Original Article: http://www.bbc.co.uk/zhongwen/simp/china/2011/01/110111_j20_pingkefu.shtml
High Mobility
According to a Hong Kong military expert, Mr. Kefu Ping, the basic ideology behind the aircraft's design is to emphasise its mobility, while sacrificing invisibility to a certain degree.
According to Ping, such a design may have its own plausibility, which is practicality. The designers may have realised that their stealth materials and composites may not reach F-22 or F-35 standards, maybe not even Russian standards. So high mobility is applied to compensate the lack of invisibility.
Ping says, it is possible to guess some of the aircraft's performance by looking at its form (airframe), just like it is possible to analyze the strength of a person by looking at its body. Generally speaking, this aircraft focuses on high mobility. However, further analysis is impossible without more detailed specs.
Not a threat to USAF and Russia
Ping says, this test-flight model of J-20 is 4th-gen by Chinese standards, not 4th-gen by int'l standards not 5th-gen Russian standards. Most importantly, 4th-gen (int'l) aircraft should have a thrust of at least 16'672N (1.7t metric) and is capable of thrust vectoring. This Chinese aircraft does not have such capabilities.
He also says that it is difficult to gauge whether the radar system on the J-20 is on-par with American or Russian counterparts. According to his own analysis, it will take a long time for China to put this aircraft into service.
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