H-20 bomber (with H-X, JH-XX)

Inst said:

The B-2 is capable of carrying fuel as part of its payload package, extending its range.

It'd be sensible for the H-20 to have extended range through modular internal fuel tanks if it's needed to strike targets like California, but have the bay capacity to increase its payload on hits vs American bases in Guam / Japan.



Not necessarily. You might wish to move ZTZ-99s (or any future successor) in an area where less stealthy transport platforms would have trouble. But that requires a substantial redesign, and the most realistically you could want to move would be supplies for ground forces.

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To be honest, I would love to see the PLAAF requesting a very long range bomber. With 4 WS-15s, an aircraft with 260 tons of MTOW is possible. Such an aircraft can have 110 tons of empty weight, 30-35 tons of payload and the rest would be the fuel. This distribution (40-42% empty weight, 14% payload, 42-46% fuel) is very common among the current large long-range aircraft. This would enable around 7500 km round trip without refueling and it would also enable 12 heavy cruise missiles to be carried. The current cruise missiles of 2.5-ton class have a range of around 3500 km. This enables a 11000 km striking range. This is enough to hit Chicago from Beijing. The aircraft can also have the capability to carry fuel tanks in the bomb bay to further increase the range. With optional buddy tanking pods in the weapons bay, it would also make a terrific tanker with its high survivability. Just like the MQ-25 Stingray but oversized. With single refueling, it would be able to strike most cities of the USA from most airstrips of China. That is what would really deter the USA. The thought of a regiment of these bombers launching 196 CJ-10s to Washington DC or NYC is exactly what would make the war with China unthinkable to the USA. I don't know how close the H-20 will be to what I describe here. If it is using WS-10s, California is the furthest possible.

It might eventually use the WS-15 like the J-20 will. But it most likely will use the WS-10 to begin with simply because it is what they have available. I do not think a really long range bomber makes that much sense for China, because if a conflict ever came to it that China had to bomb the USA mainland or something like this then the conflict would have gotten to the point they would use nuclear weapons.

I think the most likely scenario where you would see China actually use a long range intercontinental bomber would be in a conflict someplace in Africa. But current Chinese policy does not enable a scenario like this.

gelgoog said:

It might eventually use the WS-15 like the J-20 will. But it most likely will use the WS-10 to begin with simply because it is what they have available. I do not think a really long range bomber makes that much sense for China, because if a conflict ever came to it that China had to bomb the USA mainland or something like this then the conflict would have gotten to the point they would use nuclear weapons.

I think the most likely scenario where you would see China actually use a long range intercontinental bomber would be in a conflict someplace in Africa. But current Chinese policy does not enable a scenario like this.

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Nuclear triad, although ICBMs are most reliable. Putting in extremely long-range (i.e, long enough to launch nuclear cruise missiles at LA) helps enhance nuclear deterrence.

Likewise, the fact that payload (to some extent) is interchangeable with range with the use of bay fuel tanks makes it rather trivial. Whatever happens, you're going to have the option to put fuel tanks into the weapons bay. The question is whether this'll be sufficient to reach LA or sufficient to reach Tokyo, and I don't see the point of launching a strategic bomber (because that's what the H-20 is) without reaching LA.

Hopefully, the aircraft will be designed with WS-15 derivatives in mind, even if it has to use WS-10 derivatives during LRIP. A very large payload as well as the range to do LA could only be a WS-15 feature, as opposed to a WS-10 feature.

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I can envision two differing set-ups. JASDF / Guam:

20,000 kg of bombs and cruise missiles.

LA:

10,000 kg of fuel, 2-4 nuclear cruise missiles.

BoraTas said:

Just look at the B-2. It has 4 7.7-ton thrust engines and a MTOW of 170 tons. Even the WS-10A has a 14-ton thrust with afterburner. If we go pessimistic for dry thrust and take 60% of the wet thrust, we still end up with 8.4 tons.

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Except the F118-GE100 for the B-2 has a 84kN (8.6tf) rating - 77kN applies to the -GE101 for the U-2S.

manqiangrexue said:

I seem to remember somewhere, although unreliable as a source, that the dry thrust for WS-10X is 89kN and it's higher as a percentage of the wet thrust than AL-31X because the WS-10 was derived from the CFM core.

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I doubt it - the WS-10 is supposed to have a higher BPR than the AL-31F, which is what primarily determines dry/wet thrust fraction.

gelgoog said:

It might eventually use the WS-15 like the J-20 will. But it most likely will use the WS-10 to begin with simply because it is what they have available.

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If it gets WS-15, it would have to be a higher-BPR derivative to make sense (pushing this option even further to the right) - in subsonic flight, the WS-10 probably has *lower* fuel consumption! To enable supercruise, the basic WS-15 will be designed for high specific thrust, which hurts its propulsive efficiency at lower speeds.

eprash said:

200 Tons MTOW is way overkill unless PLA is planning it to have troop/cargo transport capability, highly doubtful Chinese leadership would tolerate that much of risk on their first endeavour

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If the Chinese stealth bomber is intended to carry a large payload of stealth cruise missiles then a very large size makes sense. The bomber is no longer a weapon to attack a single target per mission but to hold large theater sized area under threat.

Tirdent said:

Except the F118-GE100 for the B-2 has a 84kN (8.6tf) rating - 77kN applies to the -GE101 for the U-2S.



I doubt it - the WS-10 is supposed to have a higher BPR than the AL-31F, which is what primarily determines dry/wet thrust fraction.



If it gets WS-15, it would have to be a higher-BPR derivative to make sense (pushing this option even further to the right) - in subsonic flight, the WS-10 probably has *lower* fuel consumption! To enable supercruise, the basic WS-15 will be designed for high specific thrust, which hurts its propulsive efficiency at lower speeds.

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Both Wiki and the official USAF site claims 77 kN for the F-118s of the B-2



And I don't think the WS-15 will be less efficient than the WS-10 in subsonic flight. It will certainly have a higher compression ratio and higher turbine inlet temperature. These are almost as influential as BPR too.

BoraTas said:

Both Wiki and the official USAF site claims 77 kN for the F-118s of the B-2

Please, Log in or Register to view URLs content!

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USAF spec sheets are notoriously unreliable, for example there are frequent imperial/metric conversion errors. It's always a good idea to cross-check, the information is just not very diligently curated. Wiki is probably referencing the USAF data, so you can't consider it an independent source. I'll defer to the engine manufacturer:

BoraTas said:

And I don't think the WS-15 will be less efficient than the WS-10 in subsonic flight. It will certainly have a higher compression ratio and higher turbine inlet temperature. These are almost as influential as BPR too.

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Nowhere near - the slower your intended aircraft application is, the more BPR dominates (turboprops are downright crude in terms of OPR and TIT, mostly <20:1 and <1500K, yet they are highly efficient below Mach 0.7). TIT in particular improves thermal efficiency but by increasing specific thrust simultaneously worsens propulsive efficiency, to the extent that there is little net effect in a slow aircraft.

In fact, if stealth was no requirement (necessitating buried engines with serpentine ducts), the B-2 would ideally use a civilian type high-BPR turbofan or even Tu-95-like high-speed turboprop/propfan (TP400D6 or similar).

Adding two cents past history suggest that China closely followed US designs wherever it could to avoid reinventing the wheel if that's true in this case H20 would have two thirds or half of B2's payload capability,powered by two engines and have smaller dimensions because that's how B21 is envisioned

eprash said:

Adding two cents past history suggest that China closely followed US designs wherever it could to avoid reinventing the wheel if that's true in this case H20 would have two thirds or half of B2's payload capability,powered by two engines and have smaller dimensions because that's how B21 is envisioned

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The B21 uses a F135 derived engine. You can't compare that with the engines China has available right now.
The F135 has 128 kN dry thrust. Compare that with the numbers we have been discussing above like 77 kN.
That is why the H-20 should have four engines.

gelgoog said:

The B21 uses a F135 derived engine. You can't compare that with the engines China has available right now.
The F135 has 128 kN dry thrust. Compare that with the numbers we have been discussing above like 77 kN.
That is why the H-20 should have four engines.

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Then four engines, a third of the B-2's payload and about three quarters of the B-21's and half the range

Seriously though the engine question combined with the fact that they're doing a stealth design means low bypass, concealed, no afterburning which means WS-10 or WS-15 if timing and manufacturing rates permit.

Which one will probably depend on the function of the H-20. I suspect they want more a B-2 size craft than B-21 because it needs to have the flexibility of air lunching larger ordinance which seems to be something the PLAN and PLAAF are keen on. Every emphasis in PLAAF and PLAN has been go big or go home. Big payloads and long ranges wherever possible. The only exceptions were 001 and 002 where they were building industry and doctrine forming platforms based on Kuznetsov Class. As soon as they were trained up on carrier operations, they started developing the domestic designs carrying those lessons from operating J-15s and extending them where possible. These carriers are certainly larger while no Ford class, I suspect propulsion has been a slight limiting factor along with concerns for overdoing it on the first step with still very limited carrier experience in operations and design+building.

I don't see the H-20 carrying single stage to orbit crafts or tasks with things like dropping WZ-8 to speed and altitude but launching boosted HGVs and air launched ballistics? Yes. YJ-18, YJ-12, and anything else in those classes as well. Larger spaces only mean future ordinance development aren't quite as restricted. While the modernised H-6s could do those from a safe distance, why wouldn't you want a replacement strategic ranged bomber to be capable of that at least.

Stealthy stand off weapons can be carried by anything including a J-10. More capable stand off weapons with more functions require something like an H-6. A B-21 like equivalent should be aimed to serve some other functions while being stealthy. I'd say speed and better turning performance is a minimum. That's where the JH-xx could fit it if such a program hasn't been abandoned in preference for only the H-20. They can serve very different functions and would be quite unlike the costly cold war era vs more economical updated modern era B-2, B-21 dichotomy. This is somewhere I don't think China will follow the US model quite as identically.