专家：中国隐形战机机动性强 隐形能力弱

choi

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BBC Chinese, Jan 11, 2011 (格林尼治标准时间12:47).
http://www.bbc.co.uk/zhongwen/simp/china/2011/01/110111_j20_pingkefu.shtml

My comment:
(a) The report quotes 平可夫 as saying, "目前试飞的J20战机只是中国标准的第四代战机，并不是国际标准的第四代战机和俄罗斯代号的第五代战机."

China seems to have a different term. But in US, it is called
Fifth generation jet fighter
http://en.wikipedia.org/wiki/Fifth_generation_jet_fighter
(b) He then says, "最重要的是，第四代战机发动机的推力至少要达到1.7吨."

Bill Sweetman stated in Aviation Week on Jan 3 2011 (cover date) that J-20 were bigger and heavier than expected. Two days later, a report provided detailed estimations.

Chinese Stealth Fighter Sighted. Strategy Page, Jan 5, 2011.
http://www.strategypage.com/htmw/htairfo/articles/20110105.aspx

Quote:

"The F-35A is a 31 ton, single engine fighter that is 15.7 meters (51.4 feet) long and with a 10.7 meter (35 foot) wingspan. The engine generates 12.7 ton (28,000 pounds) of thrust, or 19.5 (43,000) with afterburner. In contrast, the J-20 has two engines and appears to be 24 meters (75 feet) long and with a wingspan of 15 meters (46 feet). The engine for the J-20, the WS-15 is still in development. The prototype had afterburner thrust of 16.5 tons, although this was expected to hit 18.3 tons when development was complete. It is believed that the J-20 prototypes are powered by Russia AL31FU/117S engines, each with 14.5 tons of afterburner thrust. Two of these engines would give the 36-40 ton J-20 more power per ton than the F-35A.

(i) A J-20 is estimated to be "36-40" tons, whereas F-35A has

"Empty weight: 29,300 lb (13,300 kg)
Loaded weight: 49,540 lb (22,470 kg)"  (footnotes omitted)
Section 6 Specifications (F-35A) in
Lockheed Martin F-35 Lightning II
http://en.wikipedia.org/wiki/Lockheed_Martin_F-35_Lightning_II

In other words, J-20 is about twice or thrice as heavy as F-35A.

But it is well known that F-35 is a lighter version of F-22, whose data is

"Empty weight: 43,430 lb (19,700 kg)
Loaded weight: 64,460 lb (29,300 kg)"  (footnotes omitted)
Section 8 Specifications in
Lockheed Martin F-22 Raptor
http://en.wikipedia.org/wiki/Lockheed_Martin_F-22_Raptor

Thus J-20 is still heavier than F-22.

(ii) How does an afterburner work?  Howstuffworks (a Discovery Company), undated.
http://science.howstuffworks.com/transport/flight/modern/question374.htm
("A modern turbine engine is extremely efficient, and there is still a lot of oxygen available in the exhaust stream. The idea behind an afterburner is to inject fuel directly into the exhaust stream and burn it using this remaining oxygen. This heats and expands the exhaust gases further, and can increase the thrust of a jet engine by 50% or more")

(c) However, paragraph 2 of the BBC report states, "正在北京访问的美国国防部长盖茨随后对记者说，中国国家主席胡锦涛在当天下午向他证实，中国的确首次试飞了J20战机."

The same in

中国政府首次向媒体证实试飞J20战机. BBC Chinese, Jan 11, 2011 (格林尼治标准时间15:13).
http://www.bbc.co.uk/zhongwen/simp/china/2011/01/110111_j20_china.shtml
("盖茨在会见胡锦涛之后说，胡锦涛向他证实了中国试飞J20战机的消息，并且表示这次试飞同他对中国的访问没有任何关系，是事先安排好的事情")

Both BBC reports do not dwell in this, as if it is a fact known to everybody. (VOA Chinese has not spoken.) However, US Deaprtment of Defense (DOD) has a starkly different take.

Jim Garamone, Gates: Chinese Taking Strategic Dialogue Proposal Seriously. American Forces Press Service, DOD, Jan 11, 2011.
http://www.defense.gov/news/newsarticle.aspx?id=62397

Quote:

"Gates held a press roundtable, where he told reporters that China and the United States should engage in a strategic dialogue focusing on four areas: nuclear, missile defense, space, and cyber.

"The dialogue, Gates said, would help cement military-to-military relations between the two countries, and it could also help to bridge a possible communications gap between Chinese civilian leaders and military personnel.

"There was a demonstration of such a gap during Gates’ meeting with President Hu. The Chinese today performed the first flight test of their new J-20 stealth fighter in Chengu.

“'When Secretary Gates raised the issue of the J-20 test in the meeting with President Hu, it was clear that none of the [Chinese] civilians in the room had been informed [of the test],' said a senior U.S. defense official speaking on background.


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