Hi dear
@araz
A lot of times this has been pointed out by a lot of folks from other side of the border that HAL tries to re-invent the wheel. It is not entirely true.Let me explain why.First off all,HAL is the "manufacturing" organization(similar to PAC--albeit much bigger in their footprint) and frankly speaking they dont have a rich research experience.Their research portfolio has just begun expanding as they have started filling for industrial patents in an unprecedented manner--this is in sharp contrast to PAC(if we are interested in comparison).For instance back in 2014-2015 HAL filed close to 760 patents. This points to a growing sense of awareness about creation of intellectual property among the HAL leadership.
Now the responsibility of "core aerospace research" rested on
1) ADA(which was created sometimes in early-mid 80s). Incidentally it took best of the best lot from DRDO and ISRO at that time.Kindly note this is a fully autonomous organization under DRDO and comes directly under the purview of defence ministry
2)NAL--the lab that does some really good research in aerodynamics,controls etc. It comes under CSIR. This lab has major contribution in developing the advanced fly by wire with relaxed static stability.
Now your point that india wanted to design everything in-house stems from the political standing of india at that time. To be honest,back in 80s when this program was first mooted,no international vendor was willing to actively cooperate with india in the propulsion field. Same was the case with radars and stuff.Hence all these projects had to be taken up.Now it does seem a bit not-so-pragmatic to take up all the research activities at once--right from engine to radars! I agree,some of these costly ventures couldnt get the desired level of maturity and confidence to be put into the main platform.But it did help in achieving other objectives which perhaps you cant visualize at the moment.Firstly it helped foster an entire eco-system required for undertaking research in lets say aero-engines,radars etc. There are companies that can manufacture single crystal blades in india. Indian metallurgical research too has advanced significantly.
Then there are companies that fabricate T/R modules(again a patent of LRDE-bangalore). LRDE bangalore has been working on phased array radars for almost 3 decades now. Infact the TRMM design is an intellectual property right of LRDE. They have an array of advanced AESA radars in short to medium category-- Ashwin AESA radar(<200kms range),Arudhra,Lstar(300-400kms range)
What you again fail to realize is the fact that LCA is a cranked delta design which means it has much more surface area vis-a-vis JF-17,yet both have almost the same weight!It is this larger surface area that renders it smaller wing loading--although one might argue that as LCA is a delta in the end hence would suffer in STR performance. But then again,what a lot of people miss,is the fact that LCA is a "cranked delta" having two sweep angles.This works pretty much the same manner as the LERX in JF-17. At higher AoAs this double delta helps in creating vortices in a much more controlled manner thereby reducing drag.This has another added advantage and i.e just as in the case of LERX,this double delta helps in stretching the max AoA at which boundary layer separates.
I am sure you'd realize that a plane with lesser drag and higher thrust would dominate in a sustained turn rate performance.Pilots generally go for flaps to enhance their STR performance as it reduces velocity,increases lift(also induced drag). But since there are no provison of flaps in LCA,double delta is what saves it in sheer STR performance. Normally in tight turns,pilots go for max CL with as much thrust available to them!
LCA also happens to have slightly larger internal fuel volume as against JF-17,hence I suspect similar loitering times and combat radii.
LCA is as relevant(if not anymore) in combat scenario as any other light fighter such as your JF-17. But as I explained,IAF wants to base their backbone on a medium weight fighter and not on a light weight fighter. Hence the need for more than 400medium weight fighters.At the end of the day we still need light weight fighters!