It tends to confirm my hypothesis that those complex intakes are also part of the LO features of the aircraft…
Therefore I think that Jö Asakura is right in saying Sukhoï won’t need to add a blocker or any other device, the complexity of the intakes and their lips being sufficient to keep radar signature low enough (sorry for the “no s-duct, no stealth” chorus).
…the real ace up their sleeves being the very material that the compressor face is made of (what was it, a boron-magnesium-polycrystalline carbon nanofiber matrix composite?).
I wouldn’t rule out the use of a blocker, but my reasoning is this: if they have the capability to ‘stealthify’ the structure of the metal matrix composite structure with CNTs (I believe they’ve had the technical ability for at least 2 years), then why wouldn’t they?
In early 2008, at the Tambov State Technical University (Тамбовского государственного технического университета), a research team undertook radar absorption tests on UNM ‘Tainut’ (УНМ “Таунит”) in the frequency range of 8.5 to 12 GHz. ‘Tainut’ has a MWNT structure with tube diameter of 60nm and length of 10 micrometres.
A monolithic polymer composite plate was prepared with an 11.2% constituent (by weight) of UNM ‘Tainut’ with surface treatments’ thickness of 0.3mm and 0.17mm.
Direct experimental comparisons were made with 2 RAMs used to line the walls, floor & ceiling of anechoic chambers, namely: ‘Don’ (РПП “Дон”) , a structure made of a steel plate thickness of 3 mm, which was glued closely with another ferrite plate of thickness 8 mm. On top of which was the closely pasted ferrite structure consisting of nine (3 by 3) hollow tetrahedral pyramids with base 35mm by 35 mm and a height of 35 mm.
Also, the RAM ‘Beam’ (РПП”Луч”). This material is a mechanical mixture of organic fibres with amorphous graphite (soot), soaked in an organic binder. The electrical resistivity of the material, “Ray” is greater than 200Mw × m. Elements of this coating are made in the form of plates with thickness of about 50mm and dimensions of approximately 500mm by 1000 mm. With outer (adjacent to the walls of premises) by these plates covered with aluminium foil with a thickness of 0.1-0.2 mm.
The results were as follows: the ‘Tainut’ polymer composite of thickness 0.3mm and 0.17mm exhibited absorption of -5.2dB &-3.3dB respectively (and outperformed ‘Don’). The RAM ‘Beam’ attained an absorption of -5.8dB, that’s a difference of 0.6dB but the latter is 49.83mm thicker!!
Remember, ‘Tainut’ is now commercially available, so the CNTs infused in the modification of the CFRP in the metal matrix composite fan blade will be tailor made.
They’ll probably be happy with a -10dB absorption for a 1mm layer of CNT for the compressor fan blades. As the T-50’2 inlet/engine duct is also made of CFRP it is likely to employ CNT layers of whatever thickness & composition that is required (probably several millimetres), since inlet cavities are large radar reflectors. As the layers would be an integral part of the structure and not a post manufacture treatment, this would solve the RAM adhesion problems encountered on the F-22 ducts, and would probably be relatively maintenance free. The canted engines would mean any incident wave returns would be reflected into the CNT modified ducts.
In May 2009 the Tambov University scientists received a special award:
Представленные на конкурсе разработки вызвали интерес заместителя Председателя Правительства РФ, Председателя ВПК при Правительстве РФ С.Б. Иванова…
[Tainut’s] submission for the design competition elicited the interest of Deputy Chairman of the RF Government, the Chairman of the MIC under the Government of the Russian Federation Sergei Ivanov…
http://xn--80aa7afbgahku.xn--p1ai/nns/20158/news/?page=27288
I bet it did. The T-50 is very dear to Sergei Ivanov’s heart. 😉
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