Did Shot-Down F-117 Aid China's J-20 Development?

by Bill Sweetman at 1/24/2011

 

Danger Room links to an AP story, reporting that Chinese agents scoured the crash site of an F-117 in Serbia in 1999, and speculating as to whether what they found contributed to the stealth design of the Chengdu J-20.

As with much in the world of espionage, it is hard to produce an exact answer, but possibly helpful to set some bounds to the benefits that might have been gained. 

My own view is that with one exception, the Chinese would not have learned very much. The fundamentals of stealth start with shaping, and the Chinese could have learned all they wanted from a visit to a hobby shop.

Materials are important – but most of the materials applied to the F-117, while state-of-the-art in the 1970s, are much heavier and thicker than anything you’d want to let near a supersonic aircraft. Better absorbers eventually made their way to the F-117 fleet, but under an upgrade program that had not delivered any jets by 1999.

The devil of stealth is in the details – apertures, doors, inlets and exhausts and so on. However, an F-117 is not the best place to find out how to do that.

The designers solved the problem of radio-frequency antennas by not having any, at least in stealth mode. The only antennas were for basic communications and retracted when the jet needed to be invisible, and the “titanium tennis racket” covers for the infra-red sensors would not be used today.

The gridded inlets and high-maintenance tiled exhaust did their job but, again, have little relevance to a high-performance aircraft, and the same goes for the F-117’s unique air-data system.

The one exception might be the edge structures. In unclassified briefings in the early 1990s, F-117 chief engineer Alan Brown said that the aircraft made use of high-performance, layered radar absorbent structures to reduce the RCS peaks associated with the long, straight wing edges. Details of those structures have never been revealed.

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