J-35 carrier fighter (PLAN) thread

[siegecrossbow]

Indeed, Minnie is well known since years for several reports that are so much off, sometimes plain wrong against all which is confirmed by images and much more reliable sources. She always refers to "unknow" soures or "another military source close to" says ... and still reports, the J-15 are powered yb WS-10H, the J-20 already uses pre-serial WS-15 ... and so on.

There is now a term for getting duped by Minnie Chan's headline on Reddit --- getting "Channed".

 

[Blitzo]

In reality the USN did go through a process of "fit" that was part of the F-35C design consideration. The design threshold spot factor for the F-35C was established that it cannot exceed 1.24. (source : NAEC-ENG-7604, Maximum Density Aircraft Spotting CV and CVN Aircraft Carriers, LPH, LHA,7and LHD Class Ships, Revision U, dated 13 Jul 1994.)

Yes, i.e.: the design of a carrier fighter is shaped by the parameters of existing carriers that they are likely to be based on. Typically new fighters are designed around the physical parameters of an existing carrier type.

It is rare that a new carrier and a new fighter are designed for each other concurrently (it has happened in the past, but is not very common).



For the PLAN, it is perfectly normal for them to be building carriers first, and then to design an aircraft to accommodate the parameters of the carriers built or being built.
It is not a "problem" but just a natural step that the designing of new carrier fighters typically have to go through.

 

[Air Force Brat]

Google? Yeah, no. That's useful for declassified designs but not for extremely classified information. The FC-31 numbers, even China might not really know cus it likely has never been fully fitted yet. The only time we can get close to a reliable number on things like these are either by leaks or if AVIC makes an official statement. So far, there are a lot of statements from the development team that they have made huge weight-savings over traditional methods by 3D printing and use of composites. They were talking about some 40% weight savings over the comparable parts (such as the bulk-heads) of the F-22 design.

There's a lot of misunderstanding about additive manufacturing of aircraft parts, or 3D printing as it is often referred to in laymans circles. The spin here on SDF is that it produces a much lighter part? (it may, or may not) Additive manufacturing is primarily used to form a part that needs less machine work. Cutting down on the machine work that a forged part would require, eliminating work hardening and heat, and material waste, but more importantly, producing a much cheaper part not requiring expensive machine work...

No one here has ever mentioned the real weakness associated with additive manufacturing which is "porosity", which refers to voids in the finished product. In order to produce a 40% lighter part, the finished product of necessity contains 40% less material. As Mangiangrexue has pointed out, its possible to produce an aircraft bulkhead using additive manufacturing, but that bulkhead will NOT be as strong or tough as a forged and machined bulkhead, you would not for instance use that to form the main fuselage bulkhead for landing gear attachment, or even a wing attach point.

You would use that bulkhead as a "former" to hold the stringers or longerons in place and to support or "underlay" the skins. So there are some serious issues with structural parts.

On the other hand it produces a very accurate part which is considerably cheaper, and potentially has better fit.

 

[Brumby]

There's a lot of misunderstanding about additive manufacturing of aircraft parts, or 3D printing as it is often referred to in laymans circles. The spin here on SDF is that it produces a much lighter part? (it may, or may not) Additive manufacturing is primarily used to form a part that needs less machine work. Cutting down on the machine work that a forged part would require, eliminating work hardening and heat, and material waste, but more importantly, producing a much cheaper part not requiring expensive machine work...

No one here has ever mentioned the real weakness associated with additive manufacturing which is "porosity", which refers to voids in the finished product. In order to produce a 40% lighter part, the finished product of necessity contains 40% less material. As Mangiangrexue has pointed out, its possible to produce an aircraft bulkhead using additive manufacturing, but that bulkhead will NOT be as strong or tough as a forged and machined bulkhead, you would not for instance use that to form the main fuselage bulkhead for landing gear attachment, or even a wing attach point.

You would use that bulkhead as a "former" to hold the stringers or longerons in place and to support or "underlay" the skins. So there are some serious issues with structural parts.

On the other hand it produces a very accurate part which is considerably cheaper, and potentially has better fit.

So what's the point of the additive parts if it cannot deliver to spec performance requirement?

 

[ougoah]

There's a lot of misunderstanding about additive manufacturing of aircraft parts, or 3D printing as it is often referred to in laymans circles. The spin here on SDF is that it produces a much lighter part? (it may, or may not) Additive manufacturing is primarily used to form a part that needs less machine work. Cutting down on the machine work that a forged part would require, eliminating work hardening and heat, and material waste, but more importantly, producing a much cheaper part not requiring expensive machine work...

No one here has ever mentioned the real weakness associated with additive manufacturing which is "porosity", which refers to voids in the finished product. In order to produce a 40% lighter part, the finished product of necessity contains 40% less material. As Mangiangrexue has pointed out, its possible to produce an aircraft bulkhead using additive manufacturing, but that bulkhead will NOT be as strong or tough as a forged and machined bulkhead, you would not for instance use that to form the main fuselage bulkhead for landing gear attachment, or even a wing attach point.

You would use that bulkhead as a "former" to hold the stringers or longerons in place and to support or "underlay" the skins. So there are some serious issues with structural parts.

On the other hand it produces a very accurate part which is considerably cheaper, and potentially has better fit.

If those MASSIVE savings are to be believed. But if we are to assume that certain parts have something like 40% less mass than using a more conventional method, the loss of density must not be a critical factor. I cannot imagine a scenario where the engineers in charge of these decisions would willingly imperil the fighter's performance and airworthiness to save weight, a lower priority for than the former qualities. There is no possible way ANY single engineer working on these projects can not understand the basic mechanics that go into these considerations. So that is ruled out.

Therefore it's pretty reasonable to assume that IF there are such weight, time, cost saving components being used, they would be applied and positioned in such a way that does not pose any danger to the overall airworthiness of the fighter or its performance ie frame's tolerance of equal levels of stress. Either that or the gains are considered worthy of any drawbacks. So if they have indeed used these methods for the manufacturing of some parts, it would be an overall net improvement. That much is certain unless we're going to be entertaining the idea that these alleged new frames are not thoroughly tested or contain hidden issues. The problem with this theory is that this should be relatively preliminary and basic engineering. The usual mechanical tests can more or less verify everything even without detailed research and testing but even those I'm sure have been done exhaustively. But this is me placing more trust in the developers than they may deserve. Let's not forget that China's looking for disruptive technologies in this field to catch up to the US asap. Allowing some to take greater risks than otherwise appropriate. Weight loss is the other side of the T/W ratio.

 

[Air Force Brat]

So what's the point of the additive parts if it cannot deliver to spec performance requirement?

It delivers parts to the exact specs you wish them to be Mr. Brumby, they are cheap, efficient and accurate... but it does not replace forging/machining parts requiring high strength and toughness....

You can also use a polymer as a "binding" material that helps considerably in "reducing friction", my point is that an additive manufactured part is not necessarily a "weight saving". In any regard though you might save 40% weight on a specific part, as you build the whole aircraft you would more likely be looking at a potential weight saving in the 1 to 7% range, rather than 25% as some posters have been led to believe.

My point is that it is fine for some parts, and inadequate for parts in high stress areas due to "porosity", you might actually end up with a physically larger or heavier part if you wished to use additive manufactured parts.

 

[Air Force Brat]

If those MASSIVE savings are to be believed. But if we are to assume that certain parts have something like 40% less mass than using a more conventional method, the loss of density must not be a critical factor. I cannot imagine a scenario where the engineers in charge of these decisions would willingly imperil the fighter's performance and airworthiness to save weight, a lower priority for than the former qualities. There is no possible way ANY single engineer working on these projects can not understand the basic mechanics that go into these considerations. So that is ruled out.

Therefore it's pretty reasonable to assume that IF there are such weight, time, cost saving components being used, they would be applied and positioned in such a way that does not pose any danger to the overall airworthiness of the fighter or its performance ie frame's tolerance of equal levels of stress. Either that or the gains are considered worthy of any drawbacks. So if they have indeed used these methods for the manufacturing of some parts, it would be an overall net improvement. That much is certain unless we're going to be entertaining the idea that these alleged new frames are not thoroughly tested or contain hidden issues. The problem with this theory is that this should be relatively preliminary and basic engineering. The usual mechanical tests can more or less verify everything even without detailed research and testing but even those I'm sure have been done exhaustively. But this is me placing more trust in the developers than they may deserve. Let's not forget that China's looking for disruptive technologies in this field to catch up to the US asap. Allowing some to take greater risks than otherwise appropriate. Weight loss is the other side of the T/W ratio.

I never stated or even implied that that engineers were taking short cuts or producing inferior parts ougoah, my point is that not every part is a candidate for additive manufacturing, and that each individual part will not likely be saving 40%, it may in fact be denser and heavier?

It is a tool in weight saving, but there are other possibly better reasons to use additive manufactured parts.

 

[vesicles]

In reality the USN did go through a process of "fit" that was part of the F-35C design consideration. The design threshold spot factor for the F-35C was established that it cannot exceed 1.24. (source : NAEC-ENG-7604, Maximum Density Aircraft Spotting CV and CVN Aircraft Carriers, LPH, LHA,7and LHD Class Ships, Revision U, dated 13 Jul 1994.)

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...

 

[Deino]

Guys, I find it funny that you are discussing size, weight, density parameters and others drawn by guesswork and Wiki as if they were confirmed and at the same time you complain about conclusions drawn there from... Funny indeed to say.

...
So why can’t the PLAN do the same?
...

I'm pretty sure the PLAN and SAC or whoever is responsible for the new type is well aware of all these points. They know exactly what's going on ...

 

[manqiangrexue]

There's a lot of misunderstanding about additive manufacturing of aircraft parts, or 3D printing as it is often referred to in laymans circles. The spin here on SDF is that it produces a much lighter part? (it may, or may not) Additive manufacturing is primarily used to form a part that needs less machine work. Cutting down on the machine work that a forged part would require, eliminating work hardening and heat, and material waste, but more importantly, producing a much cheaper part not requiring expensive machine work...

No one here has ever mentioned the real weakness associated with additive manufacturing which is "porosity", which refers to voids in the finished product. In order to produce a 40% lighter part, the finished product of necessity contains 40% less material. As Mangiangrexue has pointed out, its possible to produce an aircraft bulkhead using additive manufacturing, but that bulkhead will NOT be as strong or tough as a forged and machined bulkhead, you would not for instance use that to form the main fuselage bulkhead for landing gear attachment, or even a wing attach point.

You would use that bulkhead as a "former" to hold the stringers or longerons in place and to support or "underlay" the skins. So there are some serious issues with structural parts.

On the other hand it produces a very accurate part which is considerably cheaper, and potentially has better fit.

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.