1. How is an academic paper indication that pla will actually get such a weapon?
2. as j20 is now some 8 years in service , one would think such or a similar weapon would already be in service as well. Not just in development.
What we do know is that such a weapon (IWB compatible ALCM) has long been rumoured to be either in development or (and in recent years, in service) with the PLA.
Whether it is this specific weapon depicted in the study is a different matter. After all, not everything in an academic paper is necessarily representative of what is actively developed for PLA use.... but also, it is true that what we see in academic papers published in a given time period is not necessarily indicative of the stage of development it is at. (E.g. a paper for a system might only be published years after it is in service)
3. Curious that design would call for less than 4m in length. Both j20 and j35 have a bay of similar length, and both could fit longer weapons.
That said, 1300 km range would be pretty good, given dimensions. Jassm cant get that far in its more compact variant. (Though it's
lighter and less volumenous)
Longitudinal clearance is important. In fact I would say a sub-4m length is exactly what one would expect for a ALCM sized for J-20/35 family IWBs.
To be honest if the specifications are accurate and able to be achieved I would be mightily impressed -- a 1.3t weapon, 4m or lesser in length, and 0.85m or lesser in diameter, actually seems somewhat beyond what J-20/35's IWB would be able to accommodate in terms of diameter.
Keep in mind 0.85m is the same diameter of the UVLS canister, and the diameter of an equivalent IWB ALCM like JSM is 0.48m in diameter...
J-20 does optimize air to air first and foremost. Until J-20S/A the nose mounted EOTS didn’t even have the ability to look backward, which presumably limited the air to surface capabilities.
For a weapon of this category, you don't really need something like an A2G sensor capability. This sort of weapon is generally well beyond visual range, well beyond over the horizon, and acquires targeting data from offboard sources and is guided by satellite/INS/midcourse offboard sensors before terminal seeker/s take over.
My guess for less than 4m length is that maybe they wanted to be able to stack them in the bay in such a way that more missiles (AAM or air to surface) can be fitted.
Fitting inside the weapons bay won't have any bearing on a J-20/35 family IWB being able to "stack" more missiles? Longitudinally there obviously won't be any length for any weapons in "front" or "behind" such a weapon, and of course they can't stack weapons vertically above or below it for obvious reasons.
If you mean fitting weapons alongside (horizontally alongside) this ALCM in the IWB, that has no relation to the length of the weapon -- instead it is relevant to its diameter.