The second stage engines will be ready in a couple of years. That is I think the major reason why we didn't see a big order of the Su-57 any sooner.

Have you both forgotten they have signed for a batch of 76 last year?
That was something that looked almost incredible when it was first published both in russian specialized defence press than in this forum as no similar order was EVER put in (new) Russia, in which, I wrote AGAIN for the nth time, THEY ORDER A BATCH AT TIME with no predetermined total number of a certain model fixed in advance of beginning of serial production (but even after)...
Sorry for tantrums but it has been years that I have repeat same things in both Key aereo than there: Russian procurement system is absolutely peculiar and has no foreign equivalent, so making direct comparisons is absolutely impossible...
No number fixed in advance, no IOC and FOC and ABSOLUTELY
NO LRIP but Design Bureaus, Aircraft Production Organizations (APO) State Trial and First Serial.
Above all no single decades long omni-comprensive contracts with a single firm covering anything from preliminary design to the rolling out of the last produced item of a certain model if not until the last day of service in the Air Force of the last of said planes but a series of successive contracts made with different legal entities, each one covering just a phase of development (or a productive batch) and
PAYED SEPARATELY one from the other at its own conclusion.
Actually, until the end of the first serial phase, Russian state is only happy if it has to pay more money to their counterparts, not less (because it means that everything in the development has gone smoothly and so production bonus could be awarded).
secretprojects wrote:
The AL-41F (Su-35) is an improved AL-31F akin to the F100-PW-229.
The AL-41F (Su-57) is still just an improved AL-31F, with higher thrust, akin to the F100-PW-232. Its bypass ratio isn't optimal for supercruise, for example.
No, thanking God the Su-35 engine is nothing akin to the PW-229.
That's because the precedent (F-100-)PW-220 got a Bypass ratio: 0.71:1 while the PW-229 has a bypass ratio of 0.36:1: it means that to get the required performance increase they have to drastically change the internal structure of the engine itself installing a way larger and heavy jet turbine inside without modify the outer part.
Result was that it is way heavier ((1,737 kg instead of 1,467 kg), so in the end its own trust/weight ratio increased only marginally (7,8:1 from 7,4:1) in front to a anything other than ideal bypass ratio.
AL-41F-1S has a larger outer diameter compared to original model also, so it has not just a way greater thrust to weight ratio compared to it (actually also the Al-31F has a way better one than PW-229) but also a marginally larger bypass ratio leading to a better specific consumption.
The version on Su-57 has an even larger one, equal to the one of the second stage engine but compared to it is longe as it still got the same 4LP/9HP compressor stages of the one on the Su-35.
The engine core of
izdelje 30 would sport a way lover number of stages but they would be wider hence the necessity of a larger overall diameter.
And thank God, although being perfectly capable of get the Su-57 well into such flying regime it would NOT be optimized for supercruise in the sense the F-119 is: it will still remain a turbofan with an healthy bypass ratio, not a "leaky turbojet" in disguise like the one actually propelling the F-22A and incapable to be installed in anything else or even to operate efficiently in any other flying regime than that...