RU2215670C1 - Flying vehicle at reduced notability of power plant in radar, infra-red and acoustic ranges of waves and change of thrust vector - Google Patents

Abstract

FIELD: flying vehicles equipped with protective means. SUBSTANCE: flying vehicle is provided with screening unit mounted in flow of gas and made in form of anti-radar and anti-infra-red grids reducing acoustic notability. Anti- infra-red grid is located closer to engine of power plant as compared anti- radar grid; anti-radar grid is located after anti-infra-red grid in way opposite to direction of flight of flying vehicle. EFFECT: enhanced protection of flying vehicle due to reduced notability of power plant in all aspect of screening. 17 cl, 17 dwg

Description

 The invention relates to a means of reducing the visibility of an aircraft (LA), in particular its power plant (SU).

 Known technical solution to reduce the visibility in the radar (RL) wavelength range (US patent 4149689 from 04.17.1079) (Eisenberg GZ Antennas VHF. - M .: Communication, 1977, S. 50-56.), Which is a cone lattice of many closely spaced metal rods installed in front of the entrance to the air intake and behind the nozzle exit.

The disadvantages of the known solution:
- does not provide protection against wavelengths of infrared and acoustic ranges, since heated nozzle elements are visible through the cracks between the rods;
- does not reduce the visibility from all angles, in particular, perpendicular and close to the perpendicular generatrix of the cone;
- it does not avoid the loss of traction and an increase in the orifice of the nozzle due to the fact that the rods are located at a small distance from each other L ~ λ / 4, where λ is the wavelength of the irradiating radar.

- does not provide protection against short-range radar waves, because with decreasing wavelength, the distance between the rods decreases;
- does not provide protection for aircraft sound and supersonic range of flight speeds;
- does not provide the ability to adjust the thrust vector.

 The technical result to which the invention is directed is to provide the ability to reduce the visibility of the power plant of the aircraft in the radar, infrared, acoustic wavelength ranges, to reduce its visibility in all aspects of the shielding of the power plant, to reduce traction loss and control the thrust vector of the power plant .

 This result is achieved in that in an aircraft with a device for reducing the visibility of the power plant in the radar, infrared and acoustic wavelength ranges, containing a shielding device installed in the gas stream. The specified shielding device is made in the form of anti-radar and anti-infrared gratings that reduce acoustic signature, and the anti-infrared grating is located closer to the engine of the power plant than the anti-radar grating. The anti-radar array is located behind the anti-infrared array in the direction against the flight of the aircraft.

 Lattices can be made with the possibility of interconnecting detachable connection or as a whole. In the latter case, parts of the ribs of the anti-infrared grating are installed between the ribs of the anti-radar grating.

 The ribs of the anti-infrared grating can be made inclined or profiled to smoothly change the direction of gas flow. The input and output sections of each channel do not overlap in projection onto a vertical plane.

 The edges of the anti-infrared grating can be made radial and coated with radar absorbing material.

 Lattices can be located in the subsonic or sound part of the nozzle.

 The aircraft is equipped with a cleaning mechanism for at least one of the grilles in the aircraft body to eliminate traction loss and when low visibility is not required.

To change the thrust vector of the power plant, the device is made rotary or the ribs of the anti-infrared grating are made rotary. With a supersonic nozzle, the device does not protrude beyond the critical section of the nozzle, and the angle between the surface of the supersonic part of the nozzle and the outer surface of the device exceeds 90 ^o .

 The surface of the nozzle between the grill and the critical section of the nozzle may be coated with radar absorbing material. In the subsonic or sound part of the nozzle, slots are made for the movement of the device in them when cleaning it and / or when adjusting the characteristics of the nozzle.

 For a supersonic nozzle, the device is made with the possibility of eliminating the complete overlap of the nozzle, for example, when flying on a cruise mode.

The device can also be made of two wings with the formation between them in the closed state of an angle of 100-110 ^o .

 The invention is illustrated by drawings.

Figure 1 shows a diagram of an aircraft engine with a subsonic nozzle;
figure 2 - diagram of an adjustable supersonic nozzle;
figure 3 - diagram of the anti-radar grid;
figure 4 - diagram of the options anti-infrared grating;
figure 5 - the effectiveness of the proposed nozzle device;
in FIG. 6 - indicatrix of infrared radiation without devices to reduce visibility;
in FIG. 7 - indicatrix of infrared radiation using a device to reduce visibility;
on Fig is a graph of the temperature of combustion of thermal false targets over time;
figure 9 is a variant of a universal device for a supersonic nozzle;
figure 10 - diagrams of various lattices for a subsonic and sonic nozzle and the influence of their type on the loss of traction SU;
in FIG. 11 is a diagram of an embodiment of a visibility reduction device with a thrust vector rotation function;
in FIG. 12 is a diagram of a control system with a visibility reduction device having a function of rotating a thrust vector;
on Fig - part of the anti-infrared grating;
in FIG. 14 is a schematic flat nozzle with a device for reducing visibility;
on Fig - lattice with radial ribs;
in Fig.16 - installation of the grill before entering the SU;
on Fig is a graph of the decrease in the time of hearing the volume in time.

 The device to reduce the visibility of the power plant 1 contains an anti-radar grid 2 and an anti-infrared grid 6.

 The device operates as follows.

 1. In the radar wavelength range.

 When an aircraft is irradiated from the rear hemisphere (RPS) of an adversary’s radar station (radar), electromagnetic waves do not enter SS 1 due to the presence of the anti-radar array 2 of the proposed universal device (shielding device) 3.

Missing electromagnetic energy in the nozzle 4 SU 1 is achieved by the fact that the sizes of the cells 5 of the lattice are selected accordingly. So, with a square cell, its size A (Fig. 3) should be no more than λ / 2, where λ is the length of the irradiating radar, and the depth W of the cell is determined from the relation:
P = P _o • 1 ^{-2β · W} ,
where W is the depth of the channel,
β - coefficient (determined by the schedule on p. 56 [2]),
P is the energy passed through the lattice,
P ₀ is the incident energy.

 Depending on the requirements for reducing visibility, P is equal to zero or any small value and, with known β, it is W. The thickness D is selected according to the strength conditions of the device. In this case, the energy does not fall into the SU of the aircraft (P = 0) and its visibility in the radar range (effective scattering surface σ) decreases by almost two orders of magnitude (Fig. 5).

 2. In the infrared wavelength range.

 On various parts of the control system (Fig. 1), the numbers 1 through 12 are marked with points, the temperature of which is shown in table 1 for one of the control modes.

The table shows that the lowest temperature at the nozzle exit (point 6). Therefore, if you screen hot spots and make sure that the thermal homing head (TGS) of the rocket "sees" only the nozzle section, then the probability of failure of its guidance on the SU aircraft is equal to one, since the TGS responds to a temperature of 430-650 ^o .

The function of the screen is performed by the anti-infrared lattice 6 of the proposed device 3. Its channels 7 (Fig. 4) are made in such a way that the SU hot spots are completely invisible from any viewing angle. To do this, they are made inclined or profiled (to gradually turn the flow in order to reduce traction loss) so that from any angle (± 90 ^o in azimuth and ± 90 ^o in elevation), the rear (against flight) end face of rib 8 is higher front end of the superior rib.

где Φ - мощность теплового излучения,
ε - коэффициент излучения,
к - постоянная, равная 5,6,7•10^-12 Вт/(см²• град⁴),
S - величина излучающей поверхности,
ν - пространственный угол.This method allows to reduce the radiation intensity of the control system by an order of magnitude (Fig.6, 7), calculated according to the Stefan-Boltzmann law:

where Φ is the power of thermal radiation,
ε is the emissivity,
k is a constant equal to 5.6.7 • 10 ^-12 W / (cm ² • city ⁴ ),
S is the magnitude of the radiating surface,
ν is the spatial angle.

 Since the radiation intensity J depends on the temperature of the heated body and if the temperature conditions of the control system are higher than those given (for example, in the afterburner modes of supersonic nozzles - Fig. 2), the efficiency of this method remains high even when using false thermal targets (LTC), since a much smaller number of them will be required than in the absence of a device (the time dependence of the LTC burning temperature is shown in Fig. 8). It can be seen that the lower the temperature, after which it is necessary to shoot the next LTC, the longer the time between shoots, i.e. the amount of spent LTC decreases by about 2–3 times.

All of the above applies to subsonic, sonic and supersonic nozzles. In this case, for supersonic nozzles (figure 2), the surface of the device 3 should be an obtuse angle β with the surface of the supersonic part 9 of the nozzle to avoid corner reflectors. The angle should be at least 100-110 ^o . If this cannot be ensured, then the surface of the subsonic part 10 (Fig. 9) of the nozzle between the device 3 and the critical section of the nozzle 10 should be coated with a radar absorbing material 11.

 The influence of the device on traction loss (FIGS. 5, 10) shows that the device causes traction loss of ~ 3%, with the share of the anti-radar array being ~ 1%, and the share of anti-infrared is ~ 2%. To avoid these losses, the device 3 can be moved out of the stream when the stealth mode is not required. To do this, in the subsonic or in the sound part of the nozzle, slots 12 are made, through which the gratings are removed into the aircraft body 13 using, for example, cylinder 14 (Fig. 2). These slots 12 can serve to move the movable flaps 15 and 16 of the nozzle while adjusting its thrust (figure 2). In FIG. 10 are given including schemes of a universal device in 2 versions: with separately made anti-radar and anti-infrared gratings (option 5a), and a universal device made as a single unit of two gratings (option 5b). In this case, the anti-radar array is installed between the ribs of the anti-infrared array, which reduces the mass of the device.

 Thus, the proposed device can reduce the visibility of SU with ZPS approximately two orders of magnitude in the radar range and more than an order of magnitude in the infrared wavelength range.

 The thrust vector control is as follows.

 A technical solution is known for rotating the thrust vector either with the help of rotary flaps (Fig. 12) for a flat nozzle [4], or with the help of a rotary nozzle (Fig. 11) for round nozzles [5]. The disadvantage of these devices is that a device for reducing visibility must be installed additionally, which will lead to an increase in the mass of the aircraft and complicates the design. Their common drawback is cumbersome, design complexity, large mass.

 The aim of the invention is to expand the functionality of the device to reduce the visibility of SU LA with ZPS, due to measures allowing it to perform the functions of a nozzle with rotation of the thrust vector.

 This goal is achieved by the fact that the power plant is equipped with a shielding device consisting of anti-radar and anti-infrared gratings and installed in a gas stream. At the same time, the device is made rotatable to change the vector in any given direction, while maintaining the properties of the means of reducing visibility in the radar, infrared ranges, in the acoustic range. The device may be located in the subsonic or sound part of the nozzle.

 The device operates as follows.

 1. In terms of reducing the visibility of SU.

 In the radar range does not differ from the foregoing.

 In the infrared range, the difference lies in the fact that the ribs 8 of the anti-infrared grating 6 have a larger bend at the same length, or a longer length than in the previous version, so that when turning the universal device 3 through the angle α, the nozzle hot spots were not visible (Fig. fifteen).

 2. In terms of changes in the thrust vector.

 The device comprises (Fig. 14) a universal grill 3, pivotally mounted on the housing 17 of the power plant 1 using, for example, three cylinders 18, providing the rotation of the grill 3 in any direction to a predetermined maximum deflection angle α (Fig. 15).

 The installation of a universal lattice in a flat nozzle allows you to expand the functionality of the nozzle (Fig. 5): if without a universal device the thrust vector changes only in pitch, then the universal device rotates in any direction, which is provided, for example, by 3 cylinders 18, allows you to change the thrust vector in any direction (Fig. 16). A change in the thrust vector can also be obtained by rotating the ribs of the lattice 6 using, for example, a cylinder 19. The ribs are mounted on the axles 20 and combined by a thrust 21 (Fig. 13).

 The channels 7 of the lattice 6 of the device 3 can be of arbitrary shape, including can be formed by radial curved partitions (Fig.17). In this case, the partitions are curved along the length so that through the channels formed by them the power plant elements are not visible from any angle. Such a lattice can be installed in front of the control system (Fig. 18) to reduce visibility both in the radar wave range (especially when covering the partitions with special material) and in the acoustic one.

 The device reduces the visibility of SU with ZPS and provides a change in the thrust vector in any direction. At the same time, the design is simplified, the functions of the control system are expanded, and the increase in mass is insignificant.

 The operation of a universal device in the acoustic wavelength range.

 The main elements that create noise are the engine jet and fan. The noise from the fan rotating at high speed is suppressed by the grill facing the control system. The lattice behind the SU reduces the noise intensity by ~ 5-6 dB, i.e. more than 3 times; while reducing the hearing range of the aircraft by 30% (Fig.19). Using gratings, one of the most important problems of aircraft that take off and land from airfields located near settlements can be solved.

где V - скорость потока,
d - характерный размер отверстия истечения,
k - частота колебаний частиц в потоке.Noise reduction using gratings is as follows. The noise of a gas engine jet (the main source of noise on an airplane) is explained by its turbulence and is characterized by the Strouhal number:

where V is the flow rate,
d is the characteristic size of the outflow opening,
k is the frequency of oscillation of particles in the stream.

 At the same flow rate, a decrease in the flow cross section causes an increase in the frequency, and a higher frequency decays faster in air - see Fig. 19, which reduces the range with which the plane is heard.

Sources of information
1. US patent 4149689 from 04.17.1979.

 2. Eisenberg G.Z. VHF antennas. - M .: Communication, 1977, p. 50-56.

 4. Technical information, 11. - M.: TsAGI, 1988.

 5. Review of TsAGI, 608. - M .: TsAGI, 1982.

Claims (18)

 1. Aircraft with a device for reducing the visibility of the power plant in the radar, infrared and acoustic wavelength ranges, containing a shielding device installed in the gas stream, characterized in that the shielding device is made in the form of anti-radar and anti-infrared gratings that reduce acoustic signature, moreover, anti-infrared the grill is located closer to the engine of the power plant than the anti-radar grille.  2. The apparatus according to claim 1, characterized in that the anti-radar array is located behind the anti-infrared array in the direction against the flight of the aircraft.  3. The apparatus according to p. 1 or 2, characterized in that the grilles are made with the possibility of interconnection by detachable connection.  4. The apparatus according to claim 1 or 2, characterized in that the anti-radar and anti-infrared gratings are made as a single unit.  5. The apparatus according to claim 4, characterized in that the parts of the ribs of the anti-infrared grating are installed between the ribs of the anti-radar grating.  6. The apparatus according to any one of paragraphs. 1-5, characterized in that the ribs of the anti-infrared grating are made inclined or profiled to smoothly change the direction of gas flow.  7. The apparatus according to claim 6, characterized in that the input and output sections of the channels of the lattice do not overlap each other in projection onto a vertical plane.  8. The apparatus according to any one of paragraphs. 1-7, characterized in that the edges of the infrared array are made radial and coated with radar absorbing material.  9. The apparatus according to any one of paragraphs. 1-8, characterized in that the gratings are located in the subsonic or sound part of the nozzle.  10. The apparatus according to any one of paragraphs. 1-9, characterized in that it is equipped with a mechanism for removing at least one of the gratings.  11. The apparatus according to any one of paragraphs. 1-10, characterized in that for changing the thrust vector of the power plant, the shielding device is made rotary.  12. The apparatus according to any one of paragraphs. 1-10, characterized in that for changing the thrust vector of the power plant, the ribs of the anti-infrared grating are made rotary.  13. The apparatus according to any one of paragraphs. 9-12, characterized in that with a supersonic nozzle the shielding device does not protrude beyond the critical section of the nozzle. 14. The apparatus according to any one of paragraphs. 9-13, characterized in that the angle between the surface of the supersonic part of the nozzle and the outer surface of the shielding device exceeds 90 ^o .  15. The apparatus according to any one of paragraphs. 1-13, characterized in that the surface of the nozzle between the grating and the critical section of the nozzle is coated with a radar absorbing material.  16. The apparatus according to any one of paragraphs. 9-15, characterized in that in the subsonic or sound part of the nozzle, slots are made for the movement of the shielding device in them when it is removed and / or when adjusting the characteristics of the nozzle.  17. The apparatus according to any one of paragraphs. 9-16, characterized in that for the supersonic nozzle the shielding device is configured to eliminate the complete overlap of the nozzle. 18. The apparatus according to any one of paragraphs. 1-17, characterized in that the shielding device is made of two wings with the formation between them in the closed state of an angle equal to 100-110 ^o .

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