I don't want to make anyone upset, just to set a few things as straight as I know them to be.
1) People protest to anyone that suggests the J-20 is a copy of the MiG 1.42/1.44 project.
The reality is , that unfortunately it must be. the fact that one is meant to be a stealth plane and the other wasn't doesn't change anything.
and to explain further. MiG designed an airframe. They obviously did a very good job aerodynamically wise. Someone somewhere in china after careful consideration and NOT wanting to re-invent the wheel, decided that the same airframe design, with stealth considerations would be what would provide the maximum benefit. Simple
oh and don't go about talking about the air-intakes, I could copy the same airframe and make it fly with propellers!! the airframe principle design would still hold true.
2) yes the J-10 is comparable (although inferior) to F16s and MiG 29s. It is however impressive that it exists. And most F16s will be with us for at least another 30 years. So that doesn't take anything away from the bravo for making it.
3) Yes china has still a tremendous problem reverse engineering Russian designs. But that is to be expected. I am an engineer. It is 10x more difficult to reverse engineer anything than design it from scratch. there are so many unknowns .. from the tolerance of simple bolts, to the way something was moulded and forged to withstand pressures, stresses etc.
4) How long it takes for the J20 to enter service? The amount of time it will take the engineers to decide it is ready 2 fulfil its mission.