Future PLA combat aircraft composition

gelgoog said:

My main gripe with UCAVs is that in non-permissive environments they will be jammed to death.
The loyal wingman concept minimizes that issue because the UCAVs would be operating closer to the command node.
But I don't think you would be able to control the loyal wingman aircraft easily in a single seater. You will need a twin-seat aircraft with a drone operator IMHO. Neither the F-22 nor the F-35 are twin-seat.

I think that as long as China has 4th gens with high power AESA radars, IRST, and HMDs for target acquisition plus the requisite weapons with an adequate communication network and ECM capabilities the stealth aircraft won't be as effective as claimed. At least the F-22 and F-35 in its current configuration won't be. Even less so if the Chinese have a comprehensive radar network with long-wave radar that is stealth resistant.

The Chinese will mainly need their own stealth aircraft to operate outside the envelope of their A2/AD bubble.
That is basically what the Russians are doing and I think is a lot more cost-effective than masses of 5th generation aircraft.

Sure it would be nice to have a twin-seat J-20 attack variant or a single-engine single-seat lower cost stealth fighter but I think those have a lower priority.

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Couple of points

Spread spectrum comms is standard, and is very difficult to detect or jam.

But let's say drone datalinks will be under attack.

That means you need autonomous UCAV swarms with the authority to detect, identify and shoot without outside C&C.

In such scenarios, how many manned stealth fighters would you need?

As for the effectiveness of non stealthy 4th Gen fighters, they can be detected by long range UHF or L-Band radar.

Then engaged by X-band air to air missiles.

So I struggle to see how 4th gen fighters can be effective against a stealth fighter which is immune to radar guided missiles.

AndrewS said:

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So I struggle to see how 4th gen fighters can be effective against a stealth fighter which is immune to radar guided missiles.

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Stealth fighters aren't invisible to radar. They are less visible. That's why before the US coined the "stealth" bullshit word they were just called "low observable" aircraft not "stealth". EM fields increase in power with the square of the distance, so if you are 3x closer to the target the signal will be 9x more powerful. At a certain distance even a radar guided missile will detect the target. Even if it is small it will be travelling at a speed no natural object does. There are missiles which have AESA radars as the sensor to further increase sensor sensitivity. The first missile with such a sensor was the Japanese AAM-4B. Now we have GaN radars which will likely be even more powerful in the same package.


If you have such a missile and add to that a datalink capability which allow for mid-course updates guided by the launch aircraft which is in turn connected to a long wave radar network I doubt even 5th gen aircraft would be immune to it. The British did ok with an air defense network on WW2 which was based not only on long wave radar but human spotters and a really messy voice communications system. Now that this is all automated and you have other sensors, not just a single long wave radar, but multiple bands the picture of how the battlefield looks like will be a lot more accurate. The Russians when WW2 started didn't even have proper radar, they used sound for aircraft direction finding, and this was mostly done with human operators. Of course aircraft are faster today so the same techniques aren't as applicable, but I think the idea that radar low observable is a panacea is a bit far fetched.

Guys ... you are now off topic by a wide margin.

This thread is is now again a politically spiced up discussion on comparisons of different air forces, individual pros and cons of certain systems.

Stop this.

AndrewS said:

Guam doesn't have robust defences against manoeuvring hypersonic glide missiles.
THAAD doesn't cut it, as it was designed for non-manoeuvring ballistic missiles.

Also Guam is only 3000km from Mainland China.
That is within range of current Valkyrie type drones with a range of 6000km which cost $2M.

So if you develop a version with a larger fuel tank, you can expect large number of Chinese UCAVs to sweep Guam and the surrounding areas at regular intervals. Short range stealth fighters like the F-22, F-35, J-20 will struggle to operate at these distances.

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Guam most definitely will have defenses against maneuvring hypersonic glide vehicles in time.
The idea that a few "silver bullets" are sufficient to achieve a robust OCA success is very dangerous.
Multi-domain strikes that are simultaneous, and each domain being large in volume, supported by robust ISR and EW, should be the goal.


I address UCAVs more below.

From engineering point of view, UCAVs are mechanically pretty simple.
The Vakyries are just converted cruise missiles with a landing parachute and a payload bay.
That is why they are so cheap at $2M.

It's the datalinks and training the algorithms to operate the UCAVs which is the difficult part.
But that is a straightforward deep learning software problem.

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We have yet to see what the most optimal loyal wingman UCAV will look like in terms of size and complexity.

The XQ-58A is a useful tech demonstrator to begin with but it is yet to be seen if proper loyal wingmen UCAVs will have that footprint and cost profile.

It may end up being that proper loyal wingmen UCAVs will be larger, dimensionally like F-16 sized. Already the Boeing ATS is bigger than the XQ-58A and it too is another tech demonstrator.


That said, I don't have an issue with the idea of UCAVs once they come into fruition and they obviously should be produced in large numbers as well.
But I consider those aircraft to still be force multipliers for manned fighter aircraft and not replacements, because in a high intensity conflict scenario you will still need line of sight control over the tactical decisions that your UCAVs make, and there is likely a golden ratio of manned fighters to UCAVs as well.

You suggest 6 UCAVs per manned fighter.
But what happens when the other side deploys their own UCAVs?
You end up with a UCAV attrition race, where the side with the most UCAVs wins.

Remember that UCAVs are almost analogous to one-shot guided missiles, so these are going to be expended in very large numbers in order to sweep the skies of opposing UCAVs, in order to reach their actual targets.

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My theory of future loyal wingman/UCAV augmented air combat is that there will be a golden ratio of UCAVs to manned fighters.
For the purposes of discussion, I raised that number as 6 UCAV per manned fighter.

If both sides deploy UCAVs, it's the size with the larger manned fighter and and larger UCAV fleet at the 1:6 ratio that will likely win, if all else are held equal.

Run the numbers. If the US has 2000 manned stealth fighters with 50 UCAVs each, that is a total of 100,000 UCAVs.
From a budgetary point of view, that is $200B just in procurement costs.
And today, we already see that the US has accepted there won't be large military budget increases.
Plus the US doesn't have the available landmass nor bases in the Western Pacific to field a larger UCAV force than China.

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I think the idea that the golden ratio being 50 is ridiculous to begin with so it's kind of a moot point.


At the end of the day, I don't think the maturity and capability of loyal wingmen UCAVs, and the size of the opfor's 5th gen fleet, and the current size of the PLA's 5th gen fleet, is at such a point that it is very useful to talk about "limiting" the size of the PLA's 5th generation procurement in the immediate to medium term future.

The PLA does not have that luxury yet. Perhaps in 5-10 years once loyal wingmen UCAVs do emerge into mature systems then longer term opportunity cost in terms of the optimal balance of manned and unmanned procurement can be debated in more detail -- but the industry's ability to produce many stealthy loyal wingmen UCAVs would be greatly enhanced by having had experience in producing large numbers of 5th gen manned fighters as well.

Moreover, I'd point out, a strike J-20, let's say, would have a central weapons bay length of at least 9 meters, with an extended weapons bay width / depth of 1 meter in order to accommodate a Kinzhal-class missile.

A strike J-20 would be able to carry at least 12 PL-15X internally, possibly 16, and with current external adapters it'd come up to 24-28, which brings it up into the F-15X class. With micromissiles, you'd be looking at 48-56 SACM-equivalents or 96-112 MSDM dogfight equivalents, compared to only 12 SACM on the F-35 on internal carriage and possibly 24-36 on external carriage. On internal carriage, you'd be looking at 24-32 SACM-equivalents or 48-64 MSDM dogfight equivalents on the J-20. And that's not including the side bays, which could add another 2-8 SACM-equivalents or 6-16 MSDM equivalents to internal carriage. This is some frightening firepower in the micromissile paradigm.

In other words, a strike J-20 is basically a no-brainer in terms of providing an omnirole stealth fighter.

Inst said:

Information given here is that the AL-31s/WS-10 have bands to allow them to fit inside the J-20 snugly.

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So you are saying J-20's fuselage today are NOT dimensioned for WS-10/AL-31 diameters but for a larger WS-15 that is many years away from the IOC? Are you going to wear shoes that is one-size larger than your feet, only to wait for years until you can find a better fitting pairs of shoes? I am not, and I am certain that no engineers would do such thing.

IIRC, when I measured the F-22, it roughly had a .88-1m^2 inlet size. This is within DSI modification for the WS-15; i.e, the WS-15 would have to have 160kN thrust for such a thing to be possible.

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Size of F-22 within DSI modification for WS-15. Do you understand what you are speaking? I don't.

And yes, I can remeasure it, but likely the F-22 has an inlet size that's greater than that of the F-15. The F-35, per engine, has a greater inlet size than the F-22's.

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Again, speak with data, not "likely" or "I think".
The F-35 has a bigger inlet than F-22 is because F-135 has a bigger fan. The core is the same as F-119 meaning thermal efficiency is the same. Everyone understanding engine should know it.

However, WS-15 is equivalent to F-119, NOT, NOT NOT F-135. Did you read my post before answering it? I begin to suspect that you are moving the goal post or dodging the challenge.

And rumors mentioned here state that the WS-15 has a lower turbine temperature than the J-20.

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Again, please read what you are writing. Is J-20 an engine? Or you misstyped "WS-10" and trying to say WS-15 has LOWER turbine temperature? Seriously, you trust that kind of rumor? You do know that every jet engine makers are trying to increase the turbine temperature for decades, China has made breakthroughs in quick successions in the last decade. And yet somehow WS-15 engineers are moving backwards?

Overall, you seems to be muddying the water than clearing things.

taxiya said:

So you are saying J-20's fuselage today are NOT dimensioned for WS-10/AL-31 diameters but for a larger WS-15 that is many years away from the IOC? Are you going to wear shoes that is one-size larger than your feet, only to wait for years until you can find a better fitting pairs of shoes? I am not, and I am certain that no engineers would do such thing.


Size of F-22 within DSI modification for WS-15. Do you understand what you are speaking? I don't.


Again, speak with data, not "likely" or "I think".
The F-35 has a bigger inlet than F-22 is because F-135 has a bigger fan. The core is the same as F-119 meaning thermal efficiency is the same. Everyone understanding engine should know it.

However, WS-15 is equivalent to F-119, NOT, NOT NOT F-135. Did you read my post before answering it? I begin to suspect that you are moving the goal post or dodging the challenge.


Again, please read what you are writing. Is J-20 an engine? Or you misstyped "WS-10" and trying to say WS-15 has LOWER turbine temperature? Seriously, you trust that kind of rumor? You do know that every jet engine makers are trying to increase the turbine temperature for decades, China has made breakthroughs in quick successions in the last decade. And yet somehow WS-15 engineers are moving backwards?

Overall, you seems to be muddying the water than clearing things.

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The original claims were that the J-20 was designed for the WS-15, not the WS-10. I think we can all agree with that, right? At the very least, the prototype 2001 series were designed for WS-15, and from the prototype to 2011 LRIP we saw an increase in DSI size, likely to provide better stealth and airflow management for WS-10 / AL-31 class engines.

The WS-15 being equivalent to the F119, let's put it this way, even the Izdeliye 117 engines aren't equivalent to the F119, with substantially increased thrust (160 kN class vs 170-180 kN class). If you say the WS-15 is equivalent to the F119, you're saying the WS-15 is a crap engine.

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My basic stance is that the J-20 may need an inlet adjustment once WS-15 is mature, because the airflow is likely to be inadequate for WS-15 compared to WS-10. This might come in the form of simply shrinking the DSI bump to permit greater airflow, but it could also come in the form of increasing the J-20 inlet size in terms of height.

In either case, the J-20 is ripe for a striker modification / derivative to be built, simply to remedy the weakness of the weapons bay. 4/6 missiles + 2 missiles in the side bay is competitive with the F-22, which has about the same weapons bay loading, but the F-35 is at 6 AAMRAMs and putting a heavy air superiority fighter with 6 medium-range missiles vs a light / medium strike fighter with 6 medium-range missiles is not justifying the size and cost of the J-20 and will require China to buy many more J-20s to counter the F-35 than if it had strike derivatives with a larger weapons bay.

Chengdu really doesn't need to put a hard sell to the PLAAF; all it has to do is advertise a J-20 derivative that can carry twice the central bay load of the current J-20 and the PLAAF will almost certainly be sold on it. This comes out to a decisive advantage over the F-35; i.e, the air-to-air capability is now tremendously enhanced as well as making the J-20 a strong strike fighter.

Inst said:

And what's wrong with an entirely different aircraft that shares certain commonalities with its predecessor? This is basically what happened with the F/A-18E Super Hornet compared to the F/A-18 Hornet, but it meant that the Super Hornet had drastically improved development times compared to an old-growth variant.

Likewise, consider the Su-35 vs the Su-27. There's been tremendous weight growth, and the Su-35 is probably terrible on wing loading compared to the Su-27, and the structural airframe has changed tremendously with use of composites and internally enlarged fuel tanks. But the increased thrust with new engines should make the Su-35 either the equal or better of the Su-27.

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There's nothing "wrong" with an entirely different aircraft that shares certain commonalities with a predecessor/relative -- but whether it's the best use of time, money, and aerospace industry resources is something else altogether.

As I wrote in #1265, if you want to go for a "strike variant" of J-20 there are basically two routes to go.

The first is more ambitious, where you want your aircraft to properly be a dedicated striker able to carry weapons that your baseline fighter variant is unable to carry internally -- long, large diameter weapons like YJ-12. But obviously developing a variant of J-20 that can carry YJ-12 internally -- or even something smaller like YJ-83 or other similar sized future munitions that may emerge -- would require the aircraft to be significantly enlarged to the point that it would basically be an entirely new aircraft and you start to wonder if it might be better just to go for a clean sheet medium bomber instead.

The second is the less ambitious, "FB-22"-esque configuration where you just lengthen the aircraft and lengthen the weapons bay a bit so it can carry more of the same A2G weapons that the baseline fighter can carry, but is unable to carry larger diameter strike weapons that you would hope a dedicated strike aircraft could accommodate. This option would likely require far less resources than developing the first, more ambitious proposal, but it also delivers a far less capable strike aircraft, to the extent that one could ask whether pursuing this less ambitious strike variant is even worth it as opposed to just buying more normal J-20s alongside more H-20s and stealthy UCAVs instead.


I'm not inherently opposed to the idea of a strike variant J-20, but for both the "more ambitious" and "less ambitious" strike variant options I feel like there are better, more cost effective choices if you want either of their capabilities.
OTOH, if the money and aerospace industry resources is there to pursue everything as well as a strike variant J-20, then sure, go wild.

Bltizo said:

There's nothing "wrong" with an entirely different aircraft that shares certain commonalities with a predecessor/relative -- but whether it's the best use of time, money, and aerospace industry resources is something else altogether.

As I wrote in #1265, if you want to go for a "strike variant" of J-20 there are basically two routes to go.

The first is more ambitious, where you want your aircraft to properly be a dedicated striker able to carry weapons that your baseline fighter variant is unable to carry internally -- long, large diameter weapons like YJ-12. But obviously developing a variant of J-20 that can carry YJ-12 internally -- or even something smaller like YJ-83 or other similar sized future munitions that may emerge -- would require the aircraft to be significantly enlarged to the point that it would basically be an entirely new aircraft and you start to wonder if it might be better just to go for a clean sheet medium bomber instead.

The second is the less ambitious, "FB-22"-esque configuration where you just lengthen the aircraft and lengthen the weapons bay a bit so it can carry more of the same A2G weapons that the baseline fighter can carry, but is unable to carry larger diameter strike weapons that you would hope a dedicated strike aircraft could accommodate. This option would likely require far less resources than developing the first, more ambitious proposal, but it also delivers a far less capable strike aircraft, to the extent that one could ask whether pursuing this less ambitious strike variant is even worth it as opposed to just buying more normal J-20s alongside more H-20s and stealthy UCAVs instead.


I'm not inherently opposed to the idea of a strike variant J-20, but for both the "more ambitious" and "less ambitious" strike variant options I feel like there are better, more cost effective choices if you want either of their capabilities.
OTOH, if the money and aerospace industry resources is there to pursue everything as well as a strike variant J-20, then sure, go wild.

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Problem with your proposals is, as you've stated, a strike variant of a stealth aircraft is basically a completely new plane; you'd need to redesign the fuselage to pack a greater weapons bay, and you'd need new stealth and aerodynamic testing given the change in configuration. Therefore the full J-20 mod would be more suitable because you'd be paying for semi-new development anyways.

The other point I keep on making is that a strike J-20 would be a far more capable A2A platform than the current J-20. Put another way, we can't stuff PL-XX/PL-16s into the J-20 due to bay length restrictions. But being able to do so would greatly enhance the J-20's interception capabilities, and interception is a key mission of an air superiority aircraft; air superiority aircraft are defined by their poor strike abilities.

Likewise, if the J-20 opens its bays, it's going to compromise its stealth and make it vulnerable. Better to launch 12 missiles instead of 6 missiles when it hangs the Sword of Damocles over its head. A greater missile load-out, and a more flexible missile load-out, is the way to go.

gelgoog said:

Sigh. The best way to compare military engine generations isn't by looking at the total thrust of the engine. It is to look the thrust to weight ratio of the engine. Sure the Izdeliye 117 has less total thrust than the F119 but it is also lighter than it. The Izdeliye 117 has a wet thrust to weight ratio of 9.3:1 supposedly. That makes it have around the same or more thrust to weight ratio than the known figures for the F119.
Now the issue with the Izdeliye 117 is that it has worse thrust to weight ratio compared with more modern engines like the F135. That supposedly has a thrust to weight ratio of 11.47:1. For this the Russians are developing the Izdeliye 30 engine.

Both aircraft, the Su-57 and the F-22, have a thrust to weight ratio over unity (1.0). This means they are highly agile.
An aircraft with thrust to weight ratio over unity can basically hover on the air with engine power alone. That's how agile it is.

The F-35 has thrust to weight ratio under unity. The airframe is heavy like heck. It's like an albatross around the engine.

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Izdeliye 117 has around 170-180 kn, compared to the F119's 160 kn.

Inst said:

The other point I keep on making is that a strike J-20 would be a far more capable A2A platform than the current J-20. Put another way, we can't stuff PL-XX/PL-16s into the J-20 due to bay length restrictions. But being able to do so would greatly enhance the J-20's interception capabilities, and interception is a key mission of an air superiority aircraft; air superiority aircraft are defined by their poor strike abilities.

Likewise, if the J-20 opens its bays, it's going to compromise its stealth and make it vulnerable. Better to launch 12 missiles instead of 6 missiles when it hangs the Sword of Damocles over its head. A greater missile load-out, and a more flexible missile load-out, is the way to go.

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In an air-to-air role, I find it unlikely that a fighter would need to launch 12 missiles in one go.

It seems to me that Loyal Wingman UCAVs would be a far better platform to launch air-to-air missiles.

The UCAVs can operate up front, which improves the effectiveness of the missiles in terms of engagement time and powered terminal flight.
And if you have 1 UCAV, there's no reason you can't have multiple UCAVs to increase the numbers of missiles available.

So I disagree with your assertion that a J-20 with a larger weapons bay would be a far better A2A platform