Chengdu next gen combat aircraft (?J-36)

A

ACuriousPLAFan

Brigadier
Registered Member
00CuriousObserver said:
They also discussed wind tunnels and various testing activities. The word 验证 came up often specifically in context of J-36, including in 验证机. While 验证 can mean either “to verify” or “to demonstrate,” in this context it seems closer to the former, even though in English, 验证机 refers more so to an experimental research or concept demonstration aircraft.
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Does that mean the J-36 is still in the Y-plane stage and not yet in the EMD stage?

Which sounds like a direct contrast to the following:
00CuriousObserver said:
Yankee also expressed great optimism for the speed of development (at 2745)
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If true, then it'd be absolutely hilarious if the F-47 hasn't had its first flight when the J-36 is already undergoing pre-service operational evaluation by the PLAAF.
 
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00CuriousObserver

00CuriousObserver

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Registered Member
ACuriousPLAFan said:
Does that mean the J-36 is still in the Y-plane stage, and not yet in EMD stage?
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I was a little perplexed by the terminology, but it might just be loosely applied here (Ayi at one point said the #1's 验证 properties were "very 验证"). Technically the purpose of prototypes is to "verify" technology.

They also said this at 1900:
扬基：老大跟老二的这种方式同时还可以这么理解。你想，咱们当年搞五代机预研的时候，跟踪对面那个YF-22大战YF-23的时候，你想啊，加雷特进气道，YF-23那个什么蝶形尾翼喷口尾部隐身，啊那些东西。都属于是吧，咱们在搞五代时叫有所为有所不为。在搞下一代飞机验证机的时候心想，验一验呗，完个愿呗，我们跟踪人这么些年，用一用呗，造的快点然后顺便把那东西一验证，多好

Yankee: The relationship between #1 and #2 can also be understood this way. Think about it — back when we were conducting preliminary research for our own fifth-generation fighter, we were closely following the YF-22 vs YF-23 competition on the other side. You see, things like the caret-style intakes, the YF-23’s butterfly tail and stealthy exhaust — all of those. When we were developing our fifth-gen fighter, we called that “doing some things while deliberately not doing others.” So when it came time to build the next-generation technology demonstrators, the thinking might’ve been: “Well, let’s test it out, fulfill that wish. We’ve been studying those designs for years — might as well try them out. Build it a bit faster, and while we’re at it, verify those concepts. Why not?”
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L

latenlazy

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00CuriousObserver said:
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1700:



At 2145 Yankee suggested that the second airframe's SN is 36022:


Yankee also expressed great optimism for the speed of development (at 2745)


They also discussed wind tunnels and various testing activities. The word 验证 came up often specifically in context of J-36, including in 验证机. While 验证 can mean either “to verify” or “to demonstrate,” in this context it seems closer to the former, even though in English, 验证机 refers more so to an experimental research or concept demonstration aircraft.
Click to expand...
ACuriousPLAFan said:
Does that mean the J-36 is still in the Y-plane stage and not yet in the EMD stage?

Which sounds like a direct contrast to the following:


If true, then it'd be absolutely hilarious if the F-47 hasn't had its first flight when the J-36 is already undergoing pre-service operational evaluation by the PLAAF.
Click to expand...
00CuriousObserver said:
I was a little perplexed by the terminology, but it might just be loosely applied here (Ayi at one point said the #1's 验证 properties were "very 验证"). Technically the purpose of prototypes is to "verify" technology.

They also said this at 1900:
Click to expand...

Within the formal R&D process 验证 usually refers to verification testing, and 验证机 should refer to verification samples/prototypes. Usually "demonstrator" aircraft *should* be referred to as 实验机. The YF-23 and YF-22 for example are usually referred to as 实验机, though of course the X-35 is often referred to as an 验证机, and the J-20's 200X prototypes as well. One way to make sense of this confusion is that depending on how you're approaching your development and testing process the verification phase can be quite broad and actually involve multiple rounds of design iteration. The J-36 flying with multiple prototypes testing different physical details this early in the flight testing process might be consistent with this interpretation.

00CuriousObserver said:
I was a little perplexed by the terminology, but it might just be loosely applied here (Ayi at one point said the #1's 验证 properties were "very 验证"). Technically the purpose of prototypes is to "verify" technology.

They also said this at 1900:
扬基：老大跟老二的这种方式同时还可以这么理解。你想，咱们当年搞五代机预研的时候，跟踪对面那个YF-22大战YF-23的时候，你想啊，加雷特进气道，YF-23那个什么蝶形尾翼喷口尾部隐身，啊那些东西。都属于是吧，咱们在搞五代时叫有所为有所不为。在搞下一代飞机验证机的时候心想，验一验呗，完个愿呗，我们跟踪人这么些年，用一用呗，造的快点然后顺便把那东西一验证，多好

Yankee: The relationship between #1 and #2 can also be understood this way. Think about it — back when we were conducting preliminary research for our own fifth-generation fighter, we were closely following the YF-22 vs YF-23 competition on the other side. You see, things like the caret-style intakes, the YF-23’s butterfly tail and stealthy exhaust — all of those. When we were developing our fifth-gen fighter, we called that “doing some things while deliberately not doing others.” So when it came time to build the next-generation technology demonstrators, the thinking might’ve been: “Well, let’s test it out, fulfill that wish. We’ve been studying those designs for years — might as well try them out. Build it a bit faster, and while we’re at it, verify those concepts. Why not?”
Click to expand...

So this part of the discussion might be consistent with the interpretation that the development and testing design for the J-36 is following a modularized iterative design model of development. But it also seems to show that the Chaguan guys might be using their terminology quite loosely, and they aren't making an effort to draw formal distinction between different phases of prototyping like between 实验机 and 验证机 (if they are aware of these formal distinctions at all). What I think we can say quite clearly though is that the design of the plane isn't fully "locked down" yet, but the options remaining for unsettled design details may all be very mature so it's just a matter of doing a final full scale test to confirm which directions you want to go with.

This more fluid approach to design selection is sometimes made available by the speed at which you can acquire large volumes of preliminary data using modern R&D approaches and tools like digital simulation and design, and 3D printing enabled rapid prototyping. The problem with making the design selection process too fluid in the past was that it could introduce invisible complex risk dependencies and that poor risk management can negatively impact your development time, sometimes quite drastically. That's why you'd normally want to lock down design details before proceeding to verification. However if you can study various design options more thoroughly at low cost burden and fast turnaround you can essentially sniff out potential problems and complex dependencies much earlier, so you can neutralize a lot of the risk behind introducing optionality into design selection at the verification stage. This lets you bank in some design wins by harvesting more of the potential solution space before you finalize the design without negatively impacting your testing burdens and timelines.
 
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Temstar

Temstar

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Registered Member
00CuriousObserver said:
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1700:



At 2145 Yankee suggested that the second airframe's SN is 36022:


Yankee also expressed great optimism for the speed of development (at 2745)


They also discussed wind tunnels and various testing activities. The word 验证 came up often specifically in context of J-36, including in 验证机. While 验证 can mean either “to verify” or “to demonstrate,” in this context it seems closer to the former, even though in English, 验证机 refers more so to an experimental research or concept demonstration aircraft.
Click to expand...
In this stream, Yankee was imply that 36011's caret intake was done for two reasons:

1. CAC has always wanted to give caret intake a try, if nothing else to get a hands on feel for aerodynamic and RCS characteristics of these intakes. Though unless caret intake turns out to be much better than CAC's estimation they've always perferred DSI.

2. They were judging that NGAD/F-47 prototype would fly sometime towards the middle of this year. Since caret intake was a much simpler arrangement than DSI 36011 could be ready for maiden flight much earlier than 36022, thus beating the Americans to the line.

Point 2 turned out to be too optimistic in terms of US 6th gen development, but their own estimation on when the two prototypes were correct. If indeed they only went for 36022 and the Americans worked as fast as their estimation then F-47 would have beaten J-36 for maiden flight.

Yankee said DSI is much more complicated than people realize and even for CAC, designing a completely new one for a new plane takes time. J-20's DSI is not just a fixed piece but actually has an adjustable component to it. However he has yet to observe anyone outside of China coming close to correctly guessing now the adjustability is done.
 
L

latenlazy

Brigadier
Temstar said:
Yankee said DSI is much more complicated than people realize and even for CAC, designing a completely new one for a new plane takes time. J-20's DSI is not just a fixed piece but actually has an adjustable component to it. However he has yet to observe anyone outside of China coming close to correctly guessing now the adjustability is done.
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There’s really only two feasible theories that I can think of. One is the hexagonal side vents are actually additional intake and bleed systems to deal with choked flow conditions and also spillage drag. The other is that the throat area itself is adjustable past the bump. Both kinds of solutions could probably also be employed together if they really need to have greater control authority over the flow conditions going into the inlet.
 
E

enroger

Senior Member
Registered Member
latenlazy said:
There’s really only two feasible theories that I can think of. One is the hexagonal side vents are actually additional intake and bleed systems to deal with choked flow conditions and also spillage drag. The other is that the throat area itself is adjustable past the bump. Both kinds of solutions could probably also be employed together if they really need to have greater control authority over the flow conditions going into the inlet.
Click to expand...

Is there any sign the top bump is adjustable? I'd imagine if the side DSI are adjustable then the top one must be too
 
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