{\mathrm{R}}={\mathrm{N}}_{\mathrm{th}}={\mathrm{KiN}}_{\mathrm{ref}1}+\mathrm{K}2{\mathrm{N}}_{\mathrm{ref}2})\mathrm{.}$$

   
3. Process to determine a triggering time according to one of Claims 1 or 2, wherein the distance Rf is determined using a range finder (31).
4. Process to determine a triggering time according to one of Claims 1 to 3, wherein the base distance or distances Lb is(are) determined using a small rule or abacus (14) graduated according to the ballistic characteristics of the projectile (4).
5. Process to determine a triggering time according to one of Claims 1 to 3, wherein the base distance or distances (Lb) is(are) determined using a digital firing table (33) to which the distance Rf measured or calculated is applied.
6. Process to determine a triggering time according to Claim 5 wherein after determining the base distance or distances Lb, the relative displacement of the markers is controlled by motorisation (34, M1, M2) so as to mutually move the markers (8) away from the distance or distances Lb.
7. A programming device (7) for a timer fuse (5) ensuring the triggering of a projectile (4) fired from a weapon system

   (1) and enabling the implementation of the process according to one of Claims 1 to 6, such device comprising at least two reference markers (8a, 8b), integral with the weapon system

   (1) and separated by a distance Lb, such markers in front of which the projectile (4) shall pass and intended to cooperate with detection means (8) integrated into the projectile fuse (5), such device wherein at least one of the reference markers is mobile with respect to the second marker so as to enable a modification in the distance (Lb) separating the markers (8a, 8b).
8. Programming device according to Claim 7, wherein it comprises at least three reference markers (8a, 8b, 8c, 8d), integral with the weapon system and determining between each other at least two distances Lb1 and Lb2, at least two of the reference markers being mobile with respect to a third marker so as to enable a modification in the distances separating the markers.
9. Programming device according to one of Claims 7 or 8, wherein the marker or markers (8) is(are) mobile with respect to a small rule (14) graduated in distance or time.
10. Programming device according to one of Claims 7 or 8, wherein it incorporates at least one motorisation means (34, M1, M2) ensuring the displacement of at least one marker (8) with respect to another.
11. Programming device according to Claim 10, wherein it comprises range finding means (31) connected to the motorisation means (34, M1, M2) via control means (32), thereby ensuring the automatic modification of the distance or distances separating the markers (8) according to the distance measured to the target aimed at.
12. Programming device according to one of claims 7 to 11, wherein one of the markers (8) is constituted by one end of the barrrel (3) of the weapon system (1).
13. Programming device according to one of claims 7 to 12, wherein at least one of the markers (8) is ring-shaped.
14. Programming device according to one of claims 7 to 13, wherein at least one of the markers (8) is constituted by a metallic element.
15. Programming device according to one of claims 7 to 13, wherein at least one of the markers (8) is an active marker comprising at least one electromagnetic field generating coil supplied by an electric generator (26).
16. Programming device according to one of claims 7 to 13, wherein at least one of the markers (8) is constituted by a sensor to capture the passage of the projectile (4), transmission means (28) being provided intended to transmit the information of the passage of the projectile (4) towards the projectile fuse (5).
17. A programmable timer fuse (5) for a projectile (4) that is intended to be programmed by a device according to one of Claims 7 to 16, such programming device (7) being carried by a weapon system (1) such fuse comprising at least one oscillator (15) and at least one counter (16,19) of the oscillations delivered by the oscillator, fuse wherein it incorporates :

    - means (18) enabling detection of the passage of the projectile (4) at right angles to at least two markers (8a,8b) integral with the weapon system (1),

    - at least one counter (16,19) enabling the oscillations delivered by the oscillator (15) to be counted between the two markers (8) as well as during the trajectory,

    - means (21) enabling the number of actual oscillations N_R counted from the firing of the projectile to be compared with a theoretical number of oscillations (N_th) which is proportional (K) to a so-called reference number of oscillations (N_ref), which is the number of oscillations counted between the two markers (N_th = K N_ref), K being a given constant,

    - the comparison means (21) command the triggering of the projectile when the actual number of oscillations is equal to the theoretical number of oscillations thus calculated (N_R = N_th).
18. Programmable timer fuse (5) for a projectile (4) intended to be programmed by a device according to one of Claims 7 to 16, such programming device (7) being carried by a weapon system (1), such fuse comprising at least one oscillator (15)and at least one counter (16, 19) for the oscillations delivered by the oscillator, wherein it incorporates:

    - means (18) enabling the passage of the projectile at right angles to at least three markers (8a, 8b, 8c, 8d) integral with the weapon system (1) to be detected,

    - at least one counter (16, 19) enabling the oscillations delivered by the oscillator (15) to be counted between the different markers (8) as well as during the trajectory,

    - means (21) enabling the number of actual oscillations N_R counted from the firing of the projectile to be compared with the theoretical number of oscillations (N_th) which is calculated by the fuse (5) in the form of a linear combination of at least two reference numbers (N_ref1, N_ref2) with at least two constants K1 and K2 (N_th= K1 N_ref1 + K2 N_ref2), the two reference numbers corresponding to the number of oscillations delivered by the oscillator (15) between two of the markers (8) detected,

    - the comparison means (21) control the triggering of the projectile when the number of actual oscillations is equal to the theoretical number of oscillations thus calculated (N_R = N_th).
19. Programmable timer fuse according to one of Claims 17 or 18, wherein it incorporates a contact (24) ensuring the activation of the fuse when the projectile (24) is fired.
20. Programmable timer means according to one of Claims 17 to 19, wherein the detection means (18) comprise at least one proximity sensor ensuring the detection of a metallic element forming a marker (8) or else an electromagnetic field generated by a marker.
21. Programmable timer fuse according to Claim 20, wherein the proximity sensor (18) has rotational symmetry.
22. Programmable time fuse according to one of Claims 17 to 19, wherein the detection means (18) incorporate a receiver (29) for signals (Sa, Sb) transmitted by a programming device (7) integral with the weapon system (1).

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