J-20... The New Generation Fighter III

MiG-29 said:

The americans have studied all these configurations thoughrouly, when they studied canting, wing position, all moving agaist conventional tail, they studied different angles sizes, positions etc etc.....
Second the US and Europe share technology and have a long tradition of aeronuatic design, this is supported by the fact NATO has common programs Eurofighter, Gripen, X-31, F-35 etc, etc...and NATO has very large military budget, add to that research done in third countries.

F-35 had aerodynamic concep with canards, canted V tails, SR-71 had inward canted canted tails, F-117 had inward canted v tails in the haveblue prototype and outward canted v tails on the production model.

So in few words if F-35 has no canards but tailplanes, is single engined and not twin engined or has conventional vertical and not all moving tail, it does not mean lockheed does not understand J-20 aerodynamics, it simply means F-35 has different design parameters to J-20

F-35 has troubles not because of aerodynamics but because of design contradictions, like F-111, it has compromised in a way some features are not well suited to different missions

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Yes, we've learned a lot in the short modern aviation era, but we're nowhere near the point where no model wind tunnel testing is required, or designing an advanced aircraft is just a matter of feeding your requirement into the computer without the need for much prototype testing, or any designer, especially those with the pumped-up ego, can just say I knew of and has completely analyzed an aircraft's aerodynamics anytime a new advanced aircraft comes into the scene. Two aircrafts may share the same basic designs, for example F-15 and the Flanker, but they're also very different aerodynamically in the details.

F-35 has troubles not because of aerodynamics but because of design contradictions, like F-111, it has compromised in a way some features are not well suited to different missions

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Yeah, more like they wouldn't have so much problem if they knew of the aerodynamics design contradiction during the early design stage, or maybe their predicted compromises turn out much worse than they've predicted. This is another proof that no designer can claim that he completely understands an aircraft aerodynamics because we've done aerodynamic studies of every possible shapes, control surfaces, aircraft configurations, and their every possible variations thereof.

Quickie,

If America managed to learn 'all there is to know' about delta canards from a few wind tunnel models from decades past, I guess the X31 team must not have gotten the memo and they were just wasting time re-performing the same task.

Just ignore Mig29, his claims are so fanciful and ridiculous they do not need refuting most of the times, and also because there is, quite simply, no reasoning with him. All you will accomplish by trying is get him excited and we will be wading through pages of his posts to find anything new and interesting about the J20 before you know it.

hmmwv said:

Because that's where CAC is located, it used to be the outskirt of Chengdu, sparsely populated, but in recent years the city has grown around the compound. They only want to test it there because it's close to the manufacturing plant and it's easy to resolve technical problems. The only other bases capable of handling the test flight is CFTE and Dinxing Air Base. CFTE is in populated area too so only Dinxing left, but it's way too far from any aircraft manufacturing infrastructure therefore not suitable to test a brand new prototype.

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May I venture an answer here? Acutually, I have been reading it from the Chinese forums since almost the beginning: What we have seen of all these flight tests have been done by at least six J-20's (or more if you count in the static one or ones). And that's why we see from the pictures the J-20's of apparently different degree of tear and wear, different "patches", bulges, sensors, etc. on the airframe, different nozzle colors... Which is also the cause for us to think some pics are Photoshopped, as they apparently lack some things (say, the weapons bays in some pictures are virtually nonexistent)...

Hmm, seems that I'm not answering the question yet. To answer it: The J-20 or J-20's whose pictures were taken in Chengdu are show planes to some degree. That means that some of the pics were atcually taken somewhere else!

P.S. Why do the Chinese make so many prototypes of J-20? Answer: To do different sets of tests simultaneously, therefore to get the plane inducted much sooner (2015?).

@ Player99 ... I hope that post was only ironic !

There's only one prototype (2001) flying at the moment and - at least IMO and by what I read from reliable sources - ft the second airframe was actually one it was most likely only one like the T-50KNS used for taxi-/roll-tests or a static test/mock-up, but there are surely not 6 J-20 fyling around at the moment !

Deino

Deino, I was not being sarcastic or kidding. But I was serious only in relaying that idea, instead of inventing it myself. It has been there since early last year. It's true that only a couple of guys were claiming that, yet this couple of people are believed to have military background and connections.

Personally, I have come to believe there are more than two or three J-20's, that is, there are more than just one static, one taxing, and one busy flying while getting its engines or engine nozzles swapped in between the flights and getting repainted ever so frequently (i.e. Now you see something on it, and now you don't).

At this point, with what we have seen, to claim 5-6 flying prototypes is plainly fanciful at best.

There is a possibility that there are more than 1 flying prototype, but even if that was the case, they could only be 2 flying ones in total.

If there were 5-6 flying prototypes, CAC would be silly not to fly more than 1 of them at any one time, or else there would be no need to have so many.

But logic and reason suggest that it is almost a certainty that there are nowhere near 5-6 prototypes.

Firstly, because there is no need for that many. This early in the flight test programme, the J20 would only be exploring basic to moderate moves, and the biggest bottleneck is how fast the ground team can analysis, process and incorporate the flight test data into useable data validate, amend or refine the FBW system and test out how well their scale model and computer simulations work in the real world.

Under such condictions, there is simply no need for more flying prototypes as none of them can move onto more complext part of the flight envelop until the basic stuff has been worked out first.

Just look at how long the breaks between J20 test flights can be. For most if not all of those breaks, they are waiting on the ground team to crunch the numbers and not because the J20 was unavailable to fly. Having more flying prototypes does nothing to improve the situation.

Also, the first prototype is also the most risky. Just look at the Russian T10 where they effectively redesigned the thing before they got to the Su27. Imagine how much harder it would have been to make the decision to change designs if there were 5 or 6 T10s already built by that point.

Another factor to consider is that CAC would have devoted pretty much all of their resources and expertiese into building a working prototype of the J20 asap to begin flight testing. Making a batch of 5-6 would have considerably slowed down and delayed when the J20 would have first flown.

Finally, it is almost expected that issues and problems will be found in the test flight phase, and it is virtually unheard off for a plane to go from protoype to mass production with no, or only superficial changes. Thus, but limiting the number of block 1 prototypes and delaying the construction of more after the inital batch, you allow yourself the flexibility to implement design changes directly only the second batch of flying prototypes so you can make the flight test programme go much faster and smoother by being able to do more of the flight test with a refined design instead of having to do a lot of flight tests only to repeat them after the refined prototype comes out.

Anyways, as I hope you can see, there are very good reasons why almost all planes start off with only a single flying prototype and bring in more only gradually.

I mean, even just looking at the logisitics of it, it would be hard to imagine that CAC could pump out 5-6 J20s in 1 years time right after making the first prototype.

Moving from prototype to pre-production stage takes years not just because of the requirements of flight testing. The factory will almost certainly not have the tools or expertise to build more than 1 or 2 planes at a time when everything about it is so new.

playwolf, all you were saying would be correct or applicable or logical if:

1. The J-20 we saw flying early last year was indeed the first one.

2. CAC has indeed been the only facility that has been doing the tests. Or

3. China is following the exact steps that other countries have made.

I'm not trying to say that China is more advanced here, but probably they've found ways to do things differently. Have we ever seen any country's prototypes being so much furnished and polished?

we just don't have evidence to substantiate any of that claim, photographic evidence shows that we have only 1 flying prototype, nozzle change, wear and tear, discrepancies does not mean anything, until we have a picture that shows us clearly two J-20s

i agree the J-20 looks polished for an early stage of testing, but there is a severely low number of hi-res photo of the J-20
only such photos can reveal/unravel J-20's true details, these hi-res are what people want to see, but yet to surface even until now

All fine points, and I agree with you on some of them, but none of those points alone, or in aggregate, is enough to indicated that there is more than 1 flying prototype let alone 5 or 6.

Because of the points you have listed and others, I would not be surprised if it was reveiled that there was indeed another flying prototype, or if the first flight of the J20 was actually earlier than the 'official' one we have.

However, even saying that, I would be pretty surprised if there were more than 2 flying prototypes, and would need pretty damn irrefutable proof to believe that there are as many as 5 or 6.

why would CAC would produce 5 prototypes for the first year of testing a new aircraft?? it will be stupid
nobody do that.
there are probably only 2: 2001 and 2002(for static test)