Shenyang FC-31 / J-31 Fighter Demonstrator
- Thread starter RedSky
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I'll be honest to say I am unsure of how the J-35 will look in the end.
What borked my brain was the landing gear.
It'll look almost identical to V2 V3 prototypes because the work on how it looks (aerodynamic engineering) is done. That probably means they've already factored in loads and peripheral factors with FCS. How much different can it possibly look? It'll take many millions and years to perform even slight re-designs like from J-20 prototypes 2001 and so on development.
We all know that FC-31 started out as a private venture by 601 so they did not design it from the front up as a carrier based fighter. It was only pitched as one later one. Therefore I would expect some changes overall, most definitely the enlarging of the wings to carry more fuel and strengthening of the landing gear and engine change naturally.
Maybe the J-35 will retain the weapons bay size of the FC-31, maybe it will get the size of the J-20 bay for commonality but who knows.
Anyways what I am saying is that I expect there to be some changes to the airframe for sure. Given the amount of flight testing 601 has done with the 31001 and 31003 I doubt a J-35 with exactly the same airframe would have taken so long as the aforementioned serials already did almost all of the testing required for a production prototype so I'd expect the new prototype that we expect to incorporate some airframe changes. But in any case the similarity to the FC-31 will be unquestionably there.
Maybe the J-35 will retain the weapons bay size of the FC-31, maybe it will get the size of the J-20 bay for commonality but who knows.
Anyways what I am saying is that I expect there to be some changes to the airframe for sure. Given the amount of flight testing 601 has done with the 31001 and 31003 I doubt a J-35 with exactly the same airframe would have taken so long as the aforementioned serials already did almost all of the testing required for a production prototype so I'd expect the new prototype that we expect to incorporate some airframe changes. But in any case the similarity to the FC-31 will be unquestionably there.
None of that can be done without serious redesign. It'll put balances, weights, structure, propulsion, and FCS all out of whack. Much more so than integrating avionics and weapons for FCS etc.
Enlarging J-35 from FC-31 V2/V3 prototypes would almost defeat the whole point. At a wingspan equal or greater than J-20's and nearly the same length assuming, why would the PLAN not simply decide to go for a navalised J-20? Assuming the challenges are equal. The main support for J-35 as carrier fighter is its favourable size and weight, allowing a few more fighters to be brought onboard compared to J-20 fit out.
I think they screwed up when they insisted on developing a twin engined fighter because the whole point is to offer a lower cost variant. Unless the J-35 is only for PLAN with PLAAF having zero interest in purchasing another expensive twin engine 5th gen fighter and supporting that, all while it offers zero real advantage over J-20 in that 5th gen force multiplier role.
PLAAF wanting a low cost 5th gen fighter means it has to be single engined... maybe WS-15 when it is mature enough for single engined fighter or at least an upgraded modernised WS-10. This way the fighter is certainly lower cost and will be sharing engine commonality with so many other PLAAF platforms.
J-35 being a PLAN only project makes sense because they have enough desire to forgo that cost consideration. They need a full high spec 5th gen fighter but it needs to be no larger than F-18/F-35/Rafale class mid weight. Hence twin engined J-35 - Not for PLAAF.
A medium sized twin engined fighter is still going to be cheaper than a heavy twin engine fighter. Furthermore, not all the costs are in the extra engines, and arguably you're not benefiting *that* much from engine development time or cost savings either, since a single engined stealth fighter would most likely need an uprated heavy engine to support the much heavier frame that would be necessary to support sizable internal weapons bays. The F-35 didn't directly adopt an F119, but had to use the derivate F135, which essentially ended up having to match the thrust of two medium sized engines anyways while eating some penalties to supersonic performance. And judging by the F-35, even if that program had not been over budget and delayed, its flyaway cost was still going to be substantially higher than an F-16, despite being a program that was intended to produce volume on a sensible budget. For all intents and purposes a single engined stealth fighter ends up being a medium weight fighter anyways due to all the bundled requirements that come with stealth.
Nor is the engine the only place you can look for cost savings. The *whole* point of the FC-31 was to study simplified and cheaper manufacturing techniques after all. Ultimately even if you were eating somewhat higher costs for a two engine fighter based on the FC-31, the cost difference between that and a single engined fighter probably won't be nearly as substantial as between an F-18 and an F-16, and you'd probably be purchasing something that's a bit more capable to boot.
I dunno. Small cars are often harder and more costly to develop than larger ones. Small cars are cheaper due to economies of scale. I'm not aware of any reason why a medium sized fighter has to be cheaper than a larger one if the internal systems are of equal capability and modernity. If it's a case of the medium fighter forgoing some equipment, then that lower monetary cost comes at a capability cost.
Well the J-10 is a perfect example of a low cost modern and capable fighter. Even with more modern equipment, the F-16 is still the much more effective fighter than the Mig-29 but while an equally modernised Mig-29 is still on paper the better fighter, when costs and numbers are considered, these single engined fighters really are something else. The high thrust class of engines of which WS-10 is one, is enough for a single engined stealth fighter. The lower drag compensates for greater weight and overall, a VLO or even LO fighter carrying only 4 MRAAMs and nothing else, is still far more useful than a non LO fighter carrying 20. Assuming range and subsystems are equal. There is so much merit to the idea of a F-35 equivalent but obviously without that same development and acquisition cost. Basically a J-10 for the 5th gen. Or a singe WS-10 or Ws-15 (when ready) powered FC-31. I know that's not going to happen Deino so save it. But that is the true low cost Chinese 5th gen fighter. J-35 as twin engine proves the program did not have cost control as a primary objective like the J-10 development had for example.
I feel very confident that PLAAF will not introduce J-35 or whatever that variant is. It is going to be a PLAN only carrier fighter and possibly developed into an export offering. I can't think of any country that is in a position to have the need for one and make such an expensive purchase while also not be aligned with the west or politically invested in jumping in bed with the US. So yeah export J-35 chances of success is slim to none but they might formally offer one anyway just to get the opportunity out there. Maybe Pakistan but it won't be a cheap fighter for sure otherwise there's little point.
PLAAF would be interested in a low cost 5th gen that can be built and purchased in greater numbers and one that can basically do most of what J-20 does but with much less range and lower payload. Basically the same as the J-10's role vis a vis J-11 and J-16. However we are approaching the "next" gen with the US already very much finishing development of new propulsion systems that justify a new generation. There are also those autonomous wingman trials and drone swarm ideas. Point is the room for a low cost 5th gen for PLAAF is going. What China needs is a leapfrog and forget developing a cheaper, easily mass produced single engined 5th gen and just focus on the dark sword UCAV, drone swarm tech, DEW on aircraft, future missiles/weapons, and assorted sensors comms and avionics. Then for 6th gen fully implement all those along with looking at how to extend range and how to adapt aircraft e.g. those highly variable geometry airframes even some public Chinese military papers indicate are some areas of focus.
You’re forgetting that the need to carry weapons internally makes it nearly impossible for a single engined stealth fighter to be in the J-10’s weight class. And while “leapfrogging” to a totally different force doctrine sounds great on paper you can’t just forgo updating your mainstay while you wait for that force doctrine to mature and prove itself, which itself could take years. The last thing you want to do is to make your main fleet flying combat experiments with no technically mature updates to maintain your proven capabilities. Even worse, the last thing you want is to have futuristic capabilities that are more expensive than even your current high end with no way to bring your mainstay forces to comparable capabilities.
Wrt to small cars, my understanding is that small cars are more expensive to develop because being smaller makes it harder to achieve requisite safety regulations, which means more structural work needs to be put into the design. This is not a condition that plagues fighter planes. And sure a medium weight fighter might forgo some capability relative to a heavy weight fighter *but so would a light weight fighter*.
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I said J-10 role, not class. Midsized class is a class above J-10 in overall weight, volume, and thrust.
I really don't think China will develop a low cost mid sized fighter for PLAAF. The need for at least adopting to new doctrines and technologies is already pressing. China setting a few of them and being the first onto a few is now much more possible than it was one or two generations ago. We know the US is already publicly working on loyal wingman drones. Maybe China's dark sword is much more advanced than hinted (or rather hidden) and maybe Chinese programs at the next gen R&D is further along but none of these are certainties so where's the room for staying back and building hundreds and hundreds of low cost 5th gen fighters? The US talk about reinvesting in the older 4th gen into 4.7 or whatever buzzword but they do that while pivoting towards at least working on next generations and some disrupting tech.
My point is that for a J-10 style role to be performed by a stealth fighter with the requisite internal bays, you would effectively need a middle weight class fighter.
New doctrines aren’t developed in one generation. It’s very bad force planning to put all your chips into a force doctrine that hasn’t even been properly developed yet. The problem is not a matter of technological capability but of developing tactical and strategic utility. That part of any new combat theories requires time to vet and refine. It’s not a good idea to make your force structure wait till those ideas are mature enough to invest in at scale, and and even worse idea to make broad based investments without really knowing what you’re getting. The US may be building loyal wingman drones but it’s not replacing its mainstay with those drones. That’s for a reason. They’re not dumb enough to replace their mainstay with unproven combat doctrines.
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