Sorry m8, meant that radars are developing faster than observables tech. The EDGE is getting smaller -there4 of lesser priority in some scenarios.

I don’t speak like a robot (usually) just trained to write that way..;)

No problem 😉

Yes I agree. There are infinite possibilities when it come to signal processing for detecting VLO echoes. But I think a lot of money have been invested in stealth which means this race will last for some time

Now that we have numbers, deductive reasoning can take a well-earned rest.

The commercially available CNT-based signature control material (posted above) is called the ‘Ultra-Light Radar Absorbent Material’ (Сверхлегкие радиопоглощающие материалы). As the thickness of RAM has a logarithmic relation to absorption, for arguments’ sake let’s assume a 10x increase in thickness yields a 3x increase in absorption: then 30mm would give a reflectance coefficient of -30db. Correct me if I’m wrong but -30db amounts to around 95% absorption in the broadband X-band.

Bear in mind the numbers for the T-50-specific ‘UL-RAM’/’FibreMatskii’ , are significantly better as it’s composition is considerably more complex.

As the Russians already have (imported) the autoclave-free VA-ARTM technologies then structural applications are a given: firstly, the S-duck problem- an infusion in the CF composite structure of the intake cavity and ‘banana’ duct would, no doubt, yield impressive results. Any incident waves that make it as far as striking the LO compressor will be reflected into more of the material of appropriate thickness (that’s why the engines are canted inwards & downwards), not to mention any ‘surviving’ waves will have to make the return journey out of the duct and intake.

The beauty of this particular application in the all-CF composite duct of the T-50, is that it would not be prone to the adhesion/ingestion problems that plague the F-22, as well as being significantly less maintenance intensive.

Needless to say, structural applications to other RCS ‘hotspots’ such as the under slung CF intake front and their inner-tunnel walls, will effectively negate their radar returns.

However, I would expect the current bare-metal cowlings to employ similar CNT modified CF composite casings as they now use on their SLVs. The ‘UL-RAM’ is a series of multiple layers glued together, and very high radiating engine temperatures over a prolonged time may be the reason the F-35’s panels are delaminating @ the rear (incidentally, the US FibreMat renders Carlo Kopp’s rants against the ‘lumpy-bumpy’ F-35, irrelevant). Having said that, Russian research into nano-structured thermal protection coatings for extreme temperatures is well advanced*.

Clearly, the RCS implications of the deluxe version of this RAM for the T-50 cannot be understated. That they’re gunning for F-35 levels of stealth is beyond reproach.

*http://rusnanonet.ru/news/60199/

Wasn’t in ITAE’s paper that (for the Su-35 at least) the thickness of application shouldn’t be more than ~1.5mm ? a 30mm application is beyond any engineering tolerance I have ever heard of and would blow any current design out of the water. Not a single panel would fit after the application of the coating.

On the other hand, your suggestion may indeed explain the large gap between the weapon bay doors exhibited by the T-50s so far.

Yes US has the edge in stealth technology, but remember that PAK FA is also much newer design than F-22A ( YF-22 first flight – 1990, F-22A – 1997, and PAK FA first flight – 2010). I think that Russians fill this 20 years gap in technology up to now.

I would not be able to tell if the US has the edge on VLO technology.

What I do know, is that they have spent an unbelievable amount of money since the seventies on this.

That is why I some times ask questions. Some people in this thread feel I don’t like the T-50. They should really listen how many questions I have about the J-20!!

If the americans avoid something on their designs that must be a point for thought.

Falcondude

MSpheres point is a valid one – good enough for what exactly? Clearly the VVS and Sukhoi have definined the LO / VLO parameters required for the aircraft to fulfil its operational crieria -the problem is neither you, I or anyone else on this forum (probably) can do more than speculate what these are. Given this, and the dearth of solid information on the project, this thread would probably dry up very quickly without the sort of intuitive research or deductive reasoning of which Jo is so fond.
Clearly its role would suggest it needs to be able to operate in contested airspace against the most likely projected enemy threats (ie euro canards, f-35, f-22) though possibly in a more defensively optimised role as the focus of the vvs is primarily the defense of Russian airspace. Furthermore Sukhoi and the wider Russian defense industry will be looking to ensure export success.
Jo deduces, with reasonable justification, that neither the VVS nor Sukhoi would want or invest so heavily in a lemon incapable of filling its role, and so seeks out information on the technologies that would ensure that it is competitive.
Falcondude, you, on the other hand, are sceptical about the ability of the platform to compete – at least in terms of LO/VLO and would prefer to believe that in the absence of solid information on such technologies they do not exist, a conservative and not unreasonable approach that happens also to tie in with your apparent belief in the innate superiority of western/US equipment and the perfidity of Russian exporters. Who is right? Time, I’m sure, will tell.
In the meantime though, Jos enthusiastic if speculative research is far more interesting and informative than the informed scepticism common in the thread.

Koba

Koba

truth comes only through challenge. An unchallenged truth is a weak truth.

Good enough for what exactly?

The idea of LO or VLO designs is to drop the reflected radiation below a certain threshold.

Without claiming that the US way is the only way, from the onset (SR-71) we have seen the very careful approach on aspects of the design and the meticulous attention to detail.

Smooth surfaces, minimization of gaps and panels, application of coatings to remove “roughness” of the surface of the craft. Attempt to minimize the number of surface planes of shapes on almost all but the F-117.

These are done for a reason.

I am not claiming (and never have claimed ) that because the plane has no S-shaped intakes is not VLO.

What I am -within my limited scope of things- doing, is making a simple engineering originated, contemplation of given facts.

If you look into an italian supercar you are likely to find a V8, V10, or V12 in it.

If a -non italian- manufacturer comes along and says we are going to have supercar performance with this model, and you look inside and find a simple inline four, you are going to start to ask questions.

You may not doubt the new car will reach 200mph, but you are going to start asking how an inline 4 can produce the required power and torque.

That is what I am asking. Since the T-50 is a radical departure from the established VLO design, can we attribute its -accepted as granted- VLO characteristics to something !?

hence the question. If these materials talked about in this forum, do not become available for manufacturing, is the shaping enough for VLO characteristics?

If yes, how come it is while it doesn’t follow the established approach.
What makes something OK to be used on the T-50 but avoided on previous designs?

These are some of the questions we may ask..

Do you need a bigger cornerstone than no S-ducks? What are the intakes made of? The ‘banana’ ducks are all-composite too. CNT modified composites’ research dates back to the mid-1990s. When the T-50 design was finalised sometime in 2003, this material would have played a key role in that process- just like it did for the F-35.

The CNT modified polycrystalline graphite is in the form of a raw material, like a fine black powder (soot). As such it just becomes merely an additional ingredient in the CFRP’s production process, although the customised military version is likely to employ non-autoclave advanced resin transfer moulding (A-RTM) because the polymer matrix composite fibres (including a metal/alloy dielectric)have to be carefully aligned. This type of aircraft RAM was first patented in 2008, I believe it to be the forerunner of the one destined for the T-50.

The commercially available raw material (YNM ‘Tainut’) itself with excellent radar absorption properties, is linked below. It is very expensive and the customised one for the T-50 is likely to be one of the prime reasons why it’s unit cost has increased to an eye-watering $110m+ apiece (hence the IAF order cut).
Note the link to TsAGI’s new production method (above) emphasises reduced cost of production and high quality.

In case you missed this bit:

Do you really think the Russians would be any more amenable to their newest RAM secrets being catapulted into the open simply to pander to my forum [alter] ego?

I’m quite a young man and there’s still much I want to do.

http://xn--80aa7afbgahku.xn--p1ai/nns/20158/news/?page=27288
http://nanotc.ru/index.php?option=com_content&task=view&id=11&Itemid=37

So what we have here is deduction reasoning.

The plane has different than usual characteristics for a VLO design.
The plane designers couldn’t have chosen this unless they had other solutions.
These solutions are X and Y advanced materials with Z and U behaviour.

I am an engineer by trade and I don’t particularly like deductive reasoning.

The latest alleged price hike in the per unit cost may mean developmental hurdles with costly solutions. Not necessarily this materials.

Hopefully you are right and I am just a sceptic. We’ll see.

Anyway , before i forget or it gets lost , for you more knowledgeable folks , here’s some patents relating to PAK-FA, from paralay. In particular , the engine IR masking one is intriguing , but more on that later.

http://www.findpatent.ru/patent/247/2472003.html
http://www.freepatent.ru/patents/2413161
http://www.freepatent.ru/patents/2362110

The Indian display verifies that the plane is not intended to change at all as we have already assumed so.

The patents indicate that the intakes shield the craft from centimeter range EM only and not milimeter range.

The intakes are to stay as they are apparently according to the patern and some IR reducing measures exist.

I am not sure if that is good.