RU2825905C2 - Method of guiding anti-missile to supersonic target - Google Patents

Abstract

FIELD: weapons.

SUBSTANCE: invention relates to air defence systems and can be used to guide anti-missiles to supersonic manoeuvring targets, including hypersonic ones. Anti-missile is guided by detecting the moment of crossing the shock wave front created by the target using sensors installed on board the anti-missile. Anti-missile is inserted into the Mach cone cavity, accelerated to a speed exceeding that of the target, and then piloted in the direction of the Mach cone top, where the target is located, tracking the shock wave front surface and using it as a navigation guide.

EFFECT: higher accuracy of guidance to a direct collision with a target, without the need to use accurate radio or optical location and a powerful warhead, and also provides the possibility of using small-size anti-missiles, which allow (in contrast to large-capacity anti-missiles) to obtain the overloads required for interception of high-speed and high-manoeuvrable targets.

1 cl, 3 dwg

Description

The invention concerns air defense systems (AD) and can be used in systems for intercepting maneuvering atmospheric supersonic and hypersonic aircraft, such as aircraft, cruise missiles, gliding warheads, guided missiles, including small-sized and radar-invisible targets.

Any air defense system is an inseparable unity of two parts: information and executive. The information part is represented by technical means of observing the surrounding air situation, detecting and classifying air objects and measuring the parameters of their movement. Modern air defense information systems use radio, optical and acoustic location means. The executive part of modern air defense uses various controlled aircraft, among which the predominant advantage in terms of a set of essential technical parameters belongs to missiles. They surpass aircraft in speed, acceleration, range, compactness of basing, versatility in terms of the parameters of the environment of use, etc. At the same time, for an interceptor missile (hereinafter referred to as an anti-missile), high final speed and acceleration are especially important, as well as a short time to enter the target interception zone. This is achieved by the small size of the anti-missile in combination with its multi-stage nature or another method of frequently discarding the spent mass of the structure. In this case, the final speed of the anti-missile can be calculated using the Tsiolkovsky formula:

where M ₀ is the launch mass of the rocket, M _k is the final mass of the rocket, Vfinal is the final (orbital) velocity of the rocket, Voutflow is the velocity of the gases outflowing from the nozzle, which in this formula should be replaced by the average velocity of the quasi-continuous ejection of the mass of fuel and parts of the structure (tanks, heat shielding, etc.).

If we assume that the mass of the structure is negligibly small compared to the mass of the fuel, then for rocket fuel with an exhaust velocity of 3 km/sec and a final velocity of the anti-missile of 9 kilometers per second, we obtain, using the formula given above, a ratio of the launch mass to the final mass equal to 20.

An example of technical solutions that allow small dimensions in combination with the possibility of a significant increase in the number of stages are: inventions according to the USSR Author's Certificate No. 1519279 and according to the Russian Federation Patent for Invention No. 2754475. In the specified technical solutions, the rocket is a longitudinal package of many solid-fuel stages joined together by inserting the combustion chambers of the previous stages into the supercritical part of the nozzle of the next stage without additional fastening. The burnout of the fuel of the previous stage causes automatic transfer of combustion to the next stage and ejection of the burnt-out stage by the pressure of the gases of the ignited fuel of the next stage. In this way, frequent ejection of the spent mass of the structure is carried out, almost proportional to the consumption of solid fuel, without interruption of thrust and control. At the same time, already with the number of stages of 5, the possibility of achieving the first cosmic final velocity of the rocket is ensured with a ratio of the launch mass to the final mass of about 25. That is, an anti-missile with a launch mass of 25 kilograms can accelerate the final mass of 1 kilogram to a speed of 9 kilometers per second. In this case, the acceleration of such a small-sized anti-missile can reach several tens of G (G = 10 m / sec). This allows, for example, to intercept a ballistic missile in the active phase of its flight from the launch site of the anti-missile, located several hundred kilometers from the launch site of the ballistic missile. In this case, guidance can be performed using an optical homing head (homing head), operating on the radiation of the target's rocket engines, which is the simplest in design.

Another embodiment of a small-sized anti-missile, characterized by frequent (quasi-continuous) ejection of the spent mass of the structure is presented in Russian patents for invention No. 2749235, No. 2752730, as well as in Russian application for invention No. 2019128485. This technical solution uses solid mixed fuel in a dispersed bulk state. In this case, the fuel is fed to the engine combustion chamber using a sluice mechanism, which does not require a powerful drive, and works, like any sluice, due to a small counter-flow of gases from the combustion chamber, into which the fuel is fed against the pressure drop. The electric motor is needed only to compensate for friction losses of the rotor seals of the sluice mechanism. Moreover, the shell of the fuel bunker is divided into annular sections, and the only rocket engine is installed on the bottom of the bunker, which is pushed into the shell as the fuel is consumed, like a piston - due to the thrust of the engine. In this case, the ring sections of the shell that descend below the engine lose their connection with the shell and fall off. The presence of servo-electric drives in this version somewhat limits the small size compared to the previous version. However, the ratio of the launch mass to the final mass to achieve a speed of 9 kilometers per second remains the same - approximately 25. With a final mass of 4 kg, the launch mass will be approximately 100 kg, which is also acceptable for an anti-missile under the condition of obtaining sufficiently large accelerations (scaling changes the ratio between mass and strength).

However, the use of the above-mentioned small-size anti-missiles for intercepting air targets encounters problems caused by the small mass of the warhead, which can be placed in the head of a small-size anti-missile. A solution can, in principle, be found by using a high terminal velocity for kinetic destructive action. However, this requires high target location accuracy. The use of an onboard radar homing head is complicated by the lack of space for placing an antenna with a sufficiently narrow directional pattern. The use of multi-position ground-based radar, which could solve the problem of increasing accuracy at long range, requires the creation of a complex ground infrastructure distributed over a large area, vulnerable to suppression means. The use of optical air target location systems is limited by cloud cover, which often limits the range of optical location and creates the possibility for enemy targets to fly under the cover of clouds over significant distances.

The presence of this problem makes us pay attention to acoustic information systems, which are becoming relevant again in the modern era of supersonic flights. For example, technical solutions are known that allow us to determine the location of the point of a projectile or bullet shot using several acoustic sensors fixed at several points according to a certain basic configuration (see Russian patent for invention No. 2512128 developed by the USA). In another version, the orientation of the shock wave front and the bearing on the trajectory of a supersonic target over the earth's surface are determined using several spaced three-coordinate accelerometers (see Russian patent for invention No. 2408025 developed by the USA).

However, the disadvantage of the specified technical solutions is that if the target is capable of even slightly unpredictable maneuvering, then the location of the target at the time of interception may differ from that calculated from the data received, and an accurate hit on the target will be impossible, and for interception it will be necessary to use a high-power warhead, which cannot be placed on a small-sized missile. A large-capacity anti-missile does not have (due to the strength of the structure) sufficient acceleration and maneuverability to intercept a highly maneuverable target.

Thus, the known technical solutions do not contain information on how to build a closed guidance system for a high-speed, for example hypersonic, as well as a highly maneuverable target, i.e. how to build a complete air defense system - ground or airborne, operating against highly maneuverable supersonic targets without missing, i.e. without the need to use a powerful warhead of an anti-missile.

The subject of the proposed invention is to eliminate the said drawback of known technical solutions and to ensure the possibility of intercepting a maneuvering supersonic (in particular hypersonic) target based on its acoustic location by the shock wave created by the target during its flight through the atmosphere.

A method is proposed for guiding an interceptor missile to a supersonic target using the registration of a shock wave created by the supersonic target. The objective of the invention is achieved in that the shock wave sensor is placed on board the interceptor missile, which is piloted, tracking the position of the shock wave front relative to the interceptor missile and using the surface of the shock wave front as a navigation guide. In this case, the position and orientation of the surface of the shock wave front is determined by the spatial and temporal coordinates of the fact of intersection of the shock wave front by the onboard sensor installed on the interceptor missile. These coordinates are a point belonging to the surface of the shock wave. In this case, the surface of the shock wave front is, as is known, the Mach surface, characterizing the process of supersonic flow around the target (see N. F. Krasnov, Aerodynamics, Part 1, p. 154. Moscow, Higher School, 1980) and has, in the general case, the form of a cone with curvilinear generators and with an apex rigidly connected to the nose of the target. Having determined in this way, i.e. by means of several intersections, the coordinates of several points of the surface, it is possible to determine the shape, position and spatial orientation of the conical Mach surface, and consequently the coordinates of the apex of the cone, where the target is located. This takes place if the target does not maneuver and if the cone has a regular shape. Thus, the spatiotemporal position of the target will be determined without the use of radio or optical location.

If the target maneuvers, the Mach surface cone will be curved. However, this curvature will be small due to the limited maneuvering capabilities of the target. If, after approaching the target, the determination of the shape and position of the Mach cone is repeated by additionally crossing the trajectory of the interceptor missile with the shock wave front, the error caused by the maneuvering of the target will decrease. Thus, by repeatedly correcting the calculations of the position of the cone apex, the error in the calculated determination of the target position during the approach of the interceptor missile to the target will decrease and may reach a value less than the sum of the diameters of the target and the interceptor missile. Thus, a direct collision with the target will occur, i.e. its destruction or deviation from the object of attack. Moving along the surface of the shock wave front in the direction of the target's flight, i.e. moving behind the target in the catch-up mode and at a speed exceeding the speed of the target, the interceptor missile will inevitably arrive at the apex of the cone, i.e. at the point where the target is located, and collide with it. Thus, guidance will be provided with an accuracy sufficient for kinetic destruction of the target, i.e. without using a warhead. Considering the above-mentioned possibility of a small-sized anti-missile achieving speeds significantly exceeding the speed of flight of targets in the atmosphere (even if the target speed is hypersonic), the collision speed of the anti-missile with the target will be sufficient to destroy the target with an efficiency exceeding the efficiency of cumulative munitions. The lower speed capabilities of the target compared to the capabilities of the anti-missile are due to the presence of a payload in the form of a warhead on the target. If the target does not carry a warhead, i.e. is, like the anti-missile, a kinetic action weapon, then it does not pose a great danger, which is posed by high-explosive, nuclear or other warheads at a distance. Kinetic warheads can be easily deflected from an accurate hit on the target. For this, a low collision speed with the anti-missile is sufficient. In any case, the process of intercepting a target using the proposed method is less destructive to the surrounding environment, since either the target is destroyed at a significant distance from the target of the attack, or does not carry an explosive warhead, and simply deviates from hitting the target of the attack if the target is kinetic.

The fact of the shock wave front intersection by the anti-missile can be identified by the sudden change in atmospheric air pressure. In this case, the direction of the front intersection, i.e. the entrance to the Mach cone cavity or the exit from it, is determined by the change in the acoustic background level, since inside the Mach cone, the acoustic background of the environment is supplemented by the background of turbulence created by the process of flowing around the target, as well as the operation of the target engine. Outside the Mach cone, this component of the background is absent.

The problem is how to measure this pressure, since it characterizes the state of the undisturbed part of the incident flow. If we install a Pitot tube, used on airplanes to measure airspeed, then we will measure the pressure of the stopped flow. In this case, given the hypersonic flight speed of the anti-missile, this will be the pressure of the direct shock wave, which not only many times exceeds the pressure in the undisturbed part of the incident flow, but is also accompanied by a strong jump in temperature, as well as dissociation of gases and light radiation. However, all these air parameters in the zone of the direct shock wave are clearly related to the pressure of the same stream of flow in its undisturbed part. And any of the parameters of the air state in the direct shock wave can be used to convert to the pressure of the undisturbed environment, both static and pulse and sound (acoustic). Thus, by measuring the pressure, or temperature, or density of the gas, or the intensity or spectral characteristics of the optical radiation of the gas in the normal shock wave, we will obtain information about the change in pressure of the undisturbed atmosphere in that part of the flow stream that enters the point of the normal shock wave.

A similar unambiguous connection with the parameters of the undisturbed flow also exists when the sensor is located in an oblique shock wave or at any point on the surface of the anti-missile. This connection is determined by the pattern of flow around the aircraft by a supersonic flow. However, when installing the sensor on the surface of a fuselage with a pointed nose, there is some uncertainty in the distribution of the flow jets on different sides of the tip. In this case, small deviations of the anti-missile in pitch, course or roll can switch the jets on different sides of the fuselage. Thus, the position of the intersection point of the sensor with the shock wave front will be determined with an error equal to the transverse diameter of the fuselage. This drawback can be eliminated by placing the sensor on an external stand with the air intake point moved into the undisturbed flow. In this case, as in the case of the Pitot tube, the sensor can be equipped with its own small-sized fairing, which will provide a corresponding reduction in the magnitude of the error caused by the flow being cut by the pointed tip with the separation of adjacent streams of flow on different sides of the small-sized fairing.

In order to reduce the required number of cycles of the interceptor missile crossing the shock wave front surface, necessary to determine the angular orientation of the shock wave front, several - at least two - spatially separated shock wave sensors should be installed on board the interceptor missile. Then, for one intersection of the Mach cone by the interceptor missile, we will immediately obtain several space-time coordinates of the Mach surface. In this case, for one intersection it will be possible to determine not only the coordinates of one point of the Mach surface, but also its angular orientation in the vicinity of this point, and even the curvature tensor of the cone surface at the final stage of approach to the target, when the radius of the transverse curvature of the cone is sufficiently small. This reduces the required number of intersections of the shock wave front surface, performed by maneuvering the interceptor missile.

Moreover, if the angle of the anti-missile roll relative to the ground is stabilized, for example by measuring it by the polarization of the received signals from radio beacons or using a gyroscope, then to measure the angle of inclination of the surface of the shock wave front it is sufficient to have two spaced onboard shock wave front sensors.

As the target approaches, the intensity of pressure surges from the shock wave, as well as the intensity of acoustic turbulence filling the Mach cone, increases, which simplifies the process of recording the coordinates of the interceptor missile's intersection with the Mach cone and reduces the impact of possible interference from external sources, such as other targets. At the initial stages of target tracking, the interceptor missile can be piloted using data from external radar systems, since high accuracy is not required, and the distance from the ground-based air defense infrastructure is still small. The proposed method for determining target coordinates will be required mainly at the final stage of guidance, when high location accuracy is required, which is difficult to achieve using radar, and optical location is limited by cloudiness.

Since the coordinates of the shock wave front surface points are the coordinates of the interceptor missile itself at the moment of its intersection with the shock wave front, the coordinates of the interceptor missile must be known - at least at the initial stages of target acquisition by the interceptor missile and until the moment of entering the shock wave front tracking mode in the small deviation mode. For this purpose, at the initial stages of guidance, piloting of the interceptor missile can be performed using conventional external navigation positioning systems, for example, using a system of radio beacons installed on the ground. The use of radio beacons installed on satellites (GLONASS, etc.) should be considered unreliable in the conditions of global confrontation.

In addition, when piloting an interceptor missile by tracking the position of the conical shock wave front, there is a problem of controlling the interceptor missile by the heading angle. If we simply set the flight direction towards the cone apex, then as the interceptor missile approaches the cone apex, the trajectory of motion will take the form of a helical line with an ever-decreasing propeller pitch, which will lead to the exhaustion of the interceptor missile's maneuvering capabilities in terms of lateral acceleration and to its separation from the Mach cone surface. This can be avoided by maintaining a constant bank angle of the interceptor missile relative to the ground during piloting, and also by constantly monitoring the lateral inclination of the shock wave surface relative to the interceptor missile. In this case, if an increase in the lateral inclination of the shock wave front relative to the interceptor missile is detected, the interceptor missile should be deflected along the heading to the side corresponding, as it were, to rolling down a hill on a slope. With such heading control, the interceptor missile will adhere to a trajectory close to the Mach cone generatrix and will not go into a helical trajectory. That is, problems with the increase in overloads that accompany the approach of the anti-missile to the top of the cone will be eliminated.

The invention is explained by the following detailed description of an example of implementation and three figures.

Fig. 1 illustrates an example of the proposed guidance method, namely, target 1 is shown in a coordinate system moving together with the target. The surface of shock wave front 2 at a certain point in time is also shown. In this example, shock wave surface 2 has the form of a cone curved in the area approaching the apex, which is due to target maneuvering. In this case, surface 2 remains almost motionless in Fig. 1, since the speed of its blowing away by the oncoming air flow to the left is compensated by the propagation of the sound wave front at an angle to the right. The apex of the cone remains motionless in Fig. 1 and combined with the motionless target 1. Only the cone curvatures shift to the left. Vair. Designates the air flow speed, which is opposite in sign to the so-called air speed of the target. Two shock wave cones are shown - an ideal one and a curved one. The maneuvering trajectory of antimissile 3 in the vertical plane is shown.

Fig. 2 shows an example of a possible placement of two shock wave front sensors 4 and 5 on board the anti-missile 3.

Fig. 3 shows a view along arrow A shown in Fig. 1. The trajectory of the anti-missile maneuvering along the course is shown in the process of tracking the curved generatrix of the real surface of the Mach cone with the apex at point O ^/ . The angle "a" of the transverse inclination of the shock wave front is indicated, measured by sensors 4 and 5 by the difference in the time of their intersection of the shock wave front during the movement of the anti-missile axis along the vertical.

The proposed method of guidance is as follows. The preliminary parameters of the target 1 flight are determined by conventional detection means, for example, a radar 6 located on the front line of the air defense system. The coordinates of the interceptor missile 3 at the initial stage of target acquisition and tracking are determined by triangulation using a system of radio beacons 7 spaced apart by some basic distances along a triangle. The angular current parameters of the interceptor missile position in pitch, course and roll, in order to simplify and compact the onboard equipment, can be measured by the polarization of the received radio signals of the beacons 7 using a vector antenna located on board the interceptor missile, consisting of three mutually orthogonal dipoles. However, gyroscopes can also be used if they can be made compact enough for installation on a small-sized interceptor missile.

Considering that Fig. 1 shows an image in a coordinate system moving relative to the earth, in which target 1 is stationary, the process of acceleration of the interceptor missile after launch looks like braking. In this case, the interceptor missile is piloted by introducing it into the cavity of the cone of shock wave 2. The flight trajectory of the interceptor missile at this stage has the form of arc "b". At the moment of intersection of cone 2 by the interceptor missile at point "b", the coordinates of the interceptor missile, continuously measured by the delay of the signals of radio beacons 7, are simultaneously the coordinates of one of the points on the surface of the front of shock wave 2. If there are two spatially separated sensors 4 and 5 of the front of shock wave on board the interceptor missile (see Fig. 2), then by the difference in the time of appearance of signals in these sensors and by the known vector of the velocity of movement of the interceptor missile it is possible to determine the angle "a" of the orientation of the front of shock wave (see Fig. 3). At zero value of angle "a" the signals in the sensors will be simultaneous. The sign of their divergence in time reflects the sign of the angle of the transverse inclination of the shock wave front relative to the antimissile and the ground. By maneuvering the antimissile along the course, the angle "a" is maintained near zero. In this case, the trajectory "g" of the antimissile will make small oscillations relative to the curved generatrix of the shock wave cone (Mach cone). This will eliminate the transition to a helical line enveloping the cone axis and will ensure that the antimissile trajectory is brought to the vertex O ^/ of the cone, where target 1 is located (see Fig. 3).

The anti-missile performs similar small oscillations in the vertical plane (see Fig. 1). The task of the vertical oscillations is to track the surface of the shock wave front, while the task of the small oscillations described above in the horizontal plane is to pilot along the curvilinear generatrix of the cone. An analogy is the movement of a car on the surface of the earth. In this case, the guides that track the surface of the earth are the wheels. Tracking the generatrix of the cone is analogous to the operation of the steering control, which ensures the rolling of the car along the bottom of a trough-shaped ravine that narrows in the direction of travel.

The given analogy will help to understand the distribution of functions of the three control subsystems of the anti-missile autopilot: roll, pitch and heading, which ensure the anti-missile is brought to the target with an accuracy sufficient for a direct collision. At the final stage of guidance, which ensures accuracy up to a direct collision, a radar is not required.

In order to estimate the possible parameters of the guidance process based on distances and required overloads of the anti-missile, we will calculate the time and path of acceleration of the anti-missile to a speed of 5 kilometers per second, which is the limit for possible hypersonic targets in the atmosphere.

Taking the acceleration as constant and equal to 100 m/ ^sec2 (10 G), we get the acceleration time 5000/100=50 seconds.

In this case, the acceleration path will be 100* 50 ² /2 = 125,000 m, i.e. 125 kilometers, which is acceptable for intercepting targets on the approaches to important state infrastructure facilities, usually located not on the border itself.

During this time, the target, which, unlike the anti-missile, moves at a constant speed, will travel twice as much distance, i.e. 250 kilometers. However, the additional 125 kilometers are included in the range of radar 6 and can extend into foreign territory.

The proposed method of guidance is especially necessary for intercepting hypersonic cruise missiles, as well as gliding warheads, the precise radar location of which requires the creation of an extensive ground infrastructure distributed over the territory, for example, in the form of a multi-position radar system. Or it will require the installation of a powerful warhead, compensating for the large miss caused by the errors of single-position radar at large distances. Optical location methods are limited by cloudiness.

Thus, the proposed method of guiding anti-missiles to supersonic targets has no limitations on the flow and range of radar, as well as on meteorological conditions, and can be implemented using existing single-position radars and ground-based positioning radio beacons that are part of the air defense system.

Claims (1)

A method for guiding an anti-missile to a supersonic target, carried out by determining the position of the target based on signals from a shock wave sensor installed on board the anti-missile, created by the supersonic target during movement in the atmosphere, characterized in that the anti-missile is piloted by introducing it into the cavity of the shock wave front cone, accelerating it to an air speed exceeding the air speed of the target, and then piloting the anti-missile, tracking its position relative to the surface of the shock wave front by periodically crossing the front along an oscillatory trajectory, while stabilizing the bank angle of the anti-missile relative to the ground, wherein the amplitude of the anti-missile deviation relative to the shock wave front is smoothly reduced, and the front deviation angle relative to the stabilized bank angle of the anti-missile relative to the ground is maintained in the vicinity of a zero value by maneuvering the anti-missile along the course.

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