J-35 carrier fighter (PLAN) thread

[Air Force Brat]

There's a lot of misunderstanding from you that whatever leisure reading you're doing on the subject matter is somehow the limits of technology anywhere in the world. The source is from AVIC and they specifically said: 1. 3D printing is used to make the structures and 2. they can save 40% from the weight of corresponding Raptor parts.

I don't care about your understanding of the limitations of 3D printing; you don't have nearly the expertise to contradict what professional jet makers say about their own aircraft. It's quite frankly astonishingly arrogant and delusional for you to even suggest that your knowledge is the limit in engineering a modern fighter jet. That's not to mention that these are the top engineers from the country that publishes by far the highest number of physics research papers every year in the world; you don't think that they might have a trick or 2 up their sleeves on 3D printing that you don't know about? LOL Suffice to say if they used only techniques and sciences known to you, they'd likely be making RC models rather than any sort of jets at all not to mention 5th gen fighters.

As I stated before, there is a lot of misunderstanding of additive manufacturing of aircraft parts, misstating my position will not change physics, aircraft structures, or lower the weight of J-XY or any other aircraft that happens to use additive manufacturing for parts within its structure.

I assure you that there remain many forged/machined parts in China's J-20, because forging/machining main bulkheads and heavy load bearing structure remains the industry standard. No doubt China's use of additive manufacturing for less critical structure may indeed save some weight...

J-XY will of necessity be a heavier airframe than a comparable land based fighter aircraft, that goes without stating...

Finally neither my opinion, nor your's will change the structure of J-XY by a single gram, so you are more than welcome to your opinions, what you or I think has no bearing on what is or will occur in any aircraft production, I am merely adding relevant context to the dialog about additive manufacturing.

 

[taxiya]

As I stated before, there is a lot of misunderstanding of additive manufacturing of aircraft parts, misstating my position will not change physics, aircraft structures, or lower the weight of J-XY or any other aircraft that happens to use additive manufacturing for parts within its structure.

I assure you that there remain many forged/machined parts in China's J-20, because forging/machining main bulkheads and heavy load bearing structure remains the industry standard. No doubt China's use of additive manufacturing for less critical structure may indeed save some weight...

J-XY will of necessity be a heavier airframe than a comparable land based fighter aircraft, that goes without stating...

Finally neither my opinion, nor your's will change the structure of J-XY by a single gram, so you are more than welcome to your opinions, what you or I think has no bearing on what is or will occur in any aircraft production, I am merely adding relevant context to the dialog about additive manufacturing.

I don't know your back ground of profession, so I can't say how you keep making this statement that "additive manufacturing is still no match to traditional method".

I respect your right of making your opinion known, but I believe any opinion has to be based on professional knowledge, not only ones own past experience, but also latest from others. Here are some examples which have already been repeatedly posted in this forum in case you have missed them. All the examples are load bearing structures already used, some in volumes.

1. Load bearing bulk head of a fighter jet, almost certainly being J-15

and, see the bulkhead and the wing root (on the right).


2. C919 wing root load baring beam. It was mounted on C919 in 2010.


3. According to Wang Huaming's presentation in 2012 (his name has been repeated numerous times here), his team made landing gear component by additive fabrication for a classified fighter jet in 2006. Without it, the aircraft's maiden flight would have been delayed for at least two years (using traditional method). He did not name the aircraft as being classified.

4. In the same presentation, Y-20's load bearing wing root is also made by additive method.

5. Same presentation, fatigue test of xxx's 3d printed bulkhead lasted for more than 8000 hours, that is a full year. It is implied to be J-20 when Wang was comparing with F-22.

6. Lastly and recently, this thing, guess what is it? The wholes are for air ducts. Two engines on one side, four engines in total, fully buried in fuselage.

 

[manqiangrexue]

As I stated before, there is a lot of misunderstanding of additive manufacturing of aircraft parts, misstating my position will not change physics, aircraft structures, or lower the weight of J-XY or any other aircraft that happens to use additive manufacturing for parts within its structure.

The misunderstanding is entirely with you. I'm taking a direct statement from AVIC and you have misunderstood your own casual take on this technology as the limits of the technology worldwide. And when I saw you replied, I knew I would have to re-type this to you again: Physics never changes but our understanding of it never stops changing. What was impossible yesterday could be the standard today.

I assure you that there remain many forged/machined parts in China's J-20, because forging/machining main bulkheads and heavy load bearing structure remains the industry standard. No doubt China's use of additive manufacturing for less critical structure may indeed save some weight...

Your assurance means nothing because you didn't design this jet nor do you understand the current abilities of Chinese (or probably any country's) cutting edge manufacturing. It were as if I assured you that if you dug deep enough in your backyard, you'd find oil. And there is no industry standard, at least not one known to the public, for how China makes 5th generation stealth fighters.

J-XY will of necessity be a heavier airframe than a comparable land based fighter aircraft, that goes without stating...

Yes, probably but that was never the point of contention. And to be more precise, China's naval stealth fighter should be heavier than its land-based Chinese analogue manufactured under the same standards.

Finally neither my opinion, nor your's will change the structure of J-XY by a single gram, so you are more than welcome to your opinions, what you or I think has no bearing on what is or will occur in any aircraft production, I am merely adding relevant context to the dialog about additive manufacturing.

I don't have an opinion on the current abilities of 3D printing because that is not my area of study. I simply believe that engineers from China can create a structure to be 40% lighter than an American analogue made in the 90's-early 2000's using new techniques because that is what they said. You are the only one with an (unqualified) opinion and that is that you know so much more than they do that you can tell what's possible and not possible without even being in the project.

Here's the hierarchy of people to trust on the weight of J-20 structures:

1. Chengdu engineers
2. World cutting edge experts on 3D-printing design
3. Companies that extensively use 3D printing for the manufacturing of elite technological parts
4. PhDs in the subject matter
5. People who casually read about 3D printing with an open mind
6. People who don't read about 3D printing but have an open mind
7. Fine canine companions
8. Chairs
9. People with no formal education or design experience in a subject matter who insist they know things that they don't

I'm not about to take the opinion of someone in category 9 over the statements of someone in category 1.

 

[Inst]

As for trapezoidal wing, the J-20's wing is strictly a trapezoidal wing as well, as is the F-35's.

There's actually a different solution to the empty weight problem for the J-20. When it comes to take-offs and landings, the important thing is to be fast enough to have the lift to carry the plane's own weight. One way to solve this would be thrust, and strangely enough this is an argument against the carrierized J-20. For a carrierized J-20 to work, it might need WS-15 engines, and not just regular WS-15 engines, but navalized versions designed to bear up to salt air.

And IIRC, the NATF program for the USN got killed because of post-Cold War funding cuts, not because of technical difficulties. Same problem that befell both the F-22 and B-2, both of these were designed to be fielded in much greater numbers

 

[Brumby]

There's a lot of misunderstanding from you that whatever leisure reading you're doing on the subject matter is somehow the limits of technology anywhere in the world. The source is from AVIC and they specifically said: 1. 3D printing is used to make the structures and 2. they can save 40% from the weight of corresponding Raptor parts.

I don't care about your understanding of the limitations of 3D printing; you don't have nearly the expertise to contradict what professional jet makers say about their own aircraft. It's quite frankly astonishingly arrogant and delusional for you to even suggest that your knowledge is the limit in engineering a modern fighter jet. That's not to mention that these are the top engineers from the country that publishes by far the highest number of physics research papers every year in the world; you don't think that they might have a trick or 2 up their sleeves on 3D printing that you don't know about? LOL Suffice to say if they used only techniques and sciences known to you, they'd likely be making RC models rather than any sort of jets at all not to mention 5th gen fighters.

I don't know your back ground of profession, so I can't say how you keep making this statement that "additive manufacturing is still no match to traditional method".

I respect your right of making your opinion known, but I believe any opinion has to be based on professional knowledge, not only ones own past experience, but also latest from others. Here are some examples which have already been repeatedly posted in this forum in case you have missed them. All the examples are load bearing structures already used, some in volumes.

1. Load bearing bulk head of a fighter jet, almost certainly being J-15
View attachment 53536
and, see the bulkhead and the wing root (on the right).
View attachment 53538

2. C919 wing root load baring beam. It was mounted on C919 in 2010.
View attachment 53537

3. According to Wang Huaming's presentation in 2012 (his name has been repeated numerous times here), his team made landing gear component by additive fabrication for a classified fighter jet in 2006. Without it, the aircraft's maiden flight would have been delayed for at least two years (using traditional method). He did not name the aircraft as being classified.

4. In the same presentation, Y-20's load bearing wing root is also made by additive method.

5. Same presentation, fatigue test of xxx's 3d printed bulkhead lasted for more than 8000 hours, that is a full year. It is implied to be J-20 when Wang was comparing with F-22.

6. Lastly and recently, this thing, guess what is it? The wholes are for air ducts. Two engines on one side, four engines in total, fully buried in fuselage.View attachment 53539

The misunderstanding is entirely with you. I'm taking a direct statement from AVIC and you have misunderstood your own casual take on this technology as the limits of the technology worldwide. And when I saw you replied, I knew I would have to re-type this to you again: Physics never changes but our understanding of it never stops changing. What was impossible yesterday could be the standard today.

Your assurance means nothing because you didn't design this jet nor do you understand the current abilities of Chinese (or probably any country's) cutting edge manufacturing. It were as if I assured you that if you dug deep enough in your backyard, you'd find oil. And there is no industry standard, at least not one known to the public, for how China makes 5th generation stealth fighters.

Yes, probably but that was never the point of contention. And to be more precise, China's naval stealth fighter should be heavier than its land-based Chinese analogue manufactured under the same standards.

I don't have an opinion on the current abilities of 3D printing because that is not my area of study. I simply believe that engineers from China can create a structure to be 40% lighter than an American analogue made in the 90's-early 2000's using new techniques because that is what they said. You are the only one with an (unqualified) opinion and that is that you know so much more than they do that you can tell what's possible and not possible without even being in the project.

Here's the hierarchy of people to trust on the weight of J-20 structures:

1. Chengdu engineers
2. World cutting edge experts on 3D-printing design
3. Companies that extensively use 3D printing for the manufacturing of elite technological parts
4. PhDs in the subject matter
5. People who casually read about 3D printing with an open mind
6. People who don't read about 3D printing but have an open mind
7. Fine canine companions
8. Chairs
9. People with no formal education or design experience in a subject matter who insist they know things that they don't

I'm not about to take the opinion of someone in category 9 over the statements of someone in category 1.

If I understand the issue of additive parts conversation, the following claim was the genesis.
"They were talking about some 40% weight savings over the comparable parts (such as the bulk-heads) of the F-22 design."

The claim itself may be factually true but the claim may be highly misleading because actual weight reduction may be limited and questionable at best as suggested by AFB.

As is often said "proof is in the pudding". Given all the Phd;'s, experts and breakthrough in weight savings as claimed, the J-20 is still a heavy bird at 19 tons. Are you saying that the 40 % weight savings breakthrough is delivering only this end result?

 

[manqiangrexue]

If I understand the issue of additive parts conversation, the following claim was the genesis.
"They were talking about some 40% weight savings over the comparable parts (such as the bulk-heads) of the F-22 design."

The claim itself may be factually true but the claim may be highly misleading because actual weight reduction may be limited and questionable at best as suggested by AFB.

You did not understand Brat correctly. He said it's basically not possible to achieve a 40% reduction in these parts based on his limited understanding of 3D printing. And that's actually the less ignorant claim; his other claim is that regardless of what Chengdu or AVIC or any PICTURES say, welding and machining are still the dominant standard used for manufacturing the load-bearing components of the J-20. He just knows that from "experience." LOL

As is often said "proof is in the pudding". Given all the Phd;'s, experts and breakthrough in weight savings as claimed, the J-20 is still a heavy bird at 19 tons. Are you saying that the 40 % weight savings breakthrough is delivering only this end result?

There are no qualified "experts" who claim a 19 ton weight in the J-20 unless you count those people who said J-20 is likely a 75 foot long bomb truck as experts. There are only insiders, one who says that the jet is in the 16 tonne-range after interviewing AVIC (just under the Su-27), and another who said that the weight had increased to 17.5 tonnes.

The 19 tonne figure is completely fictitious, fabricated by people "eye-balling" the aircraft. They used to say they eyeball it at 21 tonnes, and then when leaks came out that it was in the 16-17.5 tonne range, they thought they'd average their eyeball guesstimate with the leaked number or some other equally nonsensical way of calculation to arrive at 19 tonnes.

 

[ougoah]

If I understand the issue of additive parts conversation, the following claim was the genesis.
"They were talking about some 40% weight savings over the comparable parts (such as the bulk-heads) of the F-22 design."

The claim itself may be factually true but the claim may be highly misleading because actual weight reduction may be limited and questionable at best as suggested by AFB.

As is often said "proof is in the pudding". Given all the Phd;'s, experts and breakthrough in weight savings as claimed, the J-20 is still a heavy bird at 19 tons. Are you saying that the 40 % weight savings breakthrough is delivering only this end result?

Which Chinese experts claimed J-20 is 19T? The "official" weight claims of J-20 is 16T. I've read 15T in some places in the past. Literally no one of any supposed importance have mentioned 19T.

 

[manqiangrexue]

Which Chinese experts claimed J-20 is 19T? The "official" weight claims of J-20 is 16T. I've read 15T in some places in the past. Literally no one of any supposed importance have mentioned 19T.

There is no official claim, just leaks. The 15T number came because the person who described the J-20 as 16T class described the F-22 as 20T class, so there was the assumption that when he says "class," be means less than, so up to 15.99T was the interpretation. However, the next person said that the weight with AL-31X is just under Su-27 empty weight (16.38 tonnes) and with WS-10X is just over Su-27 empty weight, meaning it is around 16.4T. Then, after a long while, the third person said that those who wanted the J-20 to be in the 16T range will be disappointed to learn that it is now 17.5 tonnes in production form. So I believe the last number, 17.5 tonnes. I'm not sure which big Shrimp it was but I think it was a fellow who worked in the WS-10 factory.

 

[Brumby]

As for trapezoidal wing, the J-20's wing is strictly a trapezoidal wing as well, as is the F-35's.

There's actually a different solution to the empty weight problem for the J-20. When it comes to take-offs and landings, the important thing is to be fast enough to have the lift to carry the plane's own weight. One way to solve this would be thrust, and strangely enough this is an argument against the carrierized J-20. For a carrierized J-20 to work, it might need WS-15 engines, and not just regular WS-15 engines, but navalized versions designed to bear up to salt air.

And IIRC, the NATF program for the USN got killed because of post-Cold War funding cuts, not because of technical difficulties. Same problem that befell both the F-22 and B-2, both of these were designed to be fielded in much greater numbers

Success story of navalization of a fighter as TE pointed is not common because examples are few. There is a major reason for it because all the attributes build for aerodynamic performance of a land fighter may be detrimental to navalization. The underlying issue is the pesky problem associated with carrier landing. The F-18 is often criticized for sub par aerodynamic performance but the reason is because its design need to trade off for carrier landing. There is a big difference between having general aerospace knowledge and actual "know how" especially with carrier aviation. An example is the story with BAE systems when it was pushing to navalize the Eurofighter onto the British carrier. It even built a computer simulation demonstrating how easy it was to land a navalized Eurofighter except when assumptions are limited by "know how".

The Naval Air Systems Command currently defines carrier approach speed having to meet six criteria one of which is the approach attitude of the aircraft must provide the pilot enough over-the-nose field-of-view to see his visual cues for landing. This is so basic for naval aviators but "Phd experts" somehow built the simulation anyway until it was pointed out that it won't work because of the location of the canards.





Of the six criteria for approach speed, the biggest issue I believe is that the aircraft must maintain desirable flying qualities throughout the maneuver. This means that the aircraft must maintain a very narrowly defined speed window to execute a "control crash". It is a balance between not coming in too fast that will break the arrester cable but leaving insufficient speed to do a bolter but also having enough speed not to crash into the stern This "stability" issue is what I suspect was associated wth the J-15 and the crashes.

At the slow airspeed needed for approach, stability and control of an aircraft typically becomes more difficult, as aerodynamic control surfaces become less effective due to the reduced dynamic pressure. Shipboard environmental factors, such as deck motion and ship-induced airwake turbulence, further compound the challenge. Designers of the JSF have performed extensive analyses to ensure desirable flying qualities are maintained throughout the approach regime. Particularly demanding is the requirement to have enough roll control power to enable a large lineup correction during the late stages of the approach. Historically, the design metric used to quantify this attribute is the ability to command a 30 deg bank angle in no more than I sec. This roll control criterion was the primary impetus for incorporating ailerons to the F-35C.

 

[Brumby]

This would be exactly my point! You don’t change the carrier to fit the planes. You do the opposite. Ayou have agreed, any carrier can be easily repurposed to fit future planes that are nonexistent when the carriers were being built.

So why can’t the PLAN do the same?

Additionally, I’m sure the PLAN’s carrier fighters will be expected to evolve at least 1-2 generations further during the lifetime of their carriers. At this point, no one knows how a 6th or a 7th gen fighter will look like. Should they wait until they finish manufacturing their 7th gen fighters before they begin building their carriers?

As I have said before, many USN carriers have hosted 3 generations of fighters on their decks...

I did not infer nor suggest that the carrier has to change to fit the plane or that the problem is somehow unique to the PLAN. All I am saying is that some form of reconciliation would be inevitable given the situation.