Shenyang FC-31 / J-31 Fighter Demonstrator

siegecrossbow said:

I don't think the FC-31 will gain official status with the PLAAF any time soon. It's hard enough dividing the resource among J-20, J-10B/C, J-16, and the Su-35.

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Lethe said:

Isn't J-31 a downsized version of SAC's rejected pitch for the project that selected CAC's J-20 instead? Scaling it back up again would seem rather wasteful. And given J-20's greater level of maturity and capability, there is no reason to pursue such an aircraft unless J-20 simply cannot be adapted to CATOBAR operation.

I don't believe J-31 is able to meet PLAN's long-term requirements. Nonetheless, it is certainly possible to envision the project and aircraft assuming a supporting role in PLAN's ongoing carrier aviation development. J-31 could be pursued as a low-risk, comparatively low-cost option, entering service before 2025 to supplement J-15, much as F/A-18 supplemented A-6 and F-14 for USN in the 1980s/1990s. Meanwhile, a larger and more technologically ambitious aircraft -- call it J-40 -- could be designed to enter service in the 2030-2035 period to replace J-15. J-31 would continue to be available as a hedge against delays or problems with that project.

The major difficulty I see with such a path is that, unless the notional "J-40" project encounters serious problems, PLAN orders of J-31 would be unlikely to top 150 units and could be as low as 100 units. Therefore, the project would probably require additional commitment either from PLAAF or major export customers (Pakistan, Saudi Arabia, etc.) to be viable.

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Lethe said:

Isn't J-31 a downsized version of SAC's rejected pitch for the project that selected CAC's J-20 instead? Scaling it back up again would seem rather wasteful. And given J-20's greater level of maturity and capability, there is no reason to pursue such an aircraft unless J-20 simply cannot be adapted to CATOBAR operation.

I don't believe J-31 is able to meet PLAN's long-term requirements. Nonetheless, it is certainly possible to envision the project and aircraft assuming a supporting role in PLAN's ongoing carrier aviation development. J-31 could be pursued as a low-risk, comparatively low-cost option, entering service before 2025 to supplement J-15, much as F/A-18 supplemented A-6 and F-14 for USN in the 1980s/1990s. Meanwhile, a larger and more technologically ambitious aircraft -- call it J-40 -- could be designed to enter service in the 2030-2035 period to replace J-15. J-31 would continue to be available as a hedge against delays or problems with that project.

The major difficulty I see with such a path is that, unless the notional "J-40" project encounters serious problems, PLAN orders of J-31 would be unlikely to top 150 units and could be as low as 100 units. Therefore, the project would probably require additional commitment either from PLAAF or major export customers (Pakistan, Saudi Arabia, etc.) to be viable.

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Bltizo said:

As dingyibvs said, the FC-31 is not a scaled down version of SAC's J-XX proposal.


The FC-31/SAC naval 5th gen fighter is still a bit vague.

One prominently circulated idea over the last few weeks is that FC-31 may be enlarged slightly -- but perhaps not as much to be near J-20 dimensions. Possibly a fighter between FC-31 and J-20 size, and maybe with the goal of attaining a greater combat radius/endurance than what the current FC-31 can offer, but while not being as large as J-20 (which itself is only a teensy little bit smaller than a J-15 in length) so that aircraft handling is not as complex.

The problem right now imo is that any of the potential decisions that they make (whether it's going for a naval FC-31, a slightly upscaled naval FC-31, or a naval J-20) could all be argued to be fairly logical simply because we don't know what the Navy's own balance of requirements are.

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Lethe said:

Thanks for the correction re: J-31/J-XX.

The idea of enlarging J-31 to some degree is a curious one, because it immediately raises the question of how the aircraft is to be powered. You couldn't make it much larger, whilst retaining 2x WS-13 powerplant, without compromising on performance. That is assuming the rumours pegging WS-13 in the range of 20-22,000lb (on par with current EJ200/F414) are accurate. On the other hand, if WS-13 can deliver something in the range of 24-26,000lb (on par with proposed EJ230/F414EPE variants) then there would be more room to increase the size/weight of the airframe.

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Bltizo said:

Yes, as with many other projects, the big hurdle is powerplant.
There is a new generation medium thrust engine under development but it'll take quite a number of years to be ready probably well after WS-15 is ready for J-20, so if the Navy wants a 5th gen naval fighter based on FC-31 (whether it's enlarged or not) I feel like they will have to compromise on something.

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jobjed said:

The Liyang employee on CJDBY claims the planned completion date for the next-gen medium-thrust engine is 2022. He also claims the WS-15 was delayed to that same year but concedes that out of all the engine programs in China, he knows the least about WS-15. Liyang is responsible for the WS-13 and WS-13E so his information regarding medium-thrust programs should be quite credible.

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SinoSoldier said:

Initial batches of the WS-15 would certainly be delegated to PLAAF J-20s rather than naval ones, so a notional J-20H wouldn't necessarily have them by 2022.

Additionally, there is no reason for an enlarged FC-31 to require new engines since such changes would not involve a drastic upscaling of the fuselage.

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