RCS of Fighters Calculation

[quote="GarryB"]

"suggesting" hahaha, did I not say Su-27 derivative as the conversation went on?

You gave the Su-27 as an example and then compared it with later aircraft used in different roles like the Rafale and F-18, rather than the F-15 which is the only western aircraft directly comparable to it.

Right, so instead of discussing history I should of discussed more modern matters; such as the Su-35 and it's larger RCS compared to comparable planes.

Actually, a Su-35 will kill every Su-27 there are. A F-18E/F will kill every F-18 there are. A F-15SE will kill every F-15 there are. Gen 4.5 planes with some Stealth features are very much so better than their generic Gen 4 counterparts.

We were discussing their effect against stealth aircraft where you suggested the upgrades were both useful and worthless.

You keep thinking I'm suggesting anything, I mean what I say, a Gen 4.5 craft will fare better than it's Gen 4 counterpart.

For the Su-35's RCS estimate, look to the link above (1 m2 on the Front with X-band).

And for the F-15SE's:

"the Silent Eagle offers the same level of front-aspect stealth than the "international release version" of the JSF"
http://www.f-15e.info/joomla/en/export-variants/f-15se-silent-eagle/1641-f-15se-differences

Unfortunately I was unable to find a RCS estimate of the export F-35.

Totally worthless information for aircraft that carry weapons externally.

Nope. The Su-35's frontal RCS is estimated to be 1 m2, I think, with minimal external stores, while the F-15SE's is what it is with it's internal stores.

I don't care what your opinion is, I want facts!

Interesting you will accept opinions from the web links you post above but my opinion is worthless.
Good to know.

I hazard you don't have any real military experience? Thus it is your opinion!

So you aren't denying there's no evidence that the Russians are even pursuing Plasma Stealth? Thank you.

No I am not. But clearly we are drawing different conclusions from this fact.
Now that they probably have proper funding what purpose would their be to publishing results now?
Actually now that I think about it there was mention of using Plasma Stealth to reduce RCS that was to be applied to the Su-35 and Su-34. I have had a discussion on this forum about it with someone else, but I am not in the mood to help you find it right now. Normally I am happy to share info, but when things become argumentative and I am challenged to prove something wrong I sort of feel like I am being manipulated to be their library B!tch to search for info just to prove myself.
I don't do that.

You don't need to believe me... remaining ignorant is your problem, not mine.

Ha, remaining arrogant is your problem and remaining open minded is mine. Don't pretend to be right all the time because you know you're wrong and just want to save face from this plenty ole' American.

RussianStalinist wrote:Sorry if something similar to this has already been asked, but here it goes:

On the Sukhoi website, they state that the RCS of the F-22 is 0.3sqm. An Indian General (I believe) said that the PAK FA had an RCS of 0.5sqm.

The 0.3sqm for the F-22 contrasts sharply what America has said the rcs of the f-22 really is (they said something like 0.0001sqm). Why is this? Is it because Russia calculates rcs differently?

If that's the case, then what would the PAK FA's rcs be if it was calculated using the Western method?

Thanks for any answers!

You are asking a very loaded question. There is no such thing as a 'Western' or 'non-Western' method of calculating the radar cross section (RCS) of a complex body. The RCS question/value rests on how many tools you have and how effectively do you use them.

For starter...



In radar detection, the simplest body is the sphere. On this body, there are only four possible behaviors:

- Specular
- Surface wave
- Leaky wave
- Creeping wave

You can guess the matches from the illustration above. The fourth behavior -- creeping wave -- is conditional. There is a rule call the 'ten lambda' rule. Lambda is the Greek symbol for wavelength -- ANY wavelength. The 'ten lambda' rule states that if the diameter of the sphere (or cylinder) is greater than 'ten lambda' then the creeping wave effect will not occur. This is because of the leaky wave effect. The surface is called the 'electrical path' and the longer this path the greater the leaky wave loss mechanism, hence the creeping wave effect may or may not occur.

In contrast, an aircraft is a much more complex body than a sphere...



It is well known that Physical Optics (PO) is good only for specular reflections but not for anything else. Even the Iranians know this...



For cavities such as engine inlet/exhaust tunnels, more sophisticated tools have been developed, such as Iterative Physical Optics (IPO)...

http://www.jpier.org/PIER/pier.php?paper=07110803

Abstract:
It is always a challenge to predict Radar Cross Section (RCS) of a full scale military platform with a good accuracy. Most of the time antennas and cavities are the main contributors of aircrafts RCS. Several methods have been developed to compute the RCS of cavities such as analytical methods (modal methods) and asymptotic methods (geometrical optics (GO) methods and physical optics (PO) methods). This article presents the Iterative Physical Optics (IPO) method which consists in an iterative resolution of the Magnetic Field Integral Equation (MFIE) to compute the currents on the inner walls of the cavity. This method allows computing arbitrarily shaped cavity with a good accuracy even for cavity with a depth inferior to the wavelength. Comparisons of IPO results with Rays and Finite element methods show a better accuracy of IPO than Rays especially for cross polarization. But computation time represents one of the main limitations of the IPO method. We present here a new formulation of the Segmented IPO method which coupled with the generalized reciprocity theorem decreases significantly the complexity of the method and consequently the computation time. The S-IPO method has been validated by comparisons with Modal method and measurements. We have observed that the repartition of the electric currents density on the inner walls of the cavity is quite the same with IPO and S-IPO computations. Lastly we propose an evolution of the IPO method we have developed to compute the RCSof cavities under radome. This method has been validated by comparison with finite element results.

Ufimtsev developed the edge diffraction method that gave US the F-117. Edge diffraction calculations is another tool.

So your loaded question rests upon the tester's knowledge of how many behaviors are there on a complex body, how they interact with each other, how many tools available, and how good is the tester's usage of them. If there are deficiencies in any of those knowledge, and the problem here is that those deficiencies may not be known to the tester, in other words, he does not know he is wrong, the entire enterprise is compromised and a 'non-true' RCS will result. The next problem is that once as complex a body like an aircraft is considered 'complete' a project, meaning ready for volume production, you may not be able to make changes and/or corrections to that complex body without the possibility of creating negative aerodynamic compromises.

So here is a possibility: You designed a 'stealth' aircraft using only Physical Optics (PO) as your measurement tool. You did not know about edge diffraction or surface wave behaviors. You shaped your aircraft in ways to deflect specular reflections away from the seeking radar's position. Then you publish the RCS value and call the design ready for production. On the other hand, your potential adversary spent a lot of money and much more time than you developing his 'stealth' aircraft with as many available tools, known and unknown to you, as he can. It is inevitable that he will create a superior 'stealth' aircraft than yours. His may not be as fast or may not carry as much ordnance as yours but because he can bypass radar networks with greater ease his 'stealth' aircraft can greater affect the war than yours can.

Other considerations are the hardware used in running these tools. The more powerful the computers, the greater your knowledge on the interactions between these behaviors because these reflections and diffracted signals have to come off the individual bodies such as antennas or flight control surfaces some time. In a complex body, those signals will impact other surfaces at different angles and that may create a different behavior. Powerful computers can help you observe and record these complex interactions in a larger time span compared to breaking down the complex body into discrete segments and try to patch these smaller bodies together later.

This is why it is not as easy in making and/or measuring a 'stealth' aircraft as many have come to falsely believe. The US have no problem with anyone making any claims about our 'stealth' aircrafts regarding their RCS values. The critics can make those values as high or as low as they wish.

I WanT to Know Confirmed RCS Of Mig-29k and Su-35

GarryB wrote:A pretty pointless figure...

From what angle?

From what frequency range?

What is the weapon load?

There are three types of aircraft... stealthy, Low Observable, and not stealthy.

Low Observable are not stealthy planes ...a modern age with high power AESA radars will be detected at very long ranges anyway... LO might delay detection but not by enough to be critical.

Low Observsable ? RCS ? AMRAAM's effectiveness ? BVR efficiency ?   How much meaningless debats about these subjects ?

Since the begining Stealthy technique does not work. Did it work one day ? It seems that as I understood it worked during the first gulf war in 1991. Because it was a little strategic surprise at the begining of Desert Storm. Once iraqis understood the game, they deployed their old soviet/russian VHF radars, and -as Pierre Sprey, Iam not a specialist- after US military studies, Iraqis spotted several times the F-117, even one stealth was downed. The war in Serbia demonstrated that F-117 and all stealth aircrafts were useless as US lost 2 F-117, and one B-2.

In fact  after Korea war in 1953, US tried to avoid as long as it is possible, dogfights, because they know very well the result is randomly. They bet on their supposed advanced technologies for example BVR, AMRAAM, and now stealthy, or low observable fighters or bombers.
However after recurrent studies all results demonstrated that these technologies worked fine either in laboratory, or simulated exercises where the scenaris were Heavily-Scripted by the industrial military complex. Yes, let's believe an F-15 could success with 955/1, yes the let's believe that the F-22 successfully won at a rate of even 1.000.000/1. Why not ?


The reality is another thing, Mig-21 bison even now, is able to down any US fighter, at the condition that a comptetent pilot is inside. Please do not tell more about the filthy computer simulation's results, they are all meaningless. Yes a stealthy Abrams tank in laboratory could be sucessfully trialed at the rate 10.000/1, but in the battlefield a simple RPG-7 could disable it, an RPG-29 could burn it. This is the same for a F-15/F-16/F-18/F-22, they all could be downed by even a Mig 21, or Mig-23.

The reality is this, a war is not virtual, America won against Iraq, and Serbia not because their weapons were more advanced than their enemies, but mostly because they outnumbered them -because their military budget allowed it-.The dogfight is still nowadays the ultimate situation where we could see who will win, the rest is only hype.

The greatest danger now for US is as their economy is on sustainable depression, the crisis is melting their military budget -as it was the case for Russia in early 90's-, hence preventing them to outnumber their future ennemies. Now we will see the truth. We will laugh, let's see what could happen in the case of war in Syria, or against North Korea. We will have the best laughing party than we never had.

Mwahahahaahahaha         

There is a rather larger contingent of pundits out there who love to go over the Pak Fa's stealth features and look for holes. And they always compare it to the Raptor. If the Raptor has it and the Pak Fa doesn't then the Pak Fa ain't stealth is how it goes. They make these long blathering posts that question aspects of the Pak Fa. Most of them think, just by eye balling certain angles or little details, that they've uncovered a stealth deal breaker. When in reality, its usually just lame little details that they are totally blowing out of proportion. And they become so sure of themselves. I call them stealth absolutists.

And the worst part is, that they don't even realize that they are questing the very stealth designation of the Pak Fa. Do they think that the Russian MOD was bluffing when they stipulated stealth or something ? Do they think that Sukhoi is lying when they say that the aircraft has met the terms of the tender ?

One example is the air intake of course. That one famous picture that shows some of what they believe is the 1st stage of the engine. These guys say that this is a deal breaker. When in reality, the YF 23 had superior all aspect stealth than the F-22 Raptor and it has more engine exposed than the Pak Fa.

Does anyone here question the stealth of the Pak ?

I do question the stealthiness, at least of the prototypes we've seen.
There really are a bunch of obvious failures to align panel edges/minimise gaps & that means it clearly can't have as low an RCS as F-22/F-35.

If the production version actually applies this level of detailing all over then T-50 should be well up there with the US fighters in RCS reduction


On the other hand I also question widely thrown about RCS numbers 0.0x m^2 or lower for F-22/35 when you have ~0.4m^2 radar antennae like this on the front

These are literally designed to be excellent Radar Reflectors & I really can't see any reason that they would bounce back significantly less than equal-area RCS (without severely limiting capability), certainly no way they can be orders of magnitude less than their literal area.

But on the basis of what we've seen I don't think full effort at frontal RCS minimisation is a particularly important factor in T-50 design:
F-35 puts nearly all eggs in the frontal RCS basket
F-22 also has excellent manoeuvrability to fall back on.
There is almost certainly enough RCS reduction to give T-50 the jump on T4 gen planes 1v1.

T-50 shifts a lot of emphasis to 360deg situational awareness via cheek & rear antennae, extra Optical coverage & L-band wing leading edge antennae.

(not sure there are actually antennae for all those lobes/frequencies )

When you read scenarios where F-22/35 get their massive test/exercise victories vs G4 planes the G4 planes have no idea where the stealth planes are which allows the stealth planes to get on flank/rear & launch surprise attacks.

I think the Russian intent is that they're going to have at least a rough idea where the stealth planes are via wing-embedded L-band radars &/or operating defensively in range of ground based L-band radar &/or will be facing enemy AWACS.
Various articles over the years have pointed out that long wavelength radar with modern signal processing as seen on AWACS & Russian ground radar can easily locate stealth planes to within a few hundred meters which totally destroys those scenarios.

Meanwhile those cheek radars allow a high range of defensive avoidance manoeuvre for the T-50 to dodge inbound missiles while still providing guidance to outbound missiles & maintaining strong warning/EW/ECM in direction of threat (F-22/35 lose a lot outside 120deg frontal AESA arc).

Dear fellow su 57 fans

We should all realize by now that everything that has been said about the Pak Fa's stealth in the last 10 years , is pure f-ing nonsense. Whether its the uncovered engines (covered now) non serrated tips (almost done) or the famous nonsense about the engine face exposure (YF 23 had engine exposure yet had better stealth than the Raptor. Boeing X 32 had engine exposure too)

These little gimmicks got totally blown out of proportion by the haters that Pak Fa fans started to believe it. There is NOTHING here. This is as bad as Trump-Russia.

Seriously. Many pro Russian commentators and analysts got sucked into this. This has to stop. Don't give an INCH.

The facts are this. The Russian Federation put up a tender for a 5th gen STEALTH aircraft. Sukhoi delivered that stealth aircraft. To believe otherwise is to think that the Pak Fa is a conspiracy. Was it a fake tender and a fake delivery ? NO.

Even a 6 year old can see that there is SOMETHING about the Pak Fa that makes it look very much like the F-22, J-20 or F-35. And something about it doesn't look like 4th gen aircraft. What is it ? STEALTH designed fuselage. The jet was designed on the computer, to have the right angling to be stealth just like the F-22 was. That makes the Pak Fa stealth. Stealth does NOT mean "achieving invisibility". Stealth is NOT magic. Stealth is simply the scince of making things smaller on radar than they are in real life.

If anything, the Pak Fa with its tiny all moving vertical stabs and ultra low profile design (it is lower profile, by measurement) is MORE stealthy than the F-22. There's no way that there is more than a 5% difference in stealth between the 2 jets. So don't let anyone convince you otherwise.

The USA was designing the F-22 when the USSR was still around. It stands to reason that, like always, Russia had spy assets overlooking the program. These spy assets are the only ones who've ever put a number on the F-22's RCS. They say its about .03M2 and the Pak Fa is .05M2. Yet all that is ever said by the US is "its the size of a golf ball" The only reason that came out was for shows like the Discovery Channel to have something to work with. Its not serious. The real number is what the Russians have and they USED this number to make the Pak Fa within range of the F-22. Otherwise whats the point ? why make an inferior product ? The Americans actually have the audacity to claim that the F-22 is the golf ball and the Pak Fa is .05m2. Therefore the Pak Fa is way worse right ? NONSENSE.

One more thing. Its funny when westerners mock the plasma stealth idea that Russia was working on. The irony here of course is that in the first days of the Pak Fa debut , it was the western media who rightly surmised that plasma stealth had failed. Their evidence ? The careful shape of the Pak Fa (their words) was proof that Russia had to do stealth the hard way.

Early days the western defense media said "haha, plasma stealth failed and haha , its a Raptor clone" It was called the Raptorski for a couple years.

Yet now, the Pak Fa "looks nothing like the Raptor" "cant be stealth"

Respectfully

Pierre Sprey.

Let's start from the RCS figures discrepancies: the 0,000etcetera are the best possible one at a certain well determined angle (typically 45 °/ 315°) against a X band radar at a determined quote: its a developmental phase standard used to compare concurrent designs not something you would ever meet on a battlefield.
Just happened that they (the industries and the top brass involved in the acquisition process) sold it instead as it were like so to the public in order to sell the product better.
Russians (that have not to "sell" anything given that all the parts involved are state owned) talked instead above the average values they expect the respective planes to have in the frontal (i.e. the whole sector from + 45° to -45°) and rear ( from +135° to +225 °) aspects i.e. something that has a real operative value (and without revealing what there are their best RCS values instead ).
So when you see the Rafale 0,3 sqm let's bet they are its best angle value, not an average one.
Actually all planes after the F-22A beginning from the F-35 itself are designed to privilegiate the frontal aspect instead that the average 360° one and
for a very good reason.
To put it simple the mission patterns according to the F-22A but also the F-117A and the B-2A were designed up i.e. penetrate deeply an enemy controlled zone and in the case of the F-22  to stay there are simply considered impossible to get given the progresses that were made by AD systems, above all into counter stealth operative procedures than in the still notable hardware performance enhancement themselves.

Stealth is still a very valuable asset as it work also today way better than any ECM based approach but also having such planes, they are however expected to operate instead along  the ages old get in straight, drop load and haul ass operative pattern not about going inside carelessly.
An average high 360° RCS is redundant (or even counter productive if it come at the expense of max frontal one) there while a  radar return increased by 0,1 to 1 sqm passing from a front on to a tail on engagement is easily compensated by the doppler effect turning positive for the plane.

GarryB wrote:

How could the RCS of the PAK FA be that low? I think that Saab announced that the Gripen gets an rcs of something like 0.3sqm.

A Gripen clean with a RCS of 0.3sqm will be in trouble against a PAK FA armed with AAMs.



The point is that the Gripen carrys weapons externally and while the PAK FA can it normally wont.

Perhaps the 0.5sqm for the PAK FA is with external weapons?

This whole theory that the 4th gen Gripen or Rafele have a ticket to the stealth club is just bunk. There's no way a 4th gen is under 2 M2.

How could anyone seriously claim that the RCS of the Pak Fa is higher than those 4th gens ?

The USSR espionage apparatus was still around when the Raptor was being designed. They say that the RCS of the Raptor is between .03 and .05 M2. And they wanted their 5th gen to be a minimum of .05. Is the Raptor a tad better ? Perhaps. But they are close.

Why wouldnt Russia just make the Pak Fa more like the Raptor if there was such a big advantage RCS wise ? They could even get the basic layout from magazines like they did on other copies. They have the computer ability to get the right angles. The true S duct setup is easy. Russia did 2 true S duct setups on the su 37 and Mig 1.44.

This whole idea that the Raptor is more than 5% better RCS than the Pak Fa is bunk

marcellogo wrote:Let's start from the RCS figures discrepancies: the 0,000etcetera are the best possible one at a certain well determined angle (typically 45 °/ 315°) against a X band radar at a determined quote: its a developmental phase standard used to compare concurrent designs not something you would ever meet on a battlefield.
Just happened that they (the industries and the top brass involved in the acquisition process) sold it instead as it were like so to the public in order to sell the product better.
Russians (that have not to "sell" anything given that all the parts involved are state owned) talked instead above the average values they expect the respective planes to have in the frontal (i.e. the whole sector from + 45° to -45°) and rear ( from +135° to +225 °) aspects i.e. something that has a real operative value (and without revealing what there are their best RCS values instead ).
So when you see the Rafale 0,3 sqm let's bet they are its best angle value, not an average one.
Actually all planes after the F-22A beginning from the F-35 itself are designed to privilegiate the frontal aspect instead that the average 360° one and
for a very good reason.
To put it simple the mission patterns according to the F-22A but also the F-117A and the B-2A were designed up i.e. penetrate deeply an enemy controlled zone and in the case of the F-22  to stay there are simply considered impossible to get given the progresses that were made by AD systems, above all into counter stealth operative procedures than in the still notable hardware performance enhancement themselves.

Stealth is still a very valuable asset as it work also today way better than any ECM based approach but also having such planes, they are however expected to operate instead along  the ages old get in straight, drop load and haul ass operative pattern not about going inside carelessly.
An average high 360° RCS is redundant (or even counter productive if it come at the expense of max frontal one) there while a  radar return increased by 0,1 to 1 sqm passing from a front on to a tail on engagement is easily compensated by the doppler effect turning positive for the plane.

People really do believe that stealth is magic. Anyone who looks at the Raptor and the Pak Fa side by side and believes that the Raptor can have multiple standard deviations lower RCS despite having a higher profile, thinks that stealth is magic.

Russia either has a functioning computer power to optimize a fuselage design for stealth or it doesn't.

Even a 6 year old can tell that there's something about the Pak fa that makes it look like a Raptor and not a 4th gen. What is that ? Stealth angled design.

And if these 4th gen Rafele's and Gripens are anywhere near under 2 M2, without computer optimized stealth design , its because they are simply smaller. Which throws even more cold water on the idea that the Raptor can be bigger in profile than the Pak Fa, yet have multiple standard deviations smaller RCS.

In the lead up to the Raptor winning the design competition for the US 5th gen plane, the industry itself, determined that the YF 23 would have better stealth than the F-22 just by the poll model.



The fact that the industry determined the stealth qualities mostly by the poll model says something. It says that the shape of the aircraft is the biggest determining factor in the stealth of an aircraft.

Yet a certain segment of the enthusiast community things that the cosmetic details like how well hidden the engine is, or how the wings are clipped, or the canopy frame, are the biggest determining factor.

Clearly they are NOT. So 90% of the stuff that they come up with to degrade the Pak Fa, is periphery stuff and is NOT going to markedly change the RCS of the aircraft. But the relentless attacks on the Pak Fa, have led even tpak fa supporters, to believe some of this trash

Vladimir79 wrote:

RussianStalinist wrote:Sorry if something similar to this has already been asked, but here it goes:

On the Sukhoi website, they state that the RCS of the F-22 is 0.3sqm. An Indian General (I believe) said that the PAK FA had an RCS of 0.5sqm.

The 0.3sqm for the F-22 contrasts sharply what America has said the rcs of the f-22 really is (they said something like 0.0001sqm). Why is this? Is it because Russia calculates rcs differently?

If that's the case, then what would the PAK FA's rcs be if it was calculated using the Western method?

Thanks for any answers!

F-22 is far less than .3m^2.  That is the RCS of a clean Rafale.  F-22 is said to be marble to golf ball which is like .004m^2 at its largest.  There is no official figure for F-22 but the references have been given by Lockheed.  PAK FA RCS was stated by Sukhoi officials giving a debrief to Russian officials visting the production site on the dawn of their decision to sign the JV production MoU.  Ajay Shukla reported they said .5m^2.  

Every point made in this post cannot be right. Theres NO WAY that a non stealth jet is lower than 2m2. Golf ball refernce was for kids on the Discovery Chanel.

Vladimir79 wrote:

RussianStalinist wrote:Sorry if something similar to this has already been asked, but here it goes:

On the Sukhoi website, they state that the RCS of the F-22 is 0.3sqm. An Indian General (I believe) said that the PAK FA had an RCS of 0.5sqm.

The 0.3sqm for the F-22 contrasts sharply what America has said the rcs of the f-22 really is (they said something like 0.0001sqm). Why is this? Is it because Russia calculates rcs differently?

If that's the case, then what would the PAK FA's rcs be if it was calculated using the Western method?

Thanks for any answers!

F-22 is far less than .3m^2.  That is the RCS of a clean Rafale.  F-22 is said to be marble to golf ball which is like .004m^2 at its largest.  There is no official figure for F-22 but the references have been given by Lockheed.  PAK FA RCS was stated by Sukhoi officials giving a debrief to Russian officials visting the production site on the dawn of their decision to sign the JV production MoU.  Ajay Shukla reported they said .5m^2.  

F-22 is far less than .3m^2. That is the RCS of a clean Rafale.

That is totally untrue. The USSR espionage records says that the Raptor is between .3m2 and .5m2. Thats why the original tender for the 5th gen USSR/Russia jet was set at a minimum of .5m2. Why would they make the RCS way worse, like way out of the ballpark ?

The marble figure was just put out there because the Discovery Channel wanted a reference.

Anyone who believes that the F-22 can have multiple standard deviations lower RCS than the Pak Fa simply does not understand what stealth is. It is not magic.

Think about what you are saying. You are saying that a remote control replica F-22 has the same stealth as a full size Pak Fa.

RussianStalinist wrote:How could the RCS of the PAK FA be that low? I think that Saab announced that the Gripen gets an rcs of something like 0.3sqm.

I think that a plane designed with the intention of making it vlo would have a significantly lower rcs.

Because Russia is the ONLY one so far to actually disclose a real number.

However the hell the French and Swedes are measuring RCS, its not even close to a real measurement. The Gripen is probably a 3.00 m2. Not .03 m2. But even 3 is probably too low. The su 27 is around 10.00 m2 I think. The number going around for a clean Rafele is probably 5.00 m2. Not .05 m2.

And the F-22 Raptor is probably .03 m2 while the Pak Fa is .05 m2. The whole marble reference is not intended to be taken literally at all.

GarryB wrote:The design of the US aircraft (F-22 and F-35) are 100% compromised on favour of stealth.

The PAK FA is from the start a stealth fighter hunter... hense it keeps the IRST despite the reduction in stealth, it has long wave radar antennas in its wings.

Priority number one is manouver performance, stealth is important but it wont be the most stealthy aircraft that wins... when AAMs are defeated by jamming and cannons are the last resort my money would be on the PAK FA and Su-35 and MiG-35 with their cannon.

hense it keeps the IRST despite the reduction in stealth

That is just another example of a periphery detail getting totally blown out of proportion. Most people believe that stealth means "achieving invisibility". They've heard that round is not the ideal shape for RCS. Then they reason that the Raptor is invisible and it doesn't have an IRST. Therefore the Pak Fa cant be stealth because it has an IRST.

GarryB wrote:I see it more about compromise....

The F-22 does not have an IRST because it is the sniper on the hill shooting at long range at non stealthy enemy targets... it is supercruising using its alttiude and speed to increase the performance of its missiles and hopefully remaining invisible to its enemies.

Unfortunately for the US technology has moved on and the PAK FA is not a Russian F-22.... it is not supposed to fly into enemy airspace and zip about at mach 1.5 at high altitude zapping enemy fighters as they take off from long range.

It is intended to hunt stealth aircraft, so it has L band radar to detect aircraft stealthy in X band, it has IRST to detect stealth aircraft of all types it also has X band radar to detect and track all sorts of other targets and threats like AWACS aircraft and tanker aircraft and of course incoming missiles.

The point is that the F-22 is stealth at all costs which makes it expensive to buy and to operate.

The PAK FA is designed to shoot down stealth and other aircraft so it can manouver and shoot and find all sorts of targets.

The PAK FA will be a cheaper aircraft to buy and to operate but will be capable against a much wider range of target types.

More importantly they wont make 3,000 of them... they will be used together with MiG-35 and Su-35 aircraft and later probably drone aircraft too... another saving.

You are making some legit points. As I said, is the Raptor a bit better stealth wise especially all aspect  ? Possibly. Front the front, maybe they are the same. But the tone of your post seems to be that its a closed case that the F-22 has better stealth than the Pak Fa. I dont think there's enough evidence for that.

I believe the Russians when they say the F-22 ois .03m2 and that they decided to shoot for a 0.05 minimum. The difference between the 2 is 5% to 8%

Remember. The biggest determining factor in RCS is the shape. And the Pak Fa is 100% ground-up stealth optimized design.