Active radar homing head. Homing head TV homing head working principle
The creation of systems for high-precision targeting of long-range ground-to-ground missiles is one of the most important and complex problems in the development of high-precision weapons (HW). This is primarily due to the fact that other equal conditions land targets have a significantly lower “useful signal/interference” ratio compared to sea and air targets, and the missile is launched and guided without direct contact between the operator and the target.
In high-precision ground-to-ground long-range missile systems that implement the concept of effective engagement of ground targets with combat units of conventional equipment, regardless of the firing range, inertial navigation systems are integrated with missile homing systems that use the principle of navigation along geophysical fields of the Earth. The inertial navigation system as the basic one provides high noise immunity and autonomy of integrated systems. This provides a number of undeniable advantages, including in the context of continuous improvement of missile defense systems.
To integrate inertial control systems with homing systems based on the Earth's geophysical fields, first of all, a special information support system is needed.
The ideology and principles of the information support system are determined by the main characteristics of the objects of destruction and the weapons systems themselves. Functionally, the information support of high-precision missile systems includes such main components as receiving and decrypting intelligence information, developing target designation, bringing target designation information to the complexes missile weapons.
The most important element of high-precision missile guidance systems are homing heads (GOS). One of the domestic organizations involved in developments in this area is the Central Research Institute of Automation and Hydraulics (TsNIIAG), located in Moscow. A great deal of experience was accumulated there in the development of guidance systems for surface-to-surface missiles with homing heads of optical and radar types with correlation-extreme signal processing.
The use of correlation-extreme homing systems on maps of geophysical fields by comparing the values of the geophysical field measured in flight with its reference map stored in the memory of the onboard computer makes it possible to eliminate a number of accumulated control errors. For homing systems based on an optical image of the terrain, an optical reconnaissance image can serve as a reference map, in which the target is determined with virtually no errors in relation to the elements of the surrounding landscape. Because of this, the GOS, guided by the elements of the landscape, is directed precisely at the specified point, regardless of the accuracy with which its geographical coordinates are known.
The emergence of prototypes of optical and radar correlation-extreme systems and their GOS was preceded by a huge amount of theoretical and experimental research in the field of computer science, theories of pattern recognition and image processing, the fundamentals of developing hardware and software for current and reference images, organization of banks of the background-target environment of various parts of the earth's surface in various ranges of the electromagnetic spectrum, mathematical modeling of the seeker, helicopter, aircraft and missile tests.
The design of one of the variants of the optical seeker is shown in rice. one
.
The optical seeker provides in flight recognition of a landscape area in the target area by its optical image formed by the coordinator lens on the surface of a matrix multi-element photodetector. Each element of the receiver converts the brightness of the corresponding area of the terrain into an electrical signal that is fed to the input of the encoder. The binary code generated by this device is stored in the computer memory. It also stores the reference image of the desired area, obtained from a photograph and encoded using the same algorithm. When approaching the target, stepwise scaling is carried out by recalling reference images of the appropriate scale from the computer memory.
Recognition of a piece of terrain is carried out in the modes of capturing and tracking the target. In the target tracking mode, a non-search method is used, based on the algorithms of pattern recognition theory.
The operation algorithm of the optical seeker makes it possible to generate control signals both in the direct guidance mode and in the guidance angle extrapolation mode. This allows not only to increase the accuracy of pointing the missile at the target, but also to provide extrapolation of control signals in the event of a failure in target tracking. The advantage of optical seeker is a passive mode of operation, high resolution, small weight and dimensions.
Radar seekers provide high weather, seasonal and landscape reliability with a significant reduction in instrumental errors in the control and target designation systems. A general view of one of the variants of the radar seeker is shown on rice. 2
.
The principle of operation of the radar seeker is based on a correlation comparison of the current radar brightness image of the terrain in the target area, obtained on board the missile using a radar, with reference images previously synthesized from primary information materials. Topographic maps, digital maps of the area, aerial photographs, space images and a catalog of specific effective scattering surfaces are used as primary information materials, characterizing the reflective radar properties of various surfaces and providing the conversion of optical images into radar images of the terrain that are adequate to current images. The current and reference images are presented in the form of digital matrices, and their correlation processing is carried out in the on-board computer in accordance with the developed comparison algorithm. The main purpose of the radar seeker is to determine the coordinates of the projection of the center of mass of the rocket relative to the target point in the conditions of work on the terrain of different information content, given meteorological conditions, taking into account seasonal changes, the presence of electronic countermeasures and the influence of the rocket flight dynamics on the accuracy of the removal of the current image.
The development and further improvement of optical and radar seekers are based on scientific and technical achievements in the field of informatics, computer technology, image processing systems, on new technologies for creating seekers and their elements. High-precision homing systems currently being developed have absorbed the accumulated experience and modern principles for creating such systems. They use high-performance on-board processors that allow real-time implementation of complex algorithms for the functioning of systems.
The next step in creating accurate and reliable homing systems for high-precision ground-to-ground missiles was the development of multispectral correction systems for the visible, radio, infrared and ultraviolet ranges, integrated with channels for direct guidance of missiles to a target. The development of channels for direct targeting is associated with significant difficulties associated with the characteristics of targets, missile trajectories, the conditions for their use, as well as the type of warheads and their combat characteristics.
The complexity of target recognition in the direct guidance mode, which determines the complexity of the software and algorithmic support for high-precision guidance, has led to the need for intellectualization of guidance systems. One of its directions should be considered the implementation of artificial intelligence principles in systems based on neural networks.
Serious progress in fundamental and applied sciences in our country, including in the field of information theory and systems theory with artificial intelligence, make it possible to implement the concept of creating super-precise, precision missile systems for hitting ground targets, ensuring operational efficiency in a wide range of conditions combat use. One of the latest developments in this area is the Iskander operational-tactical missile system.
BALTIC STATE TECHNICAL UNIVERSITY
_____________________________________________________________
Department of Radioelectronic Devices
RADAR HOMING HEAD
St. Petersburg
2. GENERAL INFORMATION ABOUT RLGS.
2.1 Purpose
The radar homing head is installed on the surface-to-air missile to ensure automatic target acquisition, its auto-tracking and the issuance of control signals to the autopilot (AP) and radio fuse (RB) at the final stage of the missile's flight.
2.2 Specifications
RLGS is characterized by the following basic performance data:
1. search area by direction:
Elevation ± 9°
2. search area review time 1.8 - 2.0 sec.
3. target acquisition time by angle 1.5 sec (no more)
4. Maximum angles of deviation of the search area:
In azimuth ± 50° (not less than)
Elevation ± 25° (not less than)
5. Maximum deviation angles of the equisignal zone:
In azimuth ± 60° (not less than)
Elevation ± 35° (not less than)
6. target capture range of the IL-28 aircraft type with the issuance of control signals to (AP) with a probability of not less than 0.5 -19 km, and with a probability of not less than 0.95 -16 km.
7 search zone in range 10 - 25 km
8. operating frequency range f ± 2.5%
9. average transmitter power 68W
10. RF pulse duration 0.9 ± 0.1 µs
11. RF pulse repetition period T ± 5%
12. sensitivity of receiving channels - 98 dB (not less)
13.power consumption from power sources:
From the mains 115 V 400 Hz 3200 W
Mains 36V 400Hz 500W
From the network 27 600 W
14. station weight - 245 kg.
3. PRINCIPLES OF OPERATION AND CONSTRUCTION OF RLGS
3.1 The principle of operation of the radar
RLGS is a radar station of the 3-centimeter range, operating in the mode of pulsed radiation. At the most general consideration, the radar station can be divided into two parts: - the actual radar part and the automatic part, which provides target acquisition, its automatic tracking in angle and range, and the issuance of control signals to the autopilot and radio fuse.
The radar part of the station works in the usual way. High-frequency electromagnetic oscillations generated by the magnetron in the form of very short pulses are emitted using a highly directional antenna, received by the same antenna, converted and amplified in the receiving device, pass further to the automatic part of the station - the target angle tracking system and the rangefinder.
The automatic part of the station consists of the following three functional systems:
1. antenna control systems that provide antenna control in all modes of operation of the radar station (in the "guidance" mode, in the "search" mode and in the "homing" mode, which in turn is divided into "capture" and "autotracking" modes)
2. distance measuring device
3. a calculator for control signals supplied to the autopilot and radio fuse of the rocket.
The antenna control system in the "auto-tracking" mode works according to the so-called differential method, in connection with which a special antenna is used in the station, consisting of a spheroidal mirror and 4 emitters placed at some distance in front of the mirror.
When the radar station operates on radiation, a single-lobe radiation pattern is formed with a maμmum coinciding with the axis of the antenna system. This is achieved due to the different lengths of the waveguides of the emitters - there is a hard phase shift between the oscillations of different emitters.
When working at reception, the radiation patterns of the emitters are shifted relative to the optical axis of the mirror and intersect at a level of 0.4.
The connection of the emitters with the transceiver is carried out through a waveguide path, in which there are two ferrite switches connected in series:
· Axes commutator (FKO), operating at a frequency of 125 Hz.
· Receiver switch (FKP), operating at a frequency of 62.5 Hz.
Ferrite switches of the axes switch the waveguide path in such a way that first all 4 emitters are connected to the transmitter, forming a single-lobe directivity pattern, and then to a two-channel receiver, then emitters that create two directivity patterns located in a vertical plane, then emitters that create two patterns orientation in the horizontal plane. From the outputs of the receivers, the signals enter the subtraction circuit, where, depending on the position of the target relative to the equi-signal direction formed by the intersection of the radiation patterns of a given pair of emitters, a difference signal is generated, the amplitude and polarity of which is determined by the position of the target in space (Fig. 1.3).
Synchronously with the ferrite axis switch in the radar station, the antenna control signal extraction circuit operates, with the help of which the antenna control signal is generated in azimuth and elevation.
The receiver commutator switches the inputs of the receiving channels at a frequency of 62.5 Hz. The switching of receiving channels is associated with the need to average their characteristics, since the differential method of target direction finding requires the complete identity of the parameters of both receiving channels. The RLGS rangefinder is a system with two electronic integrators. From the output of the first integrator, a voltage proportional to the speed of approach to the target is removed, from the output of the second integrator - a voltage proportional to the distance to the target. The range finder captures the nearest target in the range of 10-25 km with its subsequent auto-tracking up to a range of 300 meters. At a distance of 500 meters, a signal is emitted from the rangefinder, which serves to cock the radio fuse (RV).
The RLGS calculator is a computing device and serves to generate control signals issued by the RLGS to the autopilot (AP) and RV. A signal is sent to the AP, representing the projection of the vector of the absolute angular velocity of the target sighting beam on the transverse axes of the missile. These signals are used to control the missile's heading and pitch. A signal representing the projection of the velocity vector of the target's approach to the missile onto the polar direction of the target's sighting beam arrives at the RV from the calculator.
The distinctive features of the radar station in comparison with other stations similar to it in terms of their tactical and technical data are:
1. The use of a long-focus antenna in a radar station, characterized by the fact that the beam is formed and deflected in it by deflecting one rather light mirror, the deflection angle of which is half that of the beam deflection angle. In addition, there are no rotating high-frequency transitions in such an antenna, which simplifies its design.
2. use of a receiver with a linear-logarithmic amplitude characteristic, which provides an expansion of the dynamic range of the channel up to 80 dB and, thereby, makes it possible to find the source of active interference.
3. building a system of angular tracking by the differential method, which provides high noise immunity.
4. application in the station of the original two-circuit closed yaw compensation circuit, which provides a high degree of compensation for the rocket oscillations relative to the antenna beam.
5. constructive implementation of the station according to the so-called container principle, which is characterized by a number of advantages in terms of reducing the total weight, using the allotted volume, reducing interconnections, the possibility of using a centralized cooling system, etc.
3.2 Separate functional radar systems
RLGS can be divided into a number of separate functional systems, each of which solves a well-defined particular problem (or several more or less closely related particular problems) and each of which is to some extent designed as a separate technological and structural unit. There are four such functional systems in the RLGS:
3.2.1 Radar part of the RLGS
The radar part of the RLGS consists of:
the transmitter.
receiver.
high voltage rectifier.
the high frequency part of the antenna.
The radar part of the RLGS is intended:
· to generate high-frequency electromagnetic energy of a given frequency (f ± 2.5%) and a power of 60 W, which is radiated into space in the form of short pulses (0.9 ± 0.1 μs).
· for the subsequent reception of signals reflected from the target, their conversion into intermediate frequency signals (Fpch = 30 MHz), amplification (via 2 identical channels), detection and delivery to other radar systems.
3.2.2. Synchronizer
Synchronizer consists of:
Receiving and Synchronization Manipulation Unit (MPS-2).
· receiver switching unit (KP-2).
· Control unit for ferrite switches (UF-2).
selection and integration node (SI).
Error signal selection unit (CO)
· ultrasonic delay line (ULZ).
generation of synchronization pulses for launching individual circuits in the radar station and control pulses for the receiver, SI unit and rangefinder (MPS-2 unit)
Formation of impulses for controlling the ferrite switch of axes, the ferrite switch of the receiving channels and the reference voltage (UV-2 node)
Integration and summation of received signals, voltage regulation for AGC control, conversion of target video pulses and AGC into radio frequency signals (10 MHz) for their delay in the ULZ (SI node)
· isolation of the error signal necessary for the operation of the angular tracking system (CO node).
3.2.3. Rangefinder
The rangefinder consists of:
Time modulator node (EM).
time discriminator node (VD)
two integrators.
The purpose of this part of the RLGS is:
search, capture and tracking of the target in range with the issuance of signals of the range to the target and the speed of approach to the target
issuance of signal D-500 m
State Committee of the Russian Federation for Higher Education
BALTIC STATE TECHNICAL UNIVERSITY
_____________________________________________________________
Department of Radioelectronic Devices
RADAR HOMING HEAD
St. Petersburg
2. GENERAL INFORMATION ABOUT RLGS.
2.1 Purpose
The radar homing head is installed on the surface-to-air missile to ensure automatic target acquisition, its auto-tracking and the issuance of control signals to the autopilot (AP) and radio fuse (RB) at the final stage of the missile's flight.
2.2 Specifications
RLGS is characterized by the following basic performance data:
1. search area by direction:
Azimuth ± 10°
Elevation ± 9°
2. search area review time 1.8 - 2.0 sec.
3. target acquisition time by angle 1.5 sec (no more)
4. Maximum angles of deviation of the search area:
In azimuth ± 50° (not less than)
Elevation ± 25° (not less than)
5. Maximum deviation angles of the equisignal zone:
In azimuth ± 60° (not less than)
Elevation ± 35° (not less than)
6. target capture range of the IL-28 aircraft type with the issuance of control signals to (AP) with a probability of not less than 0.5 -19 km, and with a probability of not less than 0.95 -16 km.
7 search zone in range 10 - 25 km
8. operating frequency range f ± 2.5%
9. average transmitter power 68W
10. RF pulse duration 0.9 ± 0.1 µs
11. RF pulse repetition period T ± 5%
12. sensitivity of receiving channels - 98 dB (not less)
13.power consumption from power sources:
From the mains 115 V 400 Hz 3200 W
Mains 36V 400Hz 500W
From the network 27 600 W
14. station weight - 245 kg.
3. PRINCIPLES OF OPERATION AND CONSTRUCTION OF RLGS
3.1 The principle of operation of the radar
RLGS is a radar station of the 3-centimeter range, operating in the mode of pulsed radiation. At the most general consideration, the radar station can be divided into two parts: - the actual radar part and the automatic part, which provides target acquisition, its automatic tracking in angle and range, and the issuance of control signals to the autopilot and radio fuse.
The radar part of the station works in the usual way. High-frequency electromagnetic oscillations generated by the magnetron in the form of very short pulses are emitted using a highly directional antenna, received by the same antenna, converted and amplified in the receiving device, pass further to the automatic part of the station - the target angle tracking system and the rangefinder.
The automatic part of the station consists of the following three functional systems:
1. antenna control systems that provide antenna control in all modes of operation of the radar station (in the "guidance" mode, in the "search" mode and in the "homing" mode, which in turn is divided into "capture" and "autotracking" modes)
2. distance measuring device
3. a calculator for control signals supplied to the autopilot and radio fuse of the rocket.
The antenna control system in the "auto-tracking" mode works according to the so-called differential method, in connection with which a special antenna is used in the station, consisting of a spheroidal mirror and 4 emitters placed at some distance in front of the mirror.
When the radar station operates on radiation, a single-lobe radiation pattern is formed with a maμmum coinciding with the axis of the antenna system. This is achieved due to the different lengths of the waveguides of the emitters - there is a hard phase shift between the oscillations of different emitters.
When working at reception, the radiation patterns of the emitters are shifted relative to the optical axis of the mirror and intersect at a level of 0.4.
The connection of the emitters with the transceiver is carried out through a waveguide path, in which there are two ferrite switches connected in series:
· Axes commutator (FKO), operating at a frequency of 125 Hz.
· Receiver switch (FKP), operating at a frequency of 62.5 Hz.
Ferrite switches of the axes switch the waveguide path in such a way that first all 4 emitters are connected to the transmitter, forming a single-lobe directivity pattern, and then to a two-channel receiver, then emitters that create two directivity patterns located in a vertical plane, then emitters that create two patterns orientation in the horizontal plane. From the outputs of the receivers, the signals enter the subtraction circuit, where, depending on the position of the target relative to the equi-signal direction formed by the intersection of the radiation patterns of a given pair of emitters, a difference signal is generated, the amplitude and polarity of which is determined by the position of the target in space (Fig. 1.3).
Synchronously with the ferrite axis switch in the radar station, the antenna control signal extraction circuit operates, with the help of which the antenna control signal is generated in azimuth and elevation.
The receiver commutator switches the inputs of the receiving channels at a frequency of 62.5 Hz. The switching of receiving channels is associated with the need to average their characteristics, since the differential method of target direction finding requires the complete identity of the parameters of both receiving channels. The RLGS rangefinder is a system with two electronic integrators. From the output of the first integrator, a voltage proportional to the speed of approach to the target is removed, from the output of the second integrator - a voltage proportional to the distance to the target. The range finder captures the nearest target in the range of 10-25 km with its subsequent auto-tracking up to a range of 300 meters. At a distance of 500 meters, a signal is emitted from the rangefinder, which serves to cock the radio fuse (RV).
The RLGS calculator is a computing device and serves to generate control signals issued by the RLGS to the autopilot (AP) and RV. A signal is sent to the AP, representing the projection of the vector of the absolute angular velocity of the target sighting beam on the transverse axes of the missile. These signals are used to control the missile's heading and pitch. A signal representing the projection of the velocity vector of the target's approach to the missile onto the polar direction of the target's sighting beam arrives at the RV from the calculator.
The distinctive features of the radar station in comparison with other stations similar to it in terms of their tactical and technical data are:
1. The use of a long-focus antenna in a radar station, characterized by the fact that the beam is formed and deflected in it by deflecting one rather light mirror, the deflection angle of which is half that of the beam deflection angle. In addition, there are no rotating high-frequency transitions in such an antenna, which simplifies its design.
2. use of a receiver with a linear-logarithmic amplitude characteristic, which provides an expansion of the dynamic range of the channel up to 80 dB and, thereby, makes it possible to find the source of active interference.
3. building a system of angular tracking by the differential method, which provides high noise immunity.
4. application in the station of the original two-circuit closed yaw compensation circuit, which provides a high degree of compensation for the rocket oscillations relative to the antenna beam.
5. constructive implementation of the station according to the so-called container principle, which is characterized by a number of advantages in terms of reducing the total weight, using the allotted volume, reducing interconnections, and the possibility of using centralized system cooling, etc.
3.2 Separate functional radar systems
RLGS can be divided into a number of separate functional systems, each of which solves a well-defined particular problem (or several more or less closely related particular problems) and each of which is to some extent designed as a separate technological and structural unit. There are four such functional systems in the RLGS:
3.2.1 Radar part of the RLGS
The radar part of the RLGS consists of:
the transmitter.
receiver.
high voltage rectifier.
the high frequency part of the antenna.
The radar part of the RLGS is intended:
· to generate high-frequency electromagnetic energy of a given frequency (f ± 2.5%) and a power of 60 W, which is radiated into space in the form of short pulses (0.9 ± 0.1 μs).
· for the subsequent reception of signals reflected from the target, their conversion into intermediate frequency signals (Fpch = 30 MHz), amplification (via 2 identical channels), detection and delivery to other radar systems.
3.2.2. Synchronizer
Synchronizer consists of:
Receiving and Synchronization Manipulation Unit (MPS-2).
· receiver switching unit (KP-2).
· Control unit for ferrite switches (UF-2).
selection and integration node (SI).
Error signal selection unit (CO)
· ultrasonic delay line (ULZ).
generation of synchronization pulses for launching individual circuits in the radar station and control pulses for the receiver, SI unit and rangefinder (MPS-2 unit)
Formation of impulses for controlling the ferrite switch of axes, the ferrite switch of the receiving channels and the reference voltage (UV-2 node)
Integration and summation of received signals, voltage regulation for AGC control, conversion of target video pulses and AGC into radio frequency signals (10 MHz) for their delay in the ULZ (SI node)
· isolation of the error signal necessary for the operation of the angular tracking system (CO node).
3.2.3. Rangefinder
The rangefinder consists of:
Time modulator node (EM).
time discriminator node (VD)
two integrators.
The purpose of this part of the RLGS is:
search, capture and tracking of the target in range with the issuance of signals of the range to the target and the speed of approach to the target
issuance of signal D-500 m
Issuance of selection pulses for receiver gating
Issuance of pulses limiting the reception time.
3.2.4. Antenna Control System (AMS)
The antenna control system consists of:
Search and gyro stabilization unit (PGS).
Antenna head control unit (UGA).
· knot of the automatic capture (A3).
· storage unit (ZP).
· output nodes of the antenna control system (AC) (on the channel φ and channel ξ).
Electric spring assembly (SP).
The purpose of this part of the RLGS is:
control of the antenna during rocket takeoff in the modes of guidance, search and preparation for capture (assemblies of PGS, UGA, US and ZP)
Target capture by angle and its subsequent auto-tracking (nodes A3, ZP, US, and ZP)
4. OPERATING PRINCIPLE OF THE ANGLE TRACKING SYSTEM
In the functional diagram of the angular target tracking system, the reflected high-frequency pulse signals received by two vertical or horizontal antenna radiators are fed through the ferrite switch (FKO) and the ferrite switch of the receiving channels - (FKP) to the input flanges of the radio frequency receiving unit. To reduce reflections from the detector sections of the mixers (SM1 and SM2) and from the receiver protection arresters (RZP-1 and RZP-2) during the recovery time of the RZP, which worsen the decoupling between the receiving channels, resonant ferrite valves (FV- 1 and FV-2). The reflected pulses received at the inputs of the radio frequency receiving unit are fed through the resonant valves (F A-1 and F V-2) to the mixers (CM-1 and CM-2) of the corresponding channels, where, mixing with the oscillations of the klystron generator, they are converted into pulses of the intermediate frequencies. From the outputs of the mixers of the 1st and 2nd channels, the intermediate frequency pulses are fed to the intermediate frequency preamplifiers of the corresponding channels - (PUFC unit). From the output of the PUFC, the amplified intermediate frequency signals are fed to the input of a linear-logarithmic intermediate frequency amplifier (UPCL nodes). Linear-logarithmic intermediate frequency amplifiers amplify, detect and subsequently amplify the video frequency of the intermediate frequency pulses received from the PUFC.
Each linear-logarithmic amplifier consists of the following functional elements:
Logarithmic amplifier, which includes an IF (6 stages)
Transistors (TR) for decoupling the amplifier from the addition line
Signal addition lines (LS)
Linear detector (LD), which in the range of input signals of the order of 2-15 dB gives a linear dependence of the input signals on the output
The summing cascade (Σ), in which the linear and logarithmic components of the characteristic are added
Video amplifier (VU)
The linear-logarithmic characteristic of the receiver is necessary to expand the dynamic range of the receiving path up to 30 dB and eliminate overloads caused by interference. If we consider the amplitude characteristic, then in the initial section it is linear and the signal is proportional to the input, with an increase in the input signal, the increment of the output signal decreases.
To obtain a logarithmic dependence in UPCL, the method of sequential detection is used. The first six stages of the amplifier work as linear amplifiers at low input signal levels and as detectors at high signal levels. The video pulses generated during detection are fed from the emitters of the IF transistors to the bases of the decoupling transistors, on the common collector load of which they are added.
To obtain the initial linear section of the characteristic, the signal from the output of the IF is fed to a linear detector (LD). The overall linear-logarithmic dependence is obtained by adding the logarithmic and linear amplitude characteristics in the addition stage.
Due to the need to have a fairly stable noise level of the receiving channels. In each receiving channel, a system of inertial automatic noise gain control (AGC) is used. For this purpose, the output voltage from the UPCL node of each channel is fed to the PRU node. Through the preamplifier (PRU), the key (CL), this voltage is fed to the error generation circuit (CBO), into which the reference voltage "noise level" from resistors R4, R5 is also introduced, the value of which determines the noise level at the receiver output. The difference between the noise voltage and the reference voltage is the output signal of the video amplifier of the AGC unit. After appropriate amplification and detection, the error signal in the form of a constant voltage is applied to the last stage of the PUCH. To exclude the operation of the AGC node from various kinds of signals that may occur at the input of the receiving path (the AGC should work only on noise), switching of both the AGC system and the block klystron has been introduced. The AGC system is normally locked and opens only for the duration of the AGC strobe pulse, which is located outside the area of reflected signal reception (250 μs after the TX start pulse). In order to eliminate the influence of various kinds of external interference on the noise level, the klystron generation is interrupted for the duration of the AGC, for which the strobe pulse is also fed to the klystron reflector (through the output stage of the AFC system). (Figure 2.4)
It should be noted that the disruption of klystron generation during AGC operation leads to the fact that the noise component created by the mixer is not taken into account by the AGC system, which leads to some instability in the overall noise level of the receiving channels.
Almost all control and switching voltages are connected to the PUCH nodes of both channels, which are the only linear elements of the receiving path (at the intermediate frequency):
· AGC regulating voltages;
The radio-frequency receiving unit of the radar station also contains a klystron automatic frequency control circuit (AFC), due to the fact that the tuning system uses a klystron with dual frequency control - electronic (in a small frequency range) and mechanical (in a large frequency range) AFC system also divided into electronic and electromechanical frequency control system. The voltage from the output of the electronic AFC is applied to the klystron reflector and performs electronic frequency adjustment. The same voltage is fed to the input of the electromechanical frequency control circuit, where it is converted into an alternating voltage, and then fed to the motor control winding, which performs mechanical frequency adjustment of the klystron. To find the correct setting of the local oscillator (klystron), corresponding to a difference frequency of about 30 MHz, the AFC provides for an electromechanical search and capture circuit. The search takes place over the entire frequency range of the klystron in the absence of a signal at the AFC input. The AFC system works only during the emission of a probing pulse. For this, the power supply of the 1st stage of the AFC node is carried out by a differentiated start pulse.
From the UPCL outputs, the video pulses of the target enter the synchronizer to the summation circuit (SH "+") in the SI node and to the subtraction circuit (SH "-") in the CO node. The target pulses from the outputs of the UPCL of the 1st and 2nd channels, modulated with a frequency of 123 Hz (with this frequency the axes are switched), through the emitter followers ZP1 and ZP2 enter the subtraction circuit (SH "-"). From the output of the subtraction circuit, the difference signal obtained as a result of subtracting the signals of the 1st channel from the signals of the 2nd channel of the receiver enters the key detectors (KD-1, KD-2), where it is selectively detected and the error signal is separated along the axes " ξ" and "φ". The enabling pulses necessary for the operation of the key detectors are generated in special circuits in the same node. One of the permissive pulse generation circuits (SFRI) receives integrated target pulses from the "SI" synchronizer node and a reference voltage of 125– (I) Hz, the other receives integrated target pulses and a reference voltage of 125 Hz – (II) in antiphase. Enable pulses are formed from the pulses of the integrated target at the time of the positive half-cycle of the reference voltage.
The reference voltages of 125 Hz - (I), 125 Hz - (II), shifted relative to each other by 180, necessary for the operation of the permissive pulse generation circuits (SFRI) in the CO synchronizer node, as well as the reference voltage through the "φ" channel, are generated by sequential dividing by 2 the station repetition rate in the KP-2 node (switching receivers) of the synchronizer. Frequency division is performed using frequency dividers, which are RS flip-flops. The frequency divider start pulse generation circuit (ОΦЗ) is triggered by the trailing edge of a differentiated negative reception time limit pulse (T = 250 μs), which comes from the rangefinder. From the voltage output circuit of 125 Hz - (I), and 125 Hz - (II) (CB), a synchronization pulse with a frequency of 125 Hz is taken, which is fed to the frequency divider in the UV-2 (DCh) node. In addition, a voltage of 125 Hz is supplied to the circuit forming a shift by 90 relative to the reference voltage. The circuit for generating the reference voltage over the channel (TOH φ) is assembled on a trigger. A synchronization pulse of 125 Hz is applied to the divider circuit in the UV-2 node, the reference voltage "ξ" with a frequency of 62.5 Hz is removed from the output of this divider (DF), supplied to the US node and also to the KP-2 node to form a shifted by 90 degrees of reference voltage.
The UF-2 node also generates axes switching current pulses with a frequency of 125 Hz and receiver switching current pulses with a frequency of 62.5 Hz (Fig. 4.4).
The enabling pulse opens the transistors of the key detector and the capacitor, which is the load of the key detector, is charged to a voltage equal to the amplitude of the resulting pulse coming from the subtraction circuit. Depending on the polarity of the incoming pulse, the charge will be positive or negative. The amplitude of the resulting pulses is proportional to the angle of mismatch between the direction to the target and the direction of the equisignal zone, so the voltage to which the capacitor of the key detector is charged is the voltage of the error signal.
From the key detectors, an error signal with a frequency of 62.5 Hz and an amplitude proportional to the angle of mismatch between the direction to the target and the direction of the equisignal zone arrives through the RFP (ZPZ and ZPCH) and video amplifiers (VU-3 and VU-4) to the nodes US-φ and US-ξ of the antenna control system (Fig. 6.4).
The target pulses and UPCL noise of the 1st and 2nd channels are also fed to the CX+ addition circuit in the synchronizer node (SI), in which time selection and integration are carried out. Time selection of pulses by repetition frequency is used to combat non-synchronous impulse noise. Radar protection from non-synchronous impulse interference can be carried out by applying to the coincidence circuit non-delayed reflected signals and the same signals, but delayed for a time exactly equal to the repetition period of the emitted pulses. In this case, only those signals whose repetition period is exactly equal to the repetition period of the emitted pulses will pass through the coincidence circuit.
From the output of the addition circuit, the target pulse and noise through the phase inverter (Φ1) and the emitter follower (ZP1) are fed to the coincidence stage. The summation circuit and the coincidence cascade are elements of a closed-loop integration system with positive feedback. The integration scheme and the selector work as follows. The input of the circuit (Σ) receives the pulses of the summed target with noise and the pulses of the integrated target. Their sum goes to the modulator and generator (MiG) and to the ULZ. This selector uses an ultrasonic delay line. It consists of a sound duct with electromechanical energy converters (quartz plates). ULZ can be used to delay both RF pulses (up to 15 MHz) and video pulses. But when the video pulses are delayed, a significant distortion of the waveform occurs. Therefore, in the selector circuit, the signals to be delayed are first converted using a special generator and modulator into RF pulses with a duty cycle of 10 MHz. From the output of the ULZ, the target pulse delayed for the period of repetition of the radar is fed to the UPCH-10, from the output of the UPCH-10, the signal delayed and detected on the detector (D) through the key (CL) (UPC-10) is fed to the coincidence cascade (CS), to this the same cascade is supplied with the summed target impulse.
At the output of the coincidence stage, a signal is obtained that is proportional to the product of favorable voltages, so the target pulses that synchronously arrive at both inputs of the COP easily pass the coincidence stage, and noise and non-synchronous interference are strongly suppressed. From the output (CS), the target pulses through the phase inverter (Φ-2) and (ZP-2) again enter the circuit (Σ), thereby closing the feedback ring; key impulses, detectors (OFRI 1) and (OFRI 2).
The integrated pulses from the key output (CL), in addition to the coincidence cascade, are fed to the protection circuit against non-synchronous impulse noise (SZ), on the second arm of which the summed target pulses and noises from (3P 1) are received. The anti-synchronous noise protection circuit is a diode coincidence circuit that passes the smaller of the two synchronous voltages at its inputs. Since the integrated target pulses are always much larger than the summed ones, and the voltage of noise and interference is strongly suppressed in the integration circuit, then in the coincidence circuit (CZ), in essence, the summed target pulses are selected by the integrated target pulses. The resulting "direct target" pulse has the same amplitude and shape as the stacked target pulse, while noise and jitter are suppressed. The impulse of the direct target is fed to the time discriminator of the rangefinder circuit and the node of the capture machine, the antenna control system. Obviously, when using this selection scheme, it is necessary to ensure a very accurate equality between the delay time in the CDL and the repetition period of the emitted pulses. This requirement can be met by using special schemes for generating synchronization pulses, in which the stabilization of the pulse repetition period is carried out by the LZ of the selection scheme. The synchronization pulse generator is located in the MPS - 2 node and is a blocking oscillator (ZVG) with its own period of self-oscillations, slightly longer than the delay time in the LZ, i.e. more than 1000 µs. When the radar is turned on, the first ZVG pulse is differentiated and launches the BG-1, from the output of which several synchronization pulses are taken:
· Negative clock pulse T=11 µs is supplied together with the rangefinder selection pulse to the circuit (CS), which generates control pulses of the SI node for the duration of which the manipulation cascade (CM) in the node (SI) opens and the addition cascade (CX +) and all subsequent ones work. As a result, the BG1 synchronization pulse passes through (SH +), (Φ 1), (EP-1), (Σ), (MiG), (ULZ), (UPC-10), (D) and delayed by the radar repetition period (Tp=1000µs), triggers the ZBG with a rising edge.
· Negative locking pulse UPC-10 T = 12 μs locks the key (KL) in the SI node and thereby prevents the BG-1 synchronization pulse from entering the circuit (KS) and (SZ).
· Negative differentiated impulse synchronization triggers the rangefinder start pulse generation circuit (SΦZD), the rangefinder start pulse synchronizes the time modulator (TM), and also through the delay line (DL) is fed to the start pulse generation circuit of the transmitter SΦZP. In the circuit (VM) of the range finder, negative pulses of the reception time limit f = 1 kHz and T = 250 μs are formed along the front of the range finder start pulse. They are fed back to the MPS-2 node on the CBG to exclude the possibility of triggering the CBG from the target pulse, in addition, the trailing edge of the receive time limit pulse triggers the AGC strobe pulse generation circuit (SFSI), and the AGC strobe pulse triggers the manipulation pulse generation circuit (СΦМ ). These pulses are fed into the RF unit.
Error signals from the output of the node (CO) of the synchronizer are fed to the nodes of the angular tracking (US φ, US ξ) of the antenna control system to the error signal amplifiers (USO and USO). From the output of the error signal amplifiers, the error signals are fed to the paraphase amplifiers (PFC), from the outputs of which the error signals in opposite phases are fed to the inputs of the phase detector - (PD 1). Reference voltages are also supplied to the phase detectors from the outputs of PD 2 of reference voltage multivibrators (MVON), the inputs of which are supplied with reference voltages from the UV-2 unit (φ channel) or the KP-2 unit (ξ channel) of the synchronizer. From the outputs of phase signal voltage detectors, errors are fed to the contacts of the capture preparation relay (RPZ). Further operation of the node depends on the mode of operation of the antenna control system.
5. RANGEFINDER
The RLGS 5G11 rangefinder uses an electrical range measurement circuit with two integrators. This scheme allows you to get a high speed of capturing and tracking the target, as well as giving the range to the target and the speed of approach in the form of a constant voltage. The system with two integrators memorizes the last rate of approach in case of a short-term loss of the target.
The operation of the rangefinder can be described as follows. In the time discriminator (TD), the time delay of the pulse reflected from the target is compared with the time delay of the tracking pulses ("Gate"), created by the electrical time modulator (TM), which includes a linear delay circuit. The circuit automatically provides equality between gate delay and target pulse delay. Since the target pulse delay is proportional to the distance to the target, and the gate delay is proportional to the voltage at the output of the second integrator, in the case of a linear relationship between the gate delay and this voltage, the latter will be proportional to the distance to the target.
The time modulator (TM), in addition to the “gate” pulses, generates a reception time limit pulse and a range selection pulse, and, depending on whether the radar station is in the search or target acquisition mode, its duration changes. In the "search" mode T = 100 μs, and in the "capture" mode T = 1.5 μs.
6. ANTENNA CONTROL SYSTEM
In accordance with the tasks performed by the SUA, the latter can be conditionally divided into three separate systems, each of which performs a well-defined functional task.
1. Antenna head control system. It includes:
UGA node
Scheme of storing on the channel "ξ" in the node ZP
· drive - an electric motor of the SD-10a type, controlled by an electric machine amplifier of the UDM-3A type.
2. Search and gyro stabilization system. It includes:
PGS node
output cascades of US nodes
Scheme of storing on the channel "φ" in the node ZP
· a drive on electromagnetic piston couplings with an angular velocity sensor (AVS) in the feedback circuit and the SP unit.
3. Angular target tracking system. It includes:
nodes: US φ, US ξ, A3
Scheme for highlighting the error signal in the CO synchronizer node
· drive on electromagnetic powder clutches with CRS in feedback and SP unit.
It is advisable to consider the operation of the control system sequentially, in the order in which the rocket performs the following evolutions:
1. "takeoff",
2. "guidance" on commands from the ground
3. "search for the target"
4. "pre-capture"
5. "ultimate capture"
6. "automatic tracking of a captured target"
With the help of a special kinematic scheme of the unit, the necessary law of motion of the antenna mirror is provided, and, consequently, the movement of the directivity characteristics in azimuth (φ axis) and inclination (ξ axis) (fig.8.4).
The trajectory of the antenna mirror depends on the operating mode of the system. In mode "escort" the mirror can perform only simple movements along the φ axis - through an angle of 30 °, and along the ξ axis - through an angle of 20 °. When operating in "Search", the mirror performs a sinusoidal oscillation about the φ axis (from the φ axis drive) with a frequency of 0.5 Hz and an amplitude of ± 4°, and a sinusoidal oscillation about the ξ axis (from the cam profile) with a frequency f = 3 Hz and an amplitude of ± 4°.
Thus, viewing of the 16"x16" zone is provided. the angle of deviation of the directivity characteristic is 2 times the angle of rotation of the antenna mirror.
In addition, the viewing area is moved along the axes (by the drives of the corresponding axes) by commands from the ground.
7. MODE "TAKEOFF"
When the rocket takes off, the radar antenna mirror must be in the zero position "top-left", which is provided by the PGS system (along the φ axis and along the ξ axis).
8. POINT MODE
In the guidance mode, the position of the antenna beam (ξ = 0 and φ = 0) in space is set using control voltages, which are taken from the potentiometers and the search area gyro stabilization unit (GS) and are brought into the channels of the OGM unit, respectively.
After the launch of the missile in level flight, a one-time "guidance" command is sent to the radar station through the onboard command station (SPC). On this command, the PGS node keeps the antenna beam in a horizontal position, turning it in azimuth in the direction specified by the commands from the ground "turn the zone along" φ ".
The UGA system in this mode keeps the antenna head in the zero position relative to the "ξ" axis.
9. MODE "SEARCH".
When the missile approaches the target to a distance of approximately 20-40 km, a one-time "search" command is sent to the station through the SPK. This command arrives at the node (UGA), and the node switches to the high-speed servo system mode. In this mode, the amplifier input alternating current(US) of the node (UGA) receives the sum of a fixed frequency signal of 400 Hz (36V) and the high-speed feedback voltage from the TG-5A current generator. In this case, the shaft of the executive motor SD-10A begins to rotate at a fixed speed, and through the cam mechanism causes the antenna mirror to swing relative to the rod (i.e., relative to the "ξ" axis) with a frequency of 3 Hz and an amplitude of ± 4°. At the same time, the engine rotates a sinus potentiometer - a sensor (SPD), which outputs a "winding" voltage with a frequency of 0.5 Hz to the azimuth channel of the OPO system. This voltage is applied to the summing amplifier (US) of the node (CS φ) and then to the antenna drive along the axis. As a result, the antenna mirror begins to oscillate in azimuth with a frequency of 0.5 Hz and an amplitude of ± 4°.
Synchronous swinging of the antenna mirror by the UGA and OPO systems, respectively in elevation and azimuth, creates a search beam movement shown in Fig. 3.4.
In the "search" mode, the outputs of the phase detectors of the nodes (US - φ and US - ξ) are disconnected from the input of the summing amplifiers (SU) by the contacts of a de-energized relay (RPZ).
In the "search" mode, the processing voltage "φ n" and the voltage from the gyroazimuth "φ g" are supplied to the input of the node (ZP) via the "φ" channel, and the processing voltage "ξ p" via the "ξ" channel.
10. "CAPTURE PREPARATION" MODE.
To reduce the survey time, the search for a target in the radar station is carried out with high speed. In this regard, the station uses a two-stage target acquisition system, with storing the position of the target at the first detection, followed by returning the antenna to the memorized position and the secondary final target acquisition, after which its auto-tracking follows. Both preliminary and final target acquisition are carried out by the A3 node scheme.
When a target appears in the station search area, video pulses of the "direct target" from the anti-synchronous interference protection circuit of the synchronizer node (SI) begin to flow through the error signal amplifier (USO) of the node (AZ) to the detectors (D-1 and D-2) of the node (A3 ). When the missile reaches a range at which the signal-to-noise ratio is sufficient to trigger the capture preparation relay cascade (CRPC), the latter triggers the capture preparation relay (RPR) in the nodes (CS φ and DC ξ). The capture automaton (A3) cannot work in this case, because. it is unlocked by voltage from the circuit (APZ), which is applied only 0.3 sec after operation (APZ) (0.3 sec is the time required for the antenna to return to the point where the target was originally detected).
Simultaneously with the operation of the relay (RPZ):
· from node of storage (ZP) input signals "ξ p" and "φ n" are disconnected
The voltages that control the search are removed from the inputs of the nodes (PGS) and (UGA)
· the storage node (ZP) begins to issue stored signals to the inputs of the nodes (PGS) and (UGA).
To compensate for the error of the storage and gyro stabilization circuits, the swing voltage (f = 1.5 Hz) is applied to the inputs of the nodes (OSG) and (UGA) simultaneously with the stored voltages from the node (ZP), as a result of which, when the antenna returns to the memorized point, the beam swings with a frequency of 1.5 Hz and an amplitude of ± 3°.
As a result of the operation of the relay (RPZ) in the channels of the nodes (RS) and (RS), the outputs of the nodes (RS) are connected to the input of the antenna drives via the channels "φ" and "ξ" simultaneously with the signals from the OGM, as a result of which the drives begin to be controlled also an error signal of the angle tracking system. Due to this, when the target re-enters the antenna pattern, the tracking system retracts the antenna into the equisignal zone, facilitating the return to the memorized point, thus increasing the capture reliability.
11. CAPTURE MODE
After 0.4 seconds after the capture preparation relay is triggered, the blocking is released. As a result of this, when the target re-enters the antenna pattern, the capture relay cascade (CRC) is triggered, which causes:
· actuation of the capture relay (RC) in the nodes (US "φ" and US "ξ") that turn off the signals coming from the node (SGM). Antenna control system switches to automatic target tracking mode
actuation of the relay (RZ) in the UGA node. In the latter, the signal coming from the node (ZP) is turned off and the ground potential is connected. Under the influence of the appeared signal, the UGA system returns the antenna mirror to the zero position along the "ξ p" axis. Arising in this case, due to the withdrawal of the equisignal zone of the antenna from the target, the error signal is worked out by the SUD system, according to the main drives "φ" and "ξ". In order to avoid tracking failure, the return of the antenna to zero along the axis "ξ p" is carried out at a reduced speed. When the antenna mirror reaches the zero position along the axis "ξ p ". the mirror locking system is activated.
12. MODE "AUTOMATIC TRACKING"
From the output of the CO node from the video amplifier circuits (VUZ and VU4), the error signal with a frequency of 62.5 Hz, divided along the "φ" and "ξ" axes, enters through the nodes US "φ" and US "ξ" to phase detectors. The reference voltage "φ" and "ξ" are also fed to the phase detectors, coming from the reference voltage trigger circuit (RTS "φ") of the KP-2 unit and the switching pulse formation circuit (SΦPCM "P") of the UV-2 unit. From the phase detectors, the error signals are fed to the amplifiers (CS "φ" and CS "ξ") and further to the antenna drives. Under the influence of the incoming signal, the drive turns the antenna mirror in the direction of decreasing the error signal, thereby tracking the target.
The figure is located at the end of the entire text. The scheme is divided into three parts. Transitions of conclusions from one part to another are indicated by numbers.
MOSCOW AVIATION INSTITUTE
(STATE TECHNICAL UNIVERSITY)
Air-to-surface guided missile
Compiled by:
Buzinov D.
Vankov K.
Kuzhelev I.
Levine K.
Sichkar M.
Sokolov Ya.
Moscow. 2009
Introduction.
The rocket is made according to the normal aerodynamic configuration with X-shaped wings and plumage. Welded rocket body is made of aluminum alloys without process connectors.
The power plant consists of a mid-flight turbojet engine and a starting solid-propellant booster (not available on airborne missiles). The main engine air intake is located in the lower part of the hull.
The control system is combined, it includes an inertial system and an active radar homing head ARGS-35 for the final section, capable of operating under radio countermeasures. To ensure rapid target detection and capture, the GOS antenna has a large angle of rotation (45 ° in both directions). The GOS is closed with a fiberglass radio-transparent fairing.
Penetrating high-explosive fragmentation incendiary warhead missiles allows you to reliably hit surface ships with a displacement of up to 5000 tons.
The combat effectiveness of the missile is increased by flying at extremely low altitudes (5-10 m, depending on the height of the waves), which greatly complicates its interception by shipboard anti-missile systems, and by the fact that the missile is launched without the carrier entering the air defense zone of the attacked ships.
Specifications.
Rocket modifications:
Rice. 1. Rocket 3M24 "Uranus".
3M24 "Uranus" - a ship-based and land-based missile, used from missile boats with the "Uran-E" complex and coastal missile systems "Bal-E"
Rice. 2. Rocket ITs-35.
ITs-35 - target (target simulator). Differs in the absence of warheads and GOS.
Rice. 3. X-35V missile.
X-35V - helicopter. It features a shortened starting accelerator. It is used on Ka-27, Ka-28, Ka-32A7 helicopters.
Rice. 4. Rocket X-35U.
X-35U - aviation (aircraft) missile. Distinguished by the absence of a launch booster, it is used from AKU-58, AKU-58M or APU-78 ejection launchers on the MiG-29K and Su-27K
Rice. 5. Rocket X-35E.
X-35E - export.
Rocket glider.
2.1. General information.
The rocket airframe has the following main structural elements: body, wings, rudders and stabilizers. (Fig. 6).
The hull serves to accommodate the power plant, equipment and systems that ensure the autonomous flight of the missile, targeting and hitting it. It has a monocoque structure, consisting of power sheathing and frames, and is made of separate compartments, assembled mainly with the help of flanged connections. When docking the radio transparent fairing with the housing of compartment 1 and the starting engine (compartment 6) with adjacent compartments 5 and 7, wedge connections were used.
Fig.6. General form.
The wing is the main aerodynamic surface of the rocket, which creates lift. The wing consists of a fixed part and deployable modules. The folding console is made according to a single-spar scheme with sheathing and ribs.
The rudders and stabilizers provide controllability and stability in the longitudinal and lateral movement of the rocket; like the wings, they have foldable consoles.
2.2. Hull design
The compartment body 1 (Fig. 7) is a frame structure consisting of power frames 1.3 and skin 2, connected by welding.
Fig.7. Compartment 1.
1. Front frame; 2. Sheathing; 3. Rear frame
The compartment body 2 (Fig. 8) is a frame structure; consisting of frames 1,3,5,7 and skin 4. To install the warhead, a hatch reinforced with brackets 6 and frames 3.5 is provided. Hatch with edging 2 is designed for fastening the block of the onboard tear-off connector. Brackets are provided for placing equipment and laying harnesses inside the compartment.
Fig.8. Compartment 2
1. Front frame; 2. Edging; 3. Frame; 4. Sheathing;
5. Frame; 6. Bracket; 7. Rear frame
The compartment body 3 (Fig. 9) is a welded frame structure of frames 1,3,8,9,13,15,18 and skins 4,11,16. The components of the compartment body are the frame of the hardware part 28, the fuel tank 12 and the air intake device (VZU) 27. On frames 1.3 and 13.15, yokes 2.14 are installed. On the frame 9 there is a rigging assembly (sleeve) 10.
Landing surfaces and wing attachment points are provided on frame 8. There are brackets 25.26 for equipment placement. Approach to electrical equipment and pneumatic system is carried out through hatches closed with covers 5,6,7,17. Profiles 23 are welded to the body to fasten the fairing. The air unit is installed on the brackets 21.22. Bracket 20 and cover 24 are designed to accommodate fuel system units. Ring 19 is necessary to ensure tight docking of the VDU channel with the propulsion engine.
Fig.9. Compartment 3.
1. Frame; 2. Yoke; 3. Frame; 4. Sheathing; 5. Lid;
6. Lid; 7. Lid; 8. Frame; 9. Frame; 10. Sleeve;
11. Sheathing; 12. Fuel tank; 13. Frame; 14. Rope;
15. Frame; 16. sheathing; 17. Lid; 18. Frame; 19. Ring; 20. Bracket; 21. Bracket;; 22. Bracket; 23. Profile;
24. Lid; 25. Bracket; 26. Bracket; 27. VZU;
28. Hardware part of the compartment
The compartment body 4 (Fig. 10) is a welded frame structure consisting of frames 1,5,9 and skins 2,6. There are mounting surfaces and holes for installing the engine in frames 1 and 5.
Fig.10. Compartment 4.
1. Frame; 2. Sheathing; 3. Edging; 4. Lid;
5. Frame; 6. Sheathing; 7. Edging; 8. Lid;
9. Frame; 10. Bracket; 11. Bracket.
Landing pads and holes are made in frame 5 for fixing rudders. Brackets 10,11 are designed to accommodate equipment. Approach to the equipment installed inside the compartment is provided through hatches with edging 3.7, closed with covers 4.8.
The compartment body 5 (Fig. 11) is a welded frame structure of power frames 1.3 and skin 2.
To connect the harness connector of the starting engine, a hatch is provided, reinforced with edging 4, which is closed by cover 5. Holes are made in the body to install 4 pneumo-bridges.
Rice. 11. Compartment 5.
1. Frame. 2. Sheathing. 3. Frame. 4. Edging. 5. Cover.
The starting engine is located in the body of compartment 6 (Fig. 12). The compartment housing is also the engine housing. The body is a welded structure of a cylindrical shell 4, front 3 and rear 5 clips, bottom 2 and neck 1.
Fig.12. Compartment 6.
1. Neck; 2. Bottom; 3. Front clip; 4. Shell;
5. Rear clip
Compartment 7 (Fig. 13) is a power ring, on which there are seats for stabilizers and a yoke. Behind the compartment is closed with a lid. A hole is made in the lower part of the compartment, which is used as a loading unit.
Rice. 13. Compartment 7.
Note. Compartments 5,6 and 7 are available only on missiles used in missile systems.
2.3. Wing.
The wing (Fig. 14) consists of a fixed part and a rotary part 3, connected by an axis 2. The fixed part includes a body 5, front 1 and tasks 6 fairings fixed to the body with screws 4. A pneumatic mechanism for folding the wing is placed in the body. In the rotary part there is a mechanism for locking the wing in the unfolded position.
The unfolding of the wing is carried out as follows: under the action of air pressure supplied through the passage 12, the piston 7 with the lug 8 using link 10 drives the rotary part. The link is connected to the lug and the turning part of the wing by pins 9 and 11.
The wings are locked in the unfolded position by means of pins 14 sunk into the conical holes of the bushings 13 under the action of springs 17. The action of the springs is transmitted through the pins 15, with which the pins are fixed in the sleeves 16 from falling out.
The wing is released by lifting the pins from the holes of the bushings by winding ropes 18 on the roller 19, the ends of which are fixed in the pins. The rotation of the roller is counterclockwise.
The installation of the wing on the rocket is carried out along the surface D and E and hole B. Four holes D for screws are used to fasten the wing to the rocket.
Fig.14. Wing
1. Front fairing; 2. Axis; 3. Turning part; 4. Screw; 5. Housing; 6. Rear fairing; 7. Piston; 8. Eyelet;
9. Pin; 10. Link; 11. Pin; 12. Drifter; 13. Sleeve;
14. Pin; 15. Pin; 16. Sleeve;17. Spring;18. Rope;
2.4. Steering wheel.
The rudder (Fig. 15) is a mechanism consisting of a blade 4, movably connected to the tail 5, which is installed in the housing 1 on bearings 8. The reinforcement on the rudder is transferred through the lever 6 with a hinged bearing 7. stiffening elements. The trailing edge of the blade is welded. The blade is riveted to the bracket 11, which is movably connected by the axis 10 with the tail.
The steering wheel is unfolded as follows. Under the action of air pressure supplied to the body through the fitting 2, the piston 13 through the earring 9 sets in motion the blade, which rotates around the axis 10 by 135 degrees and is fixed in the unfolded position by the latch 12, which enters the conical seat of the shank and is held in this position by a spring.
Fig.15. Steering wheel.
1. Housing; 2. Fitting; 3. Stopper; 4. Blade; 5. Shank; 6. Lever; 7. Bearing; 8. Bearing; 9. Earring; 10. Axis; 11. Bracket; 12. Retainer; 13. Piston
The steering wheel is folded as follows: through hole B, the latch is removed from the conical hole with a special key and the steering wheel is folded. In the folded position, the steering wheel is held by a spring-loaded stopper 3.
To install the rudder on the rocket in the body, there are four holes B for bolts, a hole D and a groove D for pins, as well as seats with threaded holes E for attaching fairings.
2.5. Stabilizer.
The stabilizer (Fig. 16) consists of platform 1, base 11 and console 6. The base has a hole for the axle around which the stabilizer rotates. The console is a riveted structure consisting of a skin 10, a stringer 8 and an end 9. The console is connected to the base through a pin 5.
Fig.16. Stabilizer.
1. Platform; 2. Axis; 3. Earring; 4. Spring; 5. Pin; 6. Console;
7. Loop; 8. Stringer; 9. Ending; 10. Sheathing; 11. Foundation
The stabilizers are hinged on the rocket and can be in two positions - folded and unfolded.
In the folded position, the stabilizers are located along the rocket body and are held by the loops 7 by the rods of the pneumostops installed on the compartment 5. To bring the stabilizers from the folded position to the open position, spring 4 is used, which is connected at one end to the earring 3, which is hinged on the platform, and at the other end to the pin 5.
When compressed air is supplied from the pneumatic system, the pneumatic stops release each stabilizer, and it is set to the open position under the action of a stretched spring.
Power point
3.1. Compound.
Two engines were used as a power plant on the rocket: a starting solid fuel engine (SD) and a mid-flight turbojet bypass engine (MD).
SD - compartment 6 of the rocket, provides the launch and acceleration of the rocket to the speed of the cruising flight. At the end of the work, the SD, together with compartments 5 and 7, are fired back.
MD is located in compartment 4 and serves to ensure autonomous flight of the rocket and to provide its systems with power supply and compressed air. The power plant also includes an air intake and a fuel system.
VZU - tunnel type, semi-recessed with flat walls, located in compartment 3. VZU is designed to organize the air flow entering the MD.
3.2. Starting engine.
The starting engine is designed to launch and accelerate the rocket at the initial level of the flight trajectory and is a single-mode solid propellant rocket engine.
Technical details
Length, mm__________________________________________________550
Diameter, mm________________________________________________420
Weight, kg________________________________________________________________103
Fuel mass, kg____________________________________________69±2
Maximum allowable pressure in the combustion chamber, MPa________11.5
Gas outflow velocity at the nozzle exit, m/s ______________________ 2400
Temperature of gases at the nozzle exit, K______________________________2180
The SD consists of a body with a charge of solid rocket fuel (SRT) 15, a cover 4, a nozzle block, an igniter 1, and a squib 3.
SD docking with adjacent compartments is carried out using wedges, for which there are surfaces with annular grooves on the clips. Longitudinal grooves are provided on the clips for the correct installation of the SD. On the inner surface the rear clip has an annular groove for the dowels 21 for fastening the nozzle block. The dowels are inserted through the windows, which are then closed with crackers 29 and overlays 30, fastened with screws 31.
A nut 9 is screwed on the neck 8; the correctness of its installation is ensured by pin 7 pressed into the neck.
On the inner side of the surface of the case, a heat-shielding coating 11 and 17 is applied, with which cuffs 13 and 18 are fastened, which reduce the voltage in the TRT charge when its temperature changes.
Fig.17. Starting engine.
1. Igniter; 2. Plug; 3. Igniter; 4. Lid;
5. Insert heat-shielding; 6. O-ring; 7. Pin;
8. Neck; 9. Nut; 10. Bottom; 11. Heat-shielding coating;
12. Film; 13. Front cuff; 14. Front clip; 15. TRT charge; 16. Shell; 17. Heat protection coating; 18. Cuff back; 19. Rear clip; 20. O-ring; 21. Key; 22. Lid; 23. Heat shield disk; 24. Clip; 25. O-ring; 26. Trumpet; 27. Insert; 28. Membrane;
29. Rusk; 30. Overlay; 31. Screw.
The TRT charge is a monoblock firmly fastened with cuffs, made by pouring the fuel mass into the body. The charge has an internal channel of three different diameters, which ensures an approximately constant burning surface and, consequently, an almost constant thrust when burning fuel through the channel and the rear open end. A film separating them 12 is laid between the front cuff and the heat-shielding coating.
On the cover 4 there are: a thread for mounting the igniter, a threaded hole for the squib, a threaded hole for installing a pressure sensor in the combustion chamber during testing, an annular groove for the sealing ring 6, a longitudinal groove for the pin 7. During operation, the hole for the pressure sensor is closed a plug 2. A heat-shielding insert 5 is fixed on the inner surface of the cover. The nozzle block consists of a cover 22, a clip 24, a socket 26, an insert 27 and a membrane 28.
On the outer cylindrical surface of the cover there are annular grooves for the sealing ring 20 and dowels 21, on the inner cylindrical surface there is a thread for connection with the holder 24. A heat-shielding disk 23 is attached to the cover in front. On the holder 24 there is a thread and an annular groove for the sealing ring 25.
The LED starts working when a direct current of 27 V is applied to the squib. The squib fires and ignites the igniter. The igniter flame ignites the TRT charge. When the charge burns, gases are formed that break through the diaphragm and, exiting the nozzle at high speed, create a reactive force. Under the action of the SD thrust, the rocket accelerates to the speed at which the MD comes into operation.
3.3. sustainer engine
The bypass turbojet engine is a short-life disposable engine designed to create jet thrust in an autonomous flight of a rocket and to provide its systems with power supply and compressed air.
Technical details.
Launch time, s, no more than:
At heights of 50m________________________________________________6
3500m______________________________________________8
The double-circuit turbojet engine MD includes a compressor, a combustion chamber, a turbine, a nozzle, a system of fairy tales and breathers, a system for starting, fuel supply and regulation, and electrical equipment.
The first circuit (high pressure) is formed by the flow part of the compressor, the flame tube of the combustion chamber and the flow part of the turbine up to the cut of the nozzle housing.
Second loop ( low pressure) is limited to outside the middle body and the outer wall of the MD, and on the inside - a flow separator, the body of the combustion chamber and the body of the nozzle.
The mixing of air flows of the first and second circuits occurs behind the cut of the nozzle body.
Fig.18. Marching engine.
1. Oil tank; 2. Fan case; 3. Fan;
4. Straightener 2nd stage; 5. Turbogenerator;
6. 2nd circuit; 7. Compressor; 8. 1st circuit; 9. Piroscandle; 10. Combustion chamber; 11. Turbine; 12. Nozzle; 13. Gas generator.
The MD is fixed to the rocket with a suspension bracket through the threaded holes of the front and rear suspension belts. Suspension bracket - a power element on which the units and sensors of the MD and communications connecting them are located. In front of the bracket there are holes for attaching it to the MD and eyelets for attaching the MD to the rocket.
On the outer wall of the MD, there are two hatches for installing pyro-candles and an air bleed flange for steering gears. On the body there is an air bleed nipple for pressurizing the fuel tank.
3.3.1. Compressor.
A single-shaft eight-stage axial compressor 7 is installed on the MD, consisting of a two-stage fan, a middle casing with a device for dividing the air flow into the primary and secondary circuits, and a six-stage high-pressure compressor.
In fan 3, the air entering the MD is pre-compressed, and in the high-pressure compressor, the air flow of only the primary circuit is compressed to the calculated value.
The fan rotor is of drum-disk design. The disks of the first and second stages are connected by a spacer and radial pins. The fan rotor and fairing are fixed on the shaft with a bolt and nuts. The torque from the shaft to the fan rotor is transmitted using a spline connection. The working blades of the first and second stages are installed in dovetail grooves. From axial displacements, the blades are fixed by a fairing, a spacer and a retaining ring. On the fan shaft there is a gear that serves as a drive for the gearbox of the pump unit. Breathing of the oil cavity of the compressor is carried out through the cavities of the MD transmission shafts.
Fan housing 2 is welded with cantilever blades of the first stage directing vane brazed into it. The straightener of the second stage is made as a separate unit and consists of two rings, in the grooves of which the blades are soldered.
Oil tank 1 is located in the front upper part of the housing. The fan housing together with the oil tank is fixed to the flange of the middle housing with studs.
The middle body is the main power element of the MD. In the middle case, the air flow leaving the fan is divided into circuits.
Attached to the middle body:
Suspension bracket MD to the rocket
Pump block
Middle support cover (ball bearing)
Turbogenerator stator
Combustion chamber body.
A fuel-oil heat exchanger, an oil filter, an exhaust valve and a P-102 sensor for measuring the air temperature behind the fan are installed on the outer wall of the middle housing. The body walls are connected by four power racks, inside which channels are made to accommodate fuel, oil and electrical communications.
In the middle housing there is a high-pressure compressor housing with 3-7 stage straightening vanes. The high-pressure compressor housing has openings for unregulated bypass of air from the primary to the secondary circuit, which increases the margins of gas-dynamic stability at low and medium speeds of the MD rotor.
The rotor of the high-pressure compressor is of drum-disk design, two-port. With the fan shaft and the turbine shaft, the high-pressure compressor rotor has splined connections. The working blades are installed in the annular T-shaped slots of the rotor discs.
3.3.2. The combustion chamber.
In the combustion chamber, the chemical energy of the fuel is converted into thermal energy and the temperature of the gas flow rises. An annular combustion chamber 10 is installed on the MD, which consists of the following main units:
Flame tube
Main fuel manifold
Additional fuel manifold
Two pyro-candles with electric igniters
Piroscandles.
The body of the combustion chamber is brazed and welded. In its front part, two rows of straightening vanes of the eighth stage of the compressor are soldered. In addition, oil system switches are soldered to the body. On the outer wall of the housing there are fourteen flanges for fastening the injectors of the main manifold, flanges for two pyro-plugs, a fitting for measuring air pressure behind the compressor, and a flange for fastening the adapter to the pyro-plug.
The flame tube is an annular welded structure. Fourteen cast "snail" swirlers are welded on the front wall. The main fuel manifold is made of two halves. Each has eight nozzles.
To improve the quality of the mixture and increase the reliability of starting the MD, especially at negative ambient temperatures, an additional fuel collector with fourteen centrifugal nozzles is installed in the flame tube.
3.3.3. Turbine
The turbine is designed to convert the thermal energy of the gas flow of the primary circuit into mechanical energy of rotation and drive of the compressor and units installed on the MD.
Axial two-stage turbine 11 consists of:
Nozzle apparatus of the first stage
Nozzle apparatus of the second stage
The turbine rotor consists of two wheels (first and second stages), a connecting interdisc spacer, a starting turbine wheel and a turbine shaft.
The wheels of the stages and the starting turbine are cast together with the crowns of the rotor blades. The nozzle apparatus of the first stage has 38 hollow blades and is fixed to the combustion chamber housing. The nozzle apparatus of the second stage has 36 blades. The first stage wheel is cooled by air taken from the combustion chamber housing. The internal cavity of the turbine rotor and its second stage are cooled by air taken from the fifth stage of the compressor.
The turbine rotor support is a roller bearing without an inner race. There are holes in the outer race to reduce the oil pressure under the rollers.
3.3.4. Nozzle.
In the jet nozzle 12 is mixed air currents first and second circuits. On the inner ring of the nozzle body there are 24 blades for spinning up the flow of gases leaving the starting turbine at startup, and four bosses with pins for fastening the gas generator 13. The tapering nozzle is formed by the profile of the outer wall of the MD and the surface of the gas generator body.
3.3.5. Launch system.
The starting, fuel supply and regulation system spins up the rotor, supplies metered fuel at start-up, “oncoming start” and in the “maximum” mode when starting, oxygen is supplied to the combustion chamber from an oxygen accumulator through pyro-candles.
The system consists of the following main units:
solid propellant gas generator
Pyro-candles with electric igniters
Oxygen battery
Low pressure fuel system
High pressure fuel system
Integrated engine controller (KRD)
The oxygen accumulator provides a 115 cc cylinder. The mass of the filled oxygen is 9.3 - 10.1 g.
Solid propellant gas generator (GTT) disposable is designed to spin the MD rotor when it is started. GTT consists of an empty gas generator and equipment elements: solid fuel charge 7, igniter 9 and electric igniter (EVP)
An empty gas generator consists of a cylindrical body 10 turning into a truncated cone, a cover 4 and fasteners.
A threaded hole is provided in the body for installing a fitting for measuring pressure in the GTT combustion chamber during testing. During operation, the hole is closed with a plug 11 and a gasket 12. An annular groove for the sealing ring 5 is made on the outer side of the body.
The cover has eight supersonic nozzles 1, which are located tangentially to the longitudinal axis of the GTT. The nozzles are closed with glued plugs, which ensure the tightness of the gas turbine engine and the initial pressure in the combustion chamber of the TGG, necessary for the ignition of the solid fuel charge. The cover is connected to the body by means of a nut 6. The internal cavity of the body is a combustion chamber for the charge of solid fuel and the igniter placed in it.
Fig.19. The gas generator is solid propellant.
1. Nozzle; 2. Gasket; 3. Electric igniter; 4. Lid;
5. O-ring; 6. Nut; 7. TT charge; 8. Nut;
9. Igniter; 10. Housing; 11. Plug; 12. Gasket.
The igniter is installed in the nut 8 screwed into the bottom of the housing. The charge of solid fuel is placed in the combustion chamber between the seal and the stop, which protects it from mechanical damage during operation.
The GTT is triggered when an electrical impulse is applied to the contacts of the electric igniter. Electric current heats the filaments of the electric igniter bridges and ignites the igniter compositions. The flame force pierces the igniter case and ignites the black powder placed in it. The flame from the igniter ignites the charge of solid propellant. The combustion products of the charge and the igniter destroy the nozzle plugs and flow out of the combustion chamber through the nozzle holes. Combustion products, falling on the MD rotor blades, spin it.
3.3.6. Electrical equipment.
The electrical equipment is designed to control the launch of the MD and power the rocket units with direct current during its autonomous flight.
The electrical equipment includes a turbogenerator, sensors and automation units, start-up units, a thermocouple collector and electrical communications. Sensors and assemblies automatically include air temperature sensors behind the fan, air pressure sensor behind the compressor and a sensor for the position of the metering needle installed in the fuel dispenser, an electromagnet of the dispenser control valve, an electromagnet of the stop valve.
The launch units include devices that provide preparation for the launch and launch of the DM, as well as the “counter” launch of the DM when it stalls or surges.
Active radar homing head ARGS
4.1. Purpose
The active radar homing head (ARGS) is designed to accurately guide the Kh-35 missile to a surface target in the final section of the trajectory.
To ensure the solution of this problem, the ARGS is switched on by a command from the inertial control system (IMS) when the missile reaches the final section of the trajectory, detects surface targets, selects the target to be hit, determines the position of this target in azimuth and elevation, and the angular velocity of the line of sight (LV ) targets in azimuth and elevation, range to the target and speed of approach to the target and outputs these values to the ISU. According to the signals coming from the ARGS, the ISU guides the missile to the target in the final section of the trajectory.
A target-reflector (CR) or a target-source of active interference (CIAP) can be used as a target.
ARGS can be used for both single and salvo launch of missiles. The maximum number of missiles in a salvo is 100 pcs.
ARGS provides operation at an ambient temperature from minus 50˚С to 50˚С, in the presence of precipitation and with sea waves up to 5-6 points and at any time of the day.
ARGS issues data to the ISU for aiming a missile at a target when the range to the target decreases to 150 m;
ARGS provides missile guidance to the target when exposed to active and passive interference created from target ships, ship and air cover forces.
4.2. Compound.
ARGS is located in compartment 1 of the rocket.
On a functional basis, ARGS can be divided into:
Receiving-transmitting device (PPU);
Computing complex (VC);
Block of secondary power sources (VIP).
The PPU includes:
Antenna;
Power amplifier (PA);
Intermediate frequency amplifier (IFA);
Signal shaper (FS);
Modules of reference and reference generators;
Phase shifters (FV1 and FV2);
Microwave modules.
The VC includes:
Digital Computing Device (DCU);
Synchronizer;
Information processing unit (PUI);
Control node;
Converter SKT code.
4.3. Operating principle.
Depending on the assigned operating mode, the PPU generates and radiates four types of microwave radio pulses into space:
a) pulses with linear frequency modulation (chirp) and average frequency f0;
b) pulses with highly stable frequency and phase (coherent) microwave oscillations;
c) pulses consisting of a coherent probing part and a diverting part, in which the frequency of microwave radiation oscillations varies according to a random or linear law from pulse to pulse;
d) pulses consisting of a probing part, in which the frequency of microwave oscillations varies according to a random or linear law from pulse to pulse, and a coherent distracting part.
The phase of coherent oscillations of microwave radiation, when the corresponding command is turned on, can change according to random law from impulse to impulse.
The PPU generates probing pulses and converts and pre-amplifies the reflected pulses. ARGS can generate probing pulses at the technological frequency (peacetime frequency - fmv) or at combat frequencies (flit).
To exclude the possibility of generating impulses at combat frequencies during testing, experimental and training work, the ARGS provides a toggle switch "MODE B".
When the toggle switch "MODE B" is set to the ON position, probing pulses are generated only at the frequency flit, and when the toggle switch is set to the OFF position, only at the frequency fmv.
In addition to probing pulses, the PPU generates a special pilot signal used to adjust the PPU receiving signal and organize built-in control.
VK performs digitization and processing of radar information (RLI) according to algorithms corresponding to the modes and tasks of the ARGS. The main functions of information processing are distributed between the BOI and the TsVU.
The synchronizer generates synchronizing signals and commands for controlling PPU blocks and nodes and issues service signals to the PUF that provide information recording.
CU is a high-speed computing device that processes radar data in accordance with the modes listed in Table. 4.1, under the control of the TsVU.
BOI carries out:
Analog-to-digital conversion of radar data coming from PPU;
Processing of digital radar data;
Issuance of processing results to the CC and reception of control information from the CC;
PPU synchronization.
The TsVU is designed for secondary processing of radar data and control of ARGS units and nodes in all modes of operation of the ARGS. CVU solves the following tasks:
Implementation of algorithms for switching on the operating and control modes of ARGS;
Receiving initial and current information from the IMS and processing the received information;
Reception of information from the CU, its processing, as well as the transfer of control information to the CU;
Formation of calculated angles for antenna control;
Solving AGC problems;
Formation and transfer to the IMS and automated control and verification equipment (AKPA) of the necessary information.
The control unit and the SKT-code converter ensure the formation of signals for controlling the motors of the antenna drives and the reception from the DVU and transmission to the DVU of information of the angular channel. From the CVR to the control node come:
Estimated antenna position angles in azimuth and elevation (11-bit binary code);
Clock signals and control commands.
From the SKT-code converter, the control node receives the values of the antenna position angles in azimuth and elevation (11-bit binary code).
VIP are intended for power supply of units and units of ARGS and convert the voltage of 27 V BS into direct voltages
4.4. External links.
ARGS is connected to the electrical circuit of the rocket with two connectors U1 and U2.
Through the U1 connector, the ARGS receives power supply voltages of 27 V BS and 36 V 400 Hz.
Control commands in the form of a voltage of 27 V are sent to the ARGS through the U2 connector and digital information is exchanged with a bipolar serial code.
Connector U3 is designed for control. Through it, the “Control” command is sent to the ARGS, and the integrated analog signal “Healthiness” is issued from the ARGS, information about the operability of the ARGS units and devices in the form of a bipolar serial code and the voltage of the ARGS secondary power source.
4.5. Power supply
To power the ARGS from the electrical circuit of the rocket, the following are supplied:
DC voltage BS 27 ± 2.7
Variable three-phase voltage 36 ± 3.6 V, frequency 400 ± 20 Hz.
Consumption currents from the power supply system:
In a 27 V circuit - no more than 24.5 A;
In a 36 V 400 Hz circuit - no more than 0.6 A for each phase.
4.6. Design.
The monoblock is made of a cast magnesium body, on which blocks and assemblies are installed, and a cover that is attached to the rear wall of the body. Connectors U1 - U3, technological connector "CONTROL", not used in operation, are installed on the cover, the toggle switch "MODE B" is fixed in a certain position with a protective cap (sleeve). An antenna is located in front of the monoblock. Directly on the waveguide-slotted array of the antenna are the elements of the high-frequency path and their control devices. The body of the compartment 1 is made in the form of a welded titanium structure with frames.
The cone is made of ceramic radio-transparent fiberglass and ends with a titanium ring that secures the cone to the body of compartment 1 using a wedge connection.
Rubber gaskets are installed along the perimeter of the lid and cone, ensuring the sealing of the ARGS.
After the final adjustment at the factory, before installing the monoblock into the case, all external metal parts that do not have a paintwork are degreased and coated with grease.
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