Well, based on what I understand about the Chinese govn't and Chinese traditions and culture, I would have to say that what we can see now is only the tip of an iceberg. 2001/02 are simply there for people to see, sort of a showboat. Think about it, no one knows how these planes arrived to Chengdu and where they were before they got to Chengdu. they just magically appeared on the airfield. This is especially amazing with 2002. Even with all the people camping outside of the airfield, they still managed to steak the plane into the facility without anyone finding it out. It only appeared sitting on the airfield. If they could keep it a secret when manufacturing them and shipping them, they can definitely ship them to a disclosed location for testing. That's what the Gobe desert is for? If they could successfully hide their 1st atomic bomb test sites in the 60's, they can definitely hide a small plane simply flying back and forth in the desert.
It might even be a distraction, to divert everyone's attention to Chengdu while the actual tests and whatever they are doing occurs somewhere with much tighter security. Isn't it amazing that they can shut down any website discussing political issues and certain corrupted officials, but being seemingly completely ignorant about what is going on on the web about their most top-secret weapon development program.
everyone keeps talking about how secretive the Chinese govn't is. This means the Chinese know all the little tricks of keeping things secret. Yet, why are they doing these tests in Chengdu, one of the largest cities in China? My parents worked for the Institute of Atomic Energy (Institute 401, or previously 601) when we were in China. In the height of the Cold War and during their developmental stage, the security parameter for the Institute began about 30 miles away from the institute. No one was allowed in and out of the institute without checking. Yet, in Chengdu, people can climb on the fence and take photos of the plane with the security people standing nearby...