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(A) Why are j-20 engines dark?
(1) "Nearly all aircraft are propelled by airbreathing jet engines, and most
of the airbreathing jet engines that are in use are turbofan jet engines
which give good efficiency at speeds just below the speed of sound."
jet engine
http://en.wikipedia.org/wiki/Jet_engine
F-22 is powered by twin Pratt & Whitney F119-PW-100 (turbofan) engines.
(2) Video clips in you tube show engine exhaust (even in daytime), if the
shot is close enough. See, e.g.,
(a) FlyingMachineTV, F22 Raptor Take-off at RIAT 2010. July 15 2010.
http://www.youtube.com/watch?v=16ti9GwnlVs
(b) airboyd, F-22 Taxi, Takeoff. Nov 22, 2010.
http://www.youtube.com/watch?v=3f-5edDikSY
(c) strayjay, F22 minimum radius turn. Apr 2, 2007.
http://www.youtube.com/watch?v=n34RwIUlnAo&feature=&p=AB7EB56D23CFAF52&index=0&playnext=1
The first two were shot during takeoff but the third already in the air.
So the photo may be doctored. But so far I have not seen any US report that
deals with issue.
(B) Now that we are talking about J-20 engine, please read an interesting
analysis with side-by-side comparisons--that comes out today.
Kit Eaton, China's Stealth Fighter Flies, But Does It Work By Ripping Off U.
S. Tech? Fast Company, Jan 11, 2011.
http://www.fastcompany.com/1716168/how-does-chinas-stealth-fighter-work-by-ripping-off-the-f-22
PS Let me tell you , Beijing government has developed a software to AGAIN frustrate my efforts to post. Recently the URLs of the links I provide are often truncated for no apparent reasons at all.
【 在 choi 的大作中提到: 】
: David Axe, Don’t Panic: China’s New Stealth Jet Takes to the Air (Maybe).
: Wired, Jan. 10, 2011.
: http://www.wired.com/dangerroom/2011/01/
: dont-panic-chinas-new-stealth-jet-takes-to-the-air/
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