Pretty sure the spool up time was a problem with the WS-10, which was what was tested in 2002. I believe, if I'm remembering right, the spooling issue came up in around 2006. We didn't hear about the A designation till 2008, and that was what was meant to go into production, except that was also when quality control issues emerged and was probably what stuff like Erickson's reporting of warped fan blades referred to.
Chinese Engine Development
- Thread starter jackbh
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Pretty sure the spool up time was a problem with the WS-10, which was what was tested in 2002. I believe, if I'm remembering right, the spooling issue came up in around 2006. We didn't hear about the A designation till 2008, and that was what was meant to go into production, except that was also when quality control issues emerged and was probably what stuff like Erickson's reporting of warped fan blades referred to.
Quickie
Colonel
Reasons could be, when it comes to single engined planes or new prototypes, they rather use an engine with a 20 years reliability record than a comparatively new engine with 6 years.
There was that interview with plaaf pilot Li Cunbao which said that j10 was not equipped with ws10 engine because of longer spool up time. Some variants of the interview specified the engine into ws10a, but that's really beside the matter since original ws10 was basically dead by the start of this millenium. Since ws10a already flew in 2002, it seems plausible that all the engines in that decade onward are really ws10a variants, ones with russian input (as opposed to original ws10 which was first fired up in 1992 in a test, and which had no russian input but was based on US engine transfer from 1980s)
While one has to pick and choose bits of info, at least these sources offer some info. One can always try to disprove their credibility, but i would really appreciate alternate sources then.
Anyway, why would spool up time be important? In my opinion, which that interview with pilot Cunbao concurs with, several seconds (perhaps up to five seconds?) of longer time to achieve power can mean aircraft can crash if under certain altitude and in certain flight profile and its engine cuts out and needs to be respooled. It's not as safe.
When it comes to carrier borne planes - spool time is important for take offs, because we don't know what sort of force is landing gear meant to withstand when being pushed against the take off chocks. Just because we see afterburner flames in the videos doesn't mean we can tell if thrust is at 80% or 100% or whatever before the chocks are removed.
Perhaps more importantly, the procedure at landing on a carrier with traps is to have very low power while approaching, for minimum speed, but then in the very milisecond the plane does make a touchdown, the engine is spooled up to full power in case a cable isn't trapped. Longer spool time could be quite detrimental there. Again, safetey reasons.
While one has to pick and choose bits of info, at least these sources offer some info. One can always try to disprove their credibility, but i would really appreciate alternate sources then.
Anyway, why would spool up time be important? In my opinion, which that interview with pilot Cunbao concurs with, several seconds (perhaps up to five seconds?) of longer time to achieve power can mean aircraft can crash if under certain altitude and in certain flight profile and its engine cuts out and needs to be respooled. It's not as safe.
When it comes to carrier borne planes - spool time is important for take offs, because we don't know what sort of force is landing gear meant to withstand when being pushed against the take off chocks. Just because we see afterburner flames in the videos doesn't mean we can tell if thrust is at 80% or 100% or whatever before the chocks are removed.
Perhaps more importantly, the procedure at landing on a carrier with traps is to have very low power while approaching, for minimum speed, but then in the very milisecond the plane does make a touchdown, the engine is spooled up to full power in case a cable isn't trapped. Longer spool time could be quite detrimental there. Again, safetey reasons.
Well, I seem to remember that the A designation didn't emerge until 2008, but without needing to dig through long backlogs of old forum entries, I guess we'll leave it at that.
I'm also not a fan of the idea that the WS-10A is specifically a result of Russian input with the AL-31, not because of what it may or may not say about China's own abilities to make their own engine, but because it just doesn't seem likely that you could transplant aspects of one design onto another. I often use the term "it's not plug and play", because some type of compatibility usually needs to pre exist before one design can offer you directly relatable insight to another.
i certainly don't mean to say there is no chinese input in ws10a. for all i know, maybe 90% of changes from ws10 to ws10a are purely chinese. i really don't care either way. i merely made up a story of one possible timeline, without really saying how much input, percentage wise, was from salyut.
also, i tend to agree ws10a is still very much closer to original ws10 than to any al31 variant. but it does seem plausible that technological processes and solutions that salyut may've provided helped the technical changes to ws10a. i certainly don't think whole subsystems or parts from salyut were applied to ws10a, but technological know how may've been provided. stuff like "don't make the turbine blades like that, use this process" or "use this and this to make the compressor". general stuff and certainly stuff that us/european engineers may've done themselves because i do think most problems tend to have similar solutions. chinese engineers coul'dve come up with all those by themselves, but perhaps salyut's know how sped up the process, shaving off a few years from the project.
the first link i provided is an article from 2003, mentioning ws10a and how there was a image at zhuhai 2002 with j11 testing ws10a. then, if one looks at AVIC's news one can find that design of a new turbofan was done in 2004, again another newsbit that development was complete in 2005, there were news about ws10a completing endurance tests in 2005 and yet another one newsbit that certification of the engine was done in 2006. Director of AVIC is also credited with saying in 2009 that production line issues are abound. Note that that has nothing to do with engine itself but production line. So basically from 2007 onward ws10a seems to have been finished but as we know the rfirst batch of j11b used al31. but then we saw all other j11b using ws10a so sometime in late 2009/early 2010 production line issues must've been resolved and the mass production commenced.
development of engines takes a lot of time. i am sure that even the next version of ws10 was in development for the last 5 years or easely even more. there's years of theoretical work, engineering work, lab tests, bench tests, flight tests, adjustments, certification runs, production line setup etc. so if ws10a took all that time, it's not unreasonable to expect that next variant took all this extra time and that it is only now being redied.
again, that's just an assumption on my part, based on those images of ws10 family engine on j11 with a differently sized nozzle. it remains to be seen what will that turn out to be and it remains to be seen when j15 and/or j10 will have ws10 family engines. especially the latter, since we recently learned of salyut's bench tests for a new variant of al31fn. i hardly think that's something salyut did on their own, it's more likely chinese side contracted that development. and if bench tests have only begun, it may be a few more years until those engines reach j10. then again, it could also be a hedging bet, just in case some ws10 variant tailored for j10 isn't ready. anyhow, timeline of that new al31fn variant does make it plausible its based on salyut's m2 variant, so upward of 140 kn. that would also point to chinese requirement for ws10 variant for j10b being of similar thrust.
also, i tend to agree ws10a is still very much closer to original ws10 than to any al31 variant. but it does seem plausible that technological processes and solutions that salyut may've provided helped the technical changes to ws10a. i certainly don't think whole subsystems or parts from salyut were applied to ws10a, but technological know how may've been provided. stuff like "don't make the turbine blades like that, use this process" or "use this and this to make the compressor". general stuff and certainly stuff that us/european engineers may've done themselves because i do think most problems tend to have similar solutions. chinese engineers coul'dve come up with all those by themselves, but perhaps salyut's know how sped up the process, shaving off a few years from the project.
the first link i provided is an article from 2003, mentioning ws10a and how there was a image at zhuhai 2002 with j11 testing ws10a. then, if one looks at AVIC's news one can find that design of a new turbofan was done in 2004, again another newsbit that development was complete in 2005, there were news about ws10a completing endurance tests in 2005 and yet another one newsbit that certification of the engine was done in 2006. Director of AVIC is also credited with saying in 2009 that production line issues are abound. Note that that has nothing to do with engine itself but production line. So basically from 2007 onward ws10a seems to have been finished but as we know the rfirst batch of j11b used al31. but then we saw all other j11b using ws10a so sometime in late 2009/early 2010 production line issues must've been resolved and the mass production commenced.
development of engines takes a lot of time. i am sure that even the next version of ws10 was in development for the last 5 years or easely even more. there's years of theoretical work, engineering work, lab tests, bench tests, flight tests, adjustments, certification runs, production line setup etc. so if ws10a took all that time, it's not unreasonable to expect that next variant took all this extra time and that it is only now being redied.
again, that's just an assumption on my part, based on those images of ws10 family engine on j11 with a differently sized nozzle. it remains to be seen what will that turn out to be and it remains to be seen when j15 and/or j10 will have ws10 family engines. especially the latter, since we recently learned of salyut's bench tests for a new variant of al31fn. i hardly think that's something salyut did on their own, it's more likely chinese side contracted that development. and if bench tests have only begun, it may be a few more years until those engines reach j10. then again, it could also be a hedging bet, just in case some ws10 variant tailored for j10 isn't ready. anyhow, timeline of that new al31fn variant does make it plausible its based on salyut's m2 variant, so upward of 140 kn. that would also point to chinese requirement for ws10 variant for j10b being of similar thrust.
I'm going to tackle the "spooling time" problem first.
From what I'm reading, the premise of current WS-10As still having that problem is because of the interview with the J-10 test pilot, and also because WS-10As aren't equipping carrier based J-15s.
However, that idea sort of falls apart when you consider that WS-10As do equip J-11Bs, and J-11Bs wouldn't have a lower "spool time" requirement than J-10, nor does anything about J-11B (such as having two engines) mean it can achieve competent performance with poor spool time especially if that problem existed for J-10.
As to why J-10s are still using Al-31s, it may be a host of reasons.
We know J-10s weren't equipped with WS-10As when the interview was done with spool time supposedly being one of the reasons, but since then, and since other projects have moved forward and WS-10A moved into full production, other resource pulls may influence why J-10 isn't using WS-10A. Maybe they've produced so many J-10As and are so acquainted with Al-31F they don't see the benefits in changing. Maybe they can't produce enough WS-10As for J-10s and flankers simultaneously. Maybe J-10B is using a new Al-31 variant and it simply has more thrust and is a better performer than the latest WS-10 variant.
But it's pretty conclusive that because J-11Bs are equipped with WS-10As, that the spool time issue isn't an issue anymore. Otherwise, J-11Bs would all be equipped with Al-31s as well.
As for J-15, again, the fact that J-11Bs all use WS-10As means spool time isn't an issue, and there are as many reasons for why J-15 is using Al-31 as one can imagine. Maybe it's got to do with corrosion issues on WS-10A. Maybe it's simply PLAN conservatism. But it definitely isn't spool time. If J-11Bs were not equipped with WS-10As then perhaps spool time could still be an issue, and be one of the possible reasons it is not used on flankers or J-10s.
Spool time is rightly important for a whole lot of things, as you mentioned. But unless J-11B somehow has lower spool time requirements than J-10s or J-15s, I think we can safely say spool time hasn't been an issue for WS-10A since at least the first production batch in 2009-2010.
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As for WS-10A having "russian input" -- I wouldn't be surprised if they had former soviet bloc consultants in their facilities.
However I do not think we have anywhere near enough confidence to suggest salyut had anything to do with the project, or if they took any specific inspiration from Al-31, mostly because we simply haven't even had un-credible rumours to suggest that.
From what I'm reading, the premise of current WS-10As still having that problem is because of the interview with the J-10 test pilot, and also because WS-10As aren't equipping carrier based J-15s.
However, that idea sort of falls apart when you consider that WS-10As do equip J-11Bs, and J-11Bs wouldn't have a lower "spool time" requirement than J-10, nor does anything about J-11B (such as having two engines) mean it can achieve competent performance with poor spool time especially if that problem existed for J-10.
As to why J-10s are still using Al-31s, it may be a host of reasons.
We know J-10s weren't equipped with WS-10As when the interview was done with spool time supposedly being one of the reasons, but since then, and since other projects have moved forward and WS-10A moved into full production, other resource pulls may influence why J-10 isn't using WS-10A. Maybe they've produced so many J-10As and are so acquainted with Al-31F they don't see the benefits in changing. Maybe they can't produce enough WS-10As for J-10s and flankers simultaneously. Maybe J-10B is using a new Al-31 variant and it simply has more thrust and is a better performer than the latest WS-10 variant.
But it's pretty conclusive that because J-11Bs are equipped with WS-10As, that the spool time issue isn't an issue anymore. Otherwise, J-11Bs would all be equipped with Al-31s as well.
As for J-15, again, the fact that J-11Bs all use WS-10As means spool time isn't an issue, and there are as many reasons for why J-15 is using Al-31 as one can imagine. Maybe it's got to do with corrosion issues on WS-10A. Maybe it's simply PLAN conservatism. But it definitely isn't spool time. If J-11Bs were not equipped with WS-10As then perhaps spool time could still be an issue, and be one of the possible reasons it is not used on flankers or J-10s.
Spool time is rightly important for a whole lot of things, as you mentioned. But unless J-11B somehow has lower spool time requirements than J-10s or J-15s, I think we can safely say spool time hasn't been an issue for WS-10A since at least the first production batch in 2009-2010.
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As for WS-10A having "russian input" -- I wouldn't be surprised if they had former soviet bloc consultants in their facilities.
However I do not think we have anywhere near enough confidence to suggest salyut had anything to do with the project, or if they took any specific inspiration from Al-31, mostly because we simply haven't even had un-credible rumours to suggest that.
thing is, spool up time isn't linear. and it matters much less from 50% of thrust to 100% thrust than it does from idle (say 10%) to 50% or combined up to 100%.
j11b would more or less always be near at least 50%, when in simple cruise, or going to 100% when in combat. that info more or less negates the j15 take off comment, but the safety concerns upon landing are still very much valid.
so spool up issue is not really a performance issue per se, it is an issue of decreased safety margins for certain types of planes and certain types of ops.
but hey, i've laid out my opinion and the fundations i base it on. we could go on for x pages arguing in a circle, but that wouldn't get us anywhere. some people will disagree, that's fine. I shall try to move on. and eagerly await news/photos of new ws10 variant.
j11b would more or less always be near at least 50%, when in simple cruise, or going to 100% when in combat. that info more or less negates the j15 take off comment, but the safety concerns upon landing are still very much valid.
so spool up issue is not really a performance issue per se, it is an issue of decreased safety margins for certain types of planes and certain types of ops.
but hey, i've laid out my opinion and the fundations i base it on. we could go on for x pages arguing in a circle, but that wouldn't get us anywhere. some people will disagree, that's fine. I shall try to move on. and eagerly await news/photos of new ws10 variant.
I'm sorry, but I do want to expound on the spool time issue a little.
First, I agree that spool time isn't linear, however, spool time must be acceptable enough for it to be equipped on J-11Bs (and thus probably J-10s, seeing as both are land based fighters). Therefore, at the very least, we should be able to agree that spool time isn't a current reason why it isn't equipping J-10s.
So next, the question is whether its spool time is "good enough" for J-15s. Of course, spool time isn't a categorical variable. And an engine's "acceptable" spool time might vary by tiny margins between its fitting on different aircraft.
However, we literally haven't heard anything about spool time issues since the early/mid 2000s. Therefore, spool time has about as much credence for why WS-10A isn't equipping J-15 as any other possible reason, if not a little less, given its specificity.
We also don't have any idea as to just how severe the original problem was, and in what particular domains. Assuming they've corrected it enough to fit on land based fighters but not enough for carrier landings is too specific an assumption for us, with our scant information.
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Basically, I'm saying that there is little to no evidence suggesting spool time is an issue, at least not for the last four or five years. If we can't even find any evidence suggesting that it is an issue, then it would be premature to seriously consider it as a reason for WS-10As lack of proliferation among J-10s and J-15s, especially when there are other more prevalent possibilities at hand.
I'm not dismissing spool time entirely saying it can't be a cause, but I'm saying its contribution to the "possible reasons why taihang isn't on J-10 and J-15" at this point looks far lower than many of the others: i.e.: cost, production rate limitation, PLAN conservatism (for J-15), better performing Al-31 variants, etc.
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Ah. In that sense, I think that could even be applied to the WS-10. From what I've gathered China also got a lot of this sort of technical assistance on engines from Western aerospace companies when contracted to manufacture parts for them.
Hmmm, perhaps I'm remembering wrong then. I'll probably dig around the internet graveyard for old content some day to get a clearer history of what happened and actually bother to write everything down for once.
we'll just have to disagree there, bltizo.
I find it perfectly logical that if, for example, engine A takes 6 seconds from 10% thrust to 50% thrust and another 2 seconds from 50 to 100%, while at the same time engine B takes 3 seconds from 10% to 50% and another 2 seconds from 50 to 100% that the engine A can be seen by the user as less safe for certain operations. At the same time, thrust performance and responsiveness in actual flight is the same as engine A will always be near 50% or more while in air.
We can all guess and make up things, but at least the spool up time is a documented issue. we had that pilot mention it in 2007 precisely mentioning it as a reason why it doesnt go on j10. On the other hand, i can't find any documented examples of spool up issue being fixed. Maybe it was, sure, but there simply aren't any write ups about it.
Furthermore, once an engine is ready for production, it doesn't get fiddled with every little batch, its variant goes through many batches until the next variant is ready. Sure, production process might get changed a bit, optimized a bit, but the engine itself stays pretty much the same. Spool up time issues, as documented on other (western) engines were a product of design choices or defficiencies, usually number of sections, their weight etc. They were not little imperfections that can be solved without changing the design.
Also, seeing how both in the West and in Russia there are basically always close to 10 years between old engine variant and a new engine variant (as less time wouldn't make sense investing it, because tech hasn't progressed enough to make it worthwhile to pop out new variants every 5 years or less), i find it more likely there will have to be a 5-10 gap between ws10 variant with spool up issue and next variant without it. So if back in 2006/2007 there were still issues with it, as per that pilot interview, it seems more plausible next variant (that will hopefully have it solved) won't come out before 2013-2015. Then again we may or may not have issues with getting the production up to speed.
I don't know how many times i can reiterate may stance without totally repeating myself so this may be more or less my last write up on that.
I am just very, very curious about that al31fn series 3 engine that's only now commencing bench tests. Why would China invest in that? What does that mean for j10 having a domestic engine? Is it possible some ws10 variant WILL be ready and good enough for export, but PLAAF deliberately chose al31 variant? I do think j10 programme NEEDS a domestic engine, otherwise it's export potential will be greatly diminished. Or maybe Salyut offered to develop the new variant for little money (since they're basically just reusing m2 variant tech for example) and China said "yes, go ahead" just to be on the (very) safe side, in case ws10 variants don't perform as expected. If ws10 variants do work just as well, then money spent on development of new al31 variant is wasted, but perhaps it's not such a huge sum and PLAAF thinks it was worth it, hedging its bets.
I find it perfectly logical that if, for example, engine A takes 6 seconds from 10% thrust to 50% thrust and another 2 seconds from 50 to 100%, while at the same time engine B takes 3 seconds from 10% to 50% and another 2 seconds from 50 to 100% that the engine A can be seen by the user as less safe for certain operations. At the same time, thrust performance and responsiveness in actual flight is the same as engine A will always be near 50% or more while in air.
We can all guess and make up things, but at least the spool up time is a documented issue. we had that pilot mention it in 2007 precisely mentioning it as a reason why it doesnt go on j10. On the other hand, i can't find any documented examples of spool up issue being fixed. Maybe it was, sure, but there simply aren't any write ups about it.
Furthermore, once an engine is ready for production, it doesn't get fiddled with every little batch, its variant goes through many batches until the next variant is ready. Sure, production process might get changed a bit, optimized a bit, but the engine itself stays pretty much the same. Spool up time issues, as documented on other (western) engines were a product of design choices or defficiencies, usually number of sections, their weight etc. They were not little imperfections that can be solved without changing the design.
Also, seeing how both in the West and in Russia there are basically always close to 10 years between old engine variant and a new engine variant (as less time wouldn't make sense investing it, because tech hasn't progressed enough to make it worthwhile to pop out new variants every 5 years or less), i find it more likely there will have to be a 5-10 gap between ws10 variant with spool up issue and next variant without it. So if back in 2006/2007 there were still issues with it, as per that pilot interview, it seems more plausible next variant (that will hopefully have it solved) won't come out before 2013-2015. Then again we may or may not have issues with getting the production up to speed.
I don't know how many times i can reiterate may stance without totally repeating myself so this may be more or less my last write up on that.
I am just very, very curious about that al31fn series 3 engine that's only now commencing bench tests. Why would China invest in that? What does that mean for j10 having a domestic engine? Is it possible some ws10 variant WILL be ready and good enough for export, but PLAAF deliberately chose al31 variant? I do think j10 programme NEEDS a domestic engine, otherwise it's export potential will be greatly diminished. Or maybe Salyut offered to develop the new variant for little money (since they're basically just reusing m2 variant tech for example) and China said "yes, go ahead" just to be on the (very) safe side, in case ws10 variants don't perform as expected. If ws10 variants do work just as well, then money spent on development of new al31 variant is wasted, but perhaps it's not such a huge sum and PLAAF thinks it was worth it, hedging its bets.