Shenyang FC-31 / J-31 Fighter Demonstrator

AssassinsMace said:

Huitong says the next J-31 prototype will have major changes. I read on the Chinese boards it might be larger to accommodate more fuel and an increased size weapons bay to meet PLAN requirements.

I wonder if they're showing off the first prototype at Zhuhai because this one will be closer to the export version.

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I think they're showing 31001 because to both show the world they have the capacity to build a stealth fighter for export, and also because PLA will not be inducting the plane as it is for their requirements. Being a tech demonstrator also means it lacks the in service avionics and subsystems the real plane will have.

I wouldn't be surprised if 31001 is the basis for an improved, PLA domestic version, and an adaptable export fighter -- basically an empty stealthy airframe where customers can request the kinds of avionics they want integrated depending on what they are willing to pay.

Don't mean to be a party pooper, but the J31 showing up at Zhuhai is probably a bad sign wrt it ever appearing in PLAAF or PLANAF colours.

The Zhuhai airshow is primarily an export show piece, and the only reason the J31 is there is because it's shopping for foreign investors and buyers.

If the PLA was seriously interest in the bird, the whole project would have been deemed classified and SAC would never have gotten approval to showcase the J31 to anyone.

It could be that if SAC gets foreign funds and finishes the bird, the PLA might decide to order some, and there is certainly precedent with the K8. But the general trend doesn't look all that promising, and SAC would want to avoid what is happening with the JF17, whereby a Chinese company managed to develop a perfectly respectable fighter with foreign funds, but tailored the fighter too much to the foreign customer's needs that it became a poor fit for the PLA.

plawolf said:

Don't mean to be a party pooper, but the J31 showing up at Zhuhai is probably a bad sign wrt it ever appearing in PLAAF or PLANAF colours.

The Zhuhai airshow is primarily an export show piece, and the only reason the J31 is there is because it's shopping for foreign investors and buyers.

If the PLA was seriously interest in the bird, the whole project would have been deemed classified and SAC would never have gotten approval to showcase the J31 to anyone.

It could be that if SAC gets foreign funds and finishes the bird, the PLA might decide to order some, and there is certainly precedent with the K8. But the general trend doesn't look all that promising, and SAC would want to avoid what is happening with the JF17, whereby a Chinese company managed to develop a perfectly respectable fighter with foreign funds, but tailored the fighter too much to the foreign customer's needs that it became a poor fit for the PLA.

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I agree that we won't see an airframe the same as 31001 inducted into PLA, but I think it is plausible for an improved airframe based on 31001 entering PLA service.

I think its appearance at zhuhai is definitely meant to attract foreign buyers and attention, but that doesn't preclude the possibility of PLA being interested in its potential as a fighter for themselves. This is still a tech demonstrator after all, which is meaningfully different to J-20 airframes, which can be considered prototypes. So naturally it makes sense for PLA to be more relaxed about SAC showing off a little more. It's basically just an empty airframe that likely won't represent whatever final product PLAAF/PLANAF ends up inducting.
I also suspect 31001 is far less of a "strategic" airframe as J-20 has the potential to be, making them more open about it.
Showing off 31001 also adds some prestige to AVIC overall, as they can say "see, we're so fancy we can show off a 5th generation tech demonstrator," and it adds credibility to their existing line of products as well and the overall chinese defense industry as well. Of course, 31001 is just an empty shell at this stage, using off the shelf subsystems, but it's still only one of five flyable fifth generation type airframes in the world at present.

JF-17 failed because J-10 already existed. I suspect if J-10 went nowhere, then we'd be seeing JF-17s inducted by PLAAF in large numbers right now instead.

Another problem for the JF-17 was that while it was aiming for the market of the F/A-50, it offered capacity way in excess of the Golden Eagle, not to mention that it had to compete with a ton of MLU F-16s the US government was practically giving away.

I don't think the J-31 has to worry about the USAF gifting the F-35A at knockdown prices for a very long time.

Skywatcher said:

Another problem for the JF-17 was that while it was aiming for the market of the F/A-50, it offered capacity way in excess of the Golden Eagle, not to mention that it had to compete with a ton of MLU F-16s the US government was practically giving away.

I don't think the J-31 has to worry about the USAF gifting the F-35A at knockdown prices for a very long time.

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PAF has a requirement of ~ 250 Thunders while Pakistan Navy is also considering fielding 2 squadrons. Until and unless our own requirements are met, there would be no foreign exports.

Scratch said:

A quick try

J-31 looks a little sleeker with more sweep and shorter span (if my scaling is correct), while F-35 might have a bit more internal volume.

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Hmmm...does this mean I will need to use those old fashion paper 3D glasses to see this?

Bltizo said:

I agree that we won't see an airframe the same as 31001 inducted into PLA, but I think it is plausible for an improved airframe based on 31001 entering PLA service.

I think its appearance at zhuhai is definitely meant to attract foreign buyers and attention, but that doesn't preclude the possibility of PLA being interested in its potential as a fighter for themselves. This is still a tech demonstrator after all, which is meaningfully different to J-20 airframes, which can be considered prototypes. So naturally it makes sense for PLA to be more relaxed about SAC showing off a little more. It's basically just an empty airframe that likely won't represent whatever final product PLAAF/PLANAF ends up inducting.
I also suspect 31001 is far less of a "strategic" airframe as J-20 has the potential to be, making them more open about it.
Showing off 31001 also adds some prestige to AVIC overall, as they can say "see, we're so fancy we can show off a 5th generation tech demonstrator," and it adds credibility to their existing line of products as well and the overall chinese defense industry as well. Of course, 31001 is just an empty shell at this stage, using off the shelf subsystems, but it's still only one of five flyable fifth generation type airframes in the world at present.

JF-17 failed because J-10 already existed. I suspect if J-10 went nowhere, then we'd be seeing JF-17s inducted by PLAAF in large numbers right now instead.

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Undoubtably there are many reasons why SAC and AVIC would like to show the J31 off, which is why its at Zhuhai.

My point is that if the J31 had official PLA backing, it would be a very different matter, so SAC is only able to be so open with the J31 because the bird hasn't yet been picked up by the PLA.

The implications of that are not great tbh. As I said in my last post, while it is certainly not unheard of for the PLA to pick a design that was first developed for export, it is a concern that the PLA isn't showing as much interest as you would hope/expect in the J31.

The J10 v JF17 comparison also seems an uncomfortably close analogy to the J20 v J31 relationship. The J10 is a weight class above the JF17, yet is more AA focused while the JF17 can boast of being more multi-role oriented. The J10 is more expensive than the JF17, but isn't so much so to make the PLAAF think its worth while to order it to compliment the J10s. Rather, they seem perfectly happy to fork out a bit more to get a better aircraft.

The carrier role was the best shot I could see the J31 breaking into the PLA, but I first formulated that idea before the true dimensions of the J20 were confirmed.

With the J20 being actually smaller than a flanker, the PLAN seems more interested in navalising the J20 than getting the J31 at this point.

Going with a J20 and J15 combo would mean fewer aircraft on a carrier, but maybe the PLAN feel that is a price worth paying for better range, payload and performance.

plawolf said:

Undoubtably there are many reasons why SAC and AVIC would like to show the J31 off, which is why its at Zhuhai.

My point is that if the J31 had official PLA backing, it would be a very different matter, so SAC is only able to be so open with the J31 because the bird hasn't yet been picked up by the PLA.

The implications of that are not great tbh. As I said in my last post, while it is certainly not unheard of for the PLA to pick a design that was first developed for export, it is a concern that the PLA isn't showing as much interest as you would hope/expect in the J31.

The J10 v JF17 comparison also seems an uncomfortably close analogy to the J20 v J31 relationship. The J10 is a weight class above the JF17, yet is more AA focused while the JF17 can boast of being more multi-role oriented. The J10 is more expensive than the JF17, but isn't so much so to make the PLAAF think its worth while to order it to compliment the J10s. Rather, they seem perfectly happy to fork out a bit more to get a better aircraft.

The carrier role was the best shot I could see the J31 breaking into the PLA, but I first formulated that idea before the true dimensions of the J20 were confirmed.

With the J20 being actually smaller than a flanker, the PLAN seems more interested in navalising the J20 than getting the J31 at this point.

Going with a J20 and J15 combo would mean fewer aircraft on a carrier, but maybe the PLAN feel that is a price worth paying for better range, payload and performance.

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I think comparing J-10 vs JF-17 to J-20 vs "J-31" isn't wholly fair, the weight difference between the latter two is likely far larger than the former. The difference in capability between the latter two are likely going to be far greater as well.

Note, I put J-31 in speech marks because what we are seeing right now isn't J-31 but rather a tech demonstrator called 31001.
On that note, the other difference between JF-17 and 31001 is that JF-17/FC-1 from the onset was meant to be similar to the final fighter configuration, but 31001 may not look very much like the final thing if it is inducted.

It is difficult to tell whether PLAAF would also be interested in a notional J-31 developed from 31001, because we really don't know what kind of 5th gen fleet they want, but I wouldn't be too quick to rule out their interest. It is similar for PLANAF, because we don't know if they would want all their carrier borne fighters to be heavy flanker or J-20 size or if they want something more balanced.

Basically I'm saying that we don't know enough to say whether 31001's appearance at zhuhai signifies that PLA definitely is not interested in a future variant or that it is exclusively for export. At the very least I don't think we can rule out PLA interest in a derivative of the design just because 31001 is here, because it's perfectly plausible for PLA to want a more advanced derivative of the airframe for their own use while SAC is willing to offer an export version with less capable avionics and maybe less airframe modifications from the current demonstrator.

Bltizo said:

Note, I put J-31 in speech marks because what we are seeing right now isn't J-31 but rather a tech demonstrator called 31001.

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Before any formal designation appears, J-31 is a generally accepted name. So, you don't have to worry about that.

Bltizo said:

In particular, I think I wouldnt' be opposed to J-31 having a larger, even bulbous weapons bay like F-35, even if it isn't as stealthy or sleek as its current weapons bay. After all, it is meant to be a multirole fighter and it should have the internal volume to carry a pair of powered, decent sized stand off munitions.

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I would personally be very much against any j31 development having an even larger weapons bay than what it has now. At least not without a VAST redesign with much more powerful engines. That would, however, make it basically a whole new design so i think that's out of the question.

31001 is a demonstrator, that much is likely, but we will probably not see layout/size changes in the prototypes to come. Maybe redesigned wing, maybe even slightly larger wing/tail surfaces, but overall the weapon bay should remain the same. One has to keep in mind the bay is huge as it is. We're talking about a 12-ish ton (empty) plane with a weapon bay that's similar to one on j20. That's already huge.

It is very hard to make a stealth fighter that's not small. I fear engines may be a bigger issue for any 31001 successor than they are for j20. We all know about state sponsored ws15 development. But what about engines for 31001 lineage of planes? There don't seem to be state sponsored projects beyond ws13. And ws13 is basically the only engine of choice for 31001 family. So, at best some 200 kn of thrust for a plane that is not so small nor thin.

One of the worst choices (in my opinion) for f35 family was the requirement to carry two 4+ meter, 1000 kg weapons internally, in addition to amraams. For a plane of that class it is simply too much and bound to make it quite wide. But it was designed to be a striker as well as a fighter so okay. US will have other systems with it.

Some notational future j31 will be sold to countries that can't depend nearly as much on other systems to accompany their planes. So those j31 will have to be fighters with strike capabilities. j31 isn't any larger than f-35. And Shenyang has no access to f135 level of tech for its engines. So we already have a large bay, we have a visibly thin rear end of fuselage (probably to compensate for the weapon bay and keep the overall supersonic drag at acceptable levels) and we can't have much fuel inside that plane.

Going for even larger bay, to further take away internal space (and fuel space) would be counterproductive.

Better route would be to play with what they have and find a weapons company that makes bombs/missiles that can fit inside the existing bay. there should be enough stand off solutions available already, even if they're not powered. And within next 5-10 years there may be even better, powered solutions. And frankly, it may really take 5-10 years before any j31 reaches a customer.