Sunday, January 2, 2011

J-20

The last week has really been an exciting time for PLAAF fans, because real photos of J-20 started appearing on various Chinese military forums online. I think it is also time for me to butt in with some little thoughts I have on anything J-20 related.

First of all, I would not characterize myself as knowledgeable in stealth technology or aerodynamics. When I look at J-20, I certainly see something designed to compete against other 5th generation aircraft out there. But if you were to ask me whether I think this is more stealthy than PAK-FA or more maneuverable than F-22, I simply would not be able to give you an answer on that.

However, I do find this to be an extremely interesting development. Here are some things that I find really interesting:


  1. Transparency - It is really shocking to me that the photos for J-20 came out this early. Looking back, the first real photos of J-10 came out 3 or 4 years after the first flight. Even after the first photos came out, most photos that we saw were PS'd photos or CGs. The much less hyped J-10B's first photo came out 3 months after the first flight. Now, we see J-20's first photos coming out before the first flight even happened. I think it is a combination of modern technology and increased transparency from PLA. We see many people lining up with their cameras outside of CAC taking photos with no sighting of security around them. At the same time, we see the Chinese military forums allowing these photos to be published as soon as they are available. I think this shows PLA is more willing to allow high profile projects to be unveiled earlier on. The mysterious new conventional submarine in WuChang shipyard was unveiled as soon as it got launched. Maybe PLA will become as transparent as US military in the future. But until then, they seem to just be comfortable releasing details of their new projects through internet forums and camera phones.


  2. Size - I think one thing that really shocked a lot of people is how large J-20 is or at least how large it appears to be. The original photos lead certain people like Bill Sweetman to conclude that J-20 has "overall length of 75 ft. and a wingspan of 45 ft. or more, which would suggest a takeoff weight in the 75,000-80,000-lb. class with no external load". With those assumptions, many concluded this to be designed in the role of fighter-bomber as F-111. However, recent analysis on Chinese bbs of the size of J-20 vs truck beside it compared to the size of J-10 vs the same truck yielded the conclusion that J-20 is more likely around 19 to 20 m long, which would make it shorter than flankers. Even when we factor in what appears to be greater fuel load and internal weapon bay, it should still be about the same size as flankers. Personally, I kind of see J-20 as replacing the role of flankers in PLAAF in the future. It would have to be capable of handling more long range strike missions than flankers, but it would most likely serve as the heavy fighter jet in hi-lo combination.


  3. Prototype or technology demonstrator - Another question that some have raised is whether this is a prototype or a technology demonstrator. Back in 2009 on a CCTV interview, He Weirong, deputy commander of the People’s Liberation Army Air Force, said that J-20 would be flown in 2010-11 and be operational in 2017-19. I would say from that interview that this is the first couple of prototypes. However, I would also say that the final production version could have a lot of changes from this original prototype. After all, this is China's first attempt at developing a 5th generation fighter jet. They will have a lot to figure out and make fixes to initial design issues before the production version is settled down. More than anything, the first flight will clearly be conducted with something other than WS-15. If WS-15 is intended to be the engine for J-20, then some more changes + test flights will need to be done with WS-15 fitted J-20 before that version achieves operational status.


  4. Engine - This is probably one of the biggest mysteries surrounding J-20. What is the engine that it is using right now? We know that WS-15 is still years away from being ready. We know that AL-31F and FWS-10 would be vastly underpowered options for J-20. So, I would think the most obvious solution in the early stages of testing would either be 117S or some upgraded variants of FWS-10. Since upgraded variants of FWS-10 are not ready yet, 117S is most likely the engine on the first prototype. There has been a lot of talks about worsening China/Russia military relationships due to cloning issues, but I do think turbofan engine is one area where the cooperation is still quite beneficial for both sides. As we move forward, I think it will be interesting to see how the engine situation will change over time. Will 117S be the engine for J-20 until WS-15 becomes available? Will the initial production J-20s use upgraded variants of FWS-10? When will WS-15 be ready and how long will it take to do so? These are all important things to look forward to.


  5. Industrial impact - A lot of people have called J-10 program the "Apollo program" of China's aviation industry. I have a feeling that the J-20 program will become that way too. In order to have a successful 5th generation design, J-20 will have to yield advances in stealth technology, aerodynamics, materialogy, avionics, missiles and propulsion. The J-10 program brought about an entire new generation of aerospace engineers for Chengdu Aircraft Corp (CAC) that are the driving forces behind all of the recent CAC projects. Many of the engineers are in their 30s and already have worked on many high priority programs. They should have the best years of development ahead of them. At the same time, producers of J-10's subsystems across the country also became more capable. The RnD for J-20 project should do the same thing for CAC and other suppliers.


  6. Help from civilian programs? - In many ways, China's current civilian programs will help J-20 and vice versa. In the area of electronics, the most recent CIDEX 2010 exhibition clearly showed that the advances in civilian electronics in manufacturing and design have carried over to the military side. We have also seen similar improvements in avionics/radar for recent Chinese aircraft projects. At the same time, I think the C919 will also be very helpful toward J-20 program. As part of C919 program's involvement with Western suppliers, they will learn modern project management methods, purchase/develop more advanced production tooling and manufacturing process. These are all knowledge that can be transferred to J-20. Just as importantly, the suppliers for C919 will also work with local Chinese manufacturers to produce subsystems. This will produce a whole new network of suppliers that would be able to produce high quality subsystems for J-20. And of course, the advances in J-20 program will also be able to make these suppliers more competitive in civilian programs. Problems for the FWS-10 program have often been attributed to not enough testing in the development phase and production line problems. I would think that experience working with MTU and GE in producing propulsion units for C919 could also be transferred to allow the development and production of more reliable WS-15 engines. I can go on and on here, but there are plenty of examples where civilian programs could help out J-20 and vice versa. We have seen in recent year that successes in civilian shipbuilding have really been instrumental in the mass production of naval ships. I believe that successes in civilian aviation program can do the same for J-20 and WS-15 programs.


19 comments:

SINOGASS said...

Thank you for this prompt reaction. Excellent blog!

neuron said...
This comment has been removed by the author.
neuron said...
This comment has been removed by the author.
John said...

My comment was removed by the author, is it too technical, or involving state secrets? The comment only involves common sense observation. Strange.

Feng said...

I have no clue, I did not remove any comments. It just looked removed when I got here.

mr.unknown said...

Very well summarized. I would add that another impact this may have is that of indirect PR for CAC and its J-10 and JF-17 fighters. These revelations will demonstrate that CAC is capable of developing top of the line products, giving potential customers of existing CAC fighters a greater deal of confidence that CAC is a worthy competitor to the traditional alternatives.

mr.unknown said...

By the way, if you're not already a member of CDF, I think this forum may be of interest to you. It is always looking for insightful contributors such as yourself.

http://www.china-defense.com/smf/index.php

Feng said...

Thanks. I think the recent developments have really pushed CAC past SAC as the top dog of AVIC1, but I still think SAC have a lot of good work left in them. We will just have to wait and see.

John said...

My comment won't appear even I posted few times. Is there a time lag of few days before my comment appearing, so is a special tick needed to post. My comment did disppear after I pressed the Pubish button.

Feng said...

I don't know, I think that's an issue with blogger or google

John said...

3. FY-22 and FY-23 is the way to use a plane as prototype or demonstrator, otherwise the showed one is the production type. If not, probably there are issues related to CAD, CAM, etc. In that case, the speed to catch up the US will be in trouble.
4. If only one plane is shown, that means all the parts suppliers has done their majority works for the J-20, they have already been in the R&D for the next generation of aeroplane for some time.

John said...

1. CAC is an assembly plant, albeit a sophisticated one, CAC probably does not have the luxury to alter the configuration lines by 1mm without checking the aerodynamic research institutes first.

John said...

2. The effect of weight distribution on performance is complicated. By the time CAC showed the plane, majority parts were locked down, and major R&D phase was over. Using a different engine would be difficult, unless they want to do something like the LCA in India, R&D and production on the go same time, which is plagued by chicken and egg problems endlessly.

Feng said...

well, so there is 132 and 611. 132 does the production and 611 does the design if I'm not mistaken. 601 also assists on the design. So, 611 and 132 should be working pretty closely together on this one. It's been the case with all of the CAC projects. As the flight tests go on, they will find things that they need to correct on and the next prototype will contain changes. We've seen this with J-10, J-10A and JF-17. I'm not sure how much of the changes would be external (after all, they've already run thousands of wind tunnel analysis). Now, as for changing engines. They will have to do that and conduct more testing. There is no question about that. The J-11B program was first fitted with AL-31F and is now fitted with FWS-10. The J-10A program have always been fitted with AL-31FN, but they are also conducting tests with it using FWS-10. So, it's certainly not abnormal for a PLAAF project to start with one engine in the testing phase and then fly with a different engine once the production start or change in the middle of the production run. The problem is of course China currently does not have an engine that generates the designed thrust needed for J-20. So I don't know what their plan is with the flight testing. They could change to an engine with higher thrust after a couple of years. They could tune what they have to operate at higher thrust level (and have reduced lifespan). I don't know, we will have to wait and see. Too much we don't know at this point.

neuron said...

J-20's geometry loosely resembles that of Mikoyan Project 1.44 demonstrator:

http://www.fas.org/man/dod-101/sys/ac/row/i42-001.jpg

John said...

Project has milestones to be met; otherwise a project will become a project like LCA with endless extensions. If major parts are not locked down, change of those items will most likely affect configuration lines. With time strain only limited things can do. Major changes have to wait for next version, that’s why F-16 C/D is nearly a different animal from block A/B.
I think the recent activities in Yellow Sea have a lot to do with the surprise leak of J-20. If that’s the case, J-20 has to show real stuff in order to provide deterrent. Maybe China would surprise the world again in engine development in order to back up J-20’s real stuff.

Unknown said...
This comment has been removed by the author.
Unknown said...

My estimate of the size:
length: 68+-3ft(excluding Pitot tube)
wingspan: 47+-2ft

compared with:
the height of the ISUZU truck, which should be 2221mm according to the technical details provided by manufacturer.

For those who wanna check my estimate: my estimate of the width of the "2001" mark is 1.05m

Unknown said...

O probably it should be called "length" of the "2001" mark