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

GTI said:

They typically use non-afterburning versions of fighter jet turbofans on these. It’s a bit hard to say “typical” given we only really have 2 examples (YB-35 and 49 don’t really count). The B-2 uses non-afterburning F-118s.

The B-21 is going to use a non-afterburning version of something very close to a F-135. This is probably as high a bypass as you would get, otherwise you’d end up with a flying block. For VLO stealth bombers the engines need to be deeply embedded with fan blades concealed and IR reduction at the exhaust end. Trying to do this with high bypass engines will begin to impede the design and aerodynamics. In any case, flying wings already produce a lot of lift, are fuel efficient and have internal space/volume for a lot of fuel to be stored already.

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I was talking about 'higher bypass' not 'high bypass'. Not sure if the widely cited figure of 0.25 bypass ratio for WS-15 is accurate, but the figure seems reasonable for an engine designed for a supercruising fighter jet, but likely not ideal for H-20 if it's a subsonic bomber.

Let's disregard fluid dynamics and speak purely in terms of the geometry of cross-sections. To increase cross-section area ratio from 0.25 to 0.5 requires a less than 10% increase in diameter. Not unreasonable for a stealth bomber.

OppositeDay said:

I was talking about 'higher bypass' not 'high bypass'. Not sure if the widely cited figure of 0.25 bypass ratio for WS-15 is accurate, but the figure seems reasonable for an engine designed for a supercruising fighter jet, but likely not ideal for H-20 if it's a subsonic bomber.

Let's disregard fluid dynamics and speak purely in terms of the geometry of cross-sections. To increase cross-section area ratio from 0.25 to 0.5 requires a less than 10% increase in diameter. Not unreasonable for a stealth bomber.

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So you're suggesting something like a F119 to F135 evolution? That seems reasonable since it's essentially what the B-21 is doing, and it's likely already in the works.

Previously the established rumors for H-20 is it would use non AB WS-10 variants. That is to say, there was never any consideration of WS-15 (or a variant thereof) being its powerplant.

WS-10 at baseline (i.e. including a non AB variant) should have a slightly higher BPR than WS-15 but it of course is far from a "high bypass turbofan".

OppositeDay said:

Yankeesama is now entertaining the possibility that China's 6th gen fighter might be unveiled before H-20. At least this shows he thinks H-20 is still quite a bit away from its first flight (a point when it becomes much harder to hide from the public).

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It's obvious that H-20 program was delayed from the original schedule. How likely was the delay a result of WS-15's smooth progress? A higher bypass WS-15 seems the most logical choice for H-20. Given H-20 is a lower priority program compared to fighters, it seems not unreasonable to wait for the target engine. Anyone knows of the work required for a higher bypass WS-15? Suppose the work began a couple years ago, when can we reasonably expect a flight test on the Y-20 platform?

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gelgoog said:

Why would that cause delays? There is bound to be a version of WS-15 with similar dimensions as the WS-10. How else are they going to fit it into the J-20? They could just swap engines before they started mass production if the engine was ready.

I do not understand why H-20 is not flying already.

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There is no expectation for WS-15 (or any variant thereof) at this stage to be H-20's powerplant.

As for H-20 potentially being delayed, if it is actually delayed (which we do not know) it could basically only be down to two reasons:
- technical challenges (in any domain/element for such a complex project), or
- revised requirements (in any domain/element for such a complex project), or
- a combination of the above


We have no basis to speculate as to which permutation it is right now.

OppositeDay said:

Yankeesama is now entertaining the possibility that China's 6th gen fighter might be unveiled before H-20. At least this shows he thinks H-20 is still quite a bit away from its first flight (a point when it becomes much harder to hide from the public).

Please, Log in or Register to view URLs content!

It's obvious that H-20 program was delayed from the original schedule. How likely was the delay a result of WS-15's smooth progress? A higher bypass WS-15 seems the most logical choice for H-20. Given H-20 is a lower priority program compared to fighters, it seems not unreasonable to wait for the target engine. Anyone knows of the work required for a higher bypass WS-15? Suppose the work began a couple years ago, when can we reasonably expect a flight test on the Y-20 platform?

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Well, why do you think it is "delayed from the original schedule" when we not even know anything about this "original schedule"?

I agree with you that based on earlier reports, development started at an earnest after the maiden flight of the Y-20 and assuming a similar - maybe slightly extended - timeframe between individual milestones, we simply don't know anything.

As such - and even if it hurts my impatience -, @Blitzo's summary gives three reasonable explanations, but only if there it is indeed "delayed from the original schedule".

(Just to put in some words of my own.)

To be honest, even if the H-20 development is indeed delayed from the original schedule (of which none of us here knows anything about), that shouldn't be totally surprising either.

Remember that while the US has already accumulated plenty of past experiences and expertise of designing, building and operating VLO flying-wing strategic bombers ever since the early-1970s, i.e. the B-2 Spirit - China has none of that. Blank. Empty.

The biggest flying object that even remotely resembles a bomber of the VLO flying-wing design that China is making right now is the GJ-11 Sharp Sword UCAV.

Moving from a UCAV that weighs ~10 tons to a fully-fledged manned strategic bomber that weighs ~150 tons is definitely not a small feat.

Therefore, while the anxiousness and frustration on the H-20's developmental progress by many people in this forum is totally understandable, please do give the Chinese engineers at Xi'an some time. There are loads of issues and challenges for the H-20 designers to contend with, not just with the engines.

Has there ever been an official statement regarding a next-generation bomber from Chinese officials? If not, I don't see why you would have any expectations regarding development timeline.

SlothmanAllen said:

Has there ever been an official statement regarding a next-generation bomber from Chinese officials? If not, I don't see why you would have any expectations regarding development timeline.

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There have been numerable allusions to it by state aircraft manufacturers and state media in a way that would not have been done without PLA signoff.

None of them included any sort of timespan, but at the time they did seem to suggest it would be on the horizon.

H-20 has actually been somewhat unique in being a project with high secrecy but still have some official acknowledgements of its existence in fairly high profile media.

SlothmanAllen said:

Has there ever been an official statement regarding a next-generation bomber from Chinese officials? If not, I don't see why you would have any expectations regarding development timeline.

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Yes.

Since 2016, actually:

Also in 2016, this screenshot taken during a CCTV-4(?) program:


Plus this one, which came directly from XAC in 2018:


Plus these too, which came directly from the PLAAF's official Weibo account in 2021:



So, yeah, I guess those are official enough.

What does the label read for the first image shared above? The aircraft depicted does not appear to resemble any possible configurations for a H-20, perhaps concept for JH-XX or some sort of unmanned platform? And did CCTV mistranslate "aerospace," to "airspace"?

FriedRiceNSpice said:

What does the label read for the first image shared above?

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- H-20 long-range bomber
- Range around 13000 kilometers
- Combat radius more than 5000 kilometers
- Payload capacity can reach 30-40 tons

I believe that the specifications are provisional only.

FriedRiceNSpice said:

The aircraft depicted does not appear to resemble any possible configurations for a H-20, perhaps concept for JH-XX or some sort of unmanned platform?

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I believe that the picture is just for illustrative purposes, so don't look too much into it.

FriedRiceNSpice said:

And did CCTV mistranslate "aerospace," to "airspace"?

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Yes, I think so.