Shenyang / Chengdu 6th Gen Demonstrators?

The DC-10 had three engines because of the regulations at the time (and being larger than the A-300..)
correct but no one returned to the three engine configuration, Boeing went for B767 and B757 and DC-10 never could compete, a more reliable engine is always better any way thermal efficiency has gone better so it is still engine efficiency just look at B-777 or B787 even A-320XLR they fly routes that before 4 engined aircraft flew
 
correct but no one returned to the three engine configuration, Boeing went for B767 and B757 and DC-10 never could compete, a more reliable engine is always better any way thermal efficiency has gone better so it is still engine efficiency just look at B-777 or B787 even A-320XLR they fly routes that before 4 engined aircraft flew
The 767 used the CF6, just like the DC-10 and A-300.....
 
The 767 used the CF6, just like the DC-10 and A-300.....
1736466006939.png

thermal efficiency has gone better thus modern aircraft use 2 engines, you are correct but consider engine technology now allows for 2 engines in most aircraft and A-321XLR is the latest example.

And the same is the trend for modern 6th generation fighters

Having the same engines which one is cheaper to operate? DC-10 or B-767? remember an extra engine means extra fuel, means extra weight.
 
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thermal efficiency has gone better thus modern aircraft use 2 engines, you are correct but consider engine technology now allows for 2 engines in most aircraft and A-321XLR is the latest example.

And the same if the trend for modern 6th generation fighters
Look at the thrust to weight ratios of pax transports - its generally in the range of 3-4 because that is what the math/physics needs for to/climb and cruise at alt. High bypass ratio engines allow for big aircraft like the 777x with just 2 engines. This is not some decision driven exclusively by fuel consumption as you seem to intimate.
 
Look at the thrust to weight ratios of pax transports - its generally in the range of 3-4 because that is what the math/physics needs for to/climb and cruise at alt. High bypass ratio engines allow for big aircraft like the 777x with just 2 engines. This is not some decision driven exclusively by fuel consumption as you seem to intimate.
Airbus A300-600versusMcDonnell-Douglas DC-10-30
54.10 m177 ft 6 inlength55.50 m182 ft 1 in
44.84 m147 ft 1 inwingspan50.40 m165 ft 4 in
260.00 m22,799 ft2wingarea367.70 m23,958 ft2
16.50 m54 ft 2 inheight17.70 m58 ft 1 in
2engines3
274 kN61,500 lbfthrust per engine240 kN54,000 lbf
548 kN123,000 lbftotal thrust720 kN162,000 lbf
165,000 kgs364,000 lbsMTOW263,085 kgs580,000 lbs
7,700 km4,158 nmrange7,415 km4,004 nm
M0.8cruise speedM0.84
266 passengerscapacity250 passengers



You can apply this to J-36 versus NGAD


Extra engine needs extra fuel, that implies more weight see DC-10 is heavier than A-300, but also see A-300 carries more passengers, so actually a third engine does not bring more passengers and the fuel, seat km does not bring a better aircraft DC-10 carries more fuel for the same range and less passengers.

If the USA makes better engnes means less number of engines and less engines means less fuel, better thermal efficiency means then you need less fuel, less weight and less weight is a more agile fighter
 
I'd be extremely curious if someone can explain a bit about how engine size relates to overall engine efficiency in these relatively low bypass turbofans... especially in different flight regimes. What are the upper and lower limits, and what limits are associated with efficiency?

(now I will be honest all this is speculation) I doubt China has a reliable engine since in the case of both the USA and Russia went for single engined aircraft Su-75 and F-35, while J-35 has 2 engines.

Isn't it the case that the Su-75 is aimed primarily at the export market partly because the VKS still doesn't like single-engined designs?

remember an extra engine means extra fuel, means extra weight.

Also more thrust and more maintenance costs.

Speaking of maintenance costs - what if the third engine can be kept shut down on most routine flights? How often would it need to be fired up? Could such an approach be used to massively extend the overhaul time for the third engine?
 
Actually, don't you guys think the exhaust looks similar to the design of the J-36's exhaust, with an actuated lower flap extending over the top? Imo if these speculation about exotic flight control techniques turns out to be true, the J-36 prototype might be the single most advanced fighter(prototype) in terms of aerodynamics that has ever publicly flown.

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They copied the YF-23 SERN (Single Expansion Ramp Nozzle) exhaust. Some folks speculated there are actuated flaps on the underside, not the case. Three-engine, medium attack/strike platform.
 
The position some people took in this topic is too simplistic, amateurish I might say. To claim that the Chinese had to implement a 3 engine configuration because 2 has insufficient thrust would imply that they had already experimented with a 2-engine setup, found it lacking and modified the airframe to accept a new engine slotted in the centerline. So, the base air vehicle had insufficient thrust margins but somehow enough for drag and structural integrity? And, say, they couldn't have went for a more powerful engine (couple existing core with larger fan ala F401, or goes VCE) or dumb down the specs? Those stuff are discussed at the earliest trade studies. And we don't even know the objective specs yet. If the RFI said XXX thrust and basic math says 2 WS-15 has XXX/2 thrust why would they even bother with a 2 engine config. There are also timelines and growth requirement. Say, the demo vehicle only needs XXX/4 tons of thrust, so CAC could use WS-10s and switch in VCEs later on when they start putting in more electronics.

This whole "chine bad" reminds me of the speculations about the T-50 being just a squashed Su-27 when it had its first flight. A whole lot of passively underselling others here.
As you can see some YF-23 influence in the T-50/SU-57 along with the unique Russian design philosophy.
 
The position some people took in this topic is too simplistic, amateurish I might say. To claim that the Chinese had to implement a 3 engine configuration because 2 has insufficient thrust would imply that they had already experimented with a 2-engine setup, found it lacking and modified the airframe to accept a new engine slotted in the centerline. So, the base air vehicle had insufficient thrust margins but somehow enough for drag and structural integrity?
This is a strawman argument.

Literally NOBODY is suggesting it was designed as 2 engines then somehow adapted to 3.

The suggestion made was that for speed of development, redundancy or commonality reasons it was designed around three engines of an existing type rather than design a larger engine that would allow a twin engine configuration.
 
Pardon me, was fighting internet issues yesterday.

"Wichita" and "Amarillo" are photos that have been digitally altered. Someone has added artificial noise. The only reason for adding it was to cover up the fake.
Wichita 2014 is a B-2, it's been pretty well established.

But yes it does appear to have an added noise layer for some reason.



I am sure someone at Chengdu is reading our posts. I thought of something: maybe the third engine isn’t real, but to fool us…like the XP-59 with the fake propeller.
But seriously, its GOT to be real, probably for a reason that is outrageously simple.
I'm assuming 1) raw thrust, 2) electrical generation, and 3) bleed air for whatever.


To make this rant vaguely defense related: I'm going to propose the crazy original and never before seen idea that there should be more than 1 company making fighter jets.
For what it's worth, there are 3 companies that were invited to bid on USAF NGAD, and IIRC they also bid on USN FAXX: Northrop-Grumman, LockMart, and Boeing.

NG dropped out of the USAF bid to focus on the USN contract.


My old company HR (Hydraulic Research) Textron (now Woodward) had developed some developmental fluidic flight control actuators back in the 1980s and I think some were tested by Northrop and NASA. Everybody was hot for fluidics back then but it died, no takers. Seemed to work well from what I understand. HR had also developed a fluidic actuation control "logic computer" but again, went by the wayside unfortunately.
So, like the valve core in an automatic transmission?



Chinese engines have in fact been more reliable than Russian ones from what I know, as the J-10s still mostly powered by AL-31s have crashed a few times due to engine trouble while the Sino-flankers which has been using WS-10 variants for nearly two decade has to my knowledge never have a crash specifically attributed to engine issues. Also imo Chinese building substandard stuff have been mostly disproven especially for their own use. FYI China actually has been making their own engines although at first mostly licensed clones or modified/improved variants of Soviet engines since the 60s, so they actually are quite experienced in making engines contrary to what most people believe.
That is the exact opposite of what I have heard.

Chinese engines way back in the day (1990s ish) were getting maybe 1/10 the TBO of the Russian engines they were copied from. And Russian engines at that time were getting maybe 1/10 the TBO of equivalent-era American engines like the F100 or F110.



They copied the YF-23 SERN (Single Expansion Ramp Nozzle) exhaust. Some folks speculated there are actuated flaps on the underside, not the case. Three-engine, medium attack/strike platform.
Disagree, I think it's going to be more like an interceptor with strike capabilities. Think "Stealthy MiG-31", not F-111A.

Not so hot in a dogfight because it's a ~90,000lb** airframe at combat weight, but it'll cruise at Mach 1.whatever all day.

** Assuming 3x WS10 and T:W ~=1 at combat weight.
 
If 2 engines don’t have the specific impulse to provide sufficient thrust to maintain supercruise at the elevated inlet temperature conditions, three engines won’t either. They will just burn more fuel. AB thrust is a different beast, but three engines doesn’t necessarily help supercruise.
 
Well remember to carry extra fuel and an extra engine when an engine off means lower thrust to weight ratio, each engine needs fuel.

The engines to generate electricity are not activated by water (as if they were in a coal plant), they need to spend fuel, the most logic explanation is like DC-10 and A-300, its engines are not as good as those planned for western fighters.

The J-36 very likely has engines with lower thermal efficiency, if the B-21 indeed uses 2 engines how come The B-21 can be powered with 2 engines, then NGAD with lower weight will fly much faster.

(now I will be honest all this is speculation) I doubt China has a reliable engine since in the case of both the USA and Russia went for single engined aircraft Su-75 and F-35, while J-35 has 2 engines.

But China like the soviet Union needs propaganda, who knows but in my humble opinion their engine technology still is behind because F135 is the most powerful engine operational and perhaps Russia has something similar
I agree with most points:
1) Reliability is a good point - although, as we know next to nothing about it we should probably reserve opinion until some data comes in.
2) Engines vs. consumption is also a good point - might dictate why the J-36 is so big to achieve that mission. Three engine implementation might have dictated the size to carry enough onboard fuel. Might also be something completely different.
3) Propaganda - this I disagree with, every nation needs propaganda. Chinese, USSR, USA, Europe, Africa all propaganda is the same. The point is to raise moral and rally the troops (people). Looking at mainstream media in all countries I travel through these days, its nothing but propaganda wherever I go. I also don't see what would connection would propaganda have with a third engine? Perhaps I've missed something?
 
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I agree with most points:
1) Reliability is a good point - although, as we know next to nothing about it we should probably reserve opinion until some data comes in.
2) Engines vs. consumption is also a good point - might dictate why the J-36 is so big to achieve that mission. Three engine implementation might have dictates the size to carry enough onboard fuel. Might also be something completely different.
3) Propaganda - this I disagree with, every nation needs propaganda. Chinese, USSR, USA, Europe, Africa all propaganda is the same. The point is to raise moral and rally the troops (people). Looking at mainstream media in all countries I travel through these days, its nothing but propaganda wherever I go. I also don't see what would connection would propaganda have with a third engine? Perhaps I've missed something?
there is no point going into a very long speculation let us wait, if something is true is that all hidden things will be unveiled and be known, so for those things we need time, time will tell.
 
This is a strawman argument.

Literally NOBODY is suggesting it was designed as 2 engines then somehow adapted to 3.

The suggestion made was that for speed of development, redundancy or commonality reasons it was designed around three engines of an existing type rather than design a larger engine that would allow a twin engine configuration.
That was me jumping to conclusion, and I apologize to those I've wronged with that. Nevertheless the basis of my argument remains
Those stuff are discussed at the earliest trade studies. And we don't even know the objective specs yet. If the RFI said XXX thrust and basic math says 2 WS-15 has XXX/2 thrust why would they even bother with a 2 engine config. There are also timelines and growth requirement. Say, the demo vehicle only needs XXX/4 tons of thrust, so CAC could use WS-10s and switch in VCEs later on when they start putting in more electronics.
And the J-50 that flew the exact same day used two engines despite being only slightly smaller. And the early J-20 prototypes flew with WS-10s. But they were obviously designed from the start to use WS-15, paper only at that time.
 
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Pardon me, was fighting internet issues yesterday.


Wichita 2014 is a B-2, it's been pretty well established.

But yes it does appear to have an added noise layer for some reason.




I'm assuming 1) raw thrust, 2) electrical generation, and 3) bleed air for whatever.



For what it's worth, there are 3 companies that were invited to bid on USAF NGAD, and IIRC they also bid on USN FAXX: Northrop-Grumman, LockMart, and Boeing.

NG dropped out of the USAF bid to focus on the USN contract.



So, like the valve core in an automatic transmission?




That is the exact opposite of what I have heard.

Chinese engines way back in the day (1990s ish) were getting maybe 1/10 the TBO of the Russian engines they were copied from. And Russian engines at that time were getting maybe 1/10 the TBO of equivalent-era American engines like the F100 or F110.




Disagree, I think it's going to be more like an interceptor with strike capabilities. Think "Stealthy MiG-31", not F-111A.

Not so hot in a dogfight because it's a ~90,000lb** airframe at combat weight, but it'll cruise at Mach 1.whatever all day.

** Assuming 3x WS10 and T:W ~=1 at combat weight.
Fluidics are used in automatic transmissions related to shifting logic.
 
That was me jumping to conclusion, and I apologize to those I've wronged with that. Nevertheless the base of my argument remains

And the J-50 that flew the exact same day used two engines despite being only slightly smaller. And the early J-20 prototypes flew with WS-10s. But they were obviously designed from the start to use WS-15, paper only at that time.
Actually, it just occurred to me that if the two side engines are variable cycle that would be the most important reason to put an electrical gas generator in the middle. Because the moment those engines engines switch to ramjet (or scramjet) mode, the turbine (and any attached APUs) would not be moving and hence not producing any electricity. To ensure the aircraft still has enough power for powerful radar and lasers you would need an electrical turbine. What do you think?
 
Actually, it just occurred to me that if the two side engines are variable cycle that would be the most important reason to put an electrical gas generator in the middle. Because the moment those engines engines switch to ramjet (or scramjet) mode, the turbine (and any attached APUs) would not be moving and hence not producing any electricity. To ensure the aircraft still has enough power for powerful radar and lasers you would need an electrical turbine. What do you think?
The article by the J-36 Chief Designer makes clear that ramjets etc would delay things.

You might want to read up on VCE/variable cycle engines, they do not magically turn into ramjets. VCE is about changing the bypass ratio on a turbofan.
 
Yes, Chinese are first and foremost pragmatic. So that makes sense.

VCE is many things to many people from what I read - including a cycle from turbofan to turbojet to ramjet from what I see: AstroMechanica... I do stand corrected, I use the terms as I find them. I am just a hobbyist.
 
I'm talking about three stream / VCE engines developed under Adaptive Versatile Engine Technology (ADVENT) and the Adaptive Engine Technology Development (AETD) programs.

Variable cycle turboramjets are possible but a way off. J-36 is also not a hypersonic airframe.
 
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That was me jumping to conclusion, and I apologize to those I've wronged with that. Nevertheless the basis of my argument remains

And the J-50 that flew the exact same day used two engines despite being only slightly smaller. And the early J-20 prototypes flew with WS-10s. But they were obviously designed from the start to use WS-15, paper only at that time.
Remember that the Chinese also have a need for Flanker-replacements for their carriers, just like how the US has both the USAF NGAD and the USN F/A-XX.

I suspect that the J-50 is the naval aircraft while the J-36 is the land-based version.
 
Chinese engines way back in the day (1990s ish) were getting maybe 1/10 the TBO of the Russian engines they were copied from. And Russian engines at that time were getting maybe 1/10 the TBO of equivalent-era American engines like the F100 or F110.
Thats quite outdated, they've been using WS-10 on their flankers ever since 2008 which is basically 2 decades from the 90s its safe to say in that time their engines improved to atleast as reliable as the Russian ones they have or there's no reasons to put them in their flanker fleet. Fast forward until recently I've heard over on SDF that the latest WS-10 engine's lifespan is as long as the latest Russian engines, with WS-15 likely to improve further over that standard. Although we don't have numbers for their military engines, their latest civilian engines seem to be nearly on par with similar western engines. The AES-100 turboshaft engine in development stages have showed a TBO of 3000 hours compared to the PT-6A-140's TBO of 4000 hours and is likely to improve as its still in active development.
 
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First time that I have heard that the J-50 is the Naval variant and the J-36 is the land based variant Scott Kenny, I had thought that both variants would be bought by the PLAAF and PLAN. :confused:
 
They copied the YF-23 SERN (Single Expansion Ramp Nozzle) exhaust. Some folks speculated there are actuated flaps on the underside, not the case. Three-engine, medium attack/strike platform.
I wouldn't say copied, most likely just used the same concept. However about the lower flaps being able to move, what about the picture that shows it in a seemingly different position and the fact that they are 3 separate pieces and not a single block like on the YF-23
 
If 2 engines don’t have the specific impulse to provide sufficient thrust to maintain supercruise at the elevated inlet temperature conditions, three engines won’t either. They will just burn more fuel. AB thrust is a different beast, but three engines doesn’t necessarily help supercruise.

Could you go into more detail? As a non engineer I do not understand the concept, and I had assumed that the extra dry thrust of three engines was needed for supersonic cruise.
 
First time that I have heard that the J-50 is the Naval variant and the J-36 is the land based variant Scott Kenny, I had thought that both variants would be bought by the PLAAF and PLAN. :confused:

There is no way a version of “J-36” could be an embarked aircraft for a number of dimensional reasons, even assuming augmented engines. Not at all clear what J-50 is; I am not yet absolutely convinced it is manned from what little I’ve seen.
 
I wouldn't say copied, most likely just used the same concept. However about the lower flaps being able to move, what about the picture that shows it in a seemingly different position and the fact that they are 3 separate pieces and not a single block like on the YF-23
If the surfaces deflect downwards then these could be used for additional drag say for approach and landing, I'll have to take a closer look if that is the case.
 
If the surfaces deflect downwards then these could be used for additional drag say for approach and landing, I'll have to take a closer look if that is the case.
China-J-36-Fighter.jpg
This picture shows the lower flaps most clearly, you could see they are definitely separate pieces and the outer two seem to be slightly lowered compared to the middle one.

PS: This picture was clipped from a video of it right outside the airfield coming in to land, if this helps
 
The DC-10 had three engines because of the regulations at the time (and being larger than the A-300..)
The original "Kolk machine" spec drawn up by Frank Kolk at American was a twin. United, however, had a major base at Denver and needed to reach either coast out of there on a hot day. Eastbound it was a matter of takeoff and initial climb at high TOGW after losing an engine. Westbound it was sustaining min alt over the Rockies after an en route failure. Hence three engines.

The CF6-50 on the A300 (which could meet the Denver req) was 25% more powerful than the DC-10-10 engine.
 
I really wouldn't know. It is a large aircraft so cooling (especially at higher altitude) might not necessarily be an issue? I am more of the opinion that the third engine is dedicated to power generation but who knows, Chines are practical and pragmatic. If they see another use for it why not?
Cooling is generally more difficult at altitude (density).
 
Could you go into more detail? As a non engineer I do not understand the concept, and I had assumed that the extra dry thrust of three engines was needed for supersonic cruise.
You might want to read thru this thread: https://www.secretprojects.co.uk/th...ruise-performance-and-2nd-stage-engine.38521/

Short version - for supersonic thrust, you need exhaust velocity faster than the speed of the aircraft. AB achieves this high velocity by adding a ton of heat to the exhaust. At Mil power, you need a very high exhaust pressure (i.e. nozzle pressure ratio) to get the necessary exhaust velocity. Once you reach the aircraft velocity equal the exhaust velocity, you have zero net thrust. Adding a third engine in this condition still gives you zero net thrust.

In addition to high NPR (engine pressure ratio x ram pressure ratio = nozzle pressure ratio) needed to supersonic thrust, most engines run into a turbine and / or rotor speed limit as the inlet temperature goes up with increasing Mach number. At any Mn / inlet temperature above this, the engine performance progressively goes down with both airflow and engine pressure ratio decreasing, lowering NPR and exhaust velocity, which reduces the supersonic thrust. And unless the 3rd engine design is optimized for a different part of the flight envelope, it is just as impacted by increasing inlet temperatures as the other two.
 
The AES-100 turboshaft engine in development stages have showed a TBO of 3000 hours compared to the PT-6A-140's TBO of 4000 hours and is likely to improve as its still in active development.

Comparing one with a proven 50-year old design is not a smart move, and it would be too early to claim the TBO hours.
 
TBO for the Chinese engine is quoted official figures iirc
Again it would be too early to claim, as I stand for

On mentioning the comparison between AL-31F and WS-10 issues, maybe you can elaborate more on how the PLAAF "maintain" their engines during the early stage. Of course the logistic and attitude of Russians on maintenance issue didn't help either
 
First time that I have heard that the J-50 is the Naval variant and the J-36 is the land based variant Scott Kenny, I had thought that both variants would be bought by the PLAAF and PLAN. :confused:
J-36 is just too big, doesn't fit on any existing carrier elevators even if you hang half the airframe over the edge of the deck thanks to where the main landing gear is located.

So while it's possible the PLANAF might buy a few squadrons of J-36s to strictly fly from shore bases, I find it unlikely that the Navy would buy multirole interceptors that cannot fit on their carriers.
 
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Thats quite outdated, they've been using WS-10 on their flankers ever since 2008 which is basically 2 decades from the 90s its safe to say in that time their engines improved to atleast as reliable as the Russian ones they have or there's no reasons to put them in their flanker fleet.
Basic technological independence, especially in an environment of ongoing legal disputes on flanker family(risk of outright cut off).
Making use of huge investment into ws-10.
Learning through use.
Keeping money at home working, within RMB loop.
Inner politics(engine manufacturer has teeth).
National pride, too.

Overall, you replace engines with local ones as soon as you can, immediately, even if they're good for not very reliable hundreds of hours only.
It's the right thing to do, and it's the only way to get started.

Realistically, ws-10 reached metrics matching 1990s al-31fs(not high, but a predictable bar) when they were displaced on j-10 and j-20 airframes, which is very late 2010s.

Which isn't exactly 117s level (2000s engine), much less the much hotter f-119.
 
Realistically, ws-10 reached metrics matching 1990s al-31fs(not high, but a predictable bar) when they were displaced on j-10 and j-20 airframes, which is very late 2010s.

Go somewhat ahead of that by maybe a decade or so when they put them comfortably onto domestic Flankers replacing the Al-31Fs.
 
If you have read the chief designer's paper, you will know that he said that the design of the next generation fighter jet is completed together with the engine design. The design characteristics of the next generation fighter jet he mentioned are four:
1) More comprehensive flight performance, able to balance deep penetration and maneuverability at typical combat points.
2) Higher stealth performance, expanding frequency and spatial range, enabling it to penetrate deep into high threat areas.
3) A larger weapon payload that can support sustained combat and engage in combat with enemy superior forces with a small number of troops.
4) Strong situational awareness and electronic warfare capabilities, able to prioritize evading enemy detection and gain a first sight, first shot advantage when unavoidable
 

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If each NGJ-MB pumps out 82 kW of power, having some fraction of three motors available to power an EW suite comparable to what we’ve seen on the J-16D (as a first increment) makes a ton of sense to me. The J-36 planform has good volume to work with for arrays, power generation, cooling, etc. three WS-15s seems like a lot to be able to draw from, and these engineers will hammer away until they get a good VCE and there will be even more juice to transmit.

Fighter, bomber, striker, cruiser whatever - labels suck this airframe just gives you fun options.
 

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