Chengdu J-20 5th Generation Aircraft News & Discussions

[sms]

I am not impressed with link brought by somebody.
I am impressed with explanation of somebody, as it indicate the understanding in his mine.

Everybody can googling to find internet article easily; everybody can drag internet article into this forum thread, but only qualified person can understand and explain.

The way he explain about "semi transparent" should not satisfy you about radome.

But to my surprise, you never asked him about it (you only ask me and chase me)

antonius123,
Initially my questions was J20 specific and later I realized that it's the same problem for all fighter aircrafts. Since you did not answer (the person I was expecting to get best answer) I had no option but to approach Gambit's gang.

All links and info received I'm able to understand the process and basic principles involved and that’s enough for me for time being as I’m not a professional but a person in quest for info/ knowledge.

I also hope this lin has helped you to understand it better

 

[gambit]

See, you still dont get what I've explained to you.

You 'explained' nothing here so far. The only thing you are good at is evading and lying about yourself.

I've been talking many times about traveling wave; now I am afraid you dont understand what traveling wave is.

If the traveling wave that reach fanblade could be absorbed by RAM coating the airduct, then exposure of moving part behind the blade to the traveling wave wouldn't be problem either.

I've told you the RAM material is also used to coat the moving parts of the intake ramp on F-22

I bet you picked up that 'traveling wave' somewhere but have no clue on what it means.

We are not talking about the fan blades. We are talking about your ignorance and pigheadedness in the face of education, even when it is free of charge. We are talking about your gross misunderstanding of technical issues regarding radar absorbant material (RAM).

As in this illustration and how it works regarding its effects on the SURFACE TRAVELING WAVE...

All RAM are composites and there are different designs of RAM and each design have its own formulations. The above illustration is the simplest design and formula that contains ferrite particles. Composites contains at least two different constituent materials. All RAM designs have more than two and EACH material inside the parent material may be designed to have different degrees of EM transparency. But all RAM designs have one thing in common: That the outer most layer, the one that is exposed to the environment and to radar bombardment, must be EM transparent to as high degrees as possible. No material is 100 pct transparent under this condition when it must withstand physical handling, temperature changes and rate of changes, and weather.

A radar signal have two components: Electrical and Magnetic. Hence the word 'electromagnetic' (EM), get it? When a radar signal impact a surface, even at perfectly perpendicular, a surface traveling wave is produced. The physical surface is called the 'electrical path' and if the surface has a high degree of permissivity or permittivity or 'lossy', both electrical and magnetic components will be affected. The higher the degree of 'lossy-ness', the lower the level of 'leaky waves' (LW) throughout this electrical path, which eventually leads to lower RCS contributorship.

Here is an example of materials used in radome construction...

Radome Materials

Here is something that will blow your mind: In designing radomes and absorber, we do not use the words 'block' or 'blockage'.

Absorbancy/transparency is graded and spoken in terms of percentages. Steel reflects everything, so we classify this material as 'zero percent absorbant/transparent'. A sponge is 100 pct water absorbant and a block of steel is 0 pct water absorbant. Get it? I know you have a problem understanding the technical contexts of words and phrases since we know you lied about your aviation 'background' and 'study' so I just threw that out in a sadistic twist.

A radome is a radar 'pass through' device, meaning its materials are absorbant/transparent to very high degree, but not 100 pct. To reduce this 'pass through' ability is to produce RAM for 'stealth' purposes. We do not want the radar signal to completely pass through the material and impact the aircraft structures. We want to stop the radar signal somewhere INSIDE the material. So what we do is create GRADATIONS of absorbancy/transparency inside our parent material.

For the above illustration of the typical and simple ferrite particles absorber, the outer most layer material is the most absorbant/transparent. As portions of the surface wave (SW) penetrate this layer and travels deeper into the substrate, these signals will impact those ferrite particles and get multiple reflections inside this substrate layer, some of those reflections may actually exit the material completely and back into free space, but most will get attenuated by the particles.

Complex designs such as Salisbury, Jaumann and Dallenbach absorbers and their hybrids can focus on either the electrical or the magnetic component individually.

http://pubs.drdc-rddc.gc.ca/BASIS/p...e'+ORDER+BY+Repdate/Descend&M=20&K=103061&U=1

Abstract: Radar is a sensitive detection tool and since its development, methods for reducing microwave reflections have been explored. Radar absorbers can be classified as impedance matching or resonant absorbers. Radar absorbing materials are made from resistive and/or magnetic materials. Circuit analog materials give more design freedom through access to capacitive and inductive loss mechanisms. Dynamic absorbers can tune the absorption frequency through control of resistive and capacitive terms. Many conductive and magnetic materials have been trialed for absorption including carbon, metals and conducting polymers.

Hybrid absorbers can affect the electrical component in one substrate and the magnetic component in another substrate. Instead of substrates, hybrids can even be designed to affect the electrical component on one section or length of the parent material and the magnetic component on a separate section or length of the parent material. We can study on how the SW travels on the aircraft and custom tailor our hybrid absorber designs accordingly: substrate designs at some points and sectional designs at some other points.

I will stop here because am approaching the 'classified' or 'good stuff' info.

Much more intelligent people than you will take what I said above and do their own research. They will verify that everything I said have more legitimate sources. They will exercise reasonable imagination to see where the technology can go and suspect where the US is at. They will see you for the idiot that you are.

The F-117 is retired. Yours and the Chinese boys' understanding of RAM belongs in that era. The F-22 and F-35 are not the F-117. Uncle Sam got sh1t coming down his pipe that will make the J-20 China's F-117.

Nobody said there is absorber inside the engine core. You have severe reading comprehension problem.

I am saying about absorber coating the inside wall of airduct and rampt intake of F-22.

Which have nothing to do with the cone. You have a problem keeping track of the discussion. I used the engine core as an example on how its component does not contribute to RCS.

Thats why I am saying that cone itself contribute to RCS.

No, you did not. Here is what you said...

Do you understand that Cone will be heavier, and the moving parts contributes bigger RCS?

You cannot escape your own words. If the cone's moving parts contributes to 'bigger RCS', then it must be exposed. So show us a source that have a jet engine fighter with a conical intake that have exposed cone translation mechanisms.

But since you agree on it, but you dont agree on the moving part's rcs contribution, then we are debating about RCS contribution of the moving part, not the RCS contribution of the cone itself or the DSI itself.

Yeah...So since you believe that those moving parts contribute to 'bigger RCS', show us a source that have a jet engine fighter with a conical intake that have exposed cone translation mechanisms.

How many times should I repeat this? please dont be too idiotic.

The idiot is YOU for making that claim.

See.. you are ignoring and try to evade the topic.

I am asking you, because you are making another claim that most probably is FALSE claim.

You are claiming that "Cone is less hidding the fan blade compared to DSI"

This is your claim:
The reason why the DSI structure has far less RCS contributorship is its lack of exposed items to the radar view

Source: http://www.defence.pk/forums/chines...ft-updates-discussions-182.html#ixzz24UPIeQSu

Your argument is completely contradictory. What the hell does 'Cone is less hidding the fan blade...' mean? It make no sense when compared to my real quote, which you brought on. You accused me of saying something I never did, then brought on my comment to support your accusation when my comment said nothing of the kind. You clearly have a problem with technical English.

 

[amalakas]

Copy and paste expert, dude that is all you do
atleast have the decency to post the article you copied and pasted from

You're own knowledge is limited at best.
Don't come here and act like the founder of the fighter jet and an 'expert' while copying and pasting from articles on the Internet.

Uncle SAM got one thing coming alright...... One massive economic collapse once the bond bubble bursts and the military has no money to maintain the things they have now let alone money to buy new weapons.

You have limited understanding of economics here.

I keep telling you boys, your "supposed" chinese economic growth is founded on western markets consuming chinese products.

You are forgetting that if the west crashes.. china will sell its products....... were ?

I am putting it in simple terms.

Greece is insignificant in many terms, and yet now we are bust, the germans have a dip in their exports graph just because of Greece.

International trade is a chain. always remember that.

 

[gambit]

Copy and paste expert, dude that is all you do
atleast have the decency to post the article you copied and pasted from

You're own knowledge is limited at best.
Don't come here and act like the founder of the fighter jet and an 'expert' while copying and pasting from articles on the Internet.

Uncle SAM got one thing coming alright...... One massive economic collapse once the bond bubble bursts and the military has no money to maintain the things they have now let alone money to buy new weapons.

And what can YOU do other than waste US invented Internet bandwidth and generally be a minor pest, conscript reject?

 

[gambit]

So, me and readers need to ask you why you think Cone has more items exposed to radar view than DSI?

Why dont you dare to answer?

I bet you dont know again. Thats why never throw claim that you cannot defend

Simple...The cone have more surface area. The ramp have edges and angles. I said this before. So what make you think I am 'afraid' to answer?

The DSI 'bump' is at best half a cone, so it has less surface area than the cone. How much more simple can it get?

Now...If you want to get into which is the better to hide the fan blades, it is the cone, not the DSI 'bump'.

Here is why...And people will see how I put this issue to rest...For good...

The engine's contributorship to RCS is more than just the fan blades...Much more...

In the above example, we see how a helicopter's rotating blades produces recognizable radar flash patterns. Not only do blade flashes are in recognizable patterns, but because a blade is not symmetrical in construction due to aerodynamics reasons, which will present variations in surface exposure to the radar which affects reflection amplitudes, the amplitude variations of the flashes will also be in a recognizable pattern. Odd number of blades will produce higher flash frequencies because each blade make two flashes per revolution.

Helo rotors EM analyses is called 'radar detection of agitated metals' (RADAM)...

Analysis of radar detection of agitated metals (RADAM)

It has been observed that the radar returns from moving multielement metal targets often exhibit an unexpected modulation that has both random (or noise-like) and semicoherent components.

To accomplish any of these, the effect must be well understood, and we have therefore undertaken a program of research to study the radar detection of agitated metals (RADAM).

This mean we can tell which pattern came from an even bladed rotor or from an odd bladed rotor, which hint at what model and eventually the helo's origin country.

RADAM analyses are already deployed...

MSTAR - Wikipedia, the free encyclopedia

Man-portable Surveillance and Target Acquisition Radar (MSTAR) is a light weight all-weather battlefield radar Doppler radar operating in the J band. It is usually used by Artillery Observers to acquire and engage targets in bad visibility or at night. It is capable of detecting, recognizing and tracking helicopters, slow moving fixed-wing aircraft, tracked and wheeled vehicles and troops, as well as observing and adjusting the fall of shot.

All of the highlighted have one thing in common: That each object have something on it that is repetitious, predictable in motion, and is metallic, hence the words 'agitated metals' in 'radar detection of agitated metals' (RADAM).

Amazing, ain't it? Is your supposedly aviation 'background' or 'study' helping you understanding this sh1t?

Anyway...No different than when the radar is looking face on at a jet engine's fan blades. In fact, looking face on at a jet engine's fan blades will produces far more blade flashes and recognizable patterns than looking edge on as in the helo's rotors.

In the above example, the top illustration is a simplified visual representation of the multiple stages of a jet engine.

The second illustration is a civilian type jet engine. The third illustration is a military jet engine. See the size differences and location of those differences?

The general construction and working theory of the jet engine works this way: The fan assemblies are connected to a common shaft. Each fan assembly represent a compression stage. There are different blade count per compression stage. Not only blade counts are different but blade sizes are usually different as well from one compression stage to the next successive stage. The diameters of the fan assemblies is progressively smaller into the engine. The distances between stages get shorter into the engine.

The process is called 'jet engine modulations' (JEM) detection for target recognition, tracking, and (hopefully) identification.

Radar MASINT - Wikipedia, the free encyclopedia

One open-literature study combined several pieces of radar information: cross-section, range, and Doppler measurements.[20] A 1997 Defense Department report mentions "Air Force and Navy combat identification efforts focus on noncooperative target recognition technologies, including inverse synthetic aperture radar imaging, jet engine modulation (JEM), and unintentional modulation on pulse-based specific emitters".

http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=1606562&tag=1

In this paper, the modulating mechanism of radar echo, namely jet engine modulation effect, caused by the rotating-blades, is analyzed by equivalent the engine intake as a wave-guide model in this paper. And a changing law of target RCS and modulation spectrum is studied.

PIER Online - A Novel Hybrid Aipo-MoM Technique for Jet Engine Modulation Analysis

A NOVEL HYBRID AIPO-MOM TECHNIQUE FOR JET ENGINE MODULATION ANALYSIS

A novel hybrid adaptive iterative physical optics-method of moments (AIPO-MoM) technique is presented for the electromagnetic analysis of jet engine structures that are both electrically large and complex in both stationary and dynamic cases. In this technique, the AIPO method is used to analyze the smooth inlet region, and the MoM method is used to analyze the electrically complex compressor region, including blades and a hub. It is efficient and accurate by virtue of combining the respective merits of both methods. In the dynamic case, a concept for modified impedance equation is proposed to reduce computational load. Numerical results are presented and verified through comparison with Mode-FDTD and measured and commercial simulation packages results.

RADAM is sufficient for helicopter rotor signature analyses but not for complex structures like a multistage turbine engine.

For the civilian jet engine, its mission requirement have its fan assemblies very large compared to the military engine with the humans to provide scale. Not only are the civilian engine have large fan assemblies but they are more concentrated towards the front end of the engine itself. Thrust from the civilian engine comes from the combination of fan and compressed exhaust. Thrust from the military engine comes mostly from the compressed exhaust. That is the 'bypass air' difference.

As the radar signal impact the first fan blade assembly, a recognizable pattern is produced. As portions of the transmission is diffracted and travels through the engine to successive stages, each stage produces its own recognizable pattern. The closer the fan assemblies are together, like how the civilian engine is, the greater the interactions between multiple reflections and this equals to a higher RCS contributorship. Then if the seeking radar is sophisticated enough in data processing, a very unique and complex engine signature will be produced. We can store this knowledge and disseminate it later for everyone, or the immediate radar can use it to enhance tracking. However, it is accepted that beyond stage 3 or 4, and given the fact that this is inside a highly dynamic target, the EM interactions are too mathematically complex to model and predict.

JEM analyses is much more difficult -- not impossible -- with the military engine. For the military engine, each fan stage is smaller in diameter than the civilian engine, giving the radar less surface area to reflect. The stages themselves are further apart from each other so diffracted signals will impact the stages in less consistent directions. Civilian jet engines often are podded and therefore have very short intake lengths, whereas military jet engines in the fighter class are usually fuselage enclosed and have very long intake lengths similar to a waveguide and if there are any deviations from straight, the radar signal may be weakened from multiple reflections before meeting the first fan blade stage. This short versus long intake length difference necessitate a near true frontal radar view of the engine face on the fighter aircraft for any significant radar encounter. Because the civilian jet engine is so much larger in fan stage diameter and have very short intake lengths, there is a greater range of freqs (wavelengths) available to create the JEM effect, even down to the single digit ghz freq, whereas for the military jet engine, its physical construction and layout in the aircraft does not guaranteed that the JEM effect is consistent enough for tracking, let alone identification, for any freq.

This is why the criticism against the PAK for its intake system is only PARTIALLY valid. Its engines are too deep inside the fuselage, requiring a near true frontal radar view. It is only because of JEM analyses that the PAK would have a vulnerability in that event.

Any radar can process EM reflections from the engine's first fan stage, but only radars specifically designed for specific military purposes may -- not will -- have JEM analysis capability.

So how do we deny the seeking radar the JEM effect on our fighter jet engine? Certainly not by putting a little DSI zit or boil or bump in front of the engine face.

Either make the intake system serpentine or put the engine face behind a cone.

The serpentine intake system like on the F-22 and F-35 is obvious enough in its ability to weakened a radar signal thru multiple reflections.

For the cone, its position in front of the engine face is sort of a 'mini serpentine' intake system by forcing the radar signal, especially high freq (short wavelength), to become surface wave (SW) on the cone's surface. Diffracted signals on the cone's backside edges will be weakened before they meet the engine face. Any backscatter from the engine face will meet the cone's backside, resulting in even more multiple reflections. So while as a structure, the cone does present a greater amount of surface area to the seeking radar then the DSI zit/boil/bump, its ability to protect the engine face from the seeking radar far outweighs its negative in comparison to the DSI setup.

I do not expect you to understand even 1/10th of what I presented above. You are too much of a dumbass, too stubborn and too technically illiterate. I do not expect the Chinese crowd here concede that they are wrong in the belief that the DSI zit/boil/bump was intentional for RCS control. They are too blinded by nationalism to admit to any amount of intellectual honesty, even when confronted with irrefutable proofs.

For the truly objective minded readers, any time any of the Chinese boys starts spouting off about DSI zit/boil/bump being for RCS controls, feel free to use the above arguments to debunk such nonsense. Or just point the fool to this post and watch him sputter.

 

[gambit]

If you think that the more transparent the material, the more EM absorbing it is, then you are stupid.

Molecular vibration is not caused by the transparency of the material like you think! you are misled or have misconception again

No, it is YOU who are stupid. Transparency is the 'how' that allow those molecular vibrations. It is not the cause. Absorbancy make the material transparent. Not the other way around. It is clear that you have no technical education.

Did I said that my explanation coming from myself without source? why dont you ask

When you copied practically verbatim from a source and say nothing about it, you are being dishonest. This is not the first time you got busted. That is theft.

Where is your citation that back your claim that absorbing is caused by the transparency? none!

Already explained how you got it backward.

First of all, explain us what the permissivity you mean here?

You debate on RAM but have no understanding of the words 'permissivity', of 'permittivity', or of 'lossy'.

The words 'permissivity' and 'permittivity' can be used interchangeably. Those who have relevant experience, which we know you do not and lied about it, understand when which word is used.

permissiveness - definition of permissiveness by the Free Online Dictionary, Thesaurus and Encyclopedia.
1. Granting or inclined to grant permission; tolerant or lenient.

Regarding radar absorbers, there is permeability which enables permittivity.

No wonder Martian, etc don bother to serve you; and some members warn me to ignore you. It is clearly because your STUBBORNNESS and IGNORANCE.

How many times should I tell you not to evade the topic, and suggest that you focus on the topic being debated? do you want to run away from the topic that you can't answer any more?

I have debunked those fools more often than they dare to admit and I did it the same way I made an equal fool out of you. Neither them nor you can ignore me any more than the readers can ignore superior arguments. In fact, the more you and them ignore my challenges, the more fools all of you look. What they do not want to admit is that everything they learned about military aviation so far they learned from me. Certainly not because they have any real experience. But at least they are wise enough not to make up sh1t about themselves like you have.

But we will continue with the pretense that you have an aviation 'background' and 'study'.

In post 2738 => http://www.defence.pk/forums/chines...raft-updates-discussions-183.html#post3344030

I asked you, someone who claimed to have aviation 'background' and 'study'...

Q: What are the three principles of Engineering in order of establishments and priority?

Establishment definition: Set up (an organization, system, or set of rules) on a firm or permanent basis.

A: Experimental. Empirical. Theoretical.

1- Experimental. To establish physical facts and how to manipulate those facts.
2- Empirical. To establish values of said physical facts.
3- Theoretical. To establish an explanation of events based from experiments and analyses.

For example: You determined that water is 'wet' and boils/freezes at so-and-so temperatures. That established physical properties of water. Along the way you have values such as temperatures and time to reach those temperatures. That established the empirical records. You may experiment further by doping water with different substances and record different temperature and time ranges. More known physical facts and empirical values of these properties. Finally, you posit an explanation of what you believe to be eternal for water. This is the theory of/for water.

It is pretty sad that for you who tried to shut down the Indians with your claimed aviation 'background' and 'study' -- you cannot answer even basic engineering philosophy.

Now to the flight control engineering question...

Q: Why the F-111 and F-14 have no ailerons?
A: To have the maximum allowable surface area for lift. Roll maneuvers are through split tailplane operation.

This make a dozen basic aerodynamics and eight flight control engineering questions that you failed to give even the most rudimentary answers.

Next...

Q: What constitute a 'successful' airframe design? Caveat: There are very few 'failure' with respect to 'successful'. Essentially, if an airframe flew, then it is not a failure because it exploited aerodynamic forces to its advantage to become airborne. So what this mean is that some airframes are less successful than others regarding their target audience or specific mission type. Then what other factors are there that would make some airframes more successful than others to the point where it serves as a standard to be measured against in terms of design? Hint: 3 items.

 

[anarchy 99]

You have limited understanding of economics here.

I keep telling you boys, your "supposed" chinese economic growth is founded on western markets consuming chinese products.

You are forgetting that if the west crashes.. china will sell its products....... were ?

I am putting it in simple terms.

Greece is insignificant in many terms, and yet now we are bust, the germans have a dip in their exports graph just because of Greece.

International trade is a chain. always remember that.

says a dude from greece.
learn economics son and more importantly.....learn the chinese economy.
you are brainwashed with western propaganda about china.

western consumer markets consume less than 40% of our total exports(20% europe and 18% US). and you know where you get the money to buy our products with? we lent it to you.
without us, america would be in the dustbin of history.

our economy is investment driven, not export driven. we have other non-western exports markets thats growing much much faster than the bankrupt west and our domestic consumption is rising fast with rising incomes and is now the 3rd largest consumer market in the world. we already are the largest market for many goods such as cars, smartphones, PCs, etc.

the west has crashed since 2008 and we are still growing fast, just go and ask your multinationals where their fastest growth is coming from.....

the west is bankrupt and are falling like dominoes.....

your economic knowledge is more limited than gambit's military knowledge, and that takes a beating

 

[amalakas]

says a dude from greece.
learn economics son and more importantly.....learn the chinese economy.
you are brainwashed with western propaganda about china.

western consumer markets consume less than 40% of our total exports(20% europe and 18% US). and you know where you get the money to buy our products with? we lent it to you.
without us, america would be in the dustbin of history.

our economy is investment driven, not export driven. we have other non-western exports markets thats growing much much faster than the bankrupt west and our domestic consumption is rising fast with rising incomes and is now the 3rd largest consumer market in the world. we already are the largest market for many goods such as cars, smartphones, PCs, etc.

the west has crashed since 2008 and we are still growing fast, just go and ask your multinationals where their fastest growth is coming from.....

the west is bankrupt and are falling like dominoes.....

your economic knowledge is more limited than gambit's military knowledge, and that takes a beating

Rightttttt. I am wearing my convinced face now. Your arguments really set me straight. I am actually forwarding this to the EU leaders so they can call you to help them fix this crisis straight !

 

[amalakas]

I am the guy that will put YOU down everytime you try to take me on. Just like I have done now. I quite enjoy humiliating you old man.

F-22 craptor is an overhyped piece of trash that is not even proven in battle. If the F-22 craptor is trash, F-35 cant even fly (Carlo Kopp who is a real expert says so)
But im sure you know more than all these experts riiiight my vietnamese 'reeeeeeal' expert with playstation experience?
Not hard for the J-20 to surpass a fighter where the pilot will die due to no oxygen (F-22)

F22 Raptor Exposed - Why the F22 Was Cancelled - YouTube

.......................................

 

[antonius123]

Simple...The cone have more surface area. The ramp have edges and angles. I said this before. So what make you think I am 'afraid' to answer?

The DSI 'bump' is at best half a cone, so it has less surface area than the cone. How much more simple can it get?

We are not talking about which one has more surface area, as we have agreed that Cone itself contributes to RCS.

But we are talking about things behind the cone!

So your answer about the surface area of the cone become "irrelevant" or FAILED.

And how do you prove that DSI bump is at best half a cone as you claim?

Cone inlet

DSI bump

Now...If you want to get into which is the better to hide the fan blades, it is the cone, not the DSI 'bump'.

Here is why...And people will see how I put this issue to rest...For good...

The engine's contributorship to RCS is more than just the fan blades...Much more...

In the above example, we see how a helicopter's rotating blades produces recognizable radar flash patterns. Not only do blade flashes are in recognizable patterns, but because a blade is not symmetrical in construction due to aerodynamics reasons, which will present variations in surface exposure to the radar which affects reflection amplitudes, the amplitude variations of the flashes will also be in a recognizable pattern. Odd number of blades will produce higher flash frequencies because each blade make two flashes per revolution.

Helo rotors EM analyses is called 'radar detection of agitated metals' (RADAM)...

Analysis of radar detection of agitated metals (RADAM)

This mean we can tell which pattern came from an even bladed rotor or from an odd bladed rotor, which hint at what model and eventually the helo's origin country.

RADAM analyses are already deployed...

MSTAR - Wikipedia, the free encyclopedia

All of the highlighted have one thing in common: That each object have something on it that is repetitious, predictable in motion, and is metallic, hence the words 'agitated metals' in 'radar detection of agitated metals' (RADAM).

Amazing, ain't it? Is your supposedly aviation 'background' or 'study' helping you understanding this sh1t?

Anyway...No different than when the radar is looking face on at a jet engine's fan blades. In fact, looking face on at a jet engine's fan blades will produces far more blade flashes and recognizable patterns than looking edge on as in the helo's rotors.

In the above example, the top illustration is a simplified visual representation of the multiple stages of a jet engine.

The second illustration is a civilian type jet engine. The third illustration is a military jet engine. See the size differences and location of those differences?

The general construction and working theory of the jet engine works this way: The fan assemblies are connected to a common shaft. Each fan assembly represent a compression stage. There are different blade count per compression stage. Not only blade counts are different but blade sizes are usually different as well from one compression stage to the next successive stage. The diameters of the fan assemblies is progressively smaller into the engine. The distances between stages get shorter into the engine.

The process is called 'jet engine modulations' (JEM) detection for target recognition, tracking, and (hopefully) identification.

Radar MASINT - Wikipedia, the free encyclopedia


http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=1606562&tag=1


PIER Online - A Novel Hybrid Aipo-MoM Technique for Jet Engine Modulation Analysis

RADAM is sufficient for helicopter rotor signature analyses but not for complex structures like a multistage turbine engine.

For the civilian jet engine, its mission requirement have its fan assemblies very large compared to the military engine with the humans to provide scale. Not only are the civilian engine have large fan assemblies but they are more concentrated towards the front end of the engine itself. Thrust from the civilian engine comes from the combination of fan and compressed exhaust. Thrust from the military engine comes mostly from the compressed exhaust. That is the 'bypass air' difference.

As the radar signal impact the first fan blade assembly, a recognizable pattern is produced. As portions of the transmission is diffracted and travels through the engine to successive stages, each stage produces its own recognizable pattern. The closer the fan assemblies are together, like how the civilian engine is, the greater the interactions between multiple reflections and this equals to a higher RCS contributorship. Then if the seeking radar is sophisticated enough in data processing, a very unique and complex engine signature will be produced. We can store this knowledge and disseminate it later for everyone, or the immediate radar can use it to enhance tracking. However, it is accepted that beyond stage 3 or 4, and given the fact that this is inside a highly dynamic target, the EM interactions are too mathematically complex to model and predict.

JEM analyses is much more difficult -- not impossible -- with the military engine. For the military engine, each fan stage is smaller in diameter than the civilian engine, giving the radar less surface area to reflect. The stages themselves are further apart from each other so diffracted signals will impact the stages in less consistent directions. Civilian jet engines often are podded and therefore have very short intake lengths, whereas military jet engines in the fighter class are usually fuselage enclosed and have very long intake lengths similar to a waveguide and if there are any deviations from straight, the radar signal may be weakened from multiple reflections before meeting the first fan blade stage. This short versus long intake length difference necessitate a near true frontal radar view of the engine face on the fighter aircraft for any significant radar encounter. Because the civilian jet engine is so much larger in fan stage diameter and have very short intake lengths, there is a greater range of freqs (wavelengths) available to create the JEM effect, even down to the single digit ghz freq, whereas for the military jet engine, its physical construction and layout in the aircraft does not guaranteed that the JEM effect is consistent enough for tracking, let alone identification, for any freq.

This is why the criticism against the PAK for its intake system is only PARTIALLY valid. Its engines are too deep inside the fuselage, requiring a near true frontal radar view. It is only because of JEM analyses that the PAK would have a vulnerability in that event.

Any radar can process EM reflections from the engine's first fan stage, but only radars specifically designed for specific military purposes may -- not will -- have JEM analysis capability.

So how do we deny the seeking radar the JEM effect on our fighter jet engine? Certainly not by putting a little DSI zit or boil or bump in front of the engine face.

Either make the intake system serpentine or put the engine face behind a cone.

The serpentine intake system like on the F-22 and F-35 is obvious enough in its ability to weakened a radar signal thru multiple reflections.

For the cone, its position in front of the engine face is sort of a 'mini serpentine' intake system by forcing the radar signal, especially high freq (short wavelength), to become surface wave (SW) on the cone's surface. Diffracted signals on the cone's backside edges will be weakened before they meet the engine face. Any backscatter from the engine face will meet the cone's backside, resulting in even more multiple reflections. So while as a structure, the cone does present a greater amount of surface area to the seeking radar then the DSI zit/boil/bump, its ability to protect the engine face from the seeking radar far outweighs its negative in comparison to the DSI setup.

From your explanation, I dont see yet the evidence that there is other thing of engine that contributes RCS more than Fan Blade?

If your claim is true that Cone will be effective like serpentine, then why F-22/J-20 or even PAKFA (that is still strugling to hide its fan blade) not using the Cone to hide the Fan Blade?

In fact I dont see the 5th generation/stealth fighter is still using cone, which according to your claim is very effective in hiding the Fan Blade (the big contributor to RCS of the intake)?

You are also wrong; it is not only DSI bump that hide the fan blade, but the combination between DSI bump with a forward-swept inlet cowl! and also the serpentine.

I do not expect you to understand even 1/10th of what I presented above. You are too much of a dumbass, too stubborn and too technically illiterate. I do not expect the Chinese crowd here concede that they are wrong in the belief that the DSI zit/boil/bump was intentional for RCS control. They are too blinded by nationalism to admit to any amount of intellectual honesty, even when confronted with irrefutable proofs.

For the truly objective minded readers, any time any of the Chinese boys starts spouting off about DSI zit/boil/bump being for RCS controls, feel free to use the above arguments to debunk such nonsense. Or just point the fool to this post and watch him sputter.

Why are you so proud with that long explanation but severely lack of citations of your debated claims?

Like always you either like to drag internet article, or explain things very long to impress readers, but you loose relevant point or the points of your argument are still misconceptions.

You already demonstrated clueless by saying that only DSI bump alone that works to hide the blade, ignoring the combination of forward swept inlet cowl + the serpentine (in F-35 and J-20 case).

You already demonstrated idiocy when you think that the Cone Inlet will be always like that of Mig 21!

Remember all of your debated claims will be rubbish without citation

 

[antonius123]

No, it is YOU who are stupid. Transparency is the 'how' that allow those molecular vibrations. It is not the cause. Absorbancy make the material transparent. Not the other way around. It is clear that you have no technical education.

Wrong!

Transperancy is about how much the EM wave pass through the material!

By your misconception, the transparent Radome cannot pass the EM wave therefore the wave from the radar's transmitter behind the radome cannot deliver the wave outward.

When you copied practically verbatim from a source and say nothing about it, you are being dishonest. This is not the first time you got busted. That is theft.

Dishonest if you are telling lie! just like what you are saying and claiming in this forum.

Say nothing is not lying!
You are lying here.

Already explained how you got it backward.

Your citation doesnt say so.
Either you are lying or you are demonstrating misconception.

You debate on RAM but have no understanding of the words 'permissivity', of 'permittivity', or of 'lossy'.

The words 'permissivity' and 'permittivity' can be used interchangeably. Those who have relevant experience, which we know you do not and lied about it, understand when which word is used.

permissiveness - definition of permissiveness by the Free Online Dictionary, Thesaurus and Encyclopedia.
1. Granting or inclined to grant permission; tolerant or lenient.

Regarding radar absorbers, there is permeability which enables permittivity.

I am not saying I dont know, you liar.

I am afraid you dont know the meaning of permeability/permissivity, or have wrong understanding about them, as you think that transparency is due to permeability/permittivity

I have debunked those fools more often than they dare to admit and I did it the same way I made an equal fool out of you. Neither them nor you can ignore me any more than the readers can ignore superior arguments. In fact, the more you and them ignore my challenges, the more fools all of you look. What they do not want to admit is that everything they learned about military aviation so far they learned from me. Certainly not because they have any real experience. But at least they are wise enough not to make up sh1t about themselves like you have.

You are the one debunked here, and busted many times for misconceptions; but you refuse to admit it

But we will continue with the pretense that you have an aviation 'background' and 'study'.

In post 2738 => http://www.defence.pk/forums/chines...raft-updates-discussions-183.html#post3344030

I asked you, someone who claimed to have aviation 'background' and 'study'...

Q: What are the three principles of Engineering in order of establishments and priority?

Establishment definition: Set up (an organization, system, or set of rules) on a firm or permanent basis.

A: Experimental. Empirical. Theoretical.

1- Experimental. To establish physical facts and how to manipulate those facts.
2- Empirical. To establish values of said physical facts.
3- Theoretical. To establish an explanation of events based from experiments and analyses.

For example: You determined that water is 'wet' and boils/freezes at so-and-so temperatures. That established physical properties of water. Along the way you have values such as temperatures and time to reach those temperatures. That established the empirical records. You may experiment further by doping water with different substances and record different temperature and time ranges. More known physical facts and empirical values of these properties. Finally, you posit an explanation of what you believe to be eternal for water. This is the theory of/for water.

It is pretty sad that for you who tried to shut down the Indians with your claimed aviation 'background' and 'study' -- you cannot answer even basic engineering philosophy.

Now to the flight control engineering question...

Q: Why the F-111 and F-14 have no ailerons?
A: To have the maximum allowable surface area for lift. Roll maneuvers are through split tailplane operation.

This make a dozen basic aerodynamics and eight flight control engineering questions that you failed to give even the most rudimentary answers.

Next...

Q: What constitute a 'successful' airframe design? Caveat: There are very few 'failure' with respect to 'successful'. Essentially, if an airframe flew, then it is not a failure because it exploited aerodynamic forces to its advantage to become airborne. So what this mean is that some airframes are less successful than others regarding their target audience or specific mission type. Then what other factors are there that would make some airframes more successful than others to the point where it serves as a standard to be measured against in terms of design? Hint: 3 items.

You are proving what Martian says about you => ignorance, stubborn, tend to evade the debate by bringing other topic/question.

 

[antonius123]

Copy and paste expert, dude that is all you do
atleast have the decency to post the article you copied and pasted from

You're own knowledge is limited at best.
Don't come here and act like the founder of the fighter jet and an 'expert' while copying and pasting from articles on the Internet.

Uncle SAM got one thing coming alright...... One massive economic collapse once the bond bubble bursts and the military has no money to maintain the things they have now let alone money to buy new weapons.

He likes to copy paste long article from internet, but demonstrate misconception.

He think by dragging long article or long explanation he will be admitted as an expert
Instead people will judge his point/claims and bust his misconception.

 

[antonius123]

You have limited understanding of economics here.

I keep telling you boys, your "supposed" chinese economic growth is founded on western markets consuming chinese products.

You are forgetting that if the west crashes.. china will sell its products....... were ?

I am putting it in simple terms.

Greece is insignificant in many terms, and yet now we are bust, the germans have a dip in their exports graph just because of Greece.

International trade is a chain. always remember that.

He means America economy will doom first and more severely doomed than China if USA economy is collapsed.

China growth is 8% vs USA 2 - 3%
USA is burdened with huge debt.

 

[amalakas]

He means America economy will doom first and more severely doomed than China if USA economy is collapsed.

China growth is 8% vs USA 2 - 3%
USA is burdened with huge debt.

Chinese growth is based on Western consumption. That is the point. China has growth because the west is buying. If west stops buying then China has no growth. get it?

 

[gambit]

We are not talking about which one has more surface area, as we have agreed that Cone itself contributes to RCS.

But we are talking about things behind the cone!

So your answer about the surface area of the cone become "irrelevant" or FAILED.

Then show us a source that have a jet engine fighter with exposed cone translation mechanisms.

Here are your words...

Do you understand that Cone will be heavier, and the moving parts contributes bigger RCS?

If cone translation mechanisms do contribute to RCS, then they must be exposed to radar view to some degrees. All you have to do is show everyone such a source.

And how do you prove that DSI bump is at best half a cone as you claim?

Cone inlet

DSI bump

Does look pretty much just a bump off the surface, ain't it?

From your explanation, I dont see yet the evidence that there is other thing of engine that contributes RCS more than Fan Blade?

Then you confirmed what I said that you do not understand even 1/10th of what I posted.

If your claim is true that Cone will be effective like serpentine, then why F-22/J-20 or even PAKFA (that is still strugling to hide its fan blade) not using the Cone to hide the Fan Blade?

Why have a small cone when we can design a full serpentine intake system? This just goes to show how pathetic your logical thinking really is.

In fact I dont see the 5th generation/stealth fighter is still using cone, which according to your claim is very effective in hiding the Fan Blade (the big contributor to RCS of the intake)?

Further evidence of a small mind and of lying about your aviation 'background' and 'study'. The location of the engines dictate the design of the intake system.

You are also wrong; it is not only DSI bump that hide the fan blade, but the combination between DSI bump with a forward-swept inlet cowl! and also the serpentine.

As if you really understand what all those aviation related words really mean and how they actually function.

Q: What is the dominant variable in longitudinal stability?
A: Power.

You cannot answer that first year Basic Aerodynamics question.

Why are you so proud with that long explanation but severely lack of citations of your debated claims?

You dismiss citations anyway? So why are you crying for them now?

Like always you either like to drag internet article, or explain things very long to impress readers, but you loose relevant point or the points of your argument are still misconceptions.

You are unable to be consistent. First you demand citations in one sentence, then you criticize them as 'drag internet article'.

You already demonstrated clueless by saying that only DSI bump alone that works to hide the blade, ignoring the combination of forward swept inlet cowl + the serpentine (in F-35 and J-20 case).

You already demonstrated idiocy when you think that the Cone Inlet will be always like that of Mig 21!

Show me a cone intake system that does not contain a cone.

Remember all of your debated claims will be rubbish without citation

And remember your inconsistency, demand citations in one sentence, then dismiss them the next.