DE1153299B - Display device for displaying the target deviation of a projectile flying at supersonic speed according to distance and direction - Google Patents

Description

GERMAN

PATENT OFFICE

O5366IXd / 74d

REGISTRATION DATE: 21. F E B RU AR 1957

NOTICE
THE REGISTRATION
AND ISSUE OF
EDITORIAL: AUGUST 22, 1963

The invention relates to a display device for displaying the deviation from the target of a vehicle traveling at supersonic speed flying projectile according to distance and direction using those generated by the projectile ballistic wave or shock wave, the so-called N wave.

The device is used for the transmission of shooting results both from the air target to the air gunner as well as from air target to earth protection, or vice versa.

The success of a target shooting exercise is greater, the more precisely you look at the trajectories of the projectiles that are being shot at the target. It is also interesting to know which way those projectiles took that did not reach the pane and none on it Have left traces.

It is already known that a mobile body moving in the atmosphere at supersonic speed moves, in it causes a disturbance in the form of a ballistic wave. This has in general the following structure:

The medium (air) changes from a static pressure P ₀ in a steeply rising front into a higher pressure P ₀ + p. Then the pressure decreases linearly (both in terms of time and space) up to the value P ₀ - ρ and returns with a steep increase to the value P ₀ . This structure is commonly referred to as the N-wave when dealing with small projectiles. The entire disturbance can contain three and four pressure jumps. The amplitude of the pressure jump and the distance separating the two wave edges depend on the type of body being moved (caliber, speed) and the distance between the flight path and the observation or measuring device.

The display device according to the invention is characterized in that there are four of the N-wave excitable Contains microphones that produce a signal lasting from 0.1 to several milliseconds with a distortion reflect less than 10% and the fixed and symmetrical on the circumference of a concentric and are mounted coaxially with a target ring arranged and their corresponding output signals by means of a particularly wireless (transmitter and receiver) transmission device one of four differentiators, the leading and trailing flanks convert the N-shaped signals into start and end pulses, which are transmitted via switches and timing units a quadruple registration device, which under evaluation of the between the initial display device to display the target deviation of a projectile flying at supersonic speed according to distance and direction

Applicant:

Office National d'Etudes

et de Recherches Aeronautiques,

Chatillon-sous-Bagneux (France)

Representative: Dr. B. Quarder, patent attorney,
Stuttgart, Richard-Wagner-Str. 16

Claimed priority:
France of February 22, 1956 (No. 709 010)

Jean Mattei, Vincennes, Jean Blaise,

Chatillon-sous-Bagneux,

and Rene Manganne, Paris (France),

have been named as inventors

and end pulses of the individual signal sequences and between the start pulses of the individual signal sequences are time intervals indicating the target deviation of the projectile according to distance and direction.
In the device according to the invention, it is not the amplitude change that is used for the measurement, but the change in the duration of the N-wave as a function of the distance. Time measurements are to a lesser extent subject to errors in the determination and transfer of the results than amplitude measurements. On the other hand, however, they require great accuracy in determining and transmitting the time of the two edges of the N-wave. For this reason, the microphones picking up the passage of the N-wave cover a very wide band, and the transmission of the results is carried out by frequency modulation.

The measuring arrangement allows an immediate reproduction of the shooting result for immediate or indirect instruction of the shooter.

Immediate reproduction takes the form of a planar parametric representation or target. This kind of parametric representation is for this

309 668/126

intended to enable an immediate overall evaluation by the shooter. She is with simple Switching means can be implemented that can easily be built into a device that is on board a fighter aircraft can be accommodated.

All details about the invention emerge from the following description of an exemplary embodiment on the basis of the more or less schematic drawings. In detail shows

Fig. 1 shows a ballistic N-wave, Fig. 2 shows the arrangement of the four microphones,

3 shows the electrical circuit equivalent to the microphone,

4 shows the arrangement of ammonium phosphate plates in a microphone, 5 one of the electrodes,

6, 7 and 8 different views of a microphone,

9 shows the scheme of the shot indicator,

10 shows the signals received in the receiver after differentiation,

11 shows an example of a destination display and

FIG. 12 shows an example of a transparent reading network which enables the parametric representation to be interpreted and evaluated immediately under the eyes of the shooter.

Figure 1 illustrates a ballistic wave generated by a projectile at supersonic speed. The abscissa is divided either by time or by distance. When divided by time, T is the duration of the N wave. The dashed line 27 is the N-wave with two steep spikes, which are designated 29 and 30.

In Fig. 1, the solid line 28 represents that from the microphone with less than 10% deviation reproduced signal.

In Fig. 2 you can see a ring 45 on which four microphones 41, 42, 43, 44 each at the end points of two diameters intersecting at right angles are attached. Each of these microphones is associated with an attachment, e.g. B. 51 for the microphone 41. The other attachments are - for clarity not shown because of the drawing. The output terminals of the attachments are with connected to the corresponding transmitter. One of them is shown schematically at 61.

With a deviation of less than 10%, the microphones must have a spherical N-signal from a Can reproduce duration between 0.1 and a few milliseconds. The following are approximate values necessary:

Sensitivity: 20 microvolts per bar,
Bandwidth: between 20 hertz and 100 kilohertz.

Such characteristics can be achieved with microphones, which are generally roughly cubic Have a column made of square ammonium phosphate plates. As is known, ammonium phosphate is already used used as a piezoelectric crystal and often with the abbreviation »A.D.P.« (ammonium dihydrogen phosphate).

The cube shape prevents multiple vibrations caused by coupling between different mechanical Types of vibration can be excited in the crystal.

The panels are cut so that when the ballistic pressure on the narrow edges of the panels The piezoelectric current comes into play from the large square areas on which the electrodes are in contact with it.

In Figs. 6 to 8, 1 denotes the cube of ammonium phosphate crystal plates and 2 a bowl-like container made of non-conductive material, on the bottom of which the cube is placed by means of a soft adhesive is glued on. He is also in the container 2 by the soft fillers 3 made of cork or the like.

The crystals are shaped like parallelepiped plates. In the illustrated and described embodiment, there are six plates that form a cube of approximately 1 cm ³ . Accordingly, the thickness of each plate is about 1.6 mm. The crystals are cut and the cube is arranged in the container 2 so that the ballistic wave impinges on the narrow edge of the plates.

The container 2 is located in a cylindrical metal sleeve 4 which is screwed onto a coaxial spout 2 is. The connection wire 7 of the microphone is drilled through a hole in the bottom of the container 2 Opening 10 passed and is soldered to the outer part 12 of the coaxial grommet 5. Of the another wire 8 leads through an opening 10 'also located in the bottom of the container 2 and is soldered to a pin 9 which is attached coaxially to the bottom of the container 2. The pin 9 leads to the central cavity 11 of the spout 5.

A layer 6 of saturated adhesive solution is applied to the flat surface which is covered by the Edge of the container 2, the front of the filler 3 and the active front of the crystals are formed will.

The crystal plates 13 to 18 of Fig. 4 are arranged parallel to each other, and electrodes 19 to

25 - for example made of silver foil - are on the outer surfaces of the plates 13 and 18 and in each case between two opposite surfaces of the different plates arranged. Two adjacent Plates are each arranged so that when a pressure is applied to their outer narrow edge is exerted on the large, contiguous and separated by an electrode Piezoelectric charges occurring on separate surfaces are rectified

Each of the electrodes 19, 21, 23, 25 has a tongue

26 and each of the electrodes 20, 22, 24 has a tongue 26 '(see FIG. 5). The wire 7 is attached to the tongues 26 and the wire 8 (FIG. 4) is soldered to the tongues 26 '.

The electrical circuit corresponding to the overall crystal (see FIG. 3) comprises a generator 35, an inductance L ₁ , a resistor R ₁ and a capacitor C ₁ connected in series, a shunt capacitor C _s and a leakage resistor A ₀ . On the other hand, let C be the interference capacitance.

If one provisionally assumes that the block is formed by a single cube-shaped crystal to which only the two electrodes 19 and 25 are connected, and if the charge appearing on the electrodes at a given pressure is denoted by q ₀ , then one has on the generator a tension of

^y ° 'C ₀ Tc ■

Here, C ₀ denotes the capacity of the electri-

the capacitor formed 19 and 15. For the cubic block formed by η parallel plates, the capacitance becomes

C ₈ = n ² C ₀ ,

since the capacitance of a disk is η -C ₀ ; on the other hand, the charge becomes nq ₀ . The voltage of the generator is therefore

_v ⁿ

^nc lo

If one sets - ^ - = α , becomes

η -r η for V _n receives his highest value You then get a = : « ² . V _n max = 1 + r, In

This last formula shows that it is possible to compare with one without loss of sensitivity single cube to considerably increase the output capacity of the microphone and in this way the adaptability to facilitate. If z. B.

C ₀ = IpF, C = 30pF,

and therefore α = 30, one can assume η - β , and the output capacitance of the microphone is increased to H ² C ₀ = 36 pF.

When η is between 4 and 8, the ratio α is between 16 and 64, which is sufficient for practical requirements.

The resistance R _s , which is equal to the value /? ,, in the case of only one block, is given the value -% in the case of a block with η plates. The product

Cs-Rs = Tf

has not changed in its value compared to the case of a single block. It must be on the order of ten times the maximum duration T of the N signal, which is 75 milliseconds. If C ₀ , as shown, is of the order of magnitude 1 pF for a 1 cm ^s cube and the ammonium phosphate plates have a specific resistance (corresponding to the resistance of a 1 cm ^s block) in the order of 4 × 10 ¹⁰ , one obtains a value of 40 milliseconds for the product C ₀ · R _0. This value is within the desirable range.

As already mentioned in connection with Fig. 2, an attachment is connected to each microphone, which allows from the high impedance of the microphone to the impedance of the transmission path to pass over. This can e.g. B. be an arrangement of cathode amplifiers of the known type. she also serves as a carrier for the microphone. The whole device is mounted on rubber to avoid vibrations and to limit the transmission of the sound through the wall.

The front-end device 51 is connected to the corresponding transmitter 61. These transmitters are frequency modulated. A suitable characteristic is e.g. B.

Frequency deviation 300 kilohertz and output power 2 watts. In practice this gives a range of 30 km.

The receiving system will now be described with reference to FIG. It contains four frequency-modulated receivers 71 to 74 which, after demodulation, each emit a signal corresponding approximately to line 28 in FIG. 1. After the differentiation, which takes place in the devices 81, 82, 83, 84 shown schematically, they have the shape of the prongs designated by 31, 32, 33 and 34 in FIG. 10. Each is formed by two short points, which can be referred to as the front and rear prongs. If the time of arrival of the first front spike is taken as the start of the time measurements (corresponding to the microphone that is closest to the flight path, in this example the microphone 41), the other front spikes have a delay of t ₂ or i ₃ or i ₄ . Because the distance

between the point in front of and the point behind one and the same signal is equal to the duration T of the N-wave received by the microphone, through which it was generated, and since this duration is greater, the further the microphone is from the trajectory of the projectile is removed, the distances T ₂ , T ₃ or T ₁ between the two peaks of the signals 32, 33 and 34 are so much greater than the distance T ₁ between the two peaks of the signal 31 as their corresponding delays i ₂ , t ₃ and f _{4 are} greater.

The receiver 71 corresponds to a time deflection unit 101 which it can trigger when a gate circuit 91 is open. At the moment when the timing unit 10 is triggered, it closes the gate circuit 93 of the timing unit 103 opposite it (the connection is shown schematically by the conductor 75).

The receiver 73 corresponds to the time deflection unit 103, which it can trigger when the gate circuit 93 is open. As soon as this unit is triggered, it closes the gate circuit 91 by means of connection 76, which is assigned to the time base unit 101 . The timing units 102 and 104 and the gate circuits 92 and 94 are connected to one another in the same way.

The time deflection units 101 to 104 give the deflection plates 111 to 114 of the cathode ray tube 110 a common rest potential when they are not triggered and a potential that increases with time from their triggering to their standstill.

Each of them is identified by the front spike of the corresponding signals coming to it Differentiating devices 81 to 84 triggered and switched off by their rear spikes.

Assuming that, for a given passage of the projectile, the signals coming from differentiators 81 to 84 are those indicated by 31 to 34 in Figure 10, it is timing unit 101 which is the first to operate; then, after the time ₂ , the time

deflection unit 102. After the time t _z , the time deflection unit 103 is not triggered because the time deflection unit 101 has closed the gate circuit 93 when it comes into operation. Likewise, the timing unit 104 is not reached by the trigger signal because the gate circuit 94 is closed.

The time deflection units are set up so that they are locked in place by the rear prong and in their starting position to be led back.

When the signals of Fig. 10 are terminated, the entire target device returns to its original state and is ready to respond to the following surge.

FIG. 11 shows the S record made by the display device after it received a surge corresponding to FIG. The light pointer (electron beam) has recorded the curve 120 , which consists of a horizontal branch (period from zero to t ₂ ) and a sloping branch (period from i ₂ to the moment of the appearance of the rear spike of the N-wave received in microphone 41 ) consists.

Since this microphone is reached first by the wave, the trajectory is to the left of the Disc run, and since the microphone 42 was reached before the microphone 44, the trajectory is above run along the disc. Since the microphone 41 was reached before the microphone 42, the fictitious one was The meeting point of the floor below the center plane of these two microphones. This will appear on the Screen shown in Fig. 1 in front of the shooter's eyes.

In order for the shooter to be able to estimate the distance between the target axis and the trajectory, it is advisable to place a transparent cover sheet as shown in FIG. 12 on the screen of the cathode ray tube. The equidistant lines are shown closed. Their mutual distance depends on the law of the variability of the quantity T with distance.

The illustration of FIG. 12 is a transparent net for grenades of 20 mm. The equidistant lines are squares of different sizes, and the distances corresponding to them are indicated by numerals, e.g. B. specify the distance in meters. You can show the different zones in color. A light pointer trace is shown at 120 which corresponds approximately to that in FIG.

The light trail of the cathode ray on the fluorescent screen consists of a straight line lengthways an axis between the initial momentum of the N-wave of the first of the pressure surge of the N-wave hit microphone and the initial impulse of the N-wave the second of the pressure surge of the N-wave hit microphone as well as from a second, adjoining straight line at an angle of 45 ° parallel to an angle bisector of the main axes between the initial pulse of the N-wave im second microphone and the final pulse of the N-wave in the first microphone, the numbering the position of the cover sheet on which this second rectilinear part ends, the distance of the projectile and the direction of the line that joins the center of the disc with the outer end of the underneath 45 ° connecting line, approximately indicating the direction of the floor.

On the basis of this parametric representation, an exact target box can be produced. However, this requires a device that hardly finds space on board a fighter aircraft.

However, you can proceed in the following way: Parallel to the shot indicator is another shot indicator provided, the screen of which is photographed. Used according to the circumstances the first or specially assigned. The target is set by a transmitter accordingly the results of the target photography.

It is also possible to register the signals of FIG. 10 directly. In this case, a fifth provides Line the time base. These elements are used as data for a transmission device and a computing device fed.

Claims (3)

PATENT CLAIMS: 1. Display device for displaying the target deviation of a projectile flying at supersonic speed by distance and direction using the ballistic wave or shock wave generated by the projectile, the so-called N-wave, characterized in that it contains four microphones which can be excited by the N-wave reproduce a signal lasting from 0.1 to several milliseconds with a distortion of less than 10% and which are fixedly and symmetrically attached to the circumference of a ring arranged concentrically and on the same axis as a target and their corresponding output signals by means of a particularly wireless (transmitter and receiver) Transmission device are each passed to one of four differentiating devices, which convert the leading and trailing edges of the N-shaped signals into start and end pulses, which are fed via switches and time deflection units to a quadruple registration device, which, while evaluating the between the The time intervals between the initial and final pulses of the individual signal sequences and between the initial pulses of the individual signal sequences indicate the target deviation of the projectile in terms of distance and direction. 2. Apparatus according to claim 1, characterized in that the four on the signals of the four Microphones responding switches are effective in pairs and each have a time deflection unit control triggered by the impulse of the leading edge of the N wave and by that of the trailing edge of the N-wave outgoing pulse are interrupted in such a way that the Signals from the two time deflection groups to the organs used for the right-angled deflection a cathode ray tube, the timing units of the same group of two and are also set up in such a way that the one who is triggered first the second blocked. 3. Apparatus according to claim 2, characterized in that the screen of the cathode ray tube is provided with a transparent cover sheet on which graduated concentric squares and two coordinate axes are attached which represent the main axes of the squares. Documents considered: German Patent No. 421418; British Patent No. 672,782; French Patent No. 861 088; "Journal of the Acoustical Society of America," this second gazette the same recipients as 65 Vol. 18, July 1946, No. 1, pp. 97 ff. For this purpose 2 sheets of drawings @ 309 668/126 8.63