milosh wrote:popcorn wrote:In their dreams maybe. Wasn't there speculation in The Russian press that the US 5gens had a 0.5m RCS? They never explained how they knew. Lol
You can find on net that study it is median frontal RCS.
Same thing as Chinese academical PAK-FA study from 2016, where they calculated PAK-FA median frontal RCS as 0.5m2 but lowest possible RCS they got was -40dBms and they conculded PAK-FA is VLO design but only if Russians use intake radar blocker (they concluded one in study) and develop stealthy nozzle, new nozzle design was seen in first flight of type-30 engine.
BTW speed data isn't right, it isn't 2600km/h or 2.6M (high altitude). Butowski was told on MAKS they lower max speed to 2.1M because or RAM and composites.
I think this is the study about you talk...
http://www.scielo.br/pdf/jatm/v8n1/1984 ... 1-0040.pdfAnd really they do not tell nothing about -40db is significant, only in certain angles can get this number, but you need know this happends with any airplane, and do not need to be VLO.
For example. You can see on next picture, this civil airplane can get more than -30 db in some specific angle. This is the same for Su-57 but it is not relevant data.

On this study, they take for this study a 3d perfect model of the Su-57, with no irst, pitots, dircm and other elements on its surface that you can find and real airplane as no swathood angles, etc...
And this is important note from the study:
The RCS numerical simulation method applied in the paper
is an approximate method for cavity calculation, and the exact
solution for the inlets and nozzles cannot be obtained. The
engines that have not been exposed to radar wave directly for
the inlets are closed with inclined protective screening. The
inlets of the model are also sealed with inclined planes for
the calculation of RCS. The nozzles of the model are closed
with cones and annuluses for calculation.
So, they dont take into consideration of inlets with exposed engine blades....and this is a very important contribution on frontal RCS.
On resumen, this number around 0,5 m2 from frontal view is not about real Su-57 but about perfect 3d model. If you make study about real airplane you will get bigger frontal rcs than 0,5 m2, and only you will can get around RCS sukhoi patent (0,1-1 m2) when you have apllied ram.