Su-35 Back From the Dead

Feanor · 01-11-2008, 13:21 PM

Quote:

Analysis: China seeks new Russian technology

HONG KONG, China, A Chinese military source based in Beijing has said that the People's Liberation Army Air Force is currently negotiating with the Russian Sukhoi Aircraft Company on three new projects.

Military observers based in Moscow and Beijing believe that the recent nadir of military cooperation between China and Russia is only temporary. China will have to rely on Russia to develop its military technologies, as Beijing has no other alternative.

The first new project involves Su-33 shipborne fighters. Experts from the Russian aviation industry are convinced that China is about to start the construction of an aircraft carrier. "Up to the present, on the issue of the Su-33, China and Sukhoi have had three rounds of negotiations and have reached some agreement," said the source.

Nonetheless, he did not disclose what specific progress has been made in the negotiations, merely confirming that additional rounds of talks will be held. A high-level source from Sukhoi confirmed his company is most interested in discovering whether the Chinese want to purchase whole Su-33 fighters or only require Su-33 parts, and whether they will request the transfer of production technology or design blueprints.

Other sources from the Chinese military industry said that several plans were involved in the negotiations on the Su-33. One of them is that China will buy a small number of Su-33, say 10 to 24, and later request that production technologies be transferred. However, the Chinese strategy is to use some of the Su-33 technology to develop their own shipborne fighter based on the J-11B assembled domestically.

The second project under negotiation involves the newest Su-35 fighter. At the MAKS 2007 International Aviation and Space Salon held at the Zhukovsky Air Base near Moscow in August, Chinese delegates took photos and videos of the Su-35 virtually every day.

"Several Chinese delegations have visited Sukhoi and raised technical questions," the Sukhoi company representative said. He claimed the two sides have reached a consensus and are now working on export plans.

"At least in the foreseeable future, China's indigenous aviation technologies will not be able to produce combat aircraft similar to the Su-35," he said. "Our attitude on this issue is the same as the case of the Su-33; that is, we are only interested in exporting whole Su-35s. This is not what the Chinese delegates hoped for. They hoped to import only certain subsystems, for instance the radar systems or the engines."

The third project concerns the PLA Navy's plan to import more Su-30MK2 fighters, or upgraded variants of the aircraft. No progress has been made on this as yet, however. A plan for China to import Su-30MK3 fighters, which was negotiated earlier, has not been carried out so far.

The possibility that the navy will continue importing Su-30MK2s or Su-30MK3s appears slim, mainly because it has already started to receive China-made JH-7A fighters. Meanwhile, the upgrade of the J-11B fighter aircraft has been very comprehensive. The fighter is now capable of launching precision attacks on battleships, and can basically meet the combat requirements of the navy fleet. China may not resume the import of Su-30MK2s unless the cost of the J-11B remains too high or comes close to the cost of the Su-30MK2.

Is there any possibility that the PLA Air Force may upgrade its existing Su-30MK2s and J-11s, or the Indian Air Force's Su-30MKIs, to a combat platform close to the Su-35 standard?

Dr. Yury Bely, a general designer at Russia's NIIP Radar Design Bureau, agreed to discuss the question. "It is impossible to import the Su-35's radar system only," he said. Bely stressed that it would be more feasible to import brand new Su-35s than to try upgrading the Su-30MK2.

The Su-35 is equipped with the H035 passive phased array radar system, which has extremely powerful detection capability, Bely pointed out. The average output power of this radar is 5 kW, with peak output at 20 kW; thus the output power of the Su-30MKI and Su-30MK2 would be insufficient. When the H035 radar was tested on Su-30MK No. 503, the detection range was as far as 290 kilometers with 1 kW power output, he said.

It seems like the Su-35 is back from the dead.

Feanor · 01-11-2008, 13:24 PM

Quote:

Stealth design SU-35 aircraft

Hostile radar range cut on Su-35s

Russian stealth researchers have developed materials and techniques that can reduce the head-on radar cross-section (RCS) of a Sukhoi Su-35 fighter by an order of magnitude, halving the range at which hostile radars can detect it. The research group - working with Sukhoi, but based at the Institute for Theoretical and Applied Electromagnetics (ITAE) at the Russian Academy of Sciences in Moscow - has performed more than 100 hours of testing on a reduced-RCS Su-35 and has also experimented with the use of plasmas - ionized gases - to reduce RCS.

US and European aircraft manufacturers have used specially developed materials to reduce the RCS of basically non-stealthy aircraft for many years. Notable examples include the Have Glass and Have Glass II modifications to the F-16. However, Russian work in this area was undisclosed until ITAE researchers presented a paper to a conference on stealth in London in late October 2003, which was organized by the International Quality and Productivity Centre.

According to the ITAE presentation, Russian researchers have developed mathematical tools that can calculate scattering from complex configurations, such as an Su-35 carrying a full external missile load, by breaking them down into small facets and adding the effects of edge waves and surface currents. The antennas are modelled separately and then are added to the entire RCS picture.

"A problem of huge size" is how the researchers describe the Su-35 inlet, with a straight duct that provides direct visibility to the entire face of the engine compressor. The basic solution has been to apply ferro-magnetic radar absorbent material (RAM) to the compressor face and to the inlet duct walls, but this involves challenges. The researchers note: the material cannot be allowed to 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 that meet these standards. A layer of RAM between 0.7mm and 1.4mm thick is applied to the ducts and a 0.5mm coating is applied to the front stages of the low-pressure compressor, using a robotic spray system. The result is a 10-15dB reduction in the RCS contribution from the inlets.

The modified Su-35 also has a treated cockpit canopy which reflects radar waves, concealing the high RCS contribution from metal components in the cockpit. ITAE has developed a plasma-deposition process to deposit alternating layers of metallic and polymer materials, creating a coating that blocks radio-frequency waves, is resistant to cracking and crazing and does not trap solar heat in the cockpit. The plasma-coating process is then carried out robotically in a 22 m3 vacuum chamber.

ITAE and its partners have also developed plasma-type technology for applying ceramic coatings to the exhaust and afterburner. The conference video also showed the use of hand-held sprays to apply RAM to R-27 air-to-air missiles.

ITAE has studied at least three techniques for reducing the RCS contribution of the radar antenna, in addition to the simplest method of deflecting the antenna upwards and treating or shrouding other components. One of these is to design a radome that can be switched from RF-transparent to RF-reflective. The interior of the radome would be coated with a cadmium sulphide or cadmium selenide thin-film semiconductor material which changes conductivity when illuminated with visible or ultra-violet light. However, the problem of making such a film has not been solved.

A second technique that is also described in Western literature is to place a frequency selective surface screen in front of the antenna. This is a foil-like metal screen etched with small apertures which allow RF energy to pass within a narrow waveband, corresponding to the radar's own operating frequency. This reduces RCS, according to ITAE, but at the expense of radar performance.

However, ITAE has flight-tested a more exotic technology: the use of a low-temperature plasma screen in front of the radar antenna. The screen hardware is mounted in front of the antenna and is transparent to the radar when switched off. When activated, the screen absorbs some incoming radar energy and reflects the rest in safe directions over all RF bands lower than the frequency of the plasma cloud. It switches on and off in tens of microseconds, according to ITAE.

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 100kg generator, could reduce the RCS of any aircraft by two orders of magnitude, or 20dB. ITAE has not attempted to develop a whole-aircraft system, but researchers expressed the view that it would be difficult to apply except to a high-altitude, low-airspeed aircraft because the airstream would dissipate the plasma faster than it could be generated.

The ITAE paper also gave some indications of the direction of stealth technology for future stealth aircraft. Test facilities include large compact indoor RCS ranges for large-scale models and outdoor ground-level ranges with short pylons that 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.

Source: INTERNATIONAL DEFENSE REVIEW - JANUARY 01, 2004

Stealth design SU-35 Flanker aircraft

tphuang · 01-12-2008, 04:56 AM

Quote:

Originally Posted by Feanor

It seems like the Su-35 is back from the dead.

yeah, I had a rebuttal to this PKF article on my blog. The entire assessment is flawed in everyway. The only subsystems that China is interested in on su-35 is Irbis and 117S. And the Russians won't sell those stand alone. Besides, there is still the AL-31FM series which seems to suit China better anyhow.

And the entire stuff on su-33 is overblown. The indigenous naval flankers project should be ready by the time indigenous carriers come out.

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