Shenyang FC-31 / J-31 Fighter Demonstrator

AndrewS · Jan 29, 2022

stannislas said:
How do you know? for 5th gen fighter, radar, avotronicsand and engine should take more much significant percentage of the price in compare with previous generations, if one expect these two birds have roughly same performance in these dominaces, then their price would be close, plus a land base may cause extra money to develop, so... how can you tell?

We can see the price difference between the F-22 and F-35 for example. Plus it is common sense that a smaller and lighter aircraft should cost less. If we assume that 5th gen aircraft find it very difficult to obtain a radar lock on each other, the performance of the radar matters a lot less. Remember that doubling the energy of a radar does not result in anywhere near a doubling in detection range.

stannislas said:
visual, maybe, but I won't expact the total area of these two to have a significant different. keep in mind J-20 is slimer than FC-31, with a relative small wingspan in compare with the other 5th gens. Also, given both fighter are twin engine, it's hard to tell if their IR signal could be significant reduced as well

Note that the J-31 doesn't have canards, which contributes to RCS reduction. Given that the J-31 is a smaller aircraft with smaller engines, the amount of heat produced by the engines will be lower.

stannislas said:
you sure about that??? J-20 has side weapon bays, and equipped with PL-10, where as FC-31 doesn't even has a single dogfight missle. and both fighters have no cannon as well.

Who is to say that the land-based J-31 won't have a cannon?
The naval F-35s don't have an internal gun but the Air Force F-35 does.
As for dogfight missiles, I expect short-range dogfight missiles with HOBS will be integrated into the main weapons bays of the F-35 and J-31 in the future.

stannislas said:
I don't think Chinese designers believe that, otherwise they won't develop J-20 in twin seater version

And who is to say we won't see a dual seat version of the J-31, if Loyal Wingmen become prevalent?

stannislas said:
possible, but please remember, PLANAF also has serval hunderds of fighters other than carrier based J-15 (J-10, Su-30MKK, JH-7), so even this could come ture, I would expect PLAN order more carrier based fighters and placed some on land just for rotation.

I don't think the affordability will become an issue, what matter the most is the time.

given carrier based FC-31 just came out late last year, let's just assume the land base will come out some time late this year (a year different will be most optimisitic though), than its timeframe could be estimated by the production of J-20. J-20 takes 6 years to develop into initial production stage, and another 2 years to deploy to front line brigade, and another two years to ramp up to production speed (assume it's late last year), that's 10 years in total, which is relatively fast already.

assume land based version can borrow a lot of experience from J-20, which reduced it's development dramaticly, like to 7 years, that it will still make it late 2020s' or even early 2030s', but by then I would expect at least some 6th fighter prototypes from both China and US come out ealier...

On the development timescale, I see the latest J-31 (the 4th prototype seen in 2021) as equivalent to the 4th J-20 prototype seen in 2015. J-20 LRIP must have commenced in 2016 because IOC was declared in 2017. My guess is that J-20 production really ramped up in 2021. If we apply this timescale, J-31 LRIP would begin sometime in 2022, IOC in 2023 and full-scale production in 2025.

So the start of LRIP would be the logical time to have the development team work on the prototype for a land-based variant.
At a minimum, it would have a redesigned wing without a hinge, the tailhook removed and a redesigned undercarriage that doesn't need to handle carrier takeoff and landings.

So this prototype could come out in 2023 and would be equivalent to the 3rd/4th J-20 prototypes. So LRIP would commence 1-2 years later in 2024-2025. But given limited changes compared to the naval J-31, full-rate production of the land-based variant could begin almost immediately in 2025-2026.

I also don't see 6th generation fighters being a game changer, unlike the difference between 4th gen (non-stealthy) and 5th gen (stealthy).

Blitzo · Jan 29, 2022

tphuang said:
I don't know if FC-31 will necessarily be cheaper than J-20. Over the next few years, they will be producing WS-10 equipped J-20s at around 50 units a year. That's higher than they ever consistently produced with J-10s. With that level of guaranteed production, all the vendors involved in the supply chain can make the investment needed to lower their production costs. For example, a mass produced WS-10 could have lower unit cost than WS-21 with much smaller production guarantees. Similarly, maintenance cost for J-20 will come down over time as PLAAF has more experience with it and CAC can make more investment/modifications to lower cost of maintaining things like stealth qualities. So, there is no guarantee that J-20 will necessarily cost more to produce or maintain than FC-31.

On the other hand, there are also significant reasons for PLAAF to order FC-31. It helps SAC's case that PLAN will already be funding most of the costs in getting J-35 into production and also establishing the supply for J-35. Those are things that PLAAF does not have to fund anymore. It would require a lot less money to develop a land based version. Most of the supply chain should be the same. Since they've already done a lot of testing in the FC-31 program, a land based prototype can start flying in a couple of years and join service by 2026-2027. Remember, J-20 went from first 2011 protytype to joining service in under 3 years. FC-31 should also have certain late comer advantages. It could potentially take the lessons from J-20 and have better all around stealth performance. It could also be using newer generation stealth technology that would be easier and cheaper to maintain. One could argue later J-20 variants will also incorporate those advances. Regardless, it's quite conceivable for FC-31 to be as good in A2A combat as J-20. Although, the latter would always have more range/payload and multi-role utilities. The two seater version of the latter would also be a better fit as an EW aircraft or a distribute AWACS.

More importantly, there are industrial reasons for PLAAF to order FC-31. Based on production level of 50 a year, PLAAF could have 500 J-20s by the end of this decade. Over next 20 to 25 years, we could possibly see 1000 J-20s produced. Even if they get 6 large CATOBAR carriers, I think 300 is probably the upper limit of the number of J-35s they would need over the same time frame. While SAC will also get more orders for flanker variants over the next few years, it will still leave them quite a large gap vs CAC. In order to keep SAC somewhat in parity with CAC, I think PLAAF will also have to order a lot of SAC. It also gives them a chance to match US productions of F-35s. As we've seen with F-22s, small production run really increases cost of maintenance, reduces reliability and adds pressure to early removal from service. Having SAC consistently getting orders from both PLAAF and PLANAF will help keeping the FC-31/J-35 cost down while also supporting a healthy second major aircraft producer.

There is also certain export considerations for land version of FC-31. I don't think J-20s will get exported. If they want to be competitive in the export market, a land version of FC-31 seems to be a necessity. Just think about all the Arab countries that need a 5th generation aircraft but won't have access to F-35.

First of all, welcome back, haven't seen you around these parts in a while.

Regarding the relative costs of J-20 and a land based PLA production ready FC-31 (which I've variously called land based J-35/J-XY, or for the purposes of discussion, let's call it J-XZ for now) -- I believe J-XZ would have lower unit and operating costs relative to J-20 primarily because of the additional years of advancement in production technologies and stealth technologies between when J-20 entered production and when the J-XZ (and J-XY as well) would enter production.
J-20 entered initial production in 2015, and a land based J-XZ would likely do so no earlier than 2025, likely 2026-27. That's a decade of additional time in which advancements in stealth, production, structure, could have been baked into not only the design of J-XZ, but also its production methods.
That is to say, I fully expect J-XZ to be cheaper to buy and operate than J-20 because of advancements in technology and design that were not available at the time of when J-20 was at equivalent stages of design and technology.

Now, it is certainly possible for a new variant of J-20 to be developed to leverage similar advancements in design and technology, but the one thing we know about 5th generation aircraft is that the airframe, once structurally decided on, is difficult to make significant overhauls without time and money.
If I were the PLA, putting in new money for a new J-20 variant incorporating advances in the whole scope of production and stealth technologies might not be the best use of money for Chengdu -- UCAVs, and more importantly, 6th generation fighters, may be much more valuable sites of investment instead.

That said, I do also agree there are other factors at play. The commonality between J-XZ and the carrier based J-XY/J-35 is likely to be one of them. The industry benefits of giving SAC more work, and in turn freeing up CAC to pursue other projects, again 6th gen being the most important, cannot be understated.

AndrewS · Jan 29, 2022

tphuang said:
I don't know if FC-31 will necessarily be cheaper than J-20. Over the next few years, they will be producing WS-10 equipped J-20s at around 50 units a year. That's higher than they ever consistently produced with J-10s. With that level of guaranteed production, all the vendors involved in the supply chain can make the investment needed to lower their production costs. For example, a mass produced WS-10 could have lower unit cost than WS-21 with much smaller production guarantees. Similarly, maintenance cost for J-20 will come down over time as PLAAF has more experience with it and CAC can make more investment/modifications to lower cost of maintaining things like stealth qualities. So, there is no guarantee that J-20 will necessarily cost more to produce or maintain than FC-31.

On the other hand, there are also significant reasons for PLAAF to order FC-31. It helps SAC's case that PLAN will already be funding most of the costs in getting J-35 into production and also establishing the supply for J-35. Those are things that PLAAF does not have to fund anymore. It would require a lot less money to develop a land based version. Most of the supply chain should be the same. Since they've already done a lot of testing in the FC-31 program, a land based prototype can start flying in a couple of years and join service by 2026-2027. Remember, J-20 went from first 2011 protytype to joining service in under 3 years. FC-31 should also have certain late comer advantages. It could potentially take the lessons from J-20 and have better all around stealth performance. It could also be using newer generation stealth technology that would be easier and cheaper to maintain. One could argue later J-20 variants will also incorporate those advances. Regardless, it's quite conceivable for FC-31 to be as good in A2A combat as J-20. Although, the latter would always have more range/payload and multi-role utilities. The two seater version of the latter would also be a better fit as an EW aircraft or a distribute AWACS.

More importantly, there are industrial reasons for PLAAF to order FC-31. Based on production level of 50 a year, PLAAF could have 500 J-20s by the end of this decade. Over next 20 to 25 years, we could possibly see 1000 J-20s produced. Even if they get 6 large CATOBAR carriers, I think 300 is probably the upper limit of the number of J-35s they would need over the same time frame. While SAC will also get more orders for flanker variants over the next few years, it will still leave them quite a large gap vs CAC. In order to keep SAC somewhat in parity with CAC, I think PLAAF will also have to order a lot of SAC. It also gives them a chance to match US productions of F-35s. As we've seen with F-22s, small production run really increases cost of maintenance, reduces reliability and adds pressure to early removal from service. Having SAC consistently getting orders from both PLAAF and PLANAF will help keeping the FC-31/J-35 cost down while also supporting a healthy second major aircraft producer.

There is also certain export considerations for land version of FC-31. I don't think J-20s will get exported. If they want to be competitive in the export market, a land version of FC-31 seems to be a necessity. Just think about all the Arab countries that need a 5th generation aircraft but won't have access to F-35.

I would also look at the trouble that the US is having with Lockheed Martin which has a monopoly on stealth fighters.
It's not in the interests of Lockheed Martin to see the cost of maintenance go down.

In 2018, F-35 sustainment costs were double that of the F-16.
So an F-35 costs approx $80 Mn to purchase, but the 2018 sustainment cost is $9.93 Mn per year. Over 10 years, that is $99 Mn for each F-35.
In comparison, F-16 sustainment is only $4.33 Mn per year, for a 10 year cost of $43 Mn.

But if the US had 2 competing stealth fighters being procured, they can alter purchase amounts to promote competition.
And it would be very easy for the Air Force to compare detailed costs and see where there are major differences.

I see it this as just another manifestation of US ideology, which privileges freedom over an efficient and competitive marketplace.
I would also say Western Europe, China and the rest of East Asia have a far more sophisticated view of what constitutes market success and also market failure than an ideologically rigid USA.

gelgoog · Jan 29, 2022

6th generation fighters might have vastly increased range which should make a difference in the Pacific theater of operations.

latenlazy · Jan 29, 2022

tphuang said:
I don't know if FC-31 will necessarily be cheaper than J-20. Over the next few years, they will be producing WS-10 equipped J-20s at around 50 units a year. That's higher than they ever consistently produced with J-10s. With that level of guaranteed production, all the vendors involved in the supply chain can make the investment needed to lower their production costs. For example, a mass produced WS-10 could have lower unit cost than WS-21 with much smaller production guarantees. Similarly, maintenance cost for J-20 will come down over time as PLAAF has more experience with it and CAC can make more investment/modifications to lower cost of maintaining things like stealth qualities. So, there is no guarantee that J-20 will necessarily cost more to produce or maintain than FC-31.

On the other hand, there are also significant reasons for PLAAF to order FC-31. It helps SAC's case that PLAN will already be funding most of the costs in getting J-35 into production and also establishing the supply for J-35. Those are things that PLAAF does not have to fund anymore. It would require a lot less money to develop a land based version. Most of the supply chain should be the same. Since they've already done a lot of testing in the FC-31 program, a land based prototype can start flying in a couple of years and join service by 2026-2027. Remember, J-20 went from first 2011 protytype to joining service in under 3 years. FC-31 should also have certain late comer advantages. It could potentially take the lessons from J-20 and have better all around stealth performance. It could also be using newer generation stealth technology that would be easier and cheaper to maintain. One could argue later J-20 variants will also incorporate those advances. Regardless, it's quite conceivable for FC-31 to be as good in A2A combat as J-20. Although, the latter would always have more range/payload and multi-role utilities. The two seater version of the latter would also be a better fit as an EW aircraft or a distribute AWACS.

More importantly, there are industrial reasons for PLAAF to order FC-31. Based on production level of 50 a year, PLAAF could have 500 J-20s by the end of this decade. Over next 20 to 25 years, we could possibly see 1000 J-20s produced. Even if they get 6 large CATOBAR carriers, I think 300 is probably the upper limit of the number of J-35s they would need over the same time frame. While SAC will also get more orders for flanker variants over the next few years, it will still leave them quite a large gap vs CAC. In order to keep SAC somewhat in parity with CAC, I think PLAAF will also have to order a lot of SAC. It also gives them a chance to match US productions of F-35s. As we've seen with F-22s, small production run really increases cost of maintenance, reduces reliability and adds pressure to early removal from service. Having SAC consistently getting orders from both PLAAF and PLANAF will help keeping the FC-31/J-35 cost down while also supporting a healthy second major aircraft producer.

There is also certain export considerations for land version of FC-31. I don't think J-20s will get exported. If they want to be competitive in the export market, a land version of FC-31 seems to be a necessity. Just think about all the Arab countries that need a 5th generation aircraft but won't have access to F-35.

You’re alive! It’s good to see you around.
Edit: Don’t have much more to add beyond what others have said, but on engines I suspect economies of scale for a medium thrust engine would be in part be supported by UAVs that will probably also need an engine solution of that size class.

Atomicfrog · Jan 29, 2022

tphuang said:
I don't know if FC-31 will necessarily be cheaper than J-20. Over the next few years, they will be producing WS-10 equipped J-20s at around 50 units a year. That's higher than they ever consistently produced with J-10s. With that level of guaranteed production, all the vendors involved in the supply chain can make the investment needed to lower their production costs. For example, a mass produced WS-10 could have lower unit cost than WS-21 with much smaller production guarantees. Similarly, maintenance cost for J-20 will come down over time as PLAAF has more experience with it and CAC can make more investment/modifications to lower cost of maintaining things like stealth qualities. So, there is no guarantee that J-20 will necessarily cost more to produce or maintain than FC-31.

On the other hand, there are also significant reasons for PLAAF to order FC-31. It helps SAC's case that PLAN will already be funding most of the costs in getting J-35 into production and also establishing the supply for J-35. Those are things that PLAAF does not have to fund anymore. It would require a lot less money to develop a land based version. Most of the supply chain should be the same. Since they've already done a lot of testing in the FC-31 program, a land based prototype can start flying in a couple of years and join service by 2026-2027. Remember, J-20 went from first 2011 protytype to joining service in under 3 years. FC-31 should also have certain late comer advantages. It could potentially take the lessons from J-20 and have better all around stealth performance. It could also be using newer generation stealth technology that would be easier and cheaper to maintain. One could argue later J-20 variants will also incorporate those advances. Regardless, it's quite conceivable for FC-31 to be as good in A2A combat as J-20. Although, the latter would always have more range/payload and multi-role utilities. The two seater version of the latter would also be a better fit as an EW aircraft or a distribute AWACS.

More importantly, there are industrial reasons for PLAAF to order FC-31. Based on production level of 50 a year, PLAAF could have 500 J-20s by the end of this decade. Over next 20 to 25 years, we could possibly see 1000 J-20s produced. Even if they get 6 large CATOBAR carriers, I think 300 is probably the upper limit of the number of J-35s they would need over the same time frame. While SAC will also get more orders for flanker variants over the next few years, it will still leave them quite a large gap vs CAC. In order to keep SAC somewhat in parity with CAC, I think PLAAF will also have to order a lot of SAC. It also gives them a chance to match US productions of F-35s. As we've seen with F-22s, small production run really increases cost of maintenance, reduces reliability and adds pressure to early removal from service. Having SAC consistently getting orders from both PLAAF and PLANAF will help keeping the FC-31/J-35 cost down while also supporting a healthy second major aircraft producer.

There is also certain export considerations for land version of FC-31. I don't think J-20s will get exported. If they want to be competitive in the export market, a land version of FC-31 seems to be a necessity. Just think about all the Arab countries that need a 5th generation aircraft but won't have access to F-35.

WS-21 ? you mean WS-19 ?

tphuang · Jan 29, 2022

Bltizo said:
First of all, welcome back, haven't seen you around these parts in a while.

Thanks very much. btw, really enjoyed reading a lot of your material. You and Deino's stuff are some of the best way to stay informed.

latenlazy said:
You’re alive! It’s good to see you around.
Edit: Don’t have much more to add beyond what others have said, but on engines I suspect economies of scale for a medium thrust engine would be in part be supported by UAVs that will probably also need an engine solution of that size class.

Yes, I'm still alive. Just got burnt out by it for a while and then had family reasons to step away.

Atomicfrog said:
WS-21 ? you mean WS-19 ?

I'd assume they use WS-21 to start off for a while.

I think WS-10C right now is going to be cheaper to produce than WS-21 due to the large production run. Keep in mind in aviation, larger production run allows significant cost cuts. Large and consistent order book allows aircraft maker to get big discounts from suppliers and to make the automation/production line investment to lower assembly costs. The suppliers can also make the investment needed to lower their costs. That's how they finally cut F-35 fly away cost to under $100 million.

So, I think it's worth looking at what America did and not make the same mistake. It was a terrible move to stop F-22 production at 187. They completely missed out on the cost benefits of a long production run. Now, the availability of F-22 is very low compared to everything in F-35. The maintenance cost of F-22 is too high. How long are the former suppliers to F-22 going to have to keep supporting this program? At this point, it makes more sense if they just shut it down and increase F-35 production. If there is a conflict over Taiwan, I really don't see F-22 playing a major part in it. It was also a mistake to shut Boeing out of 5th generation project. Thankfully, Boeing still has a healthy business outside of fighter jet. But as a superpower, you really do want to have multiple military aviation suppliers. That's what China has now with CAC and SAC. They will be well served to keep that going. The reason they have been able to develop things so quickly is because of all the young engineers they produced from all these investment. With more funding than ever, it should be easier to sustain 2 large aircraft makers.

With increasing defense budget, there is no reason they can't procure as many 5th gen aircraft per year as America does. Sure, CAC can continue to get more efficient with their production line. I think it's more likely they will ramp up SAC 5th generation production to eventually reach something like 80 or 90 5th gen deliveries a year.

stannislas · Jan 30, 2022

AndrewS said:
We can see the price difference between the F-22 and F-35 for example. Plus it is common sense that a smaller and lighter aircraft should cost less. If we assume that 5th gen aircraft find it very difficult to obtain a radar lock on each other, the performance of the radar matters a lot less. Remember that doubling the energy of a radar does not result in anywhere near a doubling in detection range.

yes, but price wise, I don't think it will make a significant different for PLAAF to create another supply chain and logistic system for entire new aircraft, also the reason for F-35 to be cheaper than F-22 is F-22 has only produce 187 units, and F-35 has already produced more than 700 units and likely another 3000 units to go, whereas J-20 in china would have an expected of 500+ or even 1000, and FC-31, well, 2 or 300?

AndrewS said:
Note that the J-31 doesn't have canards, which contributes to RCS reduction. Given that the J-31 is a smaller aircraft with smaller engines, the amount of heat produced by the engines will be lower.

canards reduce RCS is an old busted myth, there has been multiple occasions and papers from CAC said during the cruise, the J-20 canards could be locked, so that the RCS reduction could be neglectable

general heat detector on missle are normally more sensitive to temperature change rather than the size of the frame, if a infred detector can see WS-10 from km, I would expect it can see all the other exhaust from 50km as well (may be not F-22)

AndrewS said:
Who is to say that the land-based J-31 won't have a cannon?
The naval F-35s don't have an internal gun but the Air Force F-35 does.
As for dogfight missiles, I expect short-range dogfight missiles with HOBS will be integrated into the main weapons bays of the F-35 and J-31 in the future.

AndrewS said:
And who is to say we won't see a dual seat version of the J-31, if Loyal Wingmen become prevalent?

hi, this is contridict to what you mention later, that:

AndrewS said:
So this prototype could come out in 2023 and would be equivalent to the 3rd/4th J-20 prototypes. So LRIP would commence 1-2 years later in 2024-2025. But given limited changes compared to the naval J-31, full-rate production of the land-based variant could begin almost immediately in 2025-2026.

now we have a naval version with small airframe, to have an addition cannon, and addition side weapon bay, and dual seat means the entire airframe need be much larger, so dilemma A, how would you expect the development timeframe could be achieved with in 3 years (for a fighter we haven't saw yet)???

dilemma B, once the airframe get larger, the small engine WS-13/19 will be too small to use, to back to WS-15, which makes you smaller IR and visual amd price hypopthsis gone, and also from a logitics point of view, I'm not sure if PLAAF is happy with that.

so here you have it, to close the capacity gap of J-20, FC-31 need a larger bodyframe to cop with additonal equipment and therefore longer time to development,
otherwise, it leaves a capacity gap between J-20 and FC-31, and have only a cheap unit cost (maybe not, given the number of FC-31 production) alternative to be produce in late 20s or even early 30s, you should have a better argument than China want to save money, cause you have mentioned before that

AndrewS said:
Chinese military spending today is estimated at 1.7% of GDP by SIPRI

I also don't see 6th generation fighters being a game changer, unlike the difference between 4th gen (non-stealthy) and 5th gen (stealthy).

if it's not a game changer, like F-15 to F-4 or F-22 to F-15, than it's not a 6th gen

AndrewS said:
But if the US had 2 competing stealth fighters being procured, they can alter purchase amounts to promote competition.

sorry man, if you have any idea of manufacture or industry or production line, you won't say anything like that, in reality, the US way of produce YF-22/23 and XF-32/35 is the most inefficient and uneconomical way to R&D a product. cost more than double, recieve only half, if US defence department is a company, it will be bankrupt for a long time

getready · Jan 30, 2022

Nice to see you again tp! Welcome back.

I did a double take when i saw your name. I thought someone quoted old post of yours. Wow its been so long. Still remember the old days of reading your posts. They were very informative and fair. After your work was used in American government hearings and you left the forum, I thought they must have recruited you

stannislas · Jan 30, 2022

Bltizo said:
That is to say, I fully expect J-XZ to be cheaper to buy and operate than J-20 because of advancements in technology and design that were not available at the time of when J-20 was at equivalent stages of design and technology.

are you sure about that?

how much would you estimate J-20 production number? min 500 to ~1000?
how much would you estimate J-XZ production number? 2?3 hundards?

ok let's assume J-XY could be produced as much as 500, then the unit cost need to be less than half of J-20 to make it cheaper, and that is after the money inflation

I'm not sure how advance SAC need to be in order to produce J-XY that cheap...
also, if certain technologies do exist, why CAC can't use it to improve their further batch of J-20 and reduce its cost, unlike Boeing and Lockhead Martin, CAC and SAC are all under AVIC and they are in fact sharing technologies

Shenyang FC-31 / J-31 Fighter Demonstrator

AndrewS

Brigadier

Blitzo

Lieutenant General

AndrewS

Brigadier

gelgoog

Lieutenant General

latenlazy

Brigadier

Atomicfrog

Major

tphuang

Lieutenant General

stannislas

Junior Member

getready

Senior Member

stannislas

Junior Member