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


Stealthflanker

New Member
Registered Member
So, yeah my "little project" finally "done enough" with some result. This graphics below depicts RCS "before" and "after" application of radar blocker which summarizes the result. X-band (8 GHz) and horizontal polarization.

Without Inlet treatment (RAM linings) & blocker​
With Inlet treatment (linings) but no Blocker
With application of both Inlet blocker Treatment of inlet guide vanes and RAM linings of inlet duct​
Su57-Notreatment-XbandIRSTOpen.pngSu57-XbandNoBlocker.pngX-bandIsoWithBlocker.png
Without Blocker-treatment-xband top.pngSu-57Noblocker Top.pngX-bandtopWithBlocker.png
Remarks : Multiple reflections and reflection from engine are clearly visibleMultiple reflection from inlet ducts are suppressed, but prominent lobe from the engine remainsThe strong reflection from engine are weakened considerably

For methodology and further discussion I detailed it in my SPF post. I would love to describe it here but i ran into limitations on the number of images i can post.

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Short conclusion is that the application of Radar blocker succesfully reduces the otherwise menacing spikes from the engine.

Still the result is highly speculative as i dont know the material being used and how the blocker actually positioned within the inlet. There is patent information. It describes the methods of selecting the dimensions and position of the blocker but not how much it can reduce RCS.
 

gelgoog

Major
Registered Member
There was a TASS news report claiming all aircraft in the 2021 plan had been delivered. But we have no de facto press release that the Su-57s were delivered. So I would assume they were not. But they were seen in the production line in the middle of last year, so if they were not delivered they should be close to it.
 

Stealthflanker

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Registered Member
Now i'm kinda curious if Izedeliye-30 engine would also feature "stealthy augmenter" or "Fan blocker" as one featured in F-22 and F-35.

Both aircraft have special structure in their tailpipe which act as afterburner augmenter and flameholder AND a radar blocker to reduce RCS of the turbine blades. This augmenter appears to be shaped similarly as the inlet radar blocker. I have my doubt at first but apparently yes, high temperature capable RAM does exist plus since its an augmenter it can be actively cooled by fuel or bleed air. The only concern now is how long it could last considering the environment post engine turbine which exposes anything ahead of it with over 900 degrees celcius temperature and possible solid particles formed from burning residues of the combustion chamber.

Anyway below depicted the effect of such blocker for the RCS of the tailpipe.
Screenshot 2022-01-11 at 16-41-51 Lockheed Martin F-22A Raptor.png

The simulation is done in ANSYS, Frequency is X-band. (8 GHz) Horizontal polarization. The structure depicted is simplified jetpipe, 2 stages of turbines and mid-supporting structure (bullet). The Blocker is based on my interpretation of available imagery of F-22 tailpipe. Thus it's highly speculative in nature.

The RAM treatment is an idealized RAM with impedance of 377 Ohm. Which applied to nonmoving parts. The "bullet" and the Augmenter. Above table depicts the 3D projection and 2D contour plot of RCS of tailpipe with exposed turbine on the left with the one equipped with stealthy augmentor on the right.

3D projection wise does not appear to show the magnitude of RCS reduction. But the 2D plot shows very clearly of considerable amount of RCS reduction.

Numerical wise. the Median RCS of the result are as follows :
-Nozzle with exposed turbine stages : 1.8 Sqm
-Nozzle equipped with "stealthy augmentor" : 0.05 Sqm

Above result correspond to about 34 times reduction of RCS. This will bring about 60% reduction of radar range against nozzle equipped with the stealthy augmentor vs conventional flame-holder and augmentor configuration.

The current 117 engine tho seems to still utilize conventional configuration. I'm curious if Izd-30 may have the blocker.

The Penalty of the design however was never really mentioned.. Even there is practically no open source info. However it's mentioned that F-2's F-119 engines are suffering from "high usage rate" might be related to the blocker.
 

Tirdent

Junior Member
Registered Member
The current 117 engine tho seems to still utilize conventional configuration. I'm curious if Izd-30 may have the blocker.

Well, a while ago an insider on a Russian forum leaked three photos of the Izd. 30 fan face, and he also posted one looking up into the nozzle. The curious thing is that the interior was censored... and I'm really struggling to think of a better reason for doing so than to hide some form of RCS reduction measure. I mean, the afterburner is almost certainly going to be different to the Izd. 117(S) due to the higher temperatures, which will likely necessitate some form of cooled radial flameholder design. That in and of itself isn't something you'd need to hide, it's pretty much a given - anybody with a modicum of knowledge would be expecting it anyway.

Perhaps the more interesting question then is what solution exactly is used, the F-35-style twisted stator that you've modelled, or the retractable design from the patent shown below?

1306926.gif1306925.gif
 

Stealthflanker

New Member
Registered Member
Perhaps the more interesting question then is what solution exactly is used, the F-35-style twisted stator that you've modelled, or the retractable design from the patent shown below?

View attachment 81101View attachment 81102

Do we have patent number for this ?

looks interesting.

Anyway the Su-57 RCS spikes with and without the blocker might look something like this.

Without Rear blocker (Conventional 117)​
With Rear blocker. (hypothetical) with Izd-30​
Perfect RAM Away.png360-Su57-2.png
 

panzerfeist1

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1642734069886.png





1642734154143.png




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one is based on high supersonic conditions (perhaps mach 3-4 or thats pushing it) and the other is just regular? Here are two versions.
 

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