Not necessarily. Long lead times could reflect caution and iteration rather than problems.
J-20 5th Gen Fighter Thread V
- Thread starter Deino
- Start date
- Status
Because Chinese fighter industry is relatively lacking in experience of conducting a full design cycle for both a modern fighter turbofan engine and an modern high performance fighter airframe, it would have been preferable to conduct most of the prototype validation and pre-series development of any indiginous fighter using something close to its intended engines. This way any fundamental issue arising from engine/airframe aerodynamic incompatibility would have the opportunity to menifest itself early, and could be addressed while the opportunity still exists to make fundamental changes to the airframe before any large upfront investments in production tooling, with reduce impact on production schedule.
So it would certainly not have been ideal to so pace the fighter program as j-20 appear to have been paced, which is the final intended engine have not yet flown, while the fighter it is intended for has already gone through its main development phase, and production tooling is undoubtedly already finalized and possibly already manufactured.
This suggests WS-15 was originally intended to reach flying prototype stage by around 2010, and be flown with the first j-20 prototype. The fact that engine has not yet flown suggests the engine is well behind intended schedule.
So it would certainly not have been ideal to so pace the fighter program as j-20 appear to have been paced, which is the final intended engine have not yet flown, while the fighter it is intended for has already gone through its main development phase, and production tooling is undoubtedly already finalized and possibly already manufactured.
This suggests WS-15 was originally intended to reach flying prototype stage by around 2010, and be flown with the first j-20 prototype. The fact that engine has not yet flown suggests the engine is well behind intended schedule.
Equation
Lieutenant General
Perhaps it did so without displaying it. It's not China's job to prove to all the doubters and naysayers. Apparently the program are still continuing on strongly.
Not sure about that -- if a bottleneck for a particular subsystem exists but other subsystems are ready for testing, then I think it would make sense for development to continue with those other subsystems, while also designing the aircraft with specific knowledge that it will eventually have the one delayed subsystem replaced in due time.
That way you get to test your other subsystems and your airframe and also an earlier initial capability, though your aircraft will have substandard performance WRT, compared to intended performance with the intended subsystem.
Better than having to wait until all subsystems are ready to start testing, which may cause a major delay in all subsystems and domains of the aircraft.
I don't think any disagrees with the idea that WS-15 is delayed, relative to the other subsystems and the other domains of J-20's development. But whether it reflects problems with WS-15's development, or whether it reflects that the other domains of the aircraft and its subsystems were developed faster, or maybe a mixture of both, is another matter entirely.
While I agree that it would have been "preferable" for J-20 prototypes to have been fielded from the outset with engines similar to WS-15 (or even WS-15 itself), I don't think that was ever a serious expectation. In fact even in the early to mid 2000s when J-20 was still called J-XX by the PLA watching community, it was accepted that J-20 will initially be tested with interim engines and that the first batch may even enter service with interim engines.
The question basically comes down to whether the air force and/or CAC had scheduled WS-15's development knowing that it would not make it in time to equip initial J-20 prototypes. i.e.: were interim engines always part of the plan? That could have significant implications for what kind of trials and testing they are focusing on and which ones they are not, in this stage of development.
Ideally, yes, you would want the engine to be concurrent with the design, but simply noting the program is slow does not also lend itself to a categorical conclusion that they must've encountered issues.
If you followed the J-XX program from start to finish you will find that it's not so much that the WS-15 engine is late but, rather, that the J-20 was early. Before 2010 we all had estimates that the J-20 may not emerge until 2015-18 precisely because everything we were hearing suggested that the engine wouldn't be ready until at least then. The engine was never intended to be ready by 2010. We know this because despite building a flatbed demonstrator as early as 2006, even in 2008 we heard that they were only just beginning the construction and testing of a prototype core for a production. It seems that the PLAAF and CAC chose to separate the engine development timeline with the airframe development timeline, and there are valid reasons for doing so, such as accelerating aerodynamic and avionic testing. Overall, if you have one bottleneck but can work around it, working on the bottleneck in parallel with the rest of a product and doing reintegration speeds up your development cycle much more than simply waiting for the single item bottleneck to resolve itself, even with the additional testing work.
To draw some comparison, we don't say the Type 30 engine for the T-50 must be running into problems because the T-50 is flying before the Type 30 engine. Sukhoi and the RuAF made the same decision to separate engine development from the rest of the airframe, even though the Type 30 has been in development since 2007.
What it comes down to is that you are *assuming* the intention was for the engine to be ready concurrently with the airframe, and extrapolating from that assumption. What we are saying is that based on the history of the program before the J-20 was revealed, that is not a sound assumption.
Schumacher
Senior Member
Yup, this really does make a lot more sense than empty assumptions. Remember all those western studies years ago that said J20 wouldn't fly until after 2020 and Gates' priceless reaction from the maiden flight. If only they had followed the leaks from Chinese sources many posted here.
One really needs to follow the development for years, like many senior members here who did so literally over more than 10 years, to get a big picture view.
To suggest the plan was to fly WS15 in 2010 or as if it's out of the ordinary to test with different engines, when China has done so with J10, J11 and Y20 etc. ? LOL
I think there really should be a forum rule that says newbies should read thru say 80% of the posts before allowed to write long posts and demonstrate some basic level of knowledge on PLA development.
The development of an engine very often takes longer than that of an aircraft so you usually take an engine that is already in development or even available for the aircraft you start to develop. Sometimes you have no choice and then things might go wrong. Many of the more mature members will remember that the Lockheed L-1011 was designed for the Rolls Royce RB211 and the other way round. The carbon fibre fan blades didn't pan out and had to be replaced by titanium ones and RR had to be nationalized by the then Conservative British government. So if you have to start both projects at the same time expect that your engine will take more time and have an interim engine available for development and early use, which of course happened to be impossible with L-1011.
It must be true
since I'm leaving for a trip into the woods only to come back later this evening. Anyway ... Please with images NOW !!
Deino
kind of our luck isn't it, after two days in kindergarten this week, I became an "Illinois licensed School Bus" driver, I'm now qualified to fly Air Force One, and have a security clearance from MI-6? LOLIt must be true
Anyway ... Please with images NOW !!
Deino
I do hope you are right, I have been twiddleing my thumbs long enough??? wooo hooo! 2016, bring it on!
- Status