Chengdu next gen combat aircraft (?J-36)

Antares545 said:

like if they are gonna change the exhausts they should have at least move it further back so it does not look like the entire back section is missing lol. rn it looks so dogshit im coping so hard rn.

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I'm pretty sure the intended engine exhaust section has been taken off for whatever evaluation they're doing. That space between the prototype's nozzles and the alignment of the first prototype will be taken up by the actual nozzle design or whatever mechanism/fairing is applied after the exposed nozzle section.

There is no way they've just gone ahead and replaced the engines without knowing the engines they'll be using with the prototype and the intended engines. They will know the length and the suggestion that a more advanced engine is shorter than the first prototypes and this is why the second prototype has this "gap" just doesn't hold. They know the engine lengths or expected engine lengths. They know the design parameters well enough.

siegecrossbow said:

I don’t much like the new design since it looks like they took a bite out of the plane’s butt. But as Yankee hinted at earlier this year the redesigns are results of flight testing, and we must respect science.

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I really don’t think they would have had time to make the redesign based on flight test results unless their design and manufacturing turnaround times are insanely quick.

What is far more likely is that this is an alternative design rather than a re-design. They might have refined it with preliminary flight test data, but those would very much be tweaks around the edges rather than kind of wholesale radical redesign we are seeing here. What’s far more likely based on the observed timeline is that the major changes were planned from a long time ago.

The only way the redesign could have been caused by the flight test data is if the first flight was a hell of a lot earlier. But there is simply no evidence to support that.

plawolf said:

I really don’t think they would have had time to make the redesign based on flight test results unless their design and manufacturing turnaround times are insanely quick.

What is far more likely is that this is an alternative design rather than a re-design. They might have refined it with preliminary flight test data, but those would very much be tweaks around the edges rather than kind of wholesale radical redesign we are seeing here.

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No he explicitly stated during the talkshow that they have already gathered a lot of flight data (I think one or two months after December 26th) and will be making changes that “aviation fans may not like”.

siegecrossbow said:

No he explicitly stated during the talkshow that they have already gathered a lot of flight data (I think one or two months after December 26th) and will be making changes that “aviation fans may not like”.

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Two points, one, Yankee isn’t the infallible source of truth on PLA, so just because he said something doesn’t make it so. Second, the design changes he mentioned are not necessarily the design changes we are seeing here.

Just think about the prototype fabrication time alone to consider the reasonableness of the suggestion that the changes we now seeing are based on flight test results.

plawolf said:

Two points, one, Yankee isn’t the infallible source of truth on PLA, so just because he said something doesn’t make it so. Second, the design changes he mentioned are not necessarily the design changes we are seeing here.

Just think about the prototype fabrication time alone to consider the reasonableness of the suggestion that the changes we now seeing are based on flight test results.

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So how long does it take to fabricate a prototype, then? Especially when considering that this isn't a "start-from-zero/start-from-scratch" prototype.

I think we can safely assume that testing has been and is continuing feverishly in the air and on the ground and on other platforms out of sight, such as subscale articles, maybe even the CAC UADF as we discussed recently, or various testbeds, data from which was incorporated into the redesign we see on J-36 no. 2, this probably even before J-36 36011 flew. Unless of course we entertain the theory that 36011 flew long before 26.12.24.

Tomboy said:

Another issue with this exhaust arrangement is how are they going to do a S curve in the exhaust, the flow path is now much shorter. Americans are likely going to include that in their designs judging by all the patents out of PW and GE.

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The engine mounting position didn’t change. This is making a big deal out of nothing.

plawolf said:

I really don’t think they would have had time to make the redesign based on flight test results unless their design and manufacturing turnaround times are insanely quick.

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There’s a strong push for these newer projects to adopt rapid iteration and prototyping development paradigms. With the amount of data they can collect these days, the maturity of simulation tools, and more modular efficiency first and digitally assisted manufacturing design I don’t think rapid turnaround time on revisions is a big stretch. It’s been almost a year since first flight after all.

latenlazy said:

The engine mounting position didn’t change. This is making a big deal out of nothing.

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If you look at the patent I posted, you'll see that the S curve is very much a part of the exhaust system which is obviously changed here. I'm not talking about the intake S curve here.

Tomboy said:

If you look at the patent I posted, you'll see that the S curve is very much a part of the exhaust system which is obviously changed here. I'm not talking about the intake S curve here.

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The portion of the exhaust that got shortened was already a straightaway.