J-20 5th Gen Fighter Thread IV (Closed to posting)

[Engineer]

And at what possible specific frequency and look angle could the F-22A have a 0.1m2 RCS? I can buy 0.01m2 or even 0.05m2.

The extract from the image specifically said the estimation was based on a specific frequency, but fall short of saying what frequency that is. The extract did not mention the look angle.

 

[thunderchief]

You just made a strawman fallacy, where you created and retorted a fictitious argument rather than actually replying to my statement. No where in my statement did I ever said China achieved just 0.1 m[sup]2[/sup] RCS on their best fighter. Neither did my statement make any claim on who has better technologies.

My statement concerns with the techniques China employed in analysis of J-20 being used for analysis of F-22. You bringing in technologies is irrelevant to my statement about analysis techniques.

You claimed that China from their own experience with J-20 (and J-31) concluded that RCS of F-22 must be somewhere around 0.1 sqm . I don't know what technologies does China or US poses (and which ones are better) , but Chinese experience with their own design and without having example of F-22 , is simply not sufficient to make claims about F-22 . As I said before , US may poses technologies not visible to naked eye without close inspection .

If you claim that China obtained data about F-22 with other means (i.e. spying ) that is whole another ball game and I won't comment on that .

Such discrepancies can be explained by the different parameters used to compute the RCS figure. An aircraft company selling a stealth or semi-stealth fighter would quote the lowest RCS value resulted from using a specific frequency and a specific look angle, whereas a radar company would use parameters that maximize the RCS value.

Well , usual standard is frontal RCS (most useful in combat) and X-band . Certainly , everybody advertise their product , but end results cannot differentiate to several orders of magnitude .

The image already addressed this. At the same altitude at which the 280 km detection range can be achieved, the maximum observation range of a target of any size is only 383 km.

I don't know what would be RCS of "target of any size" , but those results seem awfully fishy to me if normal laws of physics still apply .

 

[latenlazy]

You claimed that China from their own experience with J-20 (and J-31) concluded that RCS of F-22 must be somewhere around 0.1 sqm . I don't know what technologies does China or US poses (and which ones are better) , but Chinese experience with their own design and without having example of F-22 , is simply not sufficient to make claims about F-22 . As I said before , US may poses technologies not visible to naked eye without close inspection .

If you claim that China obtained data about F-22 with other means (i.e. spying ) that is whole another ball game and I won't comment on that .

Let's just say the stereotype that the motivation for intellectual theft of military secrets is copying isn't entirely on the mark. If it were, then the competence of the PLA would be cast into serious doubt.

 

[thunderchief]

Let's just say the stereotype that the motivation for intellectual theft of military secrets is copying isn't entirely on the mark. If it were, then the competence of the PLA would be cast into serious doubt.

Countries are spying on each other since time immemorial , and copying is just one of the reasons . But to obtain reliable data on F-22 China would have to either : a) obtain one sample and test it or b) obtain classified sensitive data from US sources . Anything else is just guesswork , especially considering micro-structural technologies US may or may not posses .

 

[latenlazy]

Countries are spying on each other since time immemorial , and copying is just one of the reasons . But to obtain reliable data on F-22 China would have to either : a) obtain one sample and test it or b) obtain classified sensitive data from US sources . Anything else is just guesswork , especially considering micro-structural technologies US may or may not posses .

Think of it this way. Any information stolen that invoke fears of China replicating key technologies also should invoke fears that China now has intel on key capabilities. If information has been stolen on designs and materials that means they're likely to know what kinds of RAM and Radar absorbent structures those designs are using. It's not very hard to replicate the external geometry of an object from pictures alone, so if you couple that with key information on materials and internal geometry it's not very hard to build a computer simulation that is relatively accurate. With persistence, you can even fill in remaining gaps in your intelligence by varying the worst and best outcomes of the unknowns, giving you a bounded range of possible solutions. This is what intelligence organizations are paid to do. I seem to remember hearing that the security breaches involving the F-22 and F-35 were rather extensive, which is what I imagine invoked fears that China would try to copy the technologies. Coupled with that should have been fears that China will have the intel to develop effective countermeasures.

Now, with regards to the claims made about detecting the F-22, I myself remain skeptical. Defence companies have an incentive to put their best foot forward and exaggerate their claims at all times, American, Chinese, Russian, or whatever. Even if the claims don't pertain to a technology on sale, it boosts the credibility of the company and engenders trust in them to come up with the best possible solutions for their clients. This means that when Lock-Mart claims the F-22's RCS is 0.001 m^2, we should exercise some skepticism that this may only be a best case scenario. Similarly, when a Chinese company claims that the F-22's RCS is .1 m^2 and can be detected with their radar from 200 km away, we should weigh that information with an equal amount of skepticism. There's A LOT of room to fudge around with RCS numbers, given that they're dependent on a multitude of factors and conditions which can't possibly be incorporated in a single number figure. My take is that both claims about the F-22's RCS and the ability of a Chinese AESA to detect the F-22 are best case scenarios, and the truth lies somewhere in between. While the claims about the radar's ability may be exaggerated, I don't doubt that China now knows something, perhaps even quite a lot, about what the F-22's RCS will look like. After all, we know they put the work into acquiring this information, and any military and intelligence organization would do their due diligence to acquire as much information about potential threats as possible.

 

[Engineer]

Countries are spying on each other since time immemorial , and copying is just one of the reasons . But to obtain reliable data on F-22 China would have to either : a) obtain one sample and test it or b) obtain classified sensitive data from US sources . Anything else is just guesswork , especially considering micro-structural technologies US may or may not posses .

China does not need to do a when it can just steals the data. This leads us to b, which is what espionage is for. Information such as effectiveness of RAM coating would be sufficed for simulations without any need to know the exact molecular structure of the coating. There is no need for China to produce an exact replica of F-22 to do any testing, if that's what you are implying.

 

[Equation]

Information such as effectiveness of RAM coating would be sufficed for simulations without any need to know the exact molecular structure of the coating. There is no need for China to produce an exact replica of F-22 to do any testing, if that's what you are implying.

Just curious Engineer, so how do they do such testings to get an idea or estimation of another stealth plane RCS?

 

[vincent]

Just curious Engineer, so how do they do such testings to get an idea or estimation of another stealth plane RCS?

If the RAM reduces radar reflection by 10%, they can measure the radar returns of a F22 replica and reduce that by 10%

 

[rhino123]

If the RAM reduces radar reflection by 10%, they can measure the radar returns of a F22 replica and reduce that by 10%

And how would China get a F22 replica, plus the exact RAM formula? Each country's formula is different, unless you are implying that China somehow got hold of US RAM technology and successfully replicate (reverse engineered) and used it on their own aircraft.

So far, to my understanding, US had not release details on the F-22, its dimensions, tolerance, every single details, so if China is going to just based off a few photos they receive either from the net or otherwise, they are not going to be very accurate.

 

[latenlazy]

And how would China get a F22 replica, plus the exact RAM formula? Each country's formula is different, unless you are implying that China somehow got hold of US RAM technology and successfully replicate (reverse engineered) and used it on their own aircraft.

So far, to my understanding, US had not release details on the F-22, its dimensions, tolerance, every single details, so if China is going to just based off a few photos they receive either from the net or otherwise, they are not going to be very accurate.

You don't need the RAM formula itself, just its properties. That's the benefit of a simulation. And again, everyone seems to act as if this discussion is happening in a vacuum away from China's cyber espionage activities. Reality is not so compartmentalized.