Who knows. There are other options as well. Perhaps a combination of minimally modified J20 to make them more multirole and various large UCAVs. Trying to guess the amount of money that may or may not be pumped into new programs/new aircraft would be a futile exercise.
J-20 5th Generation Fighter VII
- Thread starter siegecrossbow
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If they make the PL-15 tail fins smaller, they could fit 2 more in the bays, 1 in each missile bay.
They could make some structural changes to widen the bays a little bit.
I actually see it as viable for the J-20 to be modified into a family of fighters for the simple fact that stealth development cycles tend to be absurdly long. The main advantage of a J-20 family over dedicated aircraft is that you already have the basics of the development work done, meaning that you can more rapidly go from prototype to aircraft in service.
Take the F/A-18E, a substantially modified variant of the F-18 (to the extent it's virtually considered a different plane), as an example. The F-18 Hornet took about 5 years to go from prototype to IOC. The F/A-18E went from prototype to IOC in only 2 years.
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The problem with the static J-20 concept (i.e, new engines, but no substantial redesigns) is that you're looking for what happened with the F-22. The F-22 couldn't strike, so it was eventually canceled for lack of air superiority opponents. Likewise, the F-22 itself is somewhat obsolete with the absence of EODAS and only an IRST (likely of limited capability) being installed in a MLU.
A J-20 family, in contrast, can be repeatedly modified and changed to adapt to the pressing vagaries of Chinese strategic needs, so that the latest fighters of the concept can remain current until 6th gen comes out.
Take the F/A-18E, a substantially modified variant of the F-18 (to the extent it's virtually considered a different plane), as an example. The F-18 Hornet took about 5 years to go from prototype to IOC. The F/A-18E went from prototype to IOC in only 2 years.
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The problem with the static J-20 concept (i.e, new engines, but no substantial redesigns) is that you're looking for what happened with the F-22. The F-22 couldn't strike, so it was eventually canceled for lack of air superiority opponents. Likewise, the F-22 itself is somewhat obsolete with the absence of EODAS and only an IRST (likely of limited capability) being installed in a MLU.
A J-20 family, in contrast, can be repeatedly modified and changed to adapt to the pressing vagaries of Chinese strategic needs, so that the latest fighters of the concept can remain current until 6th gen comes out.
Another big issue is the intakes on the J-20. These need substantial modification once WS-15 is ready; if you look at the F-35's intakes, these are roughly 1 m^2 inlets once DSI is factored in. The inlets on the J-20, once DSI is factored in, is around .67 m^2, which is what you'd need for AL-31F and WS-10.
The result is that once you have the WS-15 ready, you have two options and suboptions for one option:
1- The WS-15s choke under some pressure and airspeed conditions, because the inlets aren't large enough to provide sufficient oxygen for their operation. This happened with the F-14, where the upgraded engines were much better than the original engines, but weren't completely usable (max speed didn't change much) because the inlets weren't big enough to give the new engines their full oxygen needs.
2- The J-20 inlets are redesigned, allowing the WS-15 to perform fully. There are two ways to do this
2a. The first way is simply to shrink the DSI, which would affect the inlet performance at certain altitudes, airspeeds, and AoA. Moreover, the inlets would still not be large enough; you'd need a full fixed inlet to get the 1 m^2 inlets needed for the WS-15 to function fully.
2b. The second way to do so is to enlarge the inlet. That is going to affect stealth and aerodynamic characteristics of the J-20, effectively being similar to a full modification of the J-20's fuselage. You can lengthen it horizontally or you can lengthen it vertically, which would mean that the bay depth of the J-20 is now increased.
If 2b is selected, this is pretty much a harbinger of a J-20 strike variant. You might as well modify the J-20 so it can carry a Kinzhal-class missile in its weapons bay, if you're going to increase the fuselage thickness, and this entire enlarged weapons bay can also be used for other strike missiles and AAM, putting its AAM payload for cost as equivalent or better than the F-35.
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Another factor is, well, the alternative to a strike J-20 is the JH-XX, but how do we know whether the program will mature fast enough? The PLAAF, whose primary role is air defense, is unlikely to develop a large JH-XX inventory so the PLAAF's strike capability will be impaired. On the other hand, a strike J-20 can perform both air defense and strike functions, complementing the JH-XX. A strike J-20 would increase both China's air defense capability and strike capability at the same time, forming a bridge of versatility between the conventional fighter J-20 and the strike-only JH-XX, which looks more designed as a light bomber.
===
Finally, note the difference between the F-18 and the F/A-18E.
It seems as though the F/A-18E is virtually a new aircraft, with very little inherited from the F-18. But the F/A-18E was still prototype to IOC in 3 years, compared to the 5 years of the F-18.
It's going to be easier and faster to radically modify the J-20 for new roles than to come with a complete clean-sheet aircraft like the JH-XX, and the J-20 can still provide the JH-XX a back-up should the JH-XX see unexpected delays as with all stealth fighters.
The result is that once you have the WS-15 ready, you have two options and suboptions for one option:
1- The WS-15s choke under some pressure and airspeed conditions, because the inlets aren't large enough to provide sufficient oxygen for their operation. This happened with the F-14, where the upgraded engines were much better than the original engines, but weren't completely usable (max speed didn't change much) because the inlets weren't big enough to give the new engines their full oxygen needs.
2- The J-20 inlets are redesigned, allowing the WS-15 to perform fully. There are two ways to do this
2a. The first way is simply to shrink the DSI, which would affect the inlet performance at certain altitudes, airspeeds, and AoA. Moreover, the inlets would still not be large enough; you'd need a full fixed inlet to get the 1 m^2 inlets needed for the WS-15 to function fully.
2b. The second way to do so is to enlarge the inlet. That is going to affect stealth and aerodynamic characteristics of the J-20, effectively being similar to a full modification of the J-20's fuselage. You can lengthen it horizontally or you can lengthen it vertically, which would mean that the bay depth of the J-20 is now increased.
If 2b is selected, this is pretty much a harbinger of a J-20 strike variant. You might as well modify the J-20 so it can carry a Kinzhal-class missile in its weapons bay, if you're going to increase the fuselage thickness, and this entire enlarged weapons bay can also be used for other strike missiles and AAM, putting its AAM payload for cost as equivalent or better than the F-35.
===
Another factor is, well, the alternative to a strike J-20 is the JH-XX, but how do we know whether the program will mature fast enough? The PLAAF, whose primary role is air defense, is unlikely to develop a large JH-XX inventory so the PLAAF's strike capability will be impaired. On the other hand, a strike J-20 can perform both air defense and strike functions, complementing the JH-XX. A strike J-20 would increase both China's air defense capability and strike capability at the same time, forming a bridge of versatility between the conventional fighter J-20 and the strike-only JH-XX, which looks more designed as a light bomber.
===
Finally, note the difference between the F-18 and the F/A-18E.
It seems as though the F/A-18E is virtually a new aircraft, with very little inherited from the F-18. But the F/A-18E was still prototype to IOC in 3 years, compared to the 5 years of the F-18.
It's going to be easier and faster to radically modify the J-20 for new roles than to come with a complete clean-sheet aircraft like the JH-XX, and the J-20 can still provide the JH-XX a back-up should the JH-XX see unexpected delays as with all stealth fighters.
Switching from WS-10 to WS-15 does not necessarily mean the intake area has to be drastically increased, or increased at all.
Yes, the thrust of WS-15 is much higher than WS-10, but that does not mean that WS-15's intaking air volume per unit time must be increased in the same percentage as thrust increase. Thrust increase is achieved by two main means. One is increasing intaking air volume as F-135 does with bigger fan. The other way is by increasing the temperature in the turbine, so the same amount of fuel and air can create more thrust. The limit to the second approach is the materials' ability to withstand the temperature. And we know that WS-15 (F119 as well) works on higher temperature than earlier generation engines. There is still a big room to increase the thrust without increasing air-flow so long as the material can improve until theoretical efficiency limitation of turbo jet takes over. In another words, new engines are improving their thermal efficiencies rather than wastefully sucking more air and burning more fuel.
Yes, the thrust of WS-15 is much higher than WS-10, but that does not mean that WS-15's intaking air volume per unit time must be increased in the same percentage as thrust increase. Thrust increase is achieved by two main means. One is increasing intaking air volume as F-135 does with bigger fan. The other way is by increasing the temperature in the turbine, so the same amount of fuel and air can create more thrust. The limit to the second approach is the materials' ability to withstand the temperature. And we know that WS-15 (F119 as well) works on higher temperature than earlier generation engines. There is still a big room to increase the thrust without increasing air-flow so long as the material can improve until theoretical efficiency limitation of turbo jet takes over. In another words, new engines are improving their thermal efficiencies rather than wastefully sucking more air and burning more fuel.
PiSigma
"the engineer"
J20 won't see a major change once ws-15 is ready to install. It was designed for ws-15 from the beginning! I already wrote about this years ago...Another big issue is the intakes on the J-20. These need substantial modification once WS-15 is ready; if you look at the F-35's intakes, these are roughly 1 m^2 inlets once DSI is factored in. The inlets on the J-20, once DSI is factored in, is around .67 m^2, which is what you'd need for AL-31F and WS-10.
The result is that once you have the WS-15 ready, you have two options and suboptions for one option:
1- The WS-15s choke under some pressure and airspeed conditions, because the inlets aren't large enough to provide sufficient oxygen for their operation. This happened with the F-14, where the upgraded engines were much better than the original engines, but weren't completely usable (max speed didn't change much) because the inlets weren't big enough to give the new engines their full oxygen needs.
2- The J-20 inlets are redesigned, allowing the WS-15 to perform fully. There are two ways to do this
2a. The first way is simply to shrink the DSI, which would affect the inlet performance at certain altitudes, airspeeds, and AoA. Moreover, the inlets would still not be large enough; you'd need a full fixed inlet to get the 1 m^2 inlets needed for the WS-15 to function fully.
2b. The second way to do so is to enlarge the inlet. That is going to affect stealth and aerodynamic characteristics of the J-20, effectively being similar to a full modification of the J-20's fuselage. You can lengthen it horizontally or you can lengthen it vertically, which would mean that the bay depth of the J-20 is now increased.
If 2b is selected, this is pretty much a harbinger of a J-20 strike variant. You might as well modify the J-20 so it can carry a Kinzhal-class missile in its weapons bay, if you're going to increase the fuselage thickness, and this entire enlarged weapons bay can also be used for other strike missiles and AAM, putting its AAM payload for cost as equivalent or better than the F-35.
===
Another factor is, well, the alternative to a strike J-20 is the JH-XX, but how do we know whether the program will mature fast enough? The PLAAF, whose primary role is air defense, is unlikely to develop a large JH-XX inventory so the PLAAF's strike capability will be impaired. On the other hand, a strike J-20 can perform both air defense and strike functions, complementing the JH-XX. A strike J-20 would increase both China's air defense capability and strike capability at the same time, forming a bridge of versatility between the conventional fighter J-20 and the strike-only JH-XX, which looks more designed as a light bomber.
===
Finally, note the difference between the F-18 and the F/A-18E.
It seems as though the F/A-18E is virtually a new aircraft, with very little inherited from the F-18. But the F/A-18E was still prototype to IOC in 3 years, compared to the 5 years of the F-18.
It's going to be easier and faster to radically modify the J-20 for new roles than to come with a complete clean-sheet aircraft like the JH-XX, and the J-20 can still provide the JH-XX a back-up should the JH-XX see unexpected delays as with all stealth fighters.
WS-15 has a lower bypass ratio than the WS-10. I don’t think they will enlarge the inlet.
I feel like if there wasn't enough political will for JH-XX, buying more H-20s and regular J-20s would be the solution...
If we accept the idea of a "strike variant" of a 5th generation fighter should be to enable it to carry strike payloads that the regular/normal fighter variant cannot carry, then you have to accept that the aircraft's weapons bay will have to be significantly enlarged, which is going to cause the overall aircraft to change as well.
If you want a "strike variant" of J-20 to carry proper, more capable strike weapons like a couple of KD-20s or a couple of YJ-12s internally, you are going to end up with a much more massive aircraft.
.... Otherwise you could go for a less ambitious strike variant, something along the lines of the proposed FB-22 where the aircraft's weapon bay was essentially lengthened but not made deeper, to allow it to carry more of the same weapons that F-22 could use, but unable to carry larger diameter strike weapons.
But even this would require major structural changes to the aircraft because you're lengthening it, and at a certain point you have to wonder if it's worth the cost and resources of developing the aircraft if it isn't going to be able to carry the larger diameter strike weapons that you really want your dedicated strike variant to employ.
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Larger strike weapons could be carried by H-20, so I don't think J-20 needs a strike variant. They need more multi-role J-20 that can form various functions large numbers. If China does not have a plan to create a lower cost stealth interceptor similar to J-10, so that they have a high-low mix, then they can only rely on much higher numbers of J-20 to counter US numbers of F-35+F-22.
Normal J-20 can also carry strike role if they have the A/G missiles and bombs designed for it. Even if they cannot carry more weapons, they can fly more J-20 to achieve the same outcome.
Large cruise missiles with long range can also be fit into the Weapons bay if they are designed to be "fat" instead of "long". This is how LRASM works I think, which can be carried in F-35 bay and has a much shorter length.
Well I don't think a strike variant J-20 makes much sense, that's why I said that if there wasn't a JH-XX, that buying more H-20s and J-20s would be a fine solution.
The idea of a strike variant J-20 would require the aircraft to have some rather significant modifications to make such a variant worthwhile to begin with, that it would end up basically being an entirely different aircraft.
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