J20 Stealth Fighter

rockdog

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typical Chinese forum claim, an ignorant member claims something, other people just repeat the same none sense.


Are you aware there are radar blockers?

Stealth has two ways to shield the inlet duct, one in S ducts, that allow for side internal weapons bays, the other is inlet duct Radar blockers that allow for shorter, lighter and cheaper inlet ducts.

View attachment 73795

radar blocker F-18E

View attachment 73796

inlet duct radar blocker X-32


While the engine fan blades seem to be visible on the Boeing concept–a no-no in stealth design–Boeing program manager Frank Statkus said the blades are hidden by a blocker, which is a new approach to stealth. The X-32 meets all the Pentagon’s requirements for stealth, Statkus said.
1. They are the compensation sfor the no-good design toward stealth.
Neither original F18 and F16 are designed for stealth capability, that's why they are testing this kind of intake. What i m surprised is that Su57 as an 5G still need such compensation after 10 yrs.

2. I wanna hear your POV that, why India quit the Su57 project after invested massively on it. If it's really has such powerful desgin and stealth capability.
 

MiG-29SMT

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1. They are the compensation sfor the no-good design toward stealth.
Neither original F18 and F16 are designed for stealth capability, that's why they are testing this kind of intake. What i m surprised is that Su57 as an 5G still need such compensation after 10 yrs.

2. I wanna hear your POV that, why India quit the Su57 project after invested massively on it. If it's really has such powerful desgin and stealth capability.
typical east asian assumption of Superiority over Russia, there is a few technical question you should know.

X-32 needed excellent flow, do you know why? well X-32 was a V/STOL design, thus needed high quality flow, the solution was a straight duct, same as Su-57 that over stresses good air quality in the tunnel.

Radar blockers are used when you need high quality air.

F-35B has a intake above the fuselage to add air, X-32 did not need that so a straight duct was founded better

J-20 while presented by fantasy as a Mach 2.5 fighter, in reality top ups around 1.8 Mach due to intake design.

Su-57 has a truely Mach 2.5 intakes but if you go faster the quality of the air goes down.

A long duct generates like any surface a boundary layer, longer the duct thicker boundary layer.
S ducts are longer, an ideal duct is straight for a high speed machine

1610690044298.png


If you look at this MiG-25 you can see it has a straight duct.

1610690139788.png


F-15 the same
1610690172284.png


Tomcat the same.

So I will tell you what you can not see.

Su-57 is designed to be faster and more fuel economical than F-22.

a better air intake means a better engine combustion.

J-20 is designed like F-35 for low speeds specially if it uses Al-31, it means 1.8 Mach at the most with no supercruise capability now.

With WS-10C maybe might catch up with Su-35.

But in reality Su-57 is faster, having Type 30 and variable geometry intake with less curved and shorter intake duct means It will supercruise better and fly faster.
 
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rockdog

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Russia has managed to lower the radar signature of its first stealth jet, the Su-57, by adding a new grille to the air intakes.

Photographs of the modified jet with coaxial radial grating were shared by the Russian media today.

The grating is made of radar absorbing material and is placed in the air intakes of the Su-57. In comparison, Lockheed Martin has used an S-channel design for the intakes of the F-22 aircraft to reduce the direct frontal transmission of radar by the engine compressor blades.


View attachment 73797

Su-57 aircraft's new air intake grille (via local media)

For many details, the Su57 is lack of stealth design:

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IRST:

hhj.jpg


EODAS and IRST from J20

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typical Chinese forum claim, an ignorant member claims something, other people just repeat the same none sense.
The intetresting thing is, in our military forum, there are lots of posters from the aviation industry, even some guys are from Insitutue 611, 601. There are much more technical analysis comparing here.

At least i don't expect any guy with design or production on 5g fighter experiences here ...

We are all amateurs, don't pretend guru here, at least as Mexican background.
 
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MiG-29SMT

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For many details, the Su57 is lack of stealth design:

View attachment 73811

View attachment 73812

View attachment 73813


IRST:

View attachment 73817

EODAS and IRST from J20

View attachment 73818

View attachment 73819



The intetresting thing is, in our military forum, there are lots of posters from the aviation industry, even some guys are from Insitutue 611, 601. There are much more technical analysis comparing here.

At least i don't expect any guy with design or production on 5g fighter experiences ...

We are all amateurs, don't pretend guru here, at least as Mexican background.
physics do not change, get it a longer ducts has more trouble feeding air to the engine, air over a surface generates a boundary layer, if the S duct does to radar it also does to air, you get better radar shielding true, but you get worse air quality, i highly recommend you read more, there are ample number of papers about the pros and cons of S ducts.

In fact the Russian patent says Su-57 has a less curved intake duct for the same reason, plus longer ducts mean more material so they make the aircraft intake duct longer and heavier.

X-32 whent takes off is not moving so it needs a large intake area, a straigh duct was found to be better.

I do not care your military forum, I care about aeronautical studies. F-15 or MiG-25 are faster than most aircraft, even F-14 was a speedy machine, they had straight ducts for a reason no matter how much you excuse your ignorance, you will not cover the sun with a finger.

Get it what a S duct does to radar waves, also does it to the air quality that feeds the engine.

Compromises are taken, engineering is compromises, fans like you are just cheer leaders.

X-32 and Su-57 use radar blockers and F-18E too.
 

MiG-29SMT

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1610692342820.png


3. Physical Phenomena and Approach to Assess Boundary Layer Ingestion A number of different phenomena impact the benefits of BLI. While these were not all analyzed in depth, they were all examined, either by parametric variation or by calculation, to define their importance and role. The items considered, portrayed schematically in Fig. 2, include: a) State of the boundary layer coming into the intake b) Inlet design (outside and inside) c) Evolution of the non-uniform inlet flow (distortion) from intake entrance to engine face d) Distortion transfer across the fan e) Response of the fan to the distortion (operability, aeromechanics) f) Evolution of the flow downstream of the fan g) Duct losses (high sensitivity because of low fan pressure ratio) This section gives a qualitative discussion of the rationale for the approach taken to address the above concerns


Finally, a critical feature of the current aircraft are engines with a low (1.5) fan pressure ratio and with ducts that are several times as long as those for conventional podded engines. The installed system performance is thus more sensitive to the level of inlet pressure recovery than with podded engines, and this aspect was also examined in some depth.
1610692683041.png

It is quite impossible to design an S duct diffuser with small flow distortions at all flight conditions. Therefore, many studies have focused on the reduction and control of intake flow distortion using passive [6,7] and active flow controls [8,9]. The most common methods for passive and active controls are using vanes/plates and synthetic jet actuators, respectively. Passive vortex generators have already been used to control the boundary layer separation in many applications


better read about duct losses product of duct curvature, instead of dreaming with starscream
1610692716547.png
 
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rockdog

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physics do not change, get it a longer ducts has more trouble feeding air to the engine, air over a surface generates a boundary layer, if the S duct does to radar it also does to air, you get better radar shielding true, but you get worse air quality, i highly recommend you read more, there are ample number of papers about the pros and cons of S ducts.

In fact the Russian patent says Su-57 has a less curved intake duct for the same reason, plus longer ducts mean more material so they make the aircraft intake duct longer and heavier.

X-32 whent takes off is not moving so it needs a large intake area, a straigh duct was found to be better.

I do not care your military forum, I care about aeronautical studies. F-15 or MiG-25 are faster than most aircraft, even F-14 was a speedy machine, they had straight ducts for a reason no matter how much you excuse your ignorance, you will not cover the sun with a finger.

Get it what a S duct does to radar waves, also does it to the air quality that feeds the engine.

Compromises are taken, engineering is compromises, fans like you are just cheer leaders.

X-32 and Su-57 use radar blockers and F-18E too.
Full article: http://www.ausairpower.net/APA-2011-03.html#mozTocId905140

A very old article about prototype of J20 vs T50, by some austrilian professor who "care about aeronautical studies" :

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003.jpg

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@MiG-29SMT

What's your POV about India quits the Su57 project? Dose Indian have better option or Su57 is not that good as expected?
 

MiG-29SMT

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Full article: http://www.ausairpower.net/APA-2011-03.html#mozTocId905140

A very old article about prototype of J20 vs T50, by some austrilian professor who "care about aeronautical studies" :

View attachment 73830

View attachment 73831

View attachment 73832
View attachment 73833
the article does not consider that Su-57 uses lots of composites and is designed with an intake for Mach 3 operation that very likely works up to Mach 2.4 and very high efficiency at Mach 1.9.

Add the study does not say Su-57 uses fly by light reducing considerably weight and increasing efficiency.

With no need for Ventral fins which create a lot of diffraction specially in the lower part of J-20
 

rockdog

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the article does not consider that Su-57 uses lots of composites and is designed with an intake for Mach 3 operation that very likely works up to Mach 2.4 and very high efficiency at Mach 1.9.
It's 2011 article, 5 months after J20 Prototype took off, and also neither included J20's composite and other factors:

The assessment cannot be more than preliminary for a number of good reasons:
  1. The final airframe shaping remains unknown, and changes may arise through the development cycle, to improve aerodynamic performance, operational characteristics, and LO/VLO performance;
  2. The state of Chinese Radar Absorbent Materials (RAM), Radar Absorbent Structures (RAS) and radar absorbent coatings technology is not well understood in the West;
  3. The state of Chinese technologies for sensor aperture (radar, EO, passive RF) structural mode RCS reduction is not well understood in the West;
  4. The state of Chinese technologies for RCS flare spot reduction, in areas such as navigation/communications antennas, seals, panel joins, drain apertures, cooling vents, and fasteners is not well understood in the West
The progress/modifications on J20 from 2011 is obviously more than T50/Su57. For last 10 yrs, Chinese economy and technologies might be the fastest growth rate in history.
 

MiG-29SMT

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It's 2011 article, 5 months after J20 Prototype took off, and also neither included J20's composite and other factors:



The progress/modifications on J20 from 2011 is obviously more than T50/Su57. For last 10 yrs, Chinese economy and technologies might be the fastest growth rate in history.
Standard of living is higher in Russia, 150 million Russians live better than 1.5 billion Chinese


The new Russian fighter has significantly reduced the effective scattering surface (EPR) - the main characteristic of the aircraft visibility in the radar field. The average value of this indicator in the T-50 is 0.3-0.4 m². It must be borne in mind that these data are estimated, there is no official information on the EPR of the aircraft. The only official message is the phrase of the general designer of the aircraft, Alexander Davidenko, where he compared the PAK FA and F-22: "The F-22 aircraft has 0.3-0.4 m². We have similar requirements for visibility."


he fifth-generation T-50 (PAK FA) fighter jet is equipped a number of technologies produced by Rostec companies that make the plane even less visible to the enemy radar. This design solution moves the T-50 ahead of all aircraft in its class, including the American F-22.

The aircraft company Sukhoi managed to greatly reduce the effective surface scattering of the PAK FA, which is the basic element for visibility on aircraft radars. The average value of this indicator for the T-50 fighter is between 0.1 and 1 square meter.

In order to achieve this level of stealth, designers moved all weapons to the inside of the plane and also changed the shape of the air intake channel, also lining its walls with a material that absorbs radio waves.

Thanks to these new design solutions, the T-50 is now ahead of not only all other fighters of the Russian Army, but also foreign models. For example, the visibility of the American fifth-generation F-22 fighter is 0.3-0.4 square meters, according to PAK FA chief designer Alexander Davidenko.

 

rockdog

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Standard of living is higher in Russia, 150 million Russians live better than 1.5 billion Chinese


Life expectancy:

China: 75
Russia:69.83


Standard of living is higher in Russia, 150 million Russians live better than 1.5 billion Chinese


The new Russian fighter has significantly reduced the effective scattering surface (EPR) - the main characteristic of the aircraft visibility in the radar field. The average value of this indicator in the T-50 is 0.3-0.4 m². It must be borne in mind that these data are estimated, there is no official information on the EPR of the aircraft. The only official message is the phrase of the general designer of the aircraft, Alexander Davidenko, where he compared the PAK FA and F-22: "The F-22 aircraft has 0.3-0.4 m². We have similar requirements for visibility."


he fifth-generation T-50 (PAK FA) fighter jet is equipped a number of technologies produced by Rostec companies that make the plane even less visible to the enemy radar. This design solution moves the T-50 ahead of all aircraft in its class, including the American F-22.

The aircraft company Sukhoi managed to greatly reduce the effective surface scattering of the PAK FA, which is the basic element for visibility on aircraft radars. The average value of this indicator for the T-50 fighter is between 0.1 and 1 square meter.

In order to achieve this level of stealth, designers moved all weapons to the inside of the plane and also changed the shape of the air intake channel, also lining its walls with a material that absorbs radio waves.

Thanks to these new design solutions, the T-50 is now ahead of not only all other fighters of the Russian Army, but also foreign models. For example, the visibility of the American fifth-generation F-22 fighter is 0.3-0.4 square meters, according to PAK FA chief designer Alexander Davidenko.

Still that question, if so why India quit the project?
 

Kumata

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Still that question, if so why India quit the project?
India left because ruskies were not giving us the due after paying almost putting tons of money in bottomless pit......why would i sponsor ruskies project if i don't get what i want....

 

MiG-29SMT

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Life expectancy:

China: 75
Russia:69.83






Still that question, if so why India quit the project?
Russian Federation's HDI value for 2019 is 0.824— which put the country in the very high human development category—positioning it at 52 out of 189 countries and territories. Between 1990 and 2019, Russian Federation's HDI value increased from 0.735 to 0.824, an increase of 12.1 percent.

China - Human Development Index
DateHDIHDI Ranking
20190.76185º



do you know what is the Human development index? check it.

By the way since I know you think RCS is fixed I will give you a couple of equations that Show RCS is dependant upon the antena and the power of that antena, So some radars can see F-22 oe J-20 or Su-57 at different ranges
So we get the equation to calculate the Non-directional Power Density (1)
1610712828607.png

  • PS = transmitted power [W]
  • Su = nondirectional power density
  • R1 = range from transmitter antenna to the aim [m]
1610712903998.png



In few words some radars will have a better detection range of J-20 than others
 
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MiG-29SMT

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rockdog

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Russian Federation's HDI value for 2019 is 0.824— which put the country in the very high human development category—positioning it at 52 out of 189 countries and territories. Between 1990 and 2019, Russian Federation's HDI value increased from 0.735 to 0.824, an increase of 12.1 percent.

China - Human Development Index
DateHDIHDI Ranking
20190.76185º



do you know what is the Human development index? check it.
Who told you HDI is equal to R&D capability and productivity on weapon industry? Especially on new tech and gears?


Manufacture Output reflects production capabilities.

China is the top nation in terms of manufacturing output and the percentage of its national output that is generated by that sector. Poland meanwhile has the highest percentage of its workforce employed in manufacturing.
At the low end were nations such as Brazil (51 points), Indonesia (53 points), Mexico (56 points), Russia (56 points), and India (57 points). Generally, these places do not have advantageous tax policies and are not making adequate investments in education or infrastructure.
In this thread, you mentioned Brazil, Mexicon, Russia, India... interesting coincidence i didn't realized you picked the low end on purpose ^_^ ...

https://www.brookings.edu/research/...card-how-the-us-compares-to-18-other-nations/


And R&D investment reflects how many new tech you would get in next 5-10 yrs.

20190311160451748.jpg
 

rockdog

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The J20 is still on progress now, the weapon bay might support more missiles.

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07.jpg


02.jpg


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07.jpg
02.jpg


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03.jpg
 

MiG-29SMT

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Who told you HDI is equal to R&D capability and productivity on weapon industry? Especially on new tech and gears?


Manufacture Output reflects production capabilities.





In this thread, you mentioned Brazil, Mexicon, Russia, India... interesting coincidence i didn't realized you picked the low end on purpose ^_^ ...

https://www.brookings.edu/research/...card-how-the-us-compares-to-18-other-nations/


And R&D investment reflects how many new tech you would get in next 5-10 yrs.

View attachment 73877
You still do not understand something, experience and intelligence are not gotten by money, in fact even Americans need sometimes adapt foreign technology because you invest the more you also waste more.

You are not going to especific aeronautical technical aspects but you go into economics and distractors.

Serbia downed 2 F-117s, one of them downed over its territory and one came to base but was rendered a loss, this is admitted by the USAF, Serbia downed with intelligence, out foxing more powerful nation with an old radar and SAM


Why because stealth is not what you think.

Stealth is shorter range detectability, but is dependant upon the power density of the radar, the direction of the target, the number of reflectors, the reflecting surface area.

1610735086304.png


The math can not be lied, you want to excuse your ignorance, moving the subject to unrelated topics.


The fact is J-20, F-22 and Su-57 represent different approaches to a 5th generation.

F-22 is a ultra sophisticated and expensive machine where stealth was prioritized, later high speed and later maneouvrability.

Su-57, is high speed first, later Stealth, later maneouvrability, later STOL.

J-20 is prioritized stealth, maneouvrability, later speed and later STOL.

You do not understand why


but if you read the Su-57 patent and have watched Russian documentaries you understand what is its philosophy.

It has variable geometry intake that has a design limit of Mach 3.
T-30 engines are ranked 5th generation plus plus engines, they are better than 117 of 15 tonnes of thrust.

Russia has very powerful engines just see what powered MiG-31, Tu-22M or Yak-141, however Type 30 is new because is smaller and more economical only that, it generates more power at lower fuel consumption.

So speed, STOL and Supermaneouvrability is assured, basically they already did what China can not do with WS-15


Su-57 with type 30 engines can go at supercruise speed higher than Su-35 and the current Su-57s, basically is an engine as good as F135 or more.

So J-20 can not compete with it, DSI intakes top at Mach 1.8, the recomended speed is Mach 1.5.

Examples JF-17, J-10C and F-35.

You do not know but if it tries to go faster there are issues that affect one is fuel consumtion, it will need afterburner, easy to spot, second it can damage the engines.


So J-20 flies without afterburner a low subsonic speed with Al-31 and if WS-10C is good maybe can compete with F-35.


However it has more weapons and Fuel than F-35 so China designed a Big F-35 because the Small F-35 aka J-31 is crap.

Su-57 will fly faster, so it is designed to down F-22 as its main objective, so it needs to be fast, and have faster top speed, so it can accelerate better than F-22 and have a faster top speed.

So Su-57 is designed to be competitive frontally and if fired upon escape and leave the area with speed, so J-20 can not chase it.


missiles are fast but have few seconds of flying time, and are easy to shake because if you are fast they fly few seconds and have less agility.


So get it speed is first, because as MiG-25 shown speed is life, but in close combat Su-27 will have better turn rate due to higher thrust to weight.


what philosophy is better depends in tactics luck and only in combat can be proven.
 

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