Chengdu next gen combat aircraft (?J-36) thread

[againwithfeeling]

Im not making generalizing statements that China ''does not know what its doing''? Some of you need to not be so sensitive.

What I was guessing, was that the priorities placed on stealth and payload necessitated certain tradeoffs against supersonic efficiency/performance (drag, maneuverability etc) and one way to counteract that could be a third engine at the tradeoff of fuel consumption. For example its likely that a very large IWB tradeoffs area ruling, lack of tailerons or canards means J-36 has to rely on TVC and elevons for supersonic trimming, draggier but stealthier etc. Third engine makes sense here to ''brute force'' through these tradeoffs and achieve supersonic speed when needed, its also a bonus for power generation/cooling.


Im saying it can be both

you say this like supercruise wasn't a high priority in design, which is absurd

 

[latenlazy]

Im not making generalizing statements that China ''does not know what its doing''? Some of you need to not be so sensitive.

What I was guessing, was that the priorities placed on stealth and payload necessitated certain tradeoffs against supersonic efficiency/performance (drag, maneuverability etc) and one way to counteract that could be a third engine at the tradeoff of fuel consumption. For example its likely that a very large IWB tradeoffs area ruling, lack of tailerons or canards means J-36 has to rely on TVC and elevons for supersonic trimming, draggier but stealthier etc. Third engine makes sense here to ''brute force'' through these tradeoffs and achieve supersonic speed when needed, its also a bonus for power generation/cooling.


Im saying it can be both

You can guess or you can read the design paper (it’s somewhere in this thread).

 

[Derpy]

I would not be surprised if it doesn’t feature TVC. The Chinese just doesn’t seem to rate it despite a lot of testing and first hand experience.

Interview with a F-22 pilot and it seams most would prefer trading their TVC for some extra fuel as long as they get a HMD that can queue IR missiles.
They discuss TVC from around 9:30 in the video.

 

[sevrent]

You can guess or you can read the design paper (it’s somewhere in this thread).

If you mean the Haifeng paper then yeah ive read it. The main thing I found in regard to this topic was that Haifeng makes the point that lift-drag ratio along with SFC is the most important metric for efficient long range supercruise and he brings up adaptive engines as a key enabler. Im trying to see how the J-36 lines up with this.

Interview with a F-22 pilot and it seams most would prefer trading their TVC for some extra fuel as long as they get a HMD that can queue IR missiles.
They discuss TVC from around 9:30 in the video.

Speaking of the paper, Haifeng makes a big emphasis on TVC having a much bigger role in flight control when you have no vertical tails or tailerons. TVC would also be essential for trimming the aircraft at supersonic speeds as well. I highly doubt that the J-36 lacks any form of TVC

 

[ACuriousPLAFan]

If you mean the Haifeng paper then yeah ive read it. The main thing I found in regard to this topic was that Haifeng makes the point that lift-drag ratio along with SFC is the most important metric for efficient long range supercruise and he brings up adaptive engines as a key enabler. Im trying to see how the J-36 lines up with this.

During its test flights and LRIP, the J-20 used Al-31 engines. Then the serial-produced J-20s are equipped with WS-10C engines. Starting this year, the J-20A/Ss will be equipped with WS-15 engines instead.

What makes you think that the J-36 is never going to have adaptive cycle engines (ACE) in the future? In fact, what makes you think that China has somehow lost the ability to do the same, i.e. substituting the WS-10C and WS-15 engines used on prototypes and LRIP units respectively with ACE for later serial production units? Really?

 

[sevrent]

During its test flights and LRIP, the J-20 used Al-31 engines. Then the serial-produced J-20s are equipped with WS-10C engines. Starting this year, the J-20A/Ss will be equipped with WS-15 engines instead.

What makes you think that the J-36 is never going to have adaptive cycle engines (ACE) in the future? In fact, what makes you think that China has somehow lost the ability to do the same, i.e. substituting the WS-10C and WS-15 engines used on prototypes and LRIP units respectively with ACE for later serial production units? Really?

Where have I said that the J-36 is never going to have ACE? If anything I agree with you, I think they will get an ACE eventually. My comments were trying to look at what the J-36's aerodynamic layout reflects about the tradeoffs and design they were going for.

 

[enroger]

Im not making generalizing statements that China ''does not know what its doing''? Some of you need to not be so sensitive.

What I was guessing, was that the priorities placed on stealth and payload necessitated certain tradeoffs against supersonic efficiency/performance (drag, maneuverability etc) and one way to counteract that could be a third engine at the tradeoff of fuel consumption. For example its likely that a very large IWB tradeoffs area ruling, lack of tailerons or canards means J-36 has to rely on TVC and elevons for supersonic trimming, draggier but stealthier etc. Third engine makes sense here to ''brute force'' through these tradeoffs and achieve supersonic speed when needed, its also a bonus for power generation/cooling.


Im saying it can be both

Tailless delta is about the most efficient aerodynamic form there is with respect to drag, so what are you talking about "tradeoffs against supersonic efficiency/performance (drag, maneuverability etc)"?

You can say there is tradeoff against maneuverability, but what maneuverability you need to specify. If you're talking about instantaneous turn rate then I'm inclined to agree with you, due to upper intake, lack vertical surface...etc. But if we are talking about sustained turn rate then I'll have to object, again we're talking about a large area delta wing with somewhat high swept back angle, this type of wingform tends to have excellent sustained turn rate in trans/supersonic regime.

You need to put forward specific argument, you can't just say "Oh just because it has excellent stealth it therefore must have tradeoffs somewhere, I guess its supersonic performance blah blah blah..."

 

[latenlazy]

Where have I said that the J-36 is never going to have ACE? If anything I agree with you, I think they will get an ACE eventually. My comments were trying to look at what the J-36's aerodynamic layout reflects about the tradeoffs and design they were going for.

Wrt to the engine, I think the point of dispute is whether the primary motivation was to get around aerodynamic tradeoffs or to hit performance goals in other capability domains. My read based on the design paper is that the electric power design factored much more heavily in the inclusion of a third engine than kinematic performance. Having a third engine significantly simplifies power load architecture and ensures consistent power availability in all flight conditions, since you don’t have to make optimization decisions between thrust and generator output split between two engines, which is pretty important if you’re going in the direction of all electric onboard systems.

 

[TK3600]

View attachment 148777

Yeet

 

[Mearex]

Actually looking at the images again, I think the J36 does have TVC due to the noticeable gaps between the engines on the bottom of the plane.

If it went the YF23 design route, that should be one solid flat piece. The only rationale for having gaps is to allow independent movement of the nozzles, which rules out all 3 engines being synchronised for TVC, as that would also allow a single block without gaps.

I think that means the big question is whether all 3 engines have TVC, or just the two outermost ones.

I think the nozzles can probably move up and down judging by the flaps. Big question is if it can move side to side to control yaw