Chengdu J-20 5th Generation Aircraft News & Discussions

[Beast]

The pilot never used the word "supercruise".

The pilot said 一进了超音速(就是它的天下了), which translates to "once it enters supersonic speed"...

Supersonic speed and supercruise are very different.

If the pilot wanted to say that the J-20 could supercruise, the pilot would've used a different term, something like "超音速巡航".


Given what the pilot said, the best we can speculate is that J-20 can possibly supercruise, and given J-20 is not using WS-15 and is likely using Al-31F-M2, it is likely that J-20's supercruise is currently in the low Mach 1 regime at best.



As for my motivations, I think you should have a look over at the history of my posts on SDF and CDF and take a look at my website as well. I think it's been posted on this forum a few times before.



Al-31F-M2 and 117S engines are different. Al-31FM2 is from Salut, 117S is from Saturn.

I'm not saying J-20 is using 117S, I'm saying J-20 is using Al-31F-M2.
Obviously J-20 didn't suddenly use Al-31F-M2 in December 2016, they would've used that engine since at least the s/n 2011 prototype which flew in 2014 if not earlier since the original prototype/demonstrator s/n 2001.


The Russians are having challenges developing izd 30, but China's also having troubles developing WS-15, I'm not sure what you're trying to say.

I'm not sure what you mean by saying Al-31FM2 is not real -- http://www.salut.ru/ViewTopic.php?Id=1459


Of course, we've never had confirmation of what kind of engine J-20 uses, however the most plausible explanation we have is that it uses an Al-31 variant. If J-20 is able to supercruise, then it is likely using an uprated Al-31 version like the Al-31FM2 which has been put forward for quite a while, and is also one of the primary powerplants that has been considered by Huitong and Deino as well
Certainly, the idea that J-20 is currently using WS-15 is absolutely ridiculous.

What you provide is only a link about Russian plan for an uprated engine called. AL-31 FM2. Russian has many great plans and we know Russian has many stuff never materialized. Can you provide me a proof of this magical AL-31 FM2 engine project has completed and used by Russian AF or exported to foreign customers?

It might not be WS-15 engine but it can never be AL-31 engine and not to mention of your FM2 series. Remember about the documentary of shenyang liming engine talking about fabricating parts for J-20 engines. If its your so called AL-31FM2 engine. Why would Shenyang Liming need to fabricated parts for it? It shall be a whole piece imported from salyut and with proper check and install on J-20. Care to explain?

 

[DragonHunter]

The J-20B is going to be 5++.

maybe 5+++

 

[Blitzo]

What you provide is only a link about Russian plan for an uprated engine called. AL-31 FM2. Russian has many great plans and we know Russian has many stuff never materialized. Can you provide me a proof of this magical AL-31 FM2 engine project has completed and used by Russian AF or exported to foreign customers?

actually the link I showed was about Sukhoi considering the Al-31FM2 for their aircraft, and that Salut had already demonstrated Al-31FM2 at 14,500 kgf in their test facility.


The existence of this engine and its performance should not be in any doubt, the question is whether J-20 is using it or not.


And let's be honest -- it is far more likely that J-20 is using an engine like Al-31FM2 (considering CAC's good relationship with their Russian engine suppliers for powering J-10A/B/C), than the idea that J-20 is using WS-15!

It might not be WS-15 engine but it can never be AL-31 engine and not to mention of your FM2 series. Remember about the documentary of shenyang liming engine talking about fabricating parts for J-20 engines. If its your so called AL-31FM2 engine. Why would Shenyang Liming need to fabricated parts for it? It shall be a whole piece imported from salyut and with proper check and install on J-20. Care to explain?

Who knows, maybe the documentary was wrong, maybe Shenyang Liming is involved in fabricating parts for Al-31FM2 (perhaps replacement parts), or the least possible reason is that J-20 may be using a WS-10 variant.


But J-20 definitely is not using WS-15 right now.

 

[Beast]

actually the link I showed was about Sukhoi considering the Al-31FM2 for their aircraft, and that Salut had already demonstrated Al-31FM2 at 14,500 kgf in their test facility.


The existence of this engine and its performance should not be in any doubt, the question is whether J-20 is using it or not.


And let's be honest -- it is far more likely that J-20 is using an engine like Al-31FM2 (considering CAC's good relationship with their Russian engine suppliers for powering J-10A/B/C), than the idea that J-20 is using WS-15!

I ask for a proof and you give me your personal opinion? Is this what you can do? Please provide solid proof of the so called magical AL-31 FM2 engine materialized or even exported. I dont know to hear your agenda. I need proof.

If such magical engine exist for export to PLAAF, there wouldn't even be a big roar about exporting Su-35 plane to PLAAF with Russian declare no separated engine sales.

 

[Asoka]

I usually don't come onto PDF because I usually spend my time at SDF and CDF, however I think your interpretation of the pilot's words are a bit too confident.

The pilot does indeed say that subsonic maneuverability is good, and supersonic maneuverability is excellent.

However, the pilot never mentions anything about supercruise, only that the aircraft's supersonic maneuverability is very good. Whether it achieves that supersonic speed through dry thrust (supercruise) or wet thrust/afterburner is unknown.


I personally think it is reasonable to interpret the pilot's words to mean the J-20 as it currently is may be able to supercruise, but the pilot's words definitely do not mean we can confidently proclaim J-20 is able to supercruise. It merely means we are able to speculate as to whether it can.



As to how J-20 can currently supercruise, I think it is even more incorrect to assume that it means J-20 is currently using WS-15. Deino has been complaining over on SDF before about how overzealous many people here are about WS-15, and frankly he's right.

If J-20 can supercruise, there are many explanations for it, beyond the unlikely prospect of WS-15 already being ready. For example, if J-20 can supercruise, first of all, at what speed? F-22 is said to be able to supercruise at mach 1.7-1.8. For J-20, if the pilot's words does mean J-20 can supercruise, does it mean J-20 can also supercruise at mach 1.7-1.8?

For all we know J-20 may only be able to supercruise at mach 1.0 or mach 1.1! Given that rather important qualification, if we are assuming J-20 can currently supercruise, and considering that WS-15 definitely are not on production J-20s (or even being tested on a J-20 to our knowledge), a logical conclusion is that J-20s may be able to supercruise using the uprated Al-31 variants that J-20 has been rumoured to use, like Al-31F-M2 which has a wet thrust of 145 kN. Compare that to F-22's F119 engine at 156 kN wet thrust, and consider that J-20 is a stealth fighter with internal weapon bays and more importantly J-20 fields a much more elongated delta airframe compared to F-22, and it becomes very plausible that J-20 may be able to supercruise at in the low Mach 1 regime using Al-31F-M2s as its powerplant.

Also consider that PAK FA using 117 (with a similar wet thrust of 147 kN) has also been claimed to be able to supercruise given Su-35 is able to supercruise using those same engines, and the idea that J-20 may be able to achieve supercruise using uprated Al-31F-M2 variant is quite plausible.


So, to conclude, there are two overarching speculative points we can derive:

1: the pilot's words in the videos do not confirm J-20 is able to supercruise, however his words do leave the possibility that J-20 may achieve supersonic speeds routinely, and this may be via supercruise.
2: if J-20 is able to supercruise, it is likely only in the low Mach 1 domain, because J-20 is not using WS-15 engines, however it may be able to supercruise in that domain using the uprated Al-31F-M2 engines that production aircraft are most likely using.

1.) Supersonic Cruise is commonly described as the ability to cruise at Mach 1.4 for at least 30 min, without the use of Afterburner.

Why not define just Supersonic Cruise as cruising just above Mach 1.0?

Because, due to shock wave, the drag in the transonic region, rises dramatically near Mach 0.8, and peaked at Mach 1.0, then drop gradually as speed goes up, and then rise again near Mach 2.

So, it's actually requires less power to fly, if you stay out of this transonic region.

"For all we know J-20 may only be able to supercruise at mach 1.0 or mach 1.1!"

So to tell a pilot to supercruise at Mach 1.0 or Mach 1.1 is simply ridiculous. You don't know what are you talking about.

2. "the pilot never mentions anything about supercruise, only that the aircraft's supersonic maneuverability is very good."

Yes, he didn't mention anything about supersonic cruise. He only unmistakably confirmed that J-20's supersonic maneuverability is outstanding.

However, what's maneuver at supersonic speed like, while you have to turn on the Afterburner?

It means you have to burn several times more fuel, while you are making violent maneuvers, which bleeds off your speed or energy quickly, and you must push the throttle to quickly replenish it.

While at subsonic speed, this is already bad enough. Most fighters have only several minutes of extra fuel to burn, when the Afterburner is engaged. (Remember, they have go to home. You can't burn all your fuel, while fighting)

At supersonic speed, the fuel burn rate is so much worse, if you do violent maneuvers, while engaging the afterburner. You can imagine travel at in car at 50km/h, and open all four car doors or slam on the brakes, suddenly, your car will decelerate quickly. And you have to step on the gas pedal to get back to 50km/h.

Now, you do the same at 100km/h, and also slowed way down, and you have to get back to 100km/h. This time, you have to spend so much energy to get back to 100km/h, because E = 1/2mv(2). That is kinetic energy goes up by the square of the velocity.

So, supersonic maneuverability requires so much more power from the engine, to push the plane to stay above the transonic region. That's why supersonic maneuverability requires a so much more powerful engine, than subsonic maneuverability. Supersonic maneuverability is meaningless if you can't stay above supersonic speed for a few minutes, because you have to engage AB constantly.

It's safe to say, if you have outstanding/world beating supersonic maneuverability, you have a powerful engine to replenish your lost energy quickly, to stay above supersonic for a long while, without AB. If you have to turn on AB, your fuel gauge hits BINGO, very quickly.

And its also safe to say, if have superior supersonic maneuverability, without use of AB, you can do supersonic cruise, without AB, because violent maneuvers requires so much more power than just cruising at constant speed.

If you think you can excellent supersonic maneuverability without the ability of supersonic cruise, you have no idea of what are you talking about.

 

[Blitzo]

I ask for a proof and you give me your personal opinion? Is this what you can do? Please provide solid proof of the so called magical AL-31 FM2 engine materialized or even exported. I dont know to hear your agenda. I need proof.

Whoa, let's slow down here with the holier than thou.

I've given you a much better argument and proof that you have for your belief that J-20 is using WS-15.


Let me repeat my position:

1: J-20 might be able to supercruise, however it might not be able to supercruise, based on the pilot's interview because he only talks about achieving "supersonic speed" and not "supercruise"
2: if J-20 is able to supercruise, it is most likely using an Al-31 variant, possibly Al-31FM2
3: J-20 most definitely is not using WS-15
therefore...
4: if you think Al-31FM2 is unlikely, then the simple answer you can reach is just that J-20 is unable to supercruise, and that J-20 is currently using vanilla Al-31 engines and is even more underpowered than it would be if it were using Al-31FM2

 

[Beast]

1.) Supersonic Cruise is commonly described as the ability to cruise at Mach 1.4 for at least 30 min, without the use of Afterburner.

Why not define just Supersonic Cruise as cruising just above Mach 1.0?

Because, due to shock wave, the drag in the transonic region, rises dramatically near Mach 0.8, and peaked at Mach 1.0, then drop gradually as speed goes up, and then rise again near Mach 2.

View attachment 415007

So, it's actually requires less power to fly, if you stay out of this transonic region.

"For all we know J-20 may only be able to supercruise at mach 1.0 or mach 1.1!"

So to tell a pilot to supercruise at Mach 1.0 or Mach 1.1 is simply ridiculous.

2. "the pilot never mentions anything about supercruise, only that the aircraft's supersonic maneuverability is very good."

Yes, he didn't mention anything about supersonic cruise. He only unmistakably confirmed that J-20's supersonic maneuverability is outstanding.

However, what's maneuver at supersonic speed like, while you have to turn on the Afterburner?

It means you have to burn several times more fuel, while you are making violent maneuvers, which bleeds off your speed or energy quickly, and you must push the throttle to quickly replenish it.

While at subsonic speed, this is already bad enough. Most fighters have only several minutes of extra fuel to burn, when the Afterburner is engaged. (Remember, they have go to home. You can't burn all your fuel, while fighting)

At supersonic speed, the fuel burn rate is so much worse, if you do violent maneuvers, while engaging the afterburner. You can imagine travel at in car at 50km/h, and open all four car doors or slam on the brakes, suddenly, your car will decelerate quickly. And you have to step on the gas pedal to get back to 50km/h.

Now, you do the same at 100km/h, and also slowed way down, and you have to get back to 100km/h. This time, you have to spend so much energy to get back to 100km/h, because E = 1/2mv(2). That is kinetic energy goes up by the square of the velocity.

So, supersonic maneuverability requires so much more power from the engine, to push the plane to stay above the transonic region. That's why supersonic maneuverability requires a so much more powerful engine, than subsonic maneuverability. Supersonic maneuverability is meaningless if you can't stay above supersonic speed for a few minutes, because you have to engage AB constantly.

It's safe to say, if you have outstanding/world beating supersonic maneuverability, you have a powerful engine to replenish your lost energy to stay above supersonic for a long while, without AB.

And its also safe to say, if have superior supersonic maneuverability without AB, you can do supersonic cruise, without AB, because violent maneuvers requires so much more power than just cruising.

Precisely.

It so absurd and insulting some trying to say the Chinese pilot are talking things without using their head by talking excellent supersonic maneuvrability about a plane that has limited or no supercruise at all.

Whoa, let's slow down here with the holier than thou.

I've given you a much better argument and proof that you have for your belief that J-20 is using WS-15.


Let me repeat my position:

1: J-20 might be able to supercruise, however it might not be able to supercruise, based on the pilot's interview because he only talks about achieving "supersonic speed" and not "supercruise"
2: if J-20 is able to supercruise, it is most likely using an Al-31 variant, possibly Al-31FM2
3: J-20 most definitely is not using WS-15
therefore...
4: if you think Al-31FM2 is unlikely, then the simple answer you can reach is just that J-20 is unable to supercruise, and that J-20 is currently using vanilla Al-31 engines and is even more underpowered than it would be if it were using Al-31FM2

How about the engine is not WS-15 but a WS-10x high thrust engine at 150Kn powered.
First you cant prove your magical AL-31FM2 engine really exist.
Secondly, Shenyang Liming has proved they are fabricating parts for J-20 engines. So how can it be an imported engines for J-20?

 

[Blitzo]

1.) Supersonic Cruise is commonly described as the ability to cruise at Mach 1.4 for at least 30 min, without the use of Afterburner.

Why not define just Supersonic Cruise as cruising just above Mach 1.0?

Because, due to shock wave, the drag in the transonic region, rises dramatically near Mach 0.8, and peaked at Mach 1.0, then drop gradually as speed goes up, and then rise again near Mach 2.

View attachment 415007

So, it's actually requires less power to fly, if you stay out of this transonic region.

"For all we know J-20 may only be able to supercruise at mach 1.0 or mach 1.1!"

So to tell a pilot to supercruise at Mach 1.0 or Mach 1.1 is simply ridiculous.

2. "the pilot never mentions anything about supercruise, only that the aircraft's supersonic maneuverability is very good."

Yes, he didn't mention anything about supersonic cruise. He only unmistakably confirmed that J-20's supersonic maneuverability is outstanding.

However, what's maneuver at supersonic speed like, while you have to turn on the Afterburner?

It means you have to burn several times more fuel, while you are making violent maneuvers, which bleeds off your speed or energy quickly, and you must push the throttle to quickly replenish it.

While at subsonic speed, this is already bad enough. Most fighters have only several minutes of extra fuel to burn, when the Afterburner is engaged. (Remember, they have go to home. You can't burn all your fuel, while fighting)

At supersonic speed, the fuel burn rate is so much worse, if you do violent maneuvers, while engaging the afterburner. You can imagine travel at in car at 50km/h, and open all four car doors or slam on the brakes, suddenly, your car will decelerate quickly. And you have to step on the gas pedal to get back to 50km/h.

Now, you do the same at 100km/h, and also slowed way down, and you have to get back to 100km/h. This time, you have to spend so much energy to get back to 100km/h, because E = 1/2mv(2). That is kinetic energy goes up by the square of the velocity.

So, supersonic maneuverability requires so much more power from the engine, to push the plane to stay above the transonic region. That's why supersonic maneuverability requires a so much more powerful engine, than subsonic maneuverability. Supersonic maneuverability is meaningless if you can't stay above supersonic speed for a few minutes, because you have to engage AB constantly.

It's safe to say, if you have outstanding/world beating supersonic maneuverability, you have a powerful engine to replenish your lost energy to stay above supersonic for a long while, without AB.

And its also safe to say, if have superior supersonic maneuverability without AB, you can do supersonic cruise, without AB, because violent maneuvers requires so much more power than just cruising.

.... the problem is that the pilot only said "一进了超音速" which means "once entering supersonic speed". The pilot did not say "超音速巡航" which is supersonic cruise.


In other words, there is no precondition for us to suspect that J-20 must be able to achieve the definition of supercruise being Mach 1.4 for at least 30 min without afterburner based on the pilot's words (even assuming your definition of supercruise is any sort of universally accepted definition).


In fact, based on the pilot's interview there is no reason to suspect that the J-20 is even able to achieve mach 1 on dry thrust/without afterburner -- for all we know he may be saying that the J-20's supersonic maneuverability is achieved with afterburner!

We are being very generous if we want to even assume that J-20 is able to achieve mach 1 on dry thrust based on the pilot's interview in the first place.



And yes, you're right, supersonic maneuverability does not mean as much tactically if you have to use afterburner to achieve supersonic speed in the first place. However, at the end of the day the ability for us to interpret the pilot's words must be dependent on his words.

He made no statement about the combat effectiveness of J-20's supersonic maneuverability, only that its supersonic maneuverability was excellent. In other words, based on his words, we cannot exclude the possibility that he's simply saying J-20's supersonic maneuverability is when it acheives supersonic speeds via AB.


As for supercruising at mach 1 or 1.1 -- that was just an example. The point is that if J-20 were able to supercruise right now using its current non-WS-15 engines, it would likely be on the lower end of the mach 1 regime, lower than F-22's mach 1.7-1.8.

 

[Asoka]

Whoa, let's slow down here with the holier than thou.

I've given you a much better argument and proof that you have for your belief that J-20 is using WS-15.


Let me repeat my position:

1: J-20 might be able to supercruise, however it might not be able to supercruise, based on the pilot's interview because he only talks about achieving "supersonic speed" and not "supercruise"
2: if J-20 is able to supercruise, it is most likely using an Al-31 variant, possibly Al-31FM2
3: J-20 most definitely is not using WS-15
therefore...
4: if you think Al-31FM2 is unlikely, then the simple answer you can reach is just that J-20 is unable to supercruise, and that J-20 is currently using vanilla Al-31 engines and is even more underpowered than it would be if it were using Al-31FM2

You are simply presume that WS-15 is not ready, not installed on J-20 right now, and might not even tested on J-20 yet, so you presume that J-20 can't do supersonic cruise like F-22, even though the pilot clearly said J-20's supersonic maneuverability is world beating.

All you are trying to do is to deny J-20 is using WS-15.

There is absolutely no reports indicating Su-27 and Su-30 can do supersonic cruise on AL-31 variants. Not even Mach 1.1.

 

[Deino]

@Deino will it be a carry-on date today?

Actually no. Right now I enjoy my familiy-holydays in Liguria, Italy and this discussion with the fan-boys is actually nothing but boring and stupid. So if they want to boast their own feelings, so its fine ... I am actually glad with what I see.

Greetings and all the best,
Deino

@Blitzo ... Thanks for Your arguments but they will not chance anything.

 

[ChineseTiger1986]

The AL-31F has already been disproved by China's official media.

Why is someone still arguing on this? Even the most staunch AL-31F supporters in the CD forum have conceded their defeat.

At this moment, still arguing the J-20 using any AL-31F variant is just as ridiculous as saying the Type 002 will keep using the steam catapult.

 

[Blitzo]

How about the engine is not WS-15 but a WS-10x high thrust engine at 150Kn powered.
First you cant prove your magical AL-31FM2 engine really exist.
Secondly, Shenyang Liming has proved they are fabricating parts for J-20 engines. So how can it be an imported engines for J-20?

Okay, so what do you think is more likely?

A: the documentary's specific words in that scene were real and J-20 is using a new super WS-10 variant (like WS-10IPE, whose development progress we have not heard of for a while), for a few years, at least since prototype s/n 2011?
B: the documentary's specific words in that scene were wrong, and J-20 is using a known, Russian engine that was in late stages of development by the year 2012 (remember s/n 2011 first flew in 2014)? (also with the possibility that Shenyang Liming may be able to build replacement parts for an imported Russian engine)

I consider the latter to be more likely, because for A to be true then it means the super WS-10 variant must have finished testing and was ready for J-20 s/n 2011 in the year 2014, which we know is very unlikely.



Furthermore, I think we can at least settle that J-20 definitely is not using WS-15

 

[Beast]

The AL-31F has already been disproved by China's official media.

Why is someone still arguing on this? Even the most staunch AL-31F supporters in the CD forum have conceded their defeat.

At this moment, still arguing the J-20 using any AL-31F variant is just as ridiculous as saying the Type 002 will keep using the steam catapult.

You see somebody trying to play around with the word supercruise or even suggest a plane underpowered can have excellent supersonic maneurability.

Then they will come up with fantasy uprated Ruskie engine at 145kn suddenly exported to China after so much saga for Su-35 sales to PLAAF with regards to engine sales.

 

[Asoka]

" is far more likely that J-20 is using an engine like Al-31FM2"

Find me a link that says the Russian has shipped Al-31FM2 to China. This engine is an phantom. The russian has announced it on 2012, but has no more news since then. Mostly likely, it was never developed, because there is no customers for it. Why not simply use the AL-41, or 117S?

 

[Blitzo]

You are simply presume that WS-15 is not ready, not installed on J-20 right now, and might not even tested on J-20 yet, so you presume that J-20 can't do supersonic cruise like F-22, even though the pilot clearly said J-20's supersonic maneuverability is world beating.

All you are trying to do is to deny J-20 is using WS-15.

Logically speaking, for us to believe J-20 is using WS-15 we must first have strong rumours that WS-15 has completed development and is ready for J-20.

We do not have any strong rumours suggesting WS-15 has completed development.

I want J-20 to use WS-15 as much as the next person, but I also don't want to lie to myself. We cannot put the cart before the horse, and we must accept that for us to suspect J-20 may be using WS-15 must first be preceded by strong rumours, indications, or proof that WS-15 has reached a state of development where it is ready for that.

For example, photos of WS-15 being tested on the Il-76 engine test bed, or rumours of WS-15 reaching a certain test or development milestone from a well regarded big shrimp.

There is absolutely no reports indicating Su-27 and Su-30 can do supersonic cruise on AL-31 variants. Not even Mach 1.1.

Su-35BM was claimed to be able to supercruise (back when it was still called that) lenta.ru/articles/2008/07/04/su35/

Certainly, it is far more likely that Su-35 or PAK FA or J-20 are able to supercruise on high rated Al-31 variants, than J-20 using WS-15 right now.