J-20... The New Generation Fighter III

Engineer · Oct 25, 2012

If 2002 was going to have a radar installed all along, then why did it not have a gray radar dome in the first place? To me, it seems like extra hassle having to create yet another radar dome while the old one has no where to go. This is not to say that the aircraft shown cannot be 2002, but I am going to take a wait-and-see approach.

latenlazy · Oct 25, 2012

Air Force Brat said:
My point is that they must not be interested in it, or it would be on the Flanker, period, exclamation point! The Flanker is still a big deal to the PLAAF and PLAN, and it is quite capable and their go to bird for the immediate future. While I anticipate that the J-20 will eventually be their top line Air Force bird, and I anticipate that the F-60 will become their stealthy naval fighter, the J11, J15, J16 all say that I'm right. No, I have not forgotten about the J-10, I promise.
The J-20 is in full scale development stage and making outstanding progress, while I wish I were wrong, I doubt very seriously that it will ever incorporate that tech into the aircraft, or it would be on another platform in full scale development, I can almost certainly assure you that it is not, I do wish I were wrong, and in fact I could be, but after all I am the AFB.

China doesn't just stick every fancy toy onto a design thinking it will be worth it. Even though the Flanker is an important mainstay in the air force China does its cost benefit analysis. What would a Flanker with TVC help against in terms of reasonable threats? That extra maneuverability doesn't help with something that has BVR abilities (the F-22), and the design without TVC is already a counter any other 4.5 generation opponent. Furthermore would TVC really help the current Flanker airframe's performance? It is after all not a cure all. How effective TVC is depends on knowing when it helps and hurts the airframe's performance at different flight envelopes, which is certainly not something you can find for the J-20 by sticking engines with TVC on a Flanker.

Your point hinges on the idea that the Flanker is a tell for new technologies that will show up on the J-20, but that won't always be the case. It doesn't make sense to spend extra money to test something when most of the test results won't tell you anything about what you're really interested in testing for. Furthermore, the J-20 has prototypes too. While China tends to adopt very conservative testing standards they're not so risk adverse that they won't take risk when it makes sense. The whole point of prototyping is risk management. Also keep in mind that the J-20 needs TVC far more than the flanker does, both for supersonic maneuverability and to minimize surface deflections while cruising. We don't see TVC in the current air frames, but we also haven't seen the final engine yet.

Finally, China wouldn't have spent the R&D to develop TVC capable engines if they weren't going to use them. But just because they have the technology also doesn't they will stick it into everything.

Engineer said:
If 2002 was going to have a radar installed all along, then why did it not have a gray radar dome in the first place? To me, it seems like extra hassle having to create yet another radar dome while the old one has no where to go. This is not to say that the aircraft shown cannot be 2002, but I am going to take a wait-and-see approach.

Could be that they made the nose modular, and wanted to perform basic flight tests to make sure the airframe was sound before sticking an expensive radar in it.

Air Force Brat · Oct 25, 2012

latenlazy said:
China doesn't just stick every fancy toy onto a design thinking it will be worth it. Even though the Flanker is an important mainstay in the air force China does its cost benefit analysis. What would a Flanker with TVC help against in terms of reasonable threats? That extra maneuverability doesn't help with something that has BVR abilities (the F-22), and the design without TVC is already a counter any other 4.5 generation opponent. Furthermore would TVC really help the current Flanker airframe's performance? It is after all not a cure all. How effective TVC is depends on knowing when it helps and hurts the airframe's performance at different flight envelopes, which is certainly not something you can find for the J-20 by sticking engines with TVC on a Flanker.

Your point hinges on the idea that the Flanker is a tell for new technologies that will show up on the J-20, but that won't always be the case. It doesn't make sense to spend extra money to test something when most of the test results won't tell you anything about what you're really interested in testing for. Furthermore, the J-20 has prototypes too. While China tends to adopt very conservative testing standards they're not so risk adverse that they won't take risk when it makes sense. The whole point of prototyping is risk management. Also keep in mind that the J-20 needs TVC far more than the flanker does, both for supersonic maneuverability and to minimize surface deflections while cruising. We don't see TVC in the current air frames, but we also haven't seen the final engine yet.

Finally, China wouldn't have spent the R&D to develop TVC capable engines if they weren't going to use them. But just because they have the technology also doesn't they will stick it into everything.

Could be that they made the nose modular, and wanted to perform basic flight tests to make sure the airframe was sound before sticking an expensive radar in it.

My point is that you test engines on a proven airframe in order to eliminate the need to risk a prototype airframe with an unproven engine design. The Flanker is the only obviously proven airframe that would use a similar powerplant to the J-20, China has not demonstrated that they have mastered this technology, at the time Dr. Song wrote his famous paper, he was hoping the technology would be matured in time to adapt it to the J-20 in order to give it supermanueverability. My point is that it is heavy, it does bleed some thrust, it is maintenance intensive,and the idea of supermanueverability is currently not in "vogue". I apologize if something I have said is offensive, I actually agree with you wholly on this particular issue, I would love to see TVC on the J-20. So please accept my apology, I too would liked to see some of these changes on 2003, but I actually think that they are well pleased with the J-20, I know I certainly am!

plawolf · Oct 25, 2012

Engineer said:
If 2002 was going to have a radar installed all along, then why did it not have a gray radar dome in the first place? To me, it seems like extra hassle having to create yet another radar dome while the old one has no where to go. This is not to say that the aircraft shown cannot be 2002, but I am going to take a wait-and-see approach.

The original radome had an extended pitot tube, and there would have been associated testing and monitoring equipment attached inside the radome.

I cannot imagine that anyone would design flight test equipment with built-in ballast, so it is almost certain that the flight test equipment and ballast were two separate items, and the easiest way to install such two items is to affix the ballast to where the AESA radar would normally go, and build the extended pitot tube and back end testing equipment into the radome.

With normal functioning radomes, you need to make them out of special composites so they are transparent to your radar's emissions,and with stealth aircraft, there is the added complication of the radome also needing to keep out enemy emissions. That all translates to some very advanced, expensive and delicate materials, which would not take too well to having anything bolted or welded to it's inside, and even if you glued the equipment on, the weight of them and the stress and strain they would exert during flight testing could easily compromising the structural integrity and/or performance of the radome.

One of the main reason that early prototypes typically use steel nose cones is because steel is a far more forgiving, and much cheaper material. You can bolt, weld, glue stuff on the inside with no ill effects, and you can change out the equipment attached fairly easily as well.

latenlazy · Oct 25, 2012

Air Force Brat said:
My point is that you test engines on a proven airframe in order to eliminate the need to risk a prototype airframe with an unproven engine design. The Flanker is the only obviously proven airframe that would use a similar powerplant to the J-20, China has not demonstrated that they have mastered this technology, at the time Dr. Song wrote his famous paper, he was hoping the technology would be matured in time to adapt it to the J-20 in order to give it supermanueverability. My point is that it is heavy, it does bleed some thrust, it is maintenance intensive,and the idea of supermanueverability is currently not in "vogue". I apologize if something I have said is offensive, I actually agree with you wholly on this particular issue, I would love to see TVC on the J-20. So please accept my apology, I too would liked to see some of these changes on 2003, but I actually think that they are well pleased with the J-20, I know I certainly am!

And I'm saying that barring testing the engine's basic functions and performance, which can be done without an air frame, most of the test data you do on a different air frame is useless for the air frame you actually intend to install the engine in. If you want to test the engine's performance in the J-20, you don't get indicative test results from a Flanker air frame. There are too many variables for a good ceteris paribus comparison that aren't even about the TVC itself, such as whether the engine gets enough air at all flight aspects given a different intake. That's why, for example, even though they test the WS-10 on the Flanker, it still means they will have to also test the WS-10 on the J-10 if they want to install the WS-10 in the J-10.

Put it another way, when you have a new engine design you first test its basic performance, such as performance at different altitudes, reliability, operational life expectancy, etc without an air frame. Then once you know that it fits all your original expectations and design parameters, you stick it into the air frame you want to install the engine in to see how it performs with that air frame. You don't find it's basic reliability and performance by sticking it into air frame B, and then back into air frame A, because any issues with reliability that emerge from air frame B may not apply to air frame A (the new air frame introduces one or several intervening variables). Meanwhile, any reliability issues that can emerge from testing with no air frame can be taken far more seriously as a good baseline because there is no spurious variable. The control is the testing of the engine with no air frame, not one with a different air frame.

If you're going by the precedent that they tested the WS-10 on the J-11 before doing it on the J-10 though keep in mind that the reason they did so was because they can do safer reliability tests on a twin engine design over a single engine one. The roundabout way they approached the WS-10 has more to do with the J-10 being single engine, and them being exceptionally conservative about their first engine of that caliber, which also had some history of trouble during its development process. It's not a generalizable risk aversion to sticking new engines into new air frames (which has to be done at some point).

It's indicative that there has been zero designs with TVC that have tested the engine on a different air frame first. Dr Song wrote his paper in 2001, and while he was cautious about whether TVC would be ready, he was also expectant that there would be TVC. We saw a WS-10 with TVC in 2006, so we know that China has at least done all the basic research and development and has probably studied the strengths and weaknesses of the technology. That said even after 2006 TVC was strictly one feature we kept hearing about stuck to the design of the J-20, so on this matter I'm pretty certain.

Haha, sorry if I pushed my points a bit strongly. I'm not offended or anything. I simply think the evidence to suggest that the J-20 will go without a feature that it has been mentioned with on a frequent basis is weak, and that the evidence to the counter is far stronger.

Air Force Brat · Oct 25, 2012

latenlazy said:
And I'm saying that barring testing the engine's basic functions and performance, which can be done without an air frame, most of the test data you do on a different air frame is useless for the air frame you actually intend to install the engine in. If you want to test the engine's performance in the J-20, you don't get indicative test results from a Flanker air frame. There are too many variables for a good ceteris paribus comparison that aren't even about the TVC itself, such as whether the engine gets enough air at all flight aspects given a different intake. That's why, for example, even though they test the WS-10 on the Flanker, it still means they will have to also test the WS-10 on the J-10 if they want to install the WS-10 in the J-10.

Put it another way, when you have a new engine design you first test its basic performance, such as performance at different altitudes, reliability, operational life expectancy, etc without an air frame. Then once you know that it fits all your original expectations and design parameters, you stick it into the air frame you want to install the engine in to see how it performs with that air frame. You don't find it's basic reliability and performance by sticking it into air frame B, and then back into air frame A, because any issues with reliability that emerge from air frame B may not apply to air frame A (the new air frame introduces one or several intervening variables). Meanwhile, any reliability issues that can emerge from testing with no air frame can be taken far more seriously as a good baseline because there is no spurious variable. The control is the testing of the engine with no air frame, not one with a different air frame.

If you're going by the precedent that they tested the WS-10 on the J-11 before doing it on the J-10 though keep in mind that the reason they did so was because they can do safer reliability tests on a twin engine design over a single engine one. The roundabout way they approached the WS-10 has more to do with the J-10 being single engine, and them being exceptionally conservative about their first engine of that caliber, which also had some history of trouble during its development process. It's not a generalizable risk aversion to sticking new engines into new air frames (which has to be done at some point).

It's indicative that there has been zero designs with TVC that have tested the engine on a different air frame first. Dr Song wrote his paper in 2001, and while he was cautious about whether TVC would be ready, he was also expectant that there would be TVC. We saw a WS-10 with TVC in 2006, so we know that China has at least done all the basic research and development and has probably studied the strengths and weaknesses of the technology. That said even after 2006 TVC was strictly one feature we kept hearing about stuck to the design of the J-20, so on this matter I'm pretty certain.

Haha, sorry if I pushed my points a bit strongly. I'm not offended or anything. I simply think the evidence to suggest that the J-20 will go without a feature that it has been mentioned with on a frequent basis is weak, and that the evidence to the counter is far stronger.

I do honestly hope they install TVC on the J-20, as you stated that was Dr. Songs hope, and I myself am not convinced that a slower, less agile fighter aircraft will ever be as survivable. I know you have read Dr. Songs paper, and I admire your faith in the commitment to follow his design parameters. I actually think that the only way we will continue to see further advancement is to keep pushing the envelope. When you think that the Raptor first flew nearly 20 years ago, and there is no manned follow on aircraft to fill the Raptors shoes, only an expensive "weapons platform", and while the F-35 is a fine airplane, it was anticipated to be a Strike aircraft, and while we certainly think it will also be capable A2A, it will never be the Raptor, and it would be outclassed if an adversary does come up with a peer to the Raptor.

I think the J-20 is quite unique in many respects, and I would love to see it fly a similar routine that plays to its strengths, as Col Moga developed for the Raptor. I honestly believe that if the J-20 begins to see some airtime and enters production, our team will be compelled to reenter the true fifth gen competition.

latenlazy · Oct 25, 2012

Air Force Brat said:
I do honestly hope they install TVC on the J-20, as you stated that was Dr. Songs hope, and I myself am not convinced that a slower, less agile fighter aircraft will ever be as survivable. I know you have read Dr. Songs paper, and I admire your faith in the commitment to follow his design parameters. I actually think that the only way we will continue to see further advancement is to keep pushing the envelope. When you think that the Raptor first flew nearly 20 years ago, and there is no manned follow on aircraft to fill the Raptors shoes, only an expensive "weapons platform", and while the F-35 is a fine airplane, it was anticipated to be a Strike aircraft, and while we certainly think it will also be capable A2A, it will never be the Raptor, and it would be outclassed if an adversary does come up with a peer to the Raptor.

I think the J-20 is quite unique in many respects, and I would love to see it fly a similar routine that plays to its strengths, as Col Moga developed for the Raptor. I honestly believe that if the J-20 begins to see some airtime and enters production, our team will be compelled to reenter the true fifth gen competition.

It's not really based on faith for anything. I simply haven't seen any evidence that deviates from what we already know about the development of the design, which is that they intend to install a new engine with TVC later in its testing.

escobar · Oct 25, 2012

This doc shows that some parts of the J-20 were manufactured using Friction Stir Welding technics:

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It seems that this contributes greatly to the reduction of the mass relative to the riveting without reducing structural strength. It also stated that:
- this technology has already been applied in the airframe structure of J-20 and on the future military transport aircraft
- The development of its application in the manufacturing of the wings and the airframe itself is underway
- the cost of FSW equipment is very high

jackliu · Oct 25, 2012

escobar said:
This doc shows that some parts of the J-20 were manufactured using Friction Stir Welding technics:
Please, Log in or Register to view URLs content!

It seems that this contributes greatly to the reduction of the mass relative to the riveting without reducing structural strength. It also stated that:
- this technology has already been applied in the airframe structure of J-20 and on the future military transport aircraft
- The development of its application in the manufacturing of the wings and the airframe itself is underway
- the cost of FSW equipment is very high

Sweet, one step closer to Spaceship fighter project.

antiterror13 · Oct 26, 2012

TVC engine also have a much shorter life and really doesn't provide significant advantage in BVR battle

J-20... The New Generation Fighter III

Engineer

Major

latenlazy

Brigadier

Air Force Brat

Brigadier

plawolf

Lieutenant General

latenlazy

Brigadier

Air Force Brat

Brigadier

latenlazy

Brigadier

escobar

Brigadier

jackliu

Banned Idiot

antiterror13

Brigadier