I can propose a P75i that will not be MMRCA circus -
Have a sub that has the following -
0. Design - We have ToT for HDW and Scorpene. If we cannot copy, paste and make our own, what's the point. We are also making Arihant class. The design capability in may form exist, the will and budget could be a different issue.
1. LI-Ion batteries (it is rumored that these batteries, in weight for 1-1 replacement over acid batteries store 8-10 times more power).It is in all ways more capable than lead acid. We are experimenting one currently and perhaps get a better one (if we fail) from Japan or south Korea. This in itself can take the performance of a sub (to remain in water and also move fast using batteries) to the next 2-3 level up. If Lead acid helps a sub to remain submerged for 15 days, lithium ion can make it remain underwater for 60-90 days.One can go few notches up, and put more Li-ion (in place of AIP), and increase the endurance. Totally doable on our part as either indigenous option or as a subsystem import.
https://safety4sea.com/cm-lithium-batte ... 0batteries.
2. AIP - We are validating one right now. Same can be put nd it can give us 15-30 days of additional submerged endurance.
3. Torpedo launch tubes + torpedos - we made them for HDW and Scorpione
4. Ballistic missiles (VLS?) --> We make them for Arihant class, they are after all SSBN capable of launching K6 and K5
5. Optronics and other mast related tech- Just today one of DRDO lab refurbished one. Now the navy is moving to all camera/IR/Laser/Radar based mast, which pops up, gather 360 degree view of everything in various spectrum and comes back. This tech sounds very familiar to IRST/optronics used for LCA/Sukhoi. Regardless, Japan has been offering masts with all these features.
6. Systems automation - Shame on us if we as an IT superpower cannot develop a fully automated system by integrating all the above features. Dont know if Scorpene ToT gives some of these systems/sub systems
7. Hull mounted SONARS and towed sonars - I remember we making them some 20 years ago. Ifours are not the greatest, can be bought of the self.
8 Hull material (steel) etc. - That's the ToT we got from HDW and Scorpene
9. Engine - Diesel + electric. Electric engine are easiest to make (battery storage is trickiest) +Diesel engine. We may not have one (unless Toted), that has to be made or bought. Germany stopped Chinese from importing.
10. Screws/blades (or water propulsion)- If you believe we are asking one from France
If you look above, we have almost all the building blocks. It just needs some faith and action to get it done.