Chinese Engine Development

Schumacher said:

Yes, flying on the IL76 test bed next is the most likely.
But have to add that the time it will spend there will be a lot less than say WS20 which never went thru years of ground based simulator like what WS15 did.
Flying on J20 and IL76 at the same time is possible as well. They have flown J20 for 4 years. Likely they have done some single engine flying by now.
Modifying one of the mature J20 frames to take one WS15 and the original tested engine sounds safe enough.

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Maybe future airframes, but definitely not imminent ones. Airframe redesigns will be necessary, and that takes time.

Josh Luo said:

Would you mind sending me some articles on this if possible? I would like to read more, as there are far less reports on WS-18 than WS-15. Although the common perception is that WS-18 is less of a priority than WS-15, the current H-6K production is limited by how may D-30 engines the Russians are willing to export. This is why I consider the WS-18 to be just as important as the WS-15. WS-18s and WS-20s would make China's bomber fleet completely independent from dependence on foreign technology.

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Please make some effort to go back in this thread if you want to read up more on WS-18. There is plenty of material on it.

Josh Luo said:

Well...if the WS-15 starts testing on J-20 in 2016, we could well see first batch of J-20 in service by 2018. Ultimately, I think having the WS-15 armed J-20s in service by 2020 is an achievable goal, as long as the WS-15 development goes smoothly.

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If they haven't testing it on IL-76 testbed or a more mature platform, how are they going to start testing it on J-20 in 2016?

Again, please read up on this thread.

latenlazy said:

Maybe future airframes, but definitely not imminent ones. Airframe redesigns will be necessary, and that takes time.

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Will redesign be necessary? If WS-15 was the originally intended engine for the J-20, then the aircraft may already be suitable to be re-engined with the WS-15. Current prototypes may be flying with adapters or shims to fit the AL-31. If the rear needs to be redesigned to fit the WS-15, then there will be a significant amount of re-testing that needs to be done. I just think they may have better foresight than to design the prototypes around a testing engine only to need to redesign it for the ultimate engine.

If the WS-15 turns out to be as powerful as the initial claims (demonstrator 16500kgf, production 18000kgf), then I doubt they can just fit it into the current prototype without significant modification and don't different engines require air-intakes to be modified as well? Intake might have to get larger for the WS-15?

manqiangrexue said:

Will redesign be necessary? If WS-15 was the originally intended engine for the J-20, then the aircraft may already be suitable to be re-engined with the WS-15. ...........

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Yup, hard to imagine anything major is required. Minor modification at most.
Besides, knowing the progress of WS15, the J20 team can plan years in advance. It's not like they got a call suddenly saying WS15 is ready and start working.
Again, I see the plan as a short stint on the test bed before the prototype with deployment around 2020.

Hyperwarp said:

If the WS-15 turns out to be as powerful as the initial claims (demonstrator 16500kgf, production 18000kgf), then I doubt they can just fit it into the current prototype without significant modification and don't different engines require air-intakes to be modified as well? Intake might have to get larger for the WS-15?

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You are assuming that the current prototypes were designed to withstand only the power of the AL-31, and that the intakes were designed specific to the AL-31, so they need to be upgraded to use WS-15. I'm saying that there is a possibility that the prototypes were designed to withstand WS-15 and that the intakes are large enough for WS-15, but it's being tested with an adapter to fit the AL-31 for basic flight characteristics waiting for the WS-15 to be brought out for rigorous testing. In other words, the current prototypes are WS-15 optimized, but running on sub-optimal conditions with AL-31 awaiting the WS-15 to bring out their potential. Otherwise, it just doesn't make sense to me why they would test the J-20 with AL-31 only to make serious modifications and need to test the new, significantly different design again with WS-15.

Hyperwarp said:

If the WS-15 turns out to be as powerful as the initial claims (demonstrator 16500kgf, production 18000kgf), then I doubt they can just fit it into the current prototype without significant modification and don't different engines require air-intakes to be modified as well? Intake might have to get larger for the WS-15?

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My understanding is that the J-20 was designed with the WS-15 as its main engine. The current AL-31 is simply an improvisation. Thus, the way I look at is that the performance of the current J-20 is seriously compromised because it doesn't have the fitting engines. They had to put in some temporary devices to fit the current AL-31 into the J-20 since everything on the J-20 was designed for WS-15.

Take the intake for example, the current intake could be designed for the WS-15. And instead of thinking the current intake might be too small for the future WS-15, it is actually more likely that it is too big for the current AL-31.

latenlazy said:

They don't always test an engine in the same location as the *namesake* of the firm...


The WS-15 is more important because there are high bypass variants they plan on developing from the engine core. The WS-18 is a sufficient stop gap, but strategically the WS-15 has a lot more riding on it beyond fighters.


Unlikely. For one, if true this is only the completion of ground tests. They'll probably move to high altitude tests on a flying test bed next. Second, installing the WS-15 might require a redesign of the tail, which isn't something you can just do in short order.

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For one, you are right, I'm sure. As for second, J-20 was likely designed for WS-15, whose shape and size will hardly have changed in the last ten years, and then adapted to the use of the interim engine. That adaptation will include the aft end of the aircraft but also the air intakes. Flying with intakes designed for another engine leads to a very large increase in drag especially at supersonic speeds.

Flying with intakes designed for another engine being suboptimal is precisely why I doubt that the current airframes have been optimized for the WS-15. If they intend on production before the WS-15, I don't think they would go with an unoptimized solution and wait for the untested one that's supposed to be more optimized to make their airframes whole. I'm sure they already have a redesign ready for the aft and the intake, but I'm also pretty certain that the intake geometry (if not external, than internal) and thus every structural element related to the engine will have to be changed, and those aren't trivial ones that can be done with a "plug and play" solution. Whatever changes will be needed to properly fit and utilize the WS-15 will probably need to be done on a future airframe, or else extensive modifications that could take a while would have to be done on a current one.

I myself once thought it would make sense for the solution to be plug and play, but the more I've looked into the complex needs of intake geometry and the tight tolerances for structural requirements, the less I believe that it could be that simple.