Forum: Technology

The graph also seems to indicate that the F-35 has a lower RCS than the F-22, which we know isn't true.

If the scale is to be taken literally, then they put the F-22 close to 1 square meter...

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It is looking more and more like we won't see the prototype fly in '09, contrary to what has been said before by the Russians:

From Niall O'Keefe, Flight International, Paris Air Show June 17:
"Sukhoi is still working on a prototype of its fifth-generation "PAK-FA" advanced tactical frontline fighter, but the schedule for its flight-test
programme remains unconfirmed, despite earlier indications that the aircraft would fly in 2009."

and:
"[Sukhoi] director general Mikhail Pogosyan says he will talk about the fifth-generation fighter at the next Farnborough air show "or later". It is "something for the future", he says. Pogosyan confirms that the company is creating a prototype and preparing for the start of trials, and that internal discussions regarding the prototype are under way. Beyond that, any communication on the programme awaits the outcome of trials. "

Link to the full article here: http://www.flightglobal.com/articles/20 ... ammes.html

Somehow I am not entirely surprised.

- Jetnerd

jetnerd wrote:

It is looking more and more like we won't see the prototype fly in '09, contrary to what has been said before by the Russians:

From Niall O'Keefe, Flight International, Paris Air Show June 17:
"Sukhoi is still working on a prototype of its fifth-generation "PAK-FA" advanced tactical frontline fighter, but the schedule for its flight-test
programme remains unconfirmed, despite earlier indications that the aircraft would fly in 2009."

and:
"[Sukhoi] director general Mikhail Pogosyan says he will talk about the fifth-generation fighter at the next Farnborough air show "or later". It is "something for the future", he says. Pogosyan confirms that the company is creating a prototype and preparing for the start of trials, and that internal discussions regarding the prototype are under way. Beyond that, any communication on the programme awaits the outcome of trials. "

Link to the full article here: http://www.flightglobal.com/articles/20 ... ammes.html

Somehow I am not entirely surprised.

- Jetnerd

Didn't he also say the PAK-FA was on schedule and the Su-35 would be developed in tandem???? Confused

What does he mean there are internal discussions underway? Why develop two heavy class fighters? Could they be hesitant about the capabilities of the PAK-FA? Is the development of the Su-35, a backup plan? Does India have to pony up millions or billions more in rupees?

This is not a good sign, for the formidable Russian design bureaus. Imagine the embarrassment of a second class AC.

strykerxo wrote:

What does he mean there are internal discussions underway? Why develop two heavy class fighters? Could they be hesitant about the capabilities of the PAK-FA? Is the development of the Su-35, a backup plan? Does India have to pony up millions or billions more in rupees?

This is not a good sign, for the formidable Russian design bureaus. Imagine the embarrassment of a second class AC.

Well, as of today nobody including the Russia Government has ordered the Su-35. So, who is it being developed for????? Question

strykerxo wrote:

What does he mean there are internal discussions underway? Why develop two heavy class fighters? Could they be hesitant about the capabilities of the PAK-FA? Is the development of the Su-35, a backup plan? Does India have to pony up millions or billions more in rupees?

This is not a good sign, for the formidable Russian design bureaus. Imagine the embarrassment of a second class AC.

In my humble (civilian) opinion, Sukhoi is doing something smart for the situation it's in, quoting from the article:

"Sukhoi is "keen on raising the quality" of after-sales service. "We really need it," admits Pogosyan . . ."

With these words I think Pogosyan hints at a fundamental shift in focus from new development back to shoring up their weak areas first, in this case by delaying a costly, unproven program to beef up on quality and support - weak areas with Russian defense firms that have really bloodied product sales. They are sacrificing some prestige in the short to medium term [not having a response to US 5th generation jets] to protect against long term catastrophe [large loss of income/sales of current defense programs, which even further forestall development of newer technology programs]. Given the collapse of Russian wealth from other sources [Gazprom] I'd say it's time for big companies like Sukhoi to take a conservative approach.

Maybe they are seeing what Gates sees in the F-22: In what scenario will Russia and her allies need to oppose it A2A in the next few years? I am sure there will eventually be one, , but Russia I think can afford to do without it for the near turm while they protect income from foreign military sales, which can later be rolled into 5th gen and other new tech later.

- Jetnerd

Su-35 "In Parallel" With PAK-FA

Posted by Bill Sweetman at 6/17/2009 7:14 AM CDT

Until now it has been widely assumed that the Sukhoi Su-35 is a stop-gap or interim step to the much anticipated PAK-FA future tactical fighter. Not so, says Sukhoi general director Mikhail Pogosyan. Interviewed at Le Bourget yesterday, Pogosyan said that he sees the Su-35 being produced "in parallel with the PAK-FA, like the F-22 and F-35" and said that situation would continue for "at least a decade".

Pogosyan also said that there were "no delays" with the PAK-FA, which is expected to be similar in size to the Su-35 but incorporating stealth technology. He said that the newly merged Sukhoi and MiG teams were talking about joint programs, but that it was too early to say what they were, and was equally noncommittal about a future lightweight fighter.

Corsair1963 wrote:

Well, as of today nobody including the Russia Government has ordered the Su-35. So, who is it being developed for????? Question

Well, KNAAPO insider sayd recently something like 'prepare to hear Su-35S designation soon'...[S] apparently is not Syria Wink

Saw Pogo interview from Le Bourget...always prefer direct ciatations...he said that "Dunno if we will see [PAK FA] in 2011...HERE, but apparently we will see it in 2009. In Russia."

flateric wrote:

Posted by Bill Sweetman at 6/17/2009 7:14 AM CDT

Until now it has been widely assumed that the Sukhoi Su-35 is a stop-gap or interim step to the much anticipated PAK-FA future tactical fighter. Not so, says Sukhoi general director Mikhail Pogosyan. Interviewed at Le Bourget yesterday, Pogosyan said that he sees the Su-35 being produced "in parallel with the PAK-FA, like the F-22 and F-35" and said that situation would continue for "at least a decade".

Pogosyan also said that there were "no delays" with the PAK-FA, which is expected to be similar in size to the Su-35 but incorporating stealth technology. He said that the newly merged Sukhoi and MiG teams were talking about joint programs, but that it was too early to say what they were, and was equally noncommittal about a future lightweight fighter.

I have a sneaking feeling this indicates the PAK-FA and Su-35 are extremely similer 'under the skin' which to myself adds more traction to the theory I have that the PAK-FA will be little more then an LO treated Su-35 and not a true F-22 style fighter....

Last edited by flateric on Jun 21, 2009 - 09:28 AM; edited 2 times in total

well, Plato is my friend, but truth is a better
barn door with stores

blue circle is standart Flanker RCS with stores shown
red is said to be 'reduced RCS aircraft' - which can be either stealthized Su-27 with a program a-la Have Glass II, or anything else, including virtual a/c

http://www.ato.ru/rus/cis/archive/4-2003/interview/?sess_=4e4563b23abbc3a7be9f31cc67ef52e8

Stealth Aircraft Technology:"Our Capabilities are not Inferior to Those of America"

Andrey Lagarjkov, Director General of the United Institute of High Temperatures of the Russian Academy of Sciences (and an Associate Member of the Academy), talks about Russian stealth technology in the following interview with the Russia/CIS Observer.
Until recently, all Russian developments in the field of stealth technologies were strictly classified. There weren't any reports made concerning research institutes dealing with these issues. The veil was raised somewhat last year when it was announced for the first time that the United Institute of High Temperatures of the Russian Academy of Sciences was carrying out research in the domain of reduced aircraft visibility. The information was rather sketchy. It was reported that the institute is specialized in creating materials with new properties, in particular with ferromagnetics and so-called artificial magnetics. It was pointed out that technologies developed by the institute were used in designing and manufacturing the Sukhoi Su-27M and Su-37 (Su-47). Director General Lagarjkov, who hasn't spoken about such matters in public before, told Sergey Sokut about work of his institute in greater detail.
- How does Russia's way of making aircraft stealthy differ from the American technology?
- The Americans have two approaches. The first, and earliest one, was used for the F-117 and B-2. The low radar cross-section (RCS) was achieved through the shape of the aircraft and the use of radar-absorbing materials to cover the airframe. In this application, the principle of minimal level of visibility was a cornerstone - and other characteristics had to be sacrificed. For example, both aircraft are subsonic. Later the Americans tried another approach: modern radar absorbing materials are applied to F-16 and F-18, as well as to 5th generation F-22 and JSF combat aircraft, which have a traditional shape. The low level of visibility is achieved through different techniques, which Mikhail Pogosyan, director of Sukhoi, and I are going to reveal in the near future. We and the Americans are close to each other in this type of technology. Russia possesses the technology for upgrading in-service aircraft with modern stealth characteristics, and moreover, this technology is demanded by foreign operators of Russian aircraft. We, together with Sukhoi, have achieved world-class results in this area, which are confirmed by tests of real aircraft. We also can optimize the shape of the aircraft to lower the level of visibility, but I still wouldn't like to speak about the use of our techniques for 5th generation aircraft.
- When would it be possible to speak about achieved results?
- Some discussion is possible today. The exact results of radar cross-section reduction will never be disclosed, neither here in Russia nor abroad. But sometime ago it was announced that the RCS of a MiG-21 fighter after its treatment by our institute is approximately 0.25 sq m. This corresponds to the characteristics of a cruise missile.
- How far is it possible to go in reducing visibility of the 4th generation aircraft, and what additional improvements can be achieved in the next generation?
- My MiG-21 example demonstrates that the RCS of upgraded/modernized aircraft can be reduced 12-15 times. If we speak about new designed models, I wouldn't want to discuss the numbers publically.
- In the press, information has been published about exotic technologies for providing low visibility, for example, plasma. How effective is it?
- We use plasma in solving the problems of RCS of an aircraft's nosecone. In general, plasma technologies are very useful at flight altitudes of more than 25 km. At low altitudes it is impossible to use them, because there is not enough power on board.
- What is the share of stealth technologies in the total aircraft cost?
- If stringent, but reasonable requirements for visibility are implemented in the project from the very beginning, it won't be too large. I'd like to point out here that at my institue, we have carried out advanced work in fundamental research. I also want to stress here that we had to do this without governmental support - funding our research from out-of-budget sources during the last 10-15 years.
- It is known that you cooperate closely with Sukhoi. What about the institute's work with other design bureaus?
- Recently, we have started cooperating intensively with the others as well.
- If we compare achievements of different countries in the reduction of aircraft visibility, who would the leaders be? Obviously, the Americans would hit the top, wouldn't they?
- The Americans are no. 1 because of the application of stealth to a large volume of real products. But considering the understanding of the whole problem in general - and the potential - I don't think the Americans are better than we are. We are able to achieve, and already have achieved, the same - and even in some areas, we have had somewhat better results. Another plus for the Americans is their broader application of stealth. In particular, they are entering the world market with the stealthy aircraft. Similar developments are being made in Europe, but the level of these countries is not so high. The French are tackling this problem as well. They have very good research equipment - anechoic chambers, for example. Their Rafale fighter is advertised as an aircraft with a low radar cross-section.

One stupid question, if you put a plasma stealth "emitter" (I know nothing about the stuff) in the nosecone, where does the radar go? WTF

Russian Stealth Research Revealed
Russia shows solid progress in a variety of low-observable technologies
by Bill Sweetman
Jan. 1, 2004

Russian research into low-observable (LO) technology has remained largely secret, despite the collapse of the Soviet Union and the semi-privatization of the aircraft industry. However, a newly published paper from the Institute for Theoretical and Applied Electromagnetics (ITAE) at the Russian Academy of Sciences (Moscow, Russia), presented at the International Quality and Productivity Center's conference on stealth, held in London in October 2003, shows that Russian researchers have made solid progress in key technologies for LO aircraft and have test-flown some technologies – such as the use of plasmas to protect targets from radar – that are not known to have been studied in the West.

In the paper, entitled "Stealth Technology: Fundamental and Applied Problems," Russian stealth researchers claim to have reduced the head-on radar cross-section (RCS) of a Sukhoi (Moscow, Russia) Su-35 fighter by an order of magnitude, halving the range at which hostile radars can detect it. The research group has performed more than 100 hours of testing on a reduced-RCS Su-35. According to other reports, the ITAE has demonstrated similar technology on a MiG-21bis, and it has been offered to India as part of a MiG-21 upgrade package. Similar modifications have been made to Western aircraft (such as the Have Glass package developed for the F-16), but it is not known whether they claim the same level of performance.

Russian investigators certainly have the basic scientific knowledge to apply stealth to aircraft. Some of the basic mathematical and optical theories that underlie stealth originated in Russia (such as Ufimtsev's theory of edge diffraction), and some of the most significant early work on reducing the RCS of military vehicles was carried out by Russian warship designers. The Kirov-class battlecruisers – with a 22° "tumblehome" angle imposed on normally vertical bulkheads, screens, and skirts to shield high-RCS components from radar, along with extensive use of radar-absorbent material (RAM) – were remarkably stealthy despite their size. "If you saw a big wake with nothing in front of it," British marine LO expert Peter Varnish has said, "you knew you'd found the Kirov."

There is also an LO strand in Russian aircraft design. The Tupolev (Moscow, Russia) Tu-160 Blackjack bomber is a reduced-signature design reminiscent of the B-1 Lancer. Sukhoi has designed a series of supersonic bombers with low-profile, highly blended configurations. In early 2000, Russian military leaders considered that a new, stealthy medium bomber would be the next major Russian military aircraft project, to replace the Tu-22M.

Most current Russian military aircraft show little evidence of stealth in their design, but that is not surprising, given that they were defined in the early 1970s. The more recent MiG 1.42 and Sukhoi S-32 fighter prototypes were designed as details of US stealth projects became known and, thus, represent a compromise solution. They carry their primary weapons internally, and the Vympel R-77 missile – which corresponds to this generation of aircraft – is designed for internal carriage. However, they do not reflect features found on US designs, such as the careful organization of wing, tail, and inlet edges along a few common alignments. They look like aircraft in which aerodynamics dominate the basic shape, and materials are used to eliminate RCS hotspots – very much the same as the technology described in the ITAE paper.

The dominant contributors to the Su-35's head-on RCS are the inlets, which the ITAE researchers call "a huge problem." With a straight duct that provides direct visibility to the entire face of the engine compressor, the inlet might have been designed to advertise the fighter's presence at the greatest possible range. (Lockheed stealth pioneer Alan Brown's comment on straight ducts is that "the energy comes romping out like a lighthouse beam.") The ITAE, though, has developed a high-performance, ferro-magnetic RAM for the compressor face and duct walls. The material has to be thin, because it cannot constrict airflow or impede the operation of anti-icing systems, and must withstand high-speed airflows and temperatures up to 200°C. The ITAE team has developed and tested coating materials which meet these standards. A layer of RAM between 0.7-mm and 1.4-mm thick is applied to the ducts, and a 0.5-mm coating is applied to the front stages of the low-pressure compressor, using a robotic spray system. The result is a reduction of 10-15 dB in the RCS contribution from the inlets – more than halving the RCS.

Like the Have Glass F-16, the modified Su-35 also has a treated cockpit canopy that reflects radar waves. The ITAE has developed a plasma-deposition process to deposit alternating layers of metallic and polymer materials, creating a durable coating that blocks radio-frequency (RF) waves and does not trap solar heat in the cockpit. The plasma-coating process is carried out in a vacuum chamber by a robotic tool.

The ITAE and its partners use plasma technology for applying ceramic coatings to the exhaust and afterburner. Multi-layer coatings formed from microparticles of dielectric, metal, or semi-conductor material are deposited by an arc-discharge plasma under atmospheric pressure. Challenges include the need to keep the ceramic bonded to the metal structure over a wide temperature range (600°C to 1,200°C), despite the fact that the materials have widely different thermal-expansion characteristics. The coating materials also need to maintain constant electrical characteristics in the face of widely varying temperatures. Researchers describe this problem as "partially solved," and engines treated with ceramic RAM have already been flight-tested.

Video at the conference also showed the use of hand-held sprays to apply RAM to R-27 air-to-air missiles. There is no point, researchers say, in reducing the RCS of the airframe unless the reflectivity of external weapons can be reduced as well.

The ITAE has flight-tested a unique and exotic technology to mask the Su-35's huge 35-inch radar antenna: the use of a low-temperature, "plasma-controlled screen." The screen is mounted in front of the antenna and is transparent to radar when switched off; it may be similar to a plasma TV screen, comprising cells filled with neon or xenon gas, which is excited by an electrical current. (Video shows a clearly defined luminous panel in front of the antenna.) When activated, the screen absorbs some incoming radar energy and scatters the rest in safe directions, over all RF bands lower than the frequency of the plasma-generation system. The screen switches on and off in tens of microseconds, according to the ITAE, thanks to years of intensive development of the gas mixture and plasma-generation system.

In principle, this is the same as the "plasma stealth" system that was reportedly developed by the Keldysh Scientific Research Center (also part of the Academy) in 1999. At the time, it was claimed that the system, using a 100-kg generator, could reduce the RCS of any aircraft by two orders of magnitude, or 20 dB. The ITAE has not attempted to develop a whole-aircraft system, which would use plasma-generating antennas to ionize the air flowing over the aircraft – an artificial version of St. Elmo's fire – but researchers expressed the view that it would be difficult to apply except to a high-altitude, relatively slow aircraft, because the airstream would dissipate the plasma faster than it could be generated.

The ITAE paper gave some indications of the direction of stealth technology for future aircraft. Test facilities developed in Russia include compact, indoor RCS ranges for large-scale models and outdoor, ground-level ranges with short pylons, which can be used to test full-size aircraft (rather than the models used for US pylon tests). In future designs, one emphasis is on large, complex skin panels, reducing the number of gaps and mechanical fasteners in the skin. The ITAE paper showed an example of a single, 23-ft., monolithic fuselage panel, without indicating for which aircraft it was intended. However, it might form part of the upper fuselage of the S-32 Berkut prototype.

Russia's ability to achieve an order-of-magnitude reduction in the RCS of a non-stealthy aircraft is significant for two reasons. First, it makes the Sukhoi family more competitive with Western aircraft, particularly in the case of export variants that may not feature LO modifications such as Have Glass. Second, it points to an ability to design low-maintenance, stealthy combat aircraft, missiles, and UAVs in the future.

You're not swallowing that magical plasma stuff hook line and sinker are you? Must be ten years now that stuffs been floating around the net and still no sign of this mythical 'I-win' button... just slightly sceptical Wink

Forum: Technology

Sukhoi PAK FA