Chinese Stealth, American Research

China caused a stir, and something of a minor diplomatic incident, earlier this month when they undertook the first flight of their stealth fighter jet, the J-20, during a visit by US Secretary of Defense Robert Gates. I wonder if the Chinese were kind enough to thank Gates for all the help America unwittingly gave China in building the jet?

According to a new report on the BBC, the J-20 owes much of its stealthy design to parts from an American F-117 Nighthawk stealth jet shot down during the NATO-led, and US-backed bombing campaign against Serbia in 1999. The F-117 was the first operational stealth aircraft employed by any military in the world; a stealth aircraft uses a combination of shape and radio wave-absorbing materials to make the airplane nearly invisible to radar. Yet somehow the Serbians still managed to shoot one down during the conflict, military sources from the Balkan region say that Chinese intelligence agents reached the crash site and retrieved parts of the aircraft, which were believed to have given Chinese engineers a great advantage in building the J-20 they recently unveiled. The story does make some sense since in 1999 there were deep ties between Serbia and China, at the time the US angrily accused China of sharing military intelligence with Serbia. (It's worth noting that during the bombing campaign against Serbia, the Chinese embassy was “accidentally” struck by an errant bomb.) It is also strange, based on the BBC report, that the United States didn't make an effort to secure the wreckage of the F-117, or at least destroy it. The crash site was allegedly visited by Chinese, American and Russian officials and even today pieces of the F-117 are displayed in a museum in Belgrade, Serbia.

Of course China doesn't seem to have taken the most valuable lesson from the F-117 wreckage; namely that stealth technology isn't all that it is cracked up to be. Even though building a stealth jet today is the holy grail of the world's most advanced air forces, the planes do have one glaring weakness – while it is possible to make the aircraft itself nearly invisible to radar, it's not possible to disguise the turbulence it leaves as it moves though the air. Just like a boat leaves a wake in the water as it moves, so to does an airplane. And while American officials dismissed the Serbian downing of the F-117 in 1999 as a “lucky shot”, in fact the Serbs had figured out a clever way to use Doppler radar (the same kind your local weatherman uses) to track the wake of the F-117. All they had to do then was shoot at the point where the wake was starting to hit the airplane.

Getting back to the Chinese J-20, in addition to thanking the US, China probably also owes Russia a debt of gratitude as well. A few weeks ago, the Washington Post published this article about how despite their best efforts, the Chinese defense industry has had little luck in creating durable jet engines for their air force and were looking into long-term deals with Russia for a supply of aircraft engines. Just a little something to keep in mind next time you read an article about the growing might of the Chinese military.