J20 Stealth Fighter

Karthi

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@scatterStorm yes bro Shaurya is in service, and is the most produced Missile in Indian inventory.


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From the first page to this page on this thread everyone is saying the same thing , Canards reduces the Stealth of J20, it's completely untrue , yes Canards just add a little bit I think it's almost negligible . If J20 has stealth then it is only from the front. From the pictures posted above you can clearly see the Side view of J20s which is like a wall.

2020-09-09-15-13-49.jpg


This one huge surface is enough for detecting the J20 from distances , applying RAM materials and Paints may reduce a bit . The surface is slightly angled but may not be good enough.

Another serious drawback is underpowered Engine it affects manuverablity to Radar Power , EW power and performance.

FC 31 is somewhat more stealthy. F22 also less Stealthy from sideways , but it is much better treated , clean and less surface are compared to J20 .

Still I won't think J20 is a bad Aircraft it can pose threats , but no way near what Chinese claims , they have the habit of gradually upgrading the systems , so in the next two or three iterations it will be more perfect and lethal .

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F22 side looks much much better than J20
 

MiG-29SMT

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@scatterStorm yes bro Shaurya is in service, and is the most produced Missile in Indian inventory.




From the first page to this page on this thread everyone is saying the same thing , Canards reduces the Stealth of J20, it's completely untrue , yes Canards just add a little bit I think it's almost negligible . If J20 has stealth then it is only from the front. From the pictures posted above you can clearly see the Side view of J20s which is like a wall.



This one huge surface is enough for detecting the J20 from distances , applying RAM materials and Paints may reduce a bit . The surface is slightly angled but may not be good enough.

Another serious drawback is underpowered Engine it affects manuverablity to Radar Power , EW power and performance.

FC 31 is somewhat more stealthy. F22 also less Stealthy from sideways , but it is much better treated , clean and less surface are compared to J20 .

Still I won't think J20 is a bad Aircraft it can pose threats , but no way near what Chinese claims , they have the habit of gradually upgrading the systems , so in the next two or three iterations it will be more perfect and lethal .



F22 side looks much much better than J20
The importance of the RCS relies on the fact that it takes part in the radar equation, affecting directly the maximum detection range of a target. The fundamental form of the radar equation is as follows ([17]): 136 Low Observable Principles, Stealth Aircraft and Anti-Stealth Technologies where is the maximum detection range, the transmission power, and the gain and the effective area of the transmitting and receiving antennae (which coincide in the monostatic radar), is the RCS of the target and the minimum detectable signal. Therefore, for given radar parameters , , and , the maximum detection range is proportional to the 4th root of the target RCS: .

1599691454396.png

In fact, the monostatic or backscatter RCS depends on the following ([18]):  Target geometry  Target material composition, especially for the surface K. C. Zikidis et al. 137  Position of radar antenna relative to target  Angular orientation of target relative to radar antenna  Frequency of the electromagnetic energy  Radar antenna polarization





1 Shaping The most important factor affecting the RCS is the geometry or the shape of the target, not its size. In order to reduce the RCS, the surfaces and edges should be orientated in such way so as to reflect the radar energy away from an expected radar antenna and not back to it. Considering the flat surfaces (facets) and the acute angles of the F-117, it is understood that it was designed in a way that the expected radar energy would be reflected to irrelevant directions and not back to the emitting radar. The designers tried to avoid any possible surface or edge whose normal vectors would look at a direction where a possible enemy radar might be found, especially for the frontal aspect.


Therefore, in the frame of RCS reduction, all bumps, curves etc should be avoided. In the same way, any external load (pylons, bombs, missiles, fuel tanks, pods) would considerably augment the total RCS. This is the reason why l.o. aircraft carry their armament internally, in special bays. Furthermore, armament bay and landing gear bay doors should close tightly, with no gaps in between. Generally, any irregularity of the surface could incur an RCS increase. Propellers are strictly forbidden, while the first stage engine blades should be carefully hidden inside the intake duct. The whole air intake construction is critical, when designing a low RCS aircraft.
Sharp dihedral corners and parallel surfaces contribute also to the RCS. Therefore, the twin vertical fin empennage, as in the classic F-15E (not the F-15SE), is prohibited. Stealth aircraft have either canted tail fins or no tail fin at all (as in the B-2 Spirit). Regarding existing stealth aircraft, it is also evident that the leading edges of the wings and of the horizontal tail fins (stabilizers) are parallel. This applies to the trailing edges, as well. The aim is always the same: reflect the radar energy to certain, irrelevant directions, and thus keeping the (monostatic) RCS low. Conventional (mechanically scanning) radar antennas should also be avoided, since the antenna itself is an ideal radar energy reflector, increasing the RCS when another radar is looking at it. For this reason, the F-117A carried no radar at all. More recent l.o. aircraft make use of electronically scanned array radars, which offer lower RCS contribution, notably AESA (Active Electronically Scanning Array) radars. Furthermore, these radars should exhibit LPI (Low Probability of Intercept) characteristics, in an attempt to avoid detection by enemy ESM (Electronic Support Measures) systems, trying to detect and locate radar emissions. Apart from the reduction of the aerodynamic drag, which is a positive sideeffect of the absence of external loads, optimizing the aircraft design for RCS reduction is generally incompatible with the aerodynamic principles.




1599692205262.png


less elements or reflectors of a target less interference paterns in the RCS, thus ventral fins increase RCS


1599692319274.png




A metasurface based on defect lattices and an alternative physical mechanism, multiwave destructive interference (MWDI), is proposed for ultrawideband radar cross-section (RCS) reduction. The bandwidth of RCS reduction (σR) Is greatly expanded by second destructive interference. The metasurface is composed of 16 basic defect lattices. First, the defect lattice can generate primary destructive interference with the capacity of RCS reduction and amplitude-phase manipulation, which consists of an aperiodic array of square rings with an embedded cross. Second, the interference between multiple backscattered waves produced by the defect lattices at multiple frequencies sampled in an ultrawide band is simultaneously manipulated and optimized by the principle of superposition of waves and particle swarm optimization (PSO) to obtain second destructive interference. The metasurface enables a 10-dB RCS reduction over an ultrawide frequency band ranging from 6.16 to 41.63 GHz with a ratio bandwidth (fH/fL) of 6.76:1 under normal incidence for both polarizations. The estimated, simulated, and measured results are in good agreement and prove that the proposed metasurface is of great significance for bandwidth expansion of RCS reduction.



6.1.2 Flying Wing Flying wing is an ideal stealth shape for aircrafts. It minimizes the number of leading edges, which in turn, reduces radar echo signals.

1599691454396.png
1599692205262.png
1599692319274.png
 
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Karthi

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The importance of the RCS relies on the fact that it takes part in the radar equation, affecting directly the maximum detection range of a target. The fundamental form of the radar equation is as follows ([17]): 136 Low Observable Principles, Stealth Aircraft and Anti-Stealth Technologies where is the maximum detection range, the transmission power, and the gain and the effective area of the transmitting and receiving antennae (which coincide in the monostatic radar), is the RCS of the target and the minimum detectable signal. Therefore, for given radar parameters , , and , the maximum detection range is proportional to the 4th root of the target RCS: .

View attachment 58763
In fact, the monostatic or backscatter RCS depends on the following ([18]):  Target geometry  Target material composition, especially for the surface K. C. Zikidis et al. 137  Position of radar antenna relative to target  Angular orientation of target relative to radar antenna  Frequency of the electromagnetic energy  Radar antenna polarization





1 Shaping The most important factor affecting the RCS is the geometry or the shape of the target, not its size. In order to reduce the RCS, the surfaces and edges should be orientated in such way so as to reflect the radar energy away from an expected radar antenna and not back to it. Considering the flat surfaces (facets) and the acute angles of the F-117, it is understood that it was designed in a way that the expected radar energy would be reflected to irrelevant directions and not back to the emitting radar. The designers tried to avoid any possible surface or edge whose normal vectors would look at a direction where a possible enemy radar might be found, especially for the frontal aspect.


Therefore, in the frame of RCS reduction, all bumps, curves etc should be avoided. In the same way, any external load (pylons, bombs, missiles, fuel tanks, pods) would considerably augment the total RCS. This is the reason why l.o. aircraft carry their armament internally, in special bays. Furthermore, armament bay and landing gear bay doors should close tightly, with no gaps in between. Generally, any irregularity of the surface could incur an RCS increase. Propellers are strictly forbidden, while the first stage engine blades should be carefully hidden inside the intake duct. The whole air intake construction is critical, when designing a low RCS aircraft.
Sharp dihedral corners and parallel surfaces contribute also to the RCS. Therefore, the twin vertical fin empennage, as in the classic F-15E (not the F-15SE), is prohibited. Stealth aircraft have either canted tail fins or no tail fin at all (as in the B-2 Spirit). Regarding existing stealth aircraft, it is also evident that the leading edges of the wings and of the horizontal tail fins (stabilizers) are parallel. This applies to the trailing edges, as well. The aim is always the same: reflect the radar energy to certain, irrelevant directions, and thus keeping the (monostatic) RCS low. Conventional (mechanically scanning) radar antennas should also be avoided, since the antenna itself is an ideal radar energy reflector, increasing the RCS when another radar is looking at it. For this reason, the F-117A carried no radar at all. More recent l.o. aircraft make use of electronically scanned array radars, which offer lower RCS contribution, notably AESA (Active Electronically Scanning Array) radars. Furthermore, these radars should exhibit LPI (Low Probability of Intercept) characteristics, in an attempt to avoid detection by enemy ESM (Electronic Support Measures) systems, trying to detect and locate radar emissions. Apart from the reduction of the aerodynamic drag, which is a positive sideeffect of the absence of external loads, optimizing the aircraft design for RCS reduction is generally incompatible with the aerodynamic principles.




View attachment 58768

less elements or reflectors of a target less interference paterns in the RCS, thus ventral fins increase RCS


View attachment 58769



A metasurface based on defect lattices and an alternative physical mechanism, multiwave destructive interference (MWDI), is proposed for ultrawideband radar cross-section (RCS) reduction. The bandwidth of RCS reduction (σR) Is greatly expanded by second destructive interference. The metasurface is composed of 16 basic defect lattices. First, the defect lattice can generate primary destructive interference with the capacity of RCS reduction and amplitude-phase manipulation, which consists of an aperiodic array of square rings with an embedded cross. Second, the interference between multiple backscattered waves produced by the defect lattices at multiple frequencies sampled in an ultrawide band is simultaneously manipulated and optimized by the principle of superposition of waves and particle swarm optimization (PSO) to obtain second destructive interference. The metasurface enables a 10-dB RCS reduction over an ultrawide frequency band ranging from 6.16 to 41.63 GHz with a ratio bandwidth (fH/fL) of 6.76:1 under normal incidence for both polarizations. The estimated, simulated, and measured results are in good agreement and prove that the proposed metasurface is of great significance for bandwidth expansion of RCS reduction.



6.1.2 Flying Wing Flying wing is an ideal stealth shape for aircrafts. It minimizes the number of leading edges, which in turn, reduces radar echo signals.

View attachment 58763View attachment 58768View attachment 58769

What?
 
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MiG-29SMT

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1599713592285.png



1599714799722.png

The direction of incident radar waves is an important consideration. If the aircraft will be illuminated from below, put engines on top of the wing.

(!) SHIELD INLETS. The inlets can be shielded by the fuselage. Locating the engines on top when radar is below A/C will help. If engine performance permits the use of wire mesh over the inlet, the RCS can be reduced. Mesh spacing is small fraction of X.
(2) CANT RUDDERS INWAIS. The surface normal vector n is moved upward. The big RCS which occurs when k and n are parallel will occur only when radar is above the A/C. Also when a rudder-Ilevator combination is used, the retroreflector of the dihedral is avoided.

(3) SHIELD NOZZLES. The comments for inlets apply.

(4) ROUND WING TIPS. Use the formula a - vplP2 . A rounded wing tip has small P1 and p2 .
(5) CANT FUSELAGE SIDES. This tips the surface normal n upward. For low RCS, do not have n pointing toward the radar!

(6) BLEND COMPONENTS. Waves are scattered by discontinuities in slope, curvature, etc. Blending minimizes the geometrical discontinuities

. (7) MINIMIZE BREAKS AND CORNERS. Any shape resembling a retroreflector is bad. As shown in viewgraph 1, gaps scatter EK waves.
(8) PUT ORDNANCE LOAD INSIDE AIRCRAFT. This would make both the aerodynamicists and radar engineers happy. However, internal storage may not be possible. Drag equals qCDA. Internal storage may give large A.

(9) ELIMINATE BUMPS AND PROTRUSIONS. The comments of items (6) and (7) apply here. Use retractable covers over gun parts. (1
0) USE BANDPASS RADOME. An opaque radome at the search radar wavelength eliminates this problem.

(11) USE LOW PROFILE CANOPY. Ever since the SPAD, aviators want to see. Dog-fights require good visibility. Having said that, a low profile canopy with gold plating will have much lower RCS. The thin layer of gold (or other metal) plated on the canopy screens out microwaves.

(12) SWEEP LE. The A/C is frequently illuminated by a search radar from nose-on aspect. A swept LE is one way to reduce RCS. There are two philosophies in regard to LE shape. A straight LE concentrates a big RCS in a narrow lobe. If the search radar is never in that lobe, the A/C cannot be detected because of LE return. A curved LE spreads a smaller RCS over a wide angle. Although RCS is spread over a large angle, RCS is small. FINAL NOTE: Think of A/C as a porcupine with surface normal vectors n as quills. Don't have any quills pointing toward radar!
1599714564458.png





1599713807925.png
 
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AZTEC

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Former R&AW Chief Vikram Sood has confirmed that China used stolen stealth tech from the American F-117 to make J-20. China एक नंबर का चोर है!

Here’s the excerpt from his book:
“On 27 March 1999, during the Kosovo war, a Serbian military missile brought down an F-117 Nighthawk—a first-of-its-kind US Stealth fighter. Among the first at the site of the crash were Chinese agents who scoured the countryside and bought up any parts they could find from the local farmers. In 2011, a few days before the US secretary of defence was to visit Beijing, photographs appeared in the Chinese media of J-20, stated to be the prototype of the PLA Air Force’s stealth aircraft. It soon became clear that the J-20 was manufactured with the help of spare parts and damaged equipment from the F-117 Nighthawk.”

Excerpt From
The Unending Game: A Former R&AW Chief’s Insights into Espionage
Sood, Vikram
Source: Google Books
 

johnq

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It's funny how the J-20 is supposed to be a classified program, but the Chinese psy ops propagandists manage to release new pictures every week, and with so many close-ups and different angles.:rofl:
The Chinese propagandists sure post some shiny, perfect-looking close-ups of the J-20. Many of them don't even show exhaust contrails or other contrails from wings etc that result from normal aircraft, and are present in real photographs. Maybe it's something the Chinese psy ops propaganda graphics department can improve upon. :rofl:
In any case, the J-20 has a crap engine and a crap radar. Its radar-radome combination, canopy, canards and other control surfaces, inlets, etc. are visible to radar, which is why it's not stealthy, and which is why the SU-30MKI radar was able to track it. The only real value of this barbie doll aircraft is for a propaganda psy ops purpose; in any real battle with the IAF, this toy of the PLAAF will be decimated.
 
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silentlurker

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Many of them don't even show exhaust contrails or other contrails from wings etc that result from normal aircraft, and are present in real photographs.
??? Most planes in level flight don't show exhaust or wingtip vortexes. They show up when the plane has AB on, or is banking hard. Look, none of these photos have any contrails.

 

johnq

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Please, it's so obvious that the images of the J-20 posted on the internet by Chinese fanboys are graphically enhanced. :rofl:
I've heard enough from "people in the know" that I am aware that Chinese engine and radar technology is much worse in reality than depicted on shiny propaganda brochures distributed by the Chinese Communist Party drones. But I don't blame the Chinese drones for believing the Chinese Communist Party propaganda since they have been brainwashed by the Chinese government. Even the Jf-17 is still powered by Russian engines because Chinese engines are crap, and Pakistan chose a non-Chinese radar for its JF-17s because Chinese radar technology is crap. The designers of the J-20 were not even able to make the radar and radome stealthy beyond just canting it at an angle, which is why they kept the canards in spite of it affecting RCS negatively. This is why the SU-30MKI radar is able to track the J-20, because the Chinese don't have the western level of bandpass radome technology to reduce the radar/radome RCS. Ask anyone who knows remotely about stealth design, and they will tell you that the J-20 is NOT STEALTHY given multiple radar reflecting surfaces that would not be present in a legitimate stealth aircraft. Its avionics also suck as they are copies of severely downgraded Russian avionics from the 1990's; even Russia gives only severely downgraded technology to China. Only brainwashed Chinese drones buy the propaganda sold by the Chinese Communist Party in shiny brochures. The rest of us know better. The J-20 is just another Chinese Communist Party propaganda psy ops project designed to impress people with a limited understanding of technology and how Chinese propaganda BS works.
 

silentlurker

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So are those images of the MKI graphically enhanced too? They don't have contrails either.
 

johnq

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It's funny how the J-20 is supposed to be a classified program, but the Chinese psy ops propagandists manage to release new pictures every week, and with so many close-ups and different angles.:rofl:
The Chinese propagandists sure post some shiny, perfect-looking close-ups of the J-20. Many of them don't even show exhaust contrails or other contrails from wings etc that result from normal aircraft, and are present in real photographs. Maybe it's something the Chinese psy ops propaganda graphics department can improve upon. :rofl:
In any case, the J-20 has a crap engine and a crap radar. Its radar-radome combination, canopy, canards and other control surfaces, inlets, etc. are visible to radar, which is why it's not stealthy, and which is why the SU-30MKI radar was able to track it. The only real value of this barbie doll aircraft is for a propaganda psy ops purpose; in any real battle with the IAF, this toy of the PLAAF will be decimated.
Looks like the Chinese propaganda psy ops department took my advice. Lots of contrails in new images. It still doesn't explain how they get so many new photographs of J-20 every week in spite of it being a super duper classified program in China, or why Chinese propagandists must post these pictures every week in forums? Unless it's a part of Chinese psy ops propaganda. :rofl:
And its only worth is psy ops, because the J-20 has a crappy radar copied from a severely downgraded Russian radar from 90s, no stealth (since it doesn't have a way to shield its radar from being tracked from the front, as proven by the SU-30MKI's ability to track it), and currently relies on Russian engines that it had to pull out of imported SU-35s, just so it could fly for its propaganda photo op. Hmm, I wonder why China had to import SU-35s from Russia if its aircraft radar and engine have such super duper technology? :rofl:
 
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