Sukhoi Su-57 / T-50 / PAK FA first flight - pictures, videos and analysis [2010]

[Matej]

Nice!

 

[donnage99]

-- RCS is not a straightforward measurement, changing significantly depending on the angle and type of radar.

When the general figure of the fighter aircraft is quoted by the guys who made them, it's usually from the front, looking straight at the aircraft. The reason is it's the most crucial angle to be stealthy and usually the most ideal angle to have the smallest rcs (as the makers are trying to sell it).

 

[Abraham Gubler]

Now we do not know if 0.3 m2 is the figure for average stealth of the aircraft or best figures obtained by frontal RCS.

Actually *we* know a lot about the LO levels of US stealth aircraft. An aircraft with a frontal radar cross section of 0.3 m2 is generally not considered stealthy. Because this is only around a single order of magnitude reduction in RCS and will not result in a huge reduction in radar detection range. The reduction in detection range may be tactically significant in that it provides an advantage over likely enemies but it won’t enable you to stay in the battlespace undetected.

Real stealth aircraft have much smaller RCS with several orders of magnitude reductions over their physical size. The F-35 has over three orders of magnitude reduction in RCS (8m2 to 0.001m2), the F-22 over four (15 m2 to 0.0001m2) and the B-2 over five (100m2 to 0.0001m2) from non LO aircraft of similar size. This results in big 80-90% reductions in detection range.

The T-50 does not appear to have as many LO features as a F-35 or F-22 despite looking sort of the same with the chines and angled surfaces. For example it does not have a S curve intake. The front of the engine is only blocked from frontal view from look up surface radar. [Which as a tangent begs the question where is this mythical Russian fan coating which makes the front of their engine’s disappear? If this is as good as the fanboys of the FLANKER make out why did the T-50 designers put a big RF blocker in the intake?] Also the engine bays remain circular to match the engine (circles are the worst shape for RCS as they always present a flat surface to some angle) and there are twice as many moving surfaces facing forward (LERX leading edges, all moving twin tails).

 

[Abraham Gubler]

Doesn't this remind anyone else of the good old days?

What when after the fall of the Berlin War it was found that even the best Soviet fighter equipment was decisively inferior to that in the west? And the only advantage they had in air to air combat – the helmet mounted sight linked to the IR seeker of R-73, they had copied from the South Africans… The best thing the Russians have had going for them in the past 20 years was a vacuum of real information which like in the Cold War has enabled all sorts of fantasists and political motivated partisans to talk their equipment up into a frenzy of unsupported hoopla.

 

[piko1]

Abraham Gubler you are so funny i love to read conspiracy theories of how actually Planet Earth is Flat ;D i remember that Russians had RAM coatings research in 60's or it was 70's the information for that was Published in a Club Wings Magazine the article was for the Tupolev's Voron (Raven)
and for some interesting reconnaissance aircraft i will be very happy if someone can point me to a thread about them ???

 

[Abraham Gubler]

Abraham Gubler you are so funny i love to read conspiracy theories of how actually Planet Earth is Flat ;D i remember that Russians had RAM coatings research in 60's or it was 70's the information for that was Published in a Club Wings Magazine the article was for the Tupolev's Voron (Raven)

So what? The USA had RAM coatings research in the 1940s? Does that make the Earth flat enough for you? The point here is not about what you read in Club Wings Magazine but what the T-50 can do and making an evidence based assessment of that.

 

[flateric]

For example it does not have a S curve intake.

well, it has to some extinct, plus rumors are that there's some interesting 'engineering decision' is used inside
you can't fool aerodynamics, but who knows

 

[Kryptid]

well, it has to some extinct, plus rumors are that there's some interesting 'engineering decision' is used inside
you can't fool aerodynamics, but who knows

Radar blockers perhaps? Like in the X-32?

 

[donnage99]

RAM isn't something hard to find. In fact, there are US companies that sell RAM to the open world market.
http://www.eccosorb.com/main/Home.html;jsessionid=5C2B0FD7269A6327CD33BA177F9C4F08

However, thinking that stealth aircraft is just an aircraft with blending or facet surfaces and aligning angles, then applied RAM, will make it a stealth aircraft is oversimplified, if not ignorant. Designing stealth aircraft is using the right shape with the right techniques, the right materials. The techniques used in the f-22 are different from the f-35, because their shapes are different. And not just the outer layer that gotta be stealthy, the avionic equipments have to be stealthy. The radar of the b-2 and RWR suite of the f-22 are both the most challenging aspects during their developments.

 

[sferrin]

Tupolev's Voron (Raven)

You mean the same Voron that was a direct copy of the Lockheed D-21?

 

[Pit]

Question not related to T-50 but F-22A and other US and European LO and VLO designs:

Are typical US and Euro VLO and LO designs fitted with RAM applied to engine intakes and first compressor stages?

This is a typical russian "advertisement" on RAC (coats) R&D, and we can play guessing how much this can help or mitigate the not so "S-shaped" engine duct on the T-50 (supposing the no use of a radar blocker)...

What about western designs?, they use this technology?, or they prefer RAM and RAC in other zones?

What about the "cockpit-coatings" on russian RAM R&D, we know (from that 2006 paper Bill Sweetman bring to us then) that they have developed this technology...have they shown it on some stance?, any Su-35 prototype?, it's phisically similar to "gold-coats" on US and European aircrafts?

What about trying to ID LO and VLO facets of T-50 design, and what they lacks...just a short of organized summary.

 

[piko1]

You mean the same Voron that was a direct copy of the Lockheed D-21?

yep the same thing dumb piko forgot that it was copy of D-21 ;D
now i remember the article was for the D-21

back to topic...

any ideas what weapons this Beauty can carry
besides the once shown on paralay's cutaway ?

the answer that we are all looking for can be that simple i dont know much about aerodynamics
but if i'd want to hide the Turbine Blades i will just make this

 

[Kosmos929]

Page 19 of the study referred to states that the requirement was an RCS of 0.05 square meters or -12 dBsm.

Perhaps a decimal point has been lost somewhere in this long chain of quotations.

For any dilettantes interested in stealth requirements, I recommend this .pdf of a hypothetical stealth fighter designed by Cal Poly students.

http://aerosim.calpoly.edu/files/Vendetta/Vendetta%20-%20Final%20SAWE%20Paper.pdf

On pages 22-24, you'll find a discussion about stealth considerations. A few details to note:

-- The design requirements called for an RCS of 0.5 square meters, and this number can't be a coincidence. The reports implies that this is the industry standard for an aircraft to be considered "stealthy."

-- RCS is not a straightforward measurement, changing significantly depending on the angle and type of radar.

-- Shaping alone can achieve more signature reduction than a lot of people give it credit for, even before RAM is factored in.

-- There's also an interesting discussion about the various detection ranges of different radars and wavelengths. Too often, internet posters seem to think that stealth aircraft go completely undetected, but it's really about decreasing the TIME that an enemy has to repsond before the target aircraft has come and gone from the detectable range.

In short, I suspect the quoted RCS of 0.5 square meters simply refers to an industry standard, and by quoting that figure Sukhoi is simply declaring that this design truly qualifies as "stealthy."

 

[Woody]

From This angle the blended fuselage over the engine has enough depth to accommodate an S-duct if there is enough length before the front of the engine.

Cgreers, Woody

 

[Abraham Gubler]

Page 19 of the study referred to states that the requirement was an RCS of 0.05 square meters or -12 dBsm.

Perhaps a decimal point has been lost somewhere in this long chain of quotations.

The CalPoly response to the AIAA 2001 student design competition has NOTHING to do with the PAK-FA/T-50. The RFP for the competition asked for a RCS from shape alone of -12 dbsm from dead ahead for what would have to be a 100,000 lb aircraft (ie three times as big as the F-35) to meet the range spec. Application of RAM would bring the RCS of such an aircraft down somewhat and it would also supercruise throughout its mission. That this type of Rapid Theatre Attack aircraft was rejected by USAF is probably a good indication that the -20 to -30 dbsm RCS of such a big non-flying wing shape aircraft is no longer considered survivable for the type of deep penetration mission despite the high speed.

 

[piko1]

here is а comparison f-22 and PAK-FA
PAK-FA large one = 22.5m small one 19.12m

which one is more correct ?

 

[donnage99]

This is educated assumption on my part. The S-duct is there so that radar wave would hit the wall within the inlet and duct, and with each time, the RAM painted inside wall of the inlet would absorb a bit of the radar wave. That's why the longer and the more curved the duct is, the more times the wave will bounce inside there. Aircraft like f-22 and f-35 ducts are both curved upward and sideway and are very deep for that reason, I suppose. The T-50 engine ducts either are not S-shaped or only curve upward a little.

 

[Spring]

Now we do not know if 0.3 m2 is the figure for average stealth of the aircraft or best figures obtained by frontal RCS.

Actually *we* know a lot about the LO levels of US stealth aircraft. An aircraft with a frontal radar cross section of 0.3 m2 is generally not considered stealthy. Because this is only around a single order of magnitude reduction in RCS and will not result in a huge reduction in radar detection range. The reduction in detection range may be tactically significant in that it provides an advantage over likely enemies but it won’t enable you to stay in the battlespace undetected.

Real stealth aircraft have much smaller RCS with several orders of magnitude reductions over their physical size. The F-35 has over three orders of magnitude reduction in RCS (8m2 to 0.001m2), the F-22 over four (15 m2 to 0.0001m2) and the B-2 over five (100m2 to 0.0001m2) from non LO aircraft of similar size. This results in big 80-90% reductions in detection range.

The T-50 does not appear to have as many LO features as a F-35 or F-22 despite looking sort of the same with the chines and angled surfaces. For example it does not have a S curve intake. The front of the engine is only blocked from frontal view from look up surface radar. [Which as a tangent begs the question where is this mythical Russian fan coating which makes the front of their engine’s disappear? If this is as good as the fanboys of the FLANKER make out why did the T-50 designers put a big RF blocker in the intake?] Also the engine bays remain circular to match the engine (circles are the worst shape for RCS as they always present a flat surface to some angle) and there are twice as many moving surfaces facing forward (LERX leading edges, all moving twin tails).

Baically you are saying the 'pakf' is not stealth because , is not stealth.

Ok, let's go to basics

We are talking about this radar stealth thing, the best that i can reach with my understanding is applied optics

In optics there is no s-shape rule, no line alignment, no these rules

there is only one rule applied on this issue :Angle of incidence

The s duct is limited with the airframe, size and location, the s duct is actually a source of returns, let's see an example, an intake s-duct section with 30º of incidence, and after this the duct is straight, hiding the 'fan', but with a surface exposed

Against

A conventional duct, in which it surface is not exposed, but with a structure of 60º hiding the 'fan'

Which one is better?

The su-47 and the mig144 both had S-shape duct, and these were not even LO aircrafts

Why the russians are not going with the S-duct now? there is a reason.

Russians are probably not that worried on the side RCS, because no aircraft in the world does have a good RCS from it side.

The F-23 did actually had semi circular sections on it intake

Anyways, oneimportant thing of the data from that pdf, is that actually the model was faceted..probably the RCS of this 'vendeta' thing is actually much,much higher than in this faceted simulation

 

[Abraham Gubler]

Why did the russians are not going with the S-duct now? there is a reason.

Of course: they don't have enough internal volume in the right spots to fit an S-Duct. Most likely because the T-50 appears to reuse much of the Su-27 aerostructure.

As to the rest of it the whole point of the S-Duct is to take the hits of RF. It does so because it can be shapped to reflect these hits away from their receiver and because it can be coated with RAM to absorb it. These are qualities that can't be so easily applied to the front end of a turbojet's compression section. It is in effect a Glacsis.

 

[Spring]

Ram has it limits, and it weight

Shape is always better

You don't have that freedom with a s-duct

You have that advantage with blockers

 

[Abraham Gubler]

Ram has it limits, and it weight

Shape is always better

You don't have that freedom with a s-duct

You have that advantage with blockers

Blockers aren't magic. It is highly complex - and weighty - to stick something into the airflow of an inlet. As to the shape of an S-Duct it is highly advantageous because it reflects the RF away from the receiver and into other parts of the duct which can also be shaped to make sure the RF stays in the duct. Here's another French word from fortification history that describes what it does: oubliette.

 

[Spring]

Ram has it limits, and it weight

Shape is always better

You don't have that freedom with a s-duct

You have that advantage with blockers

Blockers aren't magic. It is highly complex - and weighty - to stick something into the airflow of an inlet. As to the shape of an S-Duct it is highly advantageous because it reflects the RF away from the receiver and into other parts of the duct which can also be shaped to make sure the RF stays in the duct. Here's another French word from fortification history that describes what it does: oubliette.

Is a concave bended surface, vs a surface without line of sight and a structure with high incidence

Have Blue did not have any s-duct, they went with the second solution

 

[overscan (PaulMM)]

I don't know what level of RCS reduction they are aiming for in the production T-50. I also don't know how much of the intended RCS reduction techniques are applied to the prototypes. From the configuration we can see, we can make a basic assumption that the RCS reduction shaping is applied primarily in the front quarter, even more so than the F-35. Therefore it is unlikely to be in the F-22 league of all round stealth.

Having said that, its apparently capacious internal weapons bays should allow clean configuration missions, which will put it in a different class to Rafale, Eurofighter et al for RCS in a typical loadout.

Compared to the MiG 1.42, it clearly uses some well known techniques such as planform alignment.

Regarding Berkut:

During the 1980s and '90s, TsNII provided input on a number of programs, which according to information from the institute had a considerable impact on the observability of both aircraft and missile platforms. These included the Tupolev Tu-160 Blackjack bomber, the NPO Mashinostroenia 3M-55 Onyx/ Yakhont (SS-NX-26) antiship missile, a strategic cruise missile (Raduga Kh-101) and the Sukhoi S-37. Claimed reductions, presumably compared with an unmodified platform, range from a factor of six in the case of the Tu-160, to 10 for the S-37, and 14 for the Kh-101 design.

http://www.aviationweek.com/aw/generic/story_generic.jsp?channel=awst&id=news/081103top.xml

Regarding the RAM on the SU-27 intake:

ITAE say the engine intakes have a high performance RAM between 0.7mm and 1.4mm thick on the intake ducts and 0.5mm thick on the fan blades which reduces the intake RCS 10-15dB, which measure alone halves the Su-27 RCS.

The other measures include a treated cockpit canopy (alternating metallic and polymer layers, using plasma deposition) and hand held sprays to treat external munitions

Summarised from Bill Sweetman, 'WORTH the COST?' Janes Defence Weekly, 19 July 2006.

 

[kcran567]

T-50 is an interesting plane but looks like a jumbled hodgepodge of stealthy features borrowed from other aircraft f-22 + f-35 + yf-23 + f-18 and a bit of flanker thrown in.

Someone else commented on the wide spacing of the engines and what looks like wasted space between the nacelles. I have suspicions that this airplanes weakness is gonna be its a real fuel burner like most soviet/russian aircraft. not as refined as the f-22 and not as good fuel fraction (but we will see) T-50 looks amazing though.

 

[overscan (PaulMM)]

I am fairly sure it is at the smaller end of the scale, about 19m. Time will tell though.

 

[Spring]

Saying the s-37 or the mig144 were meant to have LO features ,is like saying that the Ho229 was a LO design

 

[overscan (PaulMM)]

Abe, you are wrong here.

Reducing intake RCS by 10-15dB (not dBSM) simply means reducing it by a factor of approx 10-30. If the intake contributed half the 20 sq m RCS, treating the intakes would give an RCS of 10 sq m (rest of aircraft) plus 0.33-1.0 sqm from the now treated inlets for a total RCS of between 10.33 and 11 sq m.

Coating the whole aircraft would thereby, at best, reduce the total RCS to between 0.66 sq m and 2 sq m. Not bad, but not stealthy, and the RAM on the canopy would be a bugger In reality, treating the intakes and compressor face will likely get multiple bounces and multiple RAM attenuations from some angles. The RAM used is probably reducing the radar signal about 10dB on average, which is completely trivial today.

 

[Spring]

Seriously,neither the 142 or the berkut were meant to have any kind of RCS feature other than RAM coatings...probably

S-Duct it is highly advantageous because it reflects the RF away from the receiver and into other parts of the duct which can also be shaped to make sure the RF stays in the duct.

Sorry but this is a word salad

You are not being specific on the most important thing, the shape aspect

What reflects away from the receiver is the aspect and the incidence, not the s-duct per ce, you can get a s-duct exposing a immense surface with low aspect, making it a good reflector

Or you can get a ras with a excellent aspect/incidence, making it much better than any s-duct

 

[overscan (PaulMM)]

So the guys who said they reduced the RCS of the S-37 by 10 times were lying?

Its not even like 10 times is that impressive. Some fairly minor mods to avoid obvious reflectors can give that level of reduction.

 

[Woody]

If you don't know how much less, how do you know it (PAK-FA) will be faster? (F-22 is Mach 2.4+)

The F-22's maximum speed is classified so where do you get this figure of Mach 2.4. I've never heard anyone seriously suggest a speed higher than Mach 2. I would have remembered

The SR-71 had a blended Fuselage ;D

So did the prop-powered XP-67.

Which was damn fast for a propeller aircraft of it's day.

Cheers, Woody

 

[ubiquitous08]

Instead of evaluating RCS as a frequency specific (assumed x band ) variable we should be looking at what frequencies the T 50 is VLO optimised for. So far we have spoken of frontal optimised RCS as if x band is the only frequency. If and its BIG if L, S band and especially VHF frequencies are taken into account we might find that even the much vaunted F 22 is deficient in the rear hemisphere and also the side. Whilst I'm not a proponent of Carlo Kopp, his evaluations of Russian counter stealth and his estimated effects of frequency on the F 35 structure might imply that if the projected threat environment for the T 50 includes a proliferation of VHF (E 2D for instance, Chinese radars) and other larger than x band wavelengths including L and S bands, than no shaping would likely be sufficient for a fighter hence a limited application of X band against opponent fighter where it won't adversely effect performance. If this is the case Russian eschewing of total X band shaping might be seen as a realisation that X band is not the dominant exclusive radar frequency threat, hence not worrying about side and rear shaping that is unlikely to be effective against higher bands versus the nose which by virtue of sharp angles is likely effective at most (VHF?) frequencies. See link on projected Carlo Kopp F 35 RCS to see what i mean...

http://www.ausairpower.net/APA-2009-01.html

 

[Abraham Gubler]

by 10-15dB (not dBSM)

Well that's different! Bloody same sounding units!

Anyway as pointed out reducing RCS by half is pretty unimportant. You need to get in the orders of magnitude reductions to start slashing detection range.

A rough yard stick is if a radar can detect an aircraft at 100 NM (km, miles, leagues, parsecs, etc) it will detect another aircraft with a 1/10 reduction in RCS compared to the first aircraft at 50 NM, then one with 1/100 at 30 NM and then one with 1/1000 reduction at 10 NM.

 

[Austin]

So can we assume that PAK-FA is currently designed to have low RCS only against X band radar compared to the broadband reduction we see with F-22 ?

 

[kcran567]

Havent read whole thread, are those "pods" or panels out board of the intakes radar cancellation units? or some type of receiver/antannae? Has anyone commented on why intake openings seem to be extremely large?

 

[ubiquitous08]

So can we assume that PAK-FA is currently designed to have low RCS only against X band radar compared to the broadband reduction we see with F-22 ?

I'm theorizing that with VHF and S / L band increasing in their utility for tracking Stealth targets, achieving all aspect stealth against these frequencies is something even the F 22 cannot achieve (VHF will require very large facets and or thick / heavy ram treatments), as such frontal all aspect stealth maybe the only realistically achievable goal. For instance the radar blockers in the F 22 which have to be heat treated (that must be obscenely expensive!) and the nozzle geometry is likely completely ineffective at VHF frequencies so incur the cost when a Su 27 aft fuselage is just as visible but costs and weighs much less and may generate more lift? In other words could the T 50 be a design focused on future achievable Rcs reduction vs F 22 which lets face it was designed against X L and S band and completely predated (RCS goals outlined 1986, last design revision circa 1997/ 1996) the concept of active array VHF and conformal L band antennas? I note the prospective B 3 designs (Boeing concept art and Northrop grumman patents) both feature very large facets and shaping geometries clearly aimed at larger wavelengths far in excess of the facet sizes evident in the F 22. The only problem with this argument is that all wing geometries like Boeing 6th gen concept WOULD work in vhf frequencies but they will require fluidic nozzles amongst other developments to first reach maturation.

 

[Woody]

...and AMRAAM seekers are dual K-band which is higher frequency/shorter wave length than even X-band!

 

[sferrin]

If you don't know how much less, how do you know it (PAK-FA) will be faster? (F-22 is Mach 2.4+)

The F-22's maximum speed is classified so where do you get this figure of Mach 2.4. I've never heard anyone seriously suggest a speed higher than Mach 2. I would have remembered

Paul Metz (if you don't know who he is let me know) said the top speed of the F-22 is classified but that it'll do 1600 mph.

The SR-71 had a blended Fuselage ;D

So did the prop-powered XP-67.

Which was damn fast for a propeller aircraft of it's day.

Cheers, Woody
[/quote]

Actually it was slow because of all the wet area.

 

[sferrin]

Saying the s-37 or the mig144 were meant to have LO features ,is like saying that the Ho229 was a LO design

Blame Mikoyan and Sukhoi, they're the ones who made the claims.

 

[Trident]

You mean the same Voron that was a direct copy of the Lockheed D-21?

So? It did lead to some RAM know-how being acquired, thirty years on the way it came about is of rather peripheral importance I'd say. It is far from the only instance of Soviet/Russian research and application in this field either, among others there's the Su-27SM, Su-30MK, MiG-29K and Su-47 in the 2000s/1990s, the T-8-12 in the 1980s and work on ballistic missile penetration aids (specifically, 'Kaktus') as early as the 1960s.

Suffice it to say that Russia has gathered enough knowledge to be quite capable of designing its own RAM coatings nowadays.

... and there are twice as many moving surfaces facing forward (LERX leading edges, all moving twin tails).

I doubt the LERX is a big contributor, basically it is little more than a leading edge flap and while large, seems to use only small deflections (so the impact is likely nothing like a canard, for example). The all-moving tails are smaller than conventional fins and would probably be in the neutral position during cruise, with the TVC taking care of stability and trimming.

The point here is not about what you read in Club Wings Magazine but what the T-50 can do and making an evidence based assessment of that.

Well, the evidence here suggests that the Russians have substantial experience with RAM so its absence on the T-50 prototype is hardly an indication that the production variant will not be coated - very much a pertinent fact to point out.

By the way, while I realize this is probably not the place to say so, I find your call for "making an evidence based assessment" and comments such as the following two to be strangely at odds with each other :

Most likely because the T-50 appears to reuse much of the Su-27 aerostructure.

I suppose it is reasonable to state that the F-22 appears to reuse much of the F-15 aerostructure then? Because we have about the same amount of evidence for both statements - a purely superficial resemblance.

If this is as good as the fanboys of the FLANKER make out why did the T-50 designers put a big RF blocker in the intake?

They did?

 

[kooskakebeen]

Can anyone tell me how many missiles the plane can carry internally.
It looks like it has two large internal bays and two small ones?

I have head that the Pak Fa has nearly twice the range of the raptor.
It seems like it can carry more missiles. Is it bigger than the raptor?

I have found video with english commentary at RT.com

Does the plane have thrust vectoring nozzles.