Method and device to determine the internal ballistic characteristics of guns.

(42) Date of commencement of the patent: 15. 6.1989 (45) Date of issue: 25. 1.1990

<td>(56) Documents:</td><td>(73) Patent owner:</td>

<td>US PS4283989</td><td>AVL SOCIETY Fl »COMBUSTION ENGINES AND MEASUREMENT TECHNOLOGY MBH PROF.DR.DR.HCHANS LIST A-8020 GRAZ, STEIERMARK (AT).</td>

<td></td><td>(72) Inventor:</td>

<td>•</td><td>MORAVIAN GERHARD GRAZ, STYRIA (AT). PANNOLD REINHARD GRAZ, STYRIA (AT). BOSCHANIG REINHARD GRAZ, STYRIA (AT).</td>

(54) PROCESS AND DEVICE FOR DETERMINING INTERNAL BALLISTIC KNIVES IN PIPE GUNS

CQ (57) For the non-destructive determination of internal ballistic characteristics in tubular weapons, an electromagnetic wave is coupled via a waveguide transition (7,7 '7 ") provided laterally on the weapon barrel (1) and after reflection on the projectile (6) located in the weapon barrel (6) ) decoupled again. By arranging at least two coupling openings (40, 40 ', 41) in the longitudinal direction of the weapon barrel (1) at a distance determined by the wavelength used, it is achieved that the coupled shaft runs virtually 100% in the direction of the projectile (6), and that the decoupling of the reflected wave is more effective. Thus, from the changed in a change in the projectile position in the barrel (1) phase between coupled and decoupled wave measurement signal for the respective floor position against interference signals is very large, so that even with a sharp shot significant measurements are possible.

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AT 389 764

WROTraais

No. 389764

The invention relates to a method for the non-destructive determination of internal ballistic characteristics in guns, wherein an electromagnetic wave is coupled via a laterally arranged on the tube waveguide transition in the barrel and coupled out after reflection on a projectile located in this again and wherein in a change of Projectile position in the weapon barrel changing phase position between coupled and decoupled wave is used as a measurement signal. Furthermore, the invention also relates to a device for carrying out such a method on a weapon barrel with a projectile therein, with a unit for generating the shaft to be coupled, a coupled thereto and a laterally in the inner surface of an area swept by the projectile on the barrel arranged waveguide transition coupling device for coupling and decoupling of the waves and a likewise communicating with the coupling device evaluation.

Such methods or Devices are known (see for example US-PS 4,283,989) and serve essentially to determine the speed or Acceleration conditions on a projectile still located in the gun barrel, which allow statements about the internal ballistic conditions and either in the further development of the weapon or find the ammunition use or can also be used for example to correct a Zeitzünders in the projectile to take into account the actual muzzle velocity. It is usually in the microwave range (wavelengths in the millimeter or Centimeter range), with the wavelength used in each case depending on the tube caliber. The weapon barrel is used as a waveguide for the coupled via the lateral transition microwaves, in which, depending essentially on frequency and tube caliber, different modes or Training wave types. In order to ensure a uniqueness of the measurement results, the frequency of the microwaves and the type of coupling are usually chosen so that only a specific type of wave can form. The projectile located in the gun barrel acts as a short shifter on which the coupled wave is reflected, with a standing wave in serving as a waveguide gun barrel is created by superposition of the coupled with the reflected wave. When firing the projectile, this standing wave is pushed from the floor in a sense in front of him or changed the phase angle between the coupled and the reflected wave. This caused by the movement of the projectile and directly influenced by it phase shift can be detected and evaluated by a suitable measuring arrangement in the form of the so-called Doppler frequency. The equipment costs or The microwave hardware speaks essentially a low-power Doppler radar, although there are various special requirements, in particular with regard to the coupling and decoupling at the gun barrel.

Apart from the originally for the coupling or Decoupling, the electromagnetic wave used and always exiting the gun barrel at least partially destroyed antennas, deflecting mirrors or the like, are for some time process or Facilities of the type mentioned for non-destructive input or Decoupling known. Despite this fact, there is still no usable in practice such system on the market, which is essentially due to the fact that the mechanical loads of the gun barrel occurring when firing the projectile exert tremendously disturbing influences on the evaluation and in particular because the useful signal heights available for the evaluation are only relatively small.

Although in the previously known designs with non-destructive coupling in simulated shots (in which the projectile is blown with compressed air through the barrel) well evaluable signals and thus useful results are achieved breaks the sharp shot the useful signal in all known versions usually together or is mostly superimposed by disturbances which are of the same order of magnitude as the useful signal.

Object of the present invention is to improve a method or a device of the type mentioned above, that the mentioned disadvantages of the known methods or devices are avoided and that especially and especially in the sharp shot meaningful and significant measurements according to sufficiently large usable Useful signals are possible.

The invention is based on the consideration that in the in the previously known methods or Devices of the type mentioned coupling elements used to be coupled at least half of the energy of the electromagnetic wave instead of towards the projectile, is emitted from the mouth of the gun barrel. The intended for the coupling itself elements usually have only a very bad standing wave ratio, which means that only a relatively small part of the energy actually gets into the barrel and the reflection on the projectile nose. When mechanical loads, as they are usually unavoidable in sharp shooting, then the standing wave ratio changes further and it comes to the formation of noise, which can easily reach or exceed the size of the useful signal.

Based on this consideration, the present invention solves the above object in a method of the type mentioned by the coupling of the electromagnetic wave split this and at least two spaced locations of the waveguide transition is supplied to the barrel so that the propagating towards the projectile Add shaft parts and compensate for the wave parts propagating in the opposite direction. By this both constructive and procedural very

-2Nr. 389764 simple principle is achieved that the coupled into the barrel shaft parts according to the distances of the actual transition openings to each other have such relative phase positions that force a clear propagation of the coupled wave in a certain direction - namely in the direction of the projectile. Thus, almost 100% of the microwave energy generated can actually be introduced into the barrel, so that any disturbances of the type mentioned remain vemachlässighar even when sharp shot against the useful signal to be evaluated.

In the device of the type mentioned, the present invention is realized in that the coupling device has at least two coupling openings, which are arranged at spaced locations of the inner surface of a swept by the floor area on the gun so that the in

Add direction to the projectile propagating shaft parts and spreading in the opposite direction

Compensate shaft parts. According to a preferred embodiment of the device according to the invention is provided in this context that at the same propagation speed of the individual shaft parts and the same phase shift at the individual coupling openings in the longitudinal direction of the gun barrel measured distance L of the individual coupling openings a natural multiple of the used

Wavelength increases by a quarter of the wavelength (L = n, lambda + lambda / 4, with n = natural number, and

Lambda = wavelength). This ensures that the wave coupled into the tube can not propagate at all in the undesired direction due to the phase shift of the overflowing shaft parts and that the corresponding addition of the shaft parts originating from the individual coupling openings takes place in the desired direction to the projectile.

According to a particularly preferred further embodiment of the method according to the invention for static calibration cooperating with the distance measuring device bullet at least partially moved through the barrel and the relationship between the current location of the projectile dummy and phase difference or Doppler frequency can be determined. This very simple possibility of calibration allows a clear and extremely accurate (depending on the tube caliber in the range between about 0.1 and a few millimeters)

Assignment of the measurement signals to the actual projectile path or location, even if different parameters, such as the slope of the trains, change over the length of the gun barrel.

In principle, the coupling device with the individual openings of the waveguide transition at any point, of course, be provided in the wall of the gun barrel itself, including essentially only the corresponding openings must be attached to the gun barrel. However, it has proved to be particularly advantageous to provide the coupling device as well as in the case of the aforementioned US Pat. No. 4,283,989 in a coupling element which can be deposited separately at the mouth of the weapon barrel and can be connected with this v . Thus, on the one hand, the necessary for the inventive process adaptation of the gun barrel on the provision of measures to enable secure attachment of the coupling element at the mouth - for example via screw or claw connections - reduced; On the other hand, Providence enables

Coupling openings at the mouth of the gun barrel, the corresponding measurements over the entire length of the gun barrel, which is located at the rear of the barrel coupling device because of the behind the passing projectile due to chemical reactions of the atmospheric oxygen with the hot powder gases possibly occurring high concentrations of free electrons and thus accompanying influencing the electromagnetic waves is at least problematic. The coupling element preferably has in the swept from the floor inner area a coupling openings having cylindrical Durchgangsausnehmung with respect to the barrel enlarged diameter, between the Durchgangsausnehmung of the coupling element and the barrel and a conical transition between the different diameters exhibiting, preferably interchangeable adapter part can be. Due to the cylindrical design of the free passage of the bullet for the inner region of the projectile

Coupling element is given a very simple way for the coupling of the electromagnetic wave, which can be very verlustaim spread in the subsequent also cylindrical barrel. The increase in diameter relative to the tube caliber serves to allow a perfect passage of the projectile, wherein by means of the conical adapter part as lossless coupling into the barrel even with the maintenance of the formation of unwanted wave types or

Reflections is ensured. Sofeme this adapter part is interchangeable, can be done within certain limits, an adaptation of a coupling element to different tube caliber.

Apart from the said cylindrical formation of the actual waveguide transition having, inner region of the coupling element of course this could have other suitable cross-sectional shape, z. B. elliptical or square.

The adapter part may according to a further advantageous embodiment of the invention in the region of the conical transition outwardly open recesses for pressure reduction, whereby any negative effects of the pressure of the powder gases behind the projectile on the waveguide transition are held back.

The coupling openings may be substantially rectangular in a further embodiment of the invention and are in communication with a corresponding rectangular waveguide, which in turn, preferably by means of coaxial cable, is connected to the unit for generating the wave to be coupled and to the evaluation unit. Thus, simple and relatively easy to control conditions for the input and output

-3Nr. 389764 created the electromagnetic waves, of course, the coupling openings, for example, for manufacturing reasons of the pure rectangular shape deviating, slot-like training may have, which allows the production about by means of a finger milling cutter.

The coupling openings can be closed off by means of electrically non-conductive closure pieces with low dielectric losses against the swept area from the projectile, which prevents the ingress of contaminants, as well as harmful effects of the pressures or hot powder gases, in the waveguide transition.

The invention will be described below with reference to the partially schematically illustrated in the drawing?

Embodiments described in more detail. FIG. 1 shows a partially schematic representation of a device for carrying out the method according to the invention, Fig. 2 shows the detail of a coupling element of another device according to the invention, Fig. 3 shows the detail of another coupling element of a device according to the invention with exchangeable adapter part, Fig. 4 shows another embodiment of a coupling element of a device according to the invention and 5 shows a schematic arrangement according to the invention for performing a static calibration.

The device of FIG. 1 is used to determine inside ballistic characteristics in a weapon barrel (1), which may be installed, for example, in a gun not shown here and up to the coupling element (2) at the mouth (3) no change from the standard Execution has.

In the projectile chamber (4) at the opposite end of the barrel (1) of the mouth (3) a cartridge (5) is inserted with a projectile (6) whose movement through the barrel (1) with respect to the path / time Context or the respective speed and acceleration, to be investigated.

For this purpose, at least one, in the region of the coupling element (2) arranged waveguide transition (7) coupled to an electromagnetic wave in the weapon barrel (1) and coupled out again after reflection on the projectile (6), according to which the changing phase position between coupled and decoupled waves can be used as a measurement signal for the projectile position and after a corresponding link with the current time for the determination of velocity and acceleration when changing the projectile position in the gun barrel.

The electromagnetic wave generated in a microwave generator (8), which depending on the caliber of the gun barrel (1) usually wavelengths in millimeter or Centimeter range, is fed via a coaxial cable (9) to a circulator (10), from where it according to the function of the same via a further coaxial cable (11) to a coaxial waveguide transition (12) passes. There, for example, an H-type wave is excited, via the waveguide transition (7) (with this designation is here and hereinafter always a waveguide-waveguide transition to understand) in a circular waveguide performing inner region (13) of the Coupling element (2) passes and is converted, for example, in the cylindrically symmetric Εθ ^ -Welle. According to the reference to FIG. 2 coupling of the electromagnetic wave explained in more detail below at least two spaced locations (39) and specifically at the two coupling openings (40, 41) passes virtually the entire coupled electromagnetic wave via a conical transition (15) into the interior of the turn a RundhohUeiter performing gun barrel (1). This conical transition (15) is therefore provided here in order to perform the inner region (13) with respect to the caliber of the weapon barrel (1) at least slightly larger diameter without at the transition point to the gun barrel (1) reflections or to risk the occurrence of additional, undesirable wave types.

However, the wave reflected from the top of the projectile (6) is decoupled from the waveguide transition (7) and, via the coaxial-waveguide transition (12) and the coaxial cable (11), again reaches the circulator (10), where due to the non-reciprocal behavior of this device decoupled from the shaft coming from the microwave generator (8) and a mixer (16) is supplied. Due to reflections and a finite stop attenuation of the circulator (10) is at this mixer (16) and a fraction of the microwave generator (8) coming wave and therefore there is a mixture between the emitted and the reflected wave. At the output (17) of the mixer (16), the phase difference between these two waves or the Doppler frequency can be tapped, which is stored after appropriate amplification in an amplifier (18) and not shown here A / D conversion for the entire time range of a shot in a transient memory (19). Via a connecting line (20) is a computer (21), such as a commercial PC, with the transient memory (19) in connection, the further processing concerned and via a line (22) with an output unit (23 '), such as a plotter , connected to the display of the results. According to the illustrated and described type of input or Decoupling of the electromagnetic wave on the side of the gun barrel is a completely non-destructive determination of the internal ballistic characteristics possible in which the projectile (6) can leave the barrel completely unhindered freely, which eliminates any need for replacement or to readjust parts of the device after each shot.

2, it can be seen that at the coaxial waveguide transition (12) an antenna pin (42) protrudes into the interior of the waveguide (27), which has a rectangular cross-section, for example taking into account the measures familiar to the person skilled in the art in a simple way, the generation of an electromagnetic wave in the interior

-4Nr. 389764 of the waveguide (27) allows. As a result of a reflective termination indicated in the illustration to the left of the transition (12), virtually 100% of this wave travel to the right in the waveguide (27) and are divided into two coupling openings (40, 40) arranged at two locations (39) spaced apart in the propagation direction of the wave. 41) in the inner region (13) of the coupling element (2). The over-coupled voltage is induced by an electric and / or magnetic field in the coupling opening and is therefore phase-shifted by 90 °. When the correct distance (L) of the two coupling openings (40, 41) is selected, the wave components propagating to the right are added, while the components running to the left compensate each other. With the same propagation velocity of the individual shaft parts and the same phase shift at the individual coupling openings, this compensation is complete when the distance (L) of the individual coupling openings (40, 41) measured in the longitudinal direction of the weapon barrel is equal to L = n. Lambda + lambda / 4 obeyed; where n = natural number (0,1,2, ...), and lambda = wavelength.

By a in the illustration of Fig. 2 at the right end of the waveguide (27) indicated reflection-free termination (43) ensures that returning shaft parts in the waveguide (27) are excluded, which interfere with the coupling or the described type of addition and compensation would.

The described type of coupling of the electromagnetic wave in the coupling element (2) or via the conical transition (15) in the gun barrel (1) ensures a high intensity of the wave in the direction of the projectile (6), which in direct consequence also makes the signal reflected at the projectile nose very intense. The reflected signal is reversed by reversing the described principle of coupling again, now the benefits of the split-in described manner affect the effect that the decoupled wave in the waveguide (27) almost completely runs to the left, as in the direction of reflection-free Completion (43) compensate current shares again.

The in Fig. 3 Coupling element (2) shown is constructed substantially similar to that in FIG. 1 or. 2 shown only schematically, but now here the conical transition (15) in a replaceable adapter part (23) is arranged, which is drawn separately in the illustration of the other parts of the coupling element and not interesting here - for example, by screwing or by means Jaw clutches - on the one hand on the end face (24) and on the other hand on the gun barrel not shown fastened. In the region of the conical transition (15) of the adapter part (23) outwardly open slot-shaped recesses (25) are distributed over the circumference, which allow a pressure reduction and of course must be designed so that the incoming or the reflected wave is disturbed as little as possible.

In the swept from the projectile when firing the shot inner region (13) is a, as described a larger diameter compared to the tube diameter, cylindrical Durchgangsausnehmung (26) arranged, in which laterally the coupling openings (here only one is shown and with (40) referred to). Seen perpendicular to the axis of the coupling element (2), this coupling opening (40) is substantially rectangular, in which case the narrow sides are rounded according to the production by a milling cutter. Apart from that, the coupling opening (40) could also have any other suitable cross section - also different cross sections or Sizes of the individual coupling openings are possible to influence the coupling behavior.

In the area of ​​the end face (24), a ground to be provided as required for the waveguide (27) is indicated in broken lines in FIG. 3, which then makes this waveguide (27) a rectangular waveguide. Apart from that, however, any other suitable type or cross-sectional shape of the waveguide (27) is conceivable and can be used as required within the discretion of the person skilled in the art.

In the area of ​​the coupling opening (40), according to FIG. 3, a closure piece (31) of electrically non-conductive material with low dielectric losses is arranged, which closes off the interior of the waveguide (27) against the interior area swept by the projectile, thus preventing the ingress of dirt or dirt prevents any negative effects of remaining pressure waves

In Fig. 4 schematically another embodiment of a coupling element (2 ') is shown, the waveguide transition (7') by a plurality of slot-shaped coupling openings (40 ') on the circumference of the projected from the floor inner region (13') is formed. The waveguide (27 '), which may in turn have a coaxial hollow conductor not shown here for connecting a coaxial cable, is bent in the region of the waveguide transition (7') and running parallel to the axis of the inner region (13 ') executed. The slot-shaped coupling openings (40 ') again have one of the wavelength of the one or to be coupled out shaft dependent distance, which in turn the advantages already described above can be achieved.

According to the schematic in FIG. 5 shown arrangement for static calibration via a push rod (32) with a displacement measuring device (33) cooperating projectile dummy (34) at least partially through the weapon barrel (1) moves, which otherwise the waveguide transition (7) not on a separate coupling element but has arranged directly on the lateral coupling openings (40, 41) of the weapon barrel (1). About the coaxial cable (11) in Fig. 1 corresponding line (36), the supply or Derivation of the signal to or from the waveguide transition (7). One of the respective position of Geschoßatrappe (34) in the gun barrel (1) corresponding path signal is applied via the line (37) to the unit (38), which here includes both the evaluation unit and the unit for generating the microwaves

The Geschoßatrappe (34) is relatively easy to move in the barrel (1) back and forth, with a precise

-5Nr. 389764

Assignment between the measurement signal obtained as described in FIG. 1 and the actual path of the projectile in the weapon barrel will be established.

Apart from the illustrated and discussed embodiment, each with a single waveguide transition is in the invention of course also the arrangement of another or Even several such transitions - each having at least two coupling openings as described - possible at the gun barrel, which can be coupled in a simple manner electromagnetic waves with different frequencies each optimally in the gun barrel and let it decouple, so that different accuracies can be achieved, for example, for the different phases of the projectile movement in the barrel.