Indranil, all great points and thanks for your insight. A few replies -
Indranil wrote:2. IAF is not thinking of AMCA as a replacement for an aircraft or set of aircrafts. Frankly, there are no airplanes in IAF's inventory which does AMCA's role, albeit stealthily. Rafale is just entering service and too few in numbers for AMCA to replace.
So the IAF will physically not replace any aircraft with the AMCA? What about the mission sets currently performed by the aircraft that will be retiring from service between 2030 and 2050?..Would the AMCA not be tasked with taking over those missions? Operational realities require an analysis of the capability you are trying to recapitalize and seeing how the incoming capability will take over - even though, the way it does that mission may be different. One could have envisioned a silver bullet 5GFA force (used like the F-117 for example) in the 2020's but if the AMCA is going into production and service for the post 2030 then it will need to proliferate into the IAF far deeper than that given how A2A and IADS capabilities of the primary opponents (China) is going to evolve over the next 30 years.
The existing fleet of medium jets, M2K, MiG29UPG and Jaguars will be replaced by MWF in numbers and mission capability. But I do not consider it to be a replacement of "Medium" capability (capability, not weight category**) of IAF, but rather it will be a new "Light" capability for IAF. IOW, IAF's bottom-line would be lifted up from MiG21/MiG27 to LCA-Mk1A/MWF. AMCA will bring in a new "Medium" capability to IAF, complimented by Rafale (complimented, because Rafale has limited 5th gen capabilities while AMCA will be a proper 5th Gen fighter. Going into 2040's AMCA will lead the category). Mission capability wise, there may be some overlap with the missions from current "medium" and "heavy" categories, but with added dimension of 5th Gen capabilities.
I think the answer to your point in the last line, is - UCAV. UCAVs will give the additional edge needed. Ghatak will come online sometime in 2030s. I would like IAF to go with a twin engine UCAV rather than spending resources on Su-57 any time in future.
IMO, need of heavy 5th Gen manned fighter is highly debatable. I personally think, its not a necessity for IAF, if they can make AMCA work satisfactorily. If someone thinks we need a heavy manned stealth fighter, I would like to hear the arguments other than "we need to replace Su-30MKI" which, IMO, itself is not a strict requirement. If someone has a cogent argument in terms of realistic mission profiles that IAF would need in 2035 onwards, but not covered by AMCA or a twin engine UCAV with equivalent weapons, then it would be interesting to hear.
Indranil wrote: If there will be no FGFA, then AMCA will be taking on the role of air dominance. All indicators point in that direction. Even in the latest spec release, the focus has been on close "combat capability" and "supersonic persistence" citing high TWR. Clean TO is 20 tons and at 220 kN of thrust, the intended TWR at clean take of would be greater than 1.1. I think they will have supercruise with caveats, e.g. cannot supercruise with full internal fuel or punch through the Mach barrier using limited AB and then sustain on military power.
Of course you make do with what you have. But it will be difficult to replace "FGFA requirements" (assuming the IAF demanded a set of requirements from Russian side) with the AMCA. Of course, it will still do the mission but will have to do it differently. Even the F-22 and Su-57 will use AB to punch through the transonic range even though they can (eventually if not at baseline for the PAKFA) do so without it. You have to stay efficient and manage your fuel and zipping past the transonic region is going to get that.
I think the only issue with AMCA vis-à-vis FGFA would be that the strike package will need more nos, especially, dedicated A2A fighters in it for same kind of mission, due to its smaller and single bay (As you already know, AMCA is limited by the availability of powerplant, rather than SQR. The shortcoming could be circumvented by nos.). Question in my mind is, did IAF have an organic mission requirement prescribing PAKFA class fighter to start with, or was it an opportunistic decision to go with PAKFA and IAF came up with FGFA in sync with it post facto...? Given there is next to nothing authentic information available on this topic its difficult to draw conclusions on it.