Russian Su-57 Aircraft Thread (PAK-FA and IAF FGFA)

[Hyperwarp]

This crude monstrosity is the perfect illustration of why the F-22 is so far superior to the PAK-FA, its huge, the nozzle is obviously very large and in-efficient, where the nozzle on the F-22 is small and highly refined. That is also why we went with the 2D nozzle as opposed to 3D, because the very last place you want to hang that much weight is at the VERY AFT station on your weight and balance???

If some of us are as bright as we think we are, you will recognize that side profile which shows this huge ducting as opposed to the starboard ducting is where all this in-efficiency of the square nozzle comes from. The F-22 aside from being very efficient is also very "Kool" and shield the very hot exhaust gases with aircraft structure.

More to the point, everything on the F-22 is of a very high level of build and refinement, as this ducting/nozzle illustrate, this is rather crude, and many of the Russian systems are still in their infancy and lack refinement.

It looks crude and humongous because it was Russia's initial attempts, allegedly targeting the T-60S supersonic bomber. Actually not Russia, but USSR. Conversion of the Su-27UB started in the late 80's and flights in 1990. This has nothing to do with the T-50. Like I said in the previous post, the T-50 might get flat nozzles when the Izdeliye 30 powered T-50 enters service in 2020 or so. Key word is "might". Most likely they will stick to the regular nozzles.

Sukhoi, NPO Saturn have been studying flat nozzles for a 5th gen fighter for a while it seems. Saturn published a patent regarding that. But whether these will ever be implemented on the T-50 is another matter. Most likely scenario we will see flat nozzles in a Russian A/C would the future intermediate and intercontinental bombers.

 

[Deino]

@b787 ... do You really have to post each and every single report about the T50 that reports nothing more than promises, expectations, plans, wishes and that were already posted in several others similar if not the same reports ???

It's quite difficult to keep on track what's really happening ....

Deino

 

[tphuang]

here you can see the Russians studied the flat nozzles
Now let us see their view on Stealth



They claim PAKFA is stealthier upon some angles and less stealthy at others than F-22, but in general it is stealthier

RT - T-50 Pak Fa Stealth Fighter Has RCS Of Tennis Ball With Passive Stealth Technology

I tell the Chinese members to not believe in every piece of propaganda and I would tell you the same thing.

and I'm also assuming that you can see me bowing deeply to you brother, even as I humbly disagree that 225 is a bargain of sorts? I absolutely agree with Master Brumby that given the Indian procurement??? voodoo???? or whatever, and the Russian gamesmanship??? it will be a total miracle if this deal ever comes to "fruition"?

seems like the cost always escalate on the Indians. I don't know how they are paying 11 billion for 36 Rafale. We will get a better idea of the cost of this thing in 5 years.

 

[Air Force Brat]

I tell the Chinese members to not believe in every piece of propaganda and I would tell you the same thing.

seems like the cost always escalate on the Indians. I don't know how they are paying 11 billion for 36 Rafale. We will get a better idea of the cost of this thing in 5 years.

Yes Sir, it makes me want to pull my hair out, and I have little hair, and no money of my own invested, any-way have a great day, I am at all times most appreciative of your honesty and integrity. We are all indebted to the thoughfullness, kindness, and honesty of our mods here on SDF, and each of you lead by example, thanks Bruda!

 

[b787]

I tell the Chinese members to not believe in every piece of propaganda and I would tell you the same thing.

.

i can answer you this way, why PAKFA carries 3 AESA systems that use different frequencies?

well the answer lies in the fact of this equation

Using this equation you know the range of detection is a result of the power density, the frequency of the electromagnetic wave and the area in square meters of the target.

this tells me no RCS is fixed thus PAKFA will have a smaller or bigger RCS depending upon what radar is painting it, to put it simple, the Irbis radar on Su-35 can detect a MiG-21 at longer range than a Saphir radar of a MiG-23, so it is the radar transmitting power what really matters.

So the MiG-21 will be detected at different ranges depending upon what radar is painting it.

All aircraft are the same

 

[Brumby]

@b787 ... do You really have to post each and every single report about the T50 that reports nothing more than promises, expectations, plans, wishes and that were already posted in several others similar if not the same reports ???

It's quite difficult to keep on track what's really happening ....

Deino

There is a logical reason for this. When there is nothing much one can report on actual progress, the substitute are promises. Something has to fill the void. The other common feature is recycling old photos or posting imaginative CGI's. There are a lot of postings on this thread concerning plans, promises, and even fantasy stuff but hardly any information on tangible progress. We should be seeing a new prototype delivery this quarter (as promised) or is it that it is so stealthy that I actually missed its appearance?

 

[Brumby]

i can answer you this way, why PAKFA carries 3 AESA systems that use different frequencies?

well the answer lies in the fact of this equation

Using this equation you know the range of detection is a result of the power density, the frequency of the electromagnetic wave and the area in square meters of the target.

Your attempt at using the radar equation to explain your views is logically incoherent. You need to take an interest in what you share in that it corresponds to what you say. As per the equation that you have shared, detection range is a result of a combination of variables i.e.
(a) transmit power;
(b) transmit wavelength;
(c)target RCS;
(d)frequency used; and
(e)antenna gain

So what is so wrong with your comments? Let us continue ....

this tells me no RCS is fixed thus PAKFA will have a smaller or bigger RCS depending upon what radar is painting it,

The equation doesn't prove or disprove that RCS is not fixed. The equation only tells us that detection range is affected by the targeted RCS. In other words, the smaller the RCS the shorter is the detection range and frankly the whole rationale of stealth.

to put it simple, the Irbis radar on Su-35 can detect a MiG-21 at longer range than a Saphir radar of a MiG-23, so it is the radar transmitting power what really matters.

No. As you have just shared with the radar equation, the detection range is dependent on at least 5 variables as I have outlined and not solely on transmit power. You seriously need to pay attention to what you yourself post.

So the MiG-21 will be detected at different ranges depending upon what radar is painting it.

That may be partially true but there are other mitigating reasons such as aspect angles, ECM and function of probability of detection.

All aircraft are the same

You have just shared in the radar equation that targeted RCS affects detection range. How can it be that all aircraft are the same because we know as a fact that different aircrafts have different RCS profile.

Finally and most importantly, you have not address the key point in your post

i can answer you this way, why PAKFA carries 3 AESA systems that use different frequencies?

I will attempt to help you with this. As you have shared in the radar equation, there are another two variables that affects detection range i.e. frequency and transmit wave length. I would suspect that the T-50 uses "X" frequency as its main, "L" frequencies at the wings and "S" as the supplementary. I would also suspect that the frequencies collected would be used as part of a technique known as frequency difference of arrival (FDOA) to be combined with time difference of arrival (TDOA) into the Complex Ambiguity Function (CAF), a technique for processing complex signals. In short, they are advanced detection techniques using very complex sensing and algorithm filtering techniques to enhance detection. The caveat though is that these techniques are best used to geo locate fixed emitters.

 

[b787]

Y


The equation doesn't prove or disprove that RCS is not fixed. The equation only tells us that detection range is affected by the targeted RCS. In other words, the smaller the RCS the shorter is the detection range and frankly the whole rationale of stealth.




.

The reflected power Pr at the radar depends on the power density Su, the antenna gain G, and the variable radar cross section σ:


Pr = Ps · G · σ in [W] Pr = reflected power [W]
σ = radar cross section [m2]
R1 = range, distance antenna - aim [m]

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The surface area σ is measured in square meters, this means no RCS is fixed

The size and ability of a target to reflect radar energy can be summarized into a single term, σ, known as the radar cross-section, which has units of m². This unit shows, that the radar cross section is an area. If absolutely all of the incident radar energy on the target were reflected equally in all directions, then the radar cross section would be equal to the target's cross-sectional area as seen by the transmitter. In practice, some energy is absorbed and the reflected energy is not distributed equally in all directions. Therefore, the radar cross-section is quite difficult to estimate and is normally determined by measurement.

The target radar cross sectional area depends of:

• the airplane’s physical geometry and exterior features,
• the direction of the illuminating radar,
• the radar transmitters frequency,
• the used material types.

The use of stealth technology to reduce radar cross section increases the survivability and decreases the target detection of military aircraft. But the stealth technology depends of the used radar transmitters frequency and has none effect against VHF- radars like

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or

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, both used by serbian air defense units during the Kosovo war.

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So as you can see it is not fixed, the RCS of a golf ball for PAKFA by RT is not fixed either it is just an approximation upon some radar types.

Rostec claims that is the reason the T-50 is designed with emphasis on agility and supercruise

 

[Brumby]

The surface area σ is measured in square meters, this means no RCS is fixed


So as you can see it is not fixed, the RCS of a golf ball for PAKFA by RT is not fixed either it is just an approximation upon some radar types.

Rostec claims that is the reason the T-50 is designed with emphasis on agility and supercruise

b787,
I have no intention to argue for the sake of it. Your initial post was to use the radar equation to support your point that RCS is not fixed (as with the PAKFA). I pointed out to you that you cannot rely on that equation to prove such a point simply that it is not the function of that equation to do so and your attempt at it is circular reasoning. What in effect you are saying is that because the RCS as an input value is variable, therefore RCS is in fact variable and not fixed. It is of course factually true that RCS is not fixed and can be affected by a number of reasons but the problem is your approach to it and reasoning is fundamentally flawed in explaining the variable RCS profile of the PAKFA. The biggest problem that you have (I am saying it constructively) is that your sense of reasoning is an area that you really need to work on.

 

[b787]

b787,
I have no intention to argue for the sake of it. Your initial post was to use the radar equation to support your point that RCS is not fixed (as with the PAKFA). I pointed out to you that you cannot rely on that equation to prove such a point simply that it is not the function of that equation to do so and your attempt at it is circular reasoning. What in effect you are saying is that because the RCS as an input value is variable, therefore RCS is in fact variable and not fixed. It is of course factually true that RCS is not fixed and can be affected by a number of reasons but the problem is your approach to it and reasoning is fundamentally flawed in explaining the variable RCS profile of the PAKFA. The biggest problem that you have (I am saying it constructively) is that your sense of reasoning is an area that you really need to work on.

if you see this

The simple radar equation is described below:



Where Pr is the power received by the radar in (watts). Pt is the transmission power in (watts). Gt is the Gain of the transmitting antenna. Gr is the gain of the receiving antenna, σ the radar cross section (RCS) (m2), λ the wavelength of the radar operating frequency (m), and R is the range between the radar and the target (m).

It takes into account that the first term in parentheses represents the power density of radar in the objective (watts/m2).
Some factors that determine the amount of electromagnetic energy returning to the source are (Maritime Safety Information, 2009):

• The material and geometry of the target in which it is made.
• The absolute size of the target.
• Relative transmitter/receiver position to the target.
• The relative size of the target in relation to the wavelength of the illuminating radar.
• The incidence angle, which is the angle at which the radar sends waves to a particular portion of the target that depends on the shape and orientation of the target to the radar source.
• The reflected angle, which is the angle at which the reflected wave leaves the target and is directly related to the angle of incidence.
• Signal strength of the radar transmitter.
• Distancebetween radar and target.

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You get the idea more watts from the transmitting power (radar) the detection range will increase, the absolute size is the surface in squared meters, something that is fixed; this tells you a MiG-21 will be detected at different ranges depending upon what radar paints it, but the angle and shape will affect the RCS but this last will be highly dependent upon the frequency.

So in few words give me a better radar and i will see any stealth fighter, Sukhoi knows that, so they know speed and agility means life, therefore PAKFA`s designers opted for solutions that fans claim are unstealthy, but the Russians decided that since they have a smaller military budget and radar technology will catch up with stealth, it was better to go for super cruise and a very agile fighter, pretty much what Pierre Sprey says.

The Russians have another aircraft philosophy regarding the 5th generation fighters