The J-10 is no copy, some say it's based off the Lavi but in reality it hardly is. if at all. China did buy some tech from Russia (such as the engines) but it is very much a unique aircraft. The Chinese are designing a domestic engine to replace the Russian one right now, should be ready soon. I_hate_China is right, it stands no chance to the F-22 raptor. But allegedly they have a "Super-10" in development which would be closer in performance. Also, I hear that there is a sucessor to the J-10 in development, called the J-XX right now, which would be stealth and comparable to the F-22.