Chengdu J-20 5th Generation Aircraft News & Discussions

[Asoka]

oh that is over capability for J-20 various site state that WS-15 have a thrust of 18 to 19 tons which it will slightly inferior or same thrust as F-135


oh that is over capability for J-20 various site state that WS-15 have a thrust of 18 to 19 tons which it will slightly inferior or same thrust as F-135

Various sites say that. But those are not official figures. Even if they are official figures, I would suspect they are not very accurate. The performances of J-20 and F-22 and T50 are of the highest state secrets. They have no need or obligations to tell anyone accurately. They are not intend for export. So they don't need to disclose them to anybody.

Even if they do export them, they would make the customers sign a non-disclosure agreement to keep those data secret.

 

[Ultima Thule]

Various sites say that. But those are not official figures. Even if they are official figures, I would suspect they are not very accurate. The performances of J-20 and F-22 and T50 are of the highest state secrets. They have no need or obligations to tell anyone accurately. They are not intend for export. So they don't need to disclose them to anybody.

Even if they do export them, they would make the customers sign a non-disclosure agreement to keep those data secret.

you know the thrust of WS-15 and no ones knows nothing, you are also guessing and assuming nothing more

 

[grey boy 2]

A little friendly comparison between J-20 and T-50

 

[Asoka]

you know the thrust of WS-15 and no ones knows nothing, you are also guessing and assuming nothing more

I am guessing the thrust of the WS-15. That I admit. By guessing, we could establish the lower bound and upper bound values of many things. Engineers and scientists routinely do that.

 

[CAPRICORN-88]

I am guessing the thrust of the WS-15. That I admit. By guessing, we could establish the lower bound and upper bound values of many things. Engineers and scientists routinely do that.

Tell me, who else is not guessing in here?

But there are ways to decipher the mystery. The slimest tell tale indications that China deliberately gave away as a clue.

1. Sound of the engine (Which they cannot hide anyway)

2. The vertical thrust without utilizing AB. (This is done deliberately)

However if one stick to an argument for a credible source as a form of verification then it will probably not happened until China offer the J-20 for export.

Right now, it remains TOP SECRET.

And for those F35 fanboys who believe that the single engine F35 is all it takes to counter the J-20, think again.

Even the experts can the Pentagon is in a state of trepidation as this point as they expects the J-20 to be in service only after 2020 and more like 2015. The F-35 fanboys will be in for a big surprise but I won't be.

That is why I find Asok postings very interesting.

Thanks bro. Asok.

Why is the Pentagon planning to revive the production of the F-22 Raptor if the F35 Lightning is such a superior stealth fighter?

 

[Asoka]

But you are not Engineer or scientists your upper bounds too much, which shows you that you lives too much in your wishful thinking and fairy tales, the reasonable guess thrust of WS-15 as same as F-135

I studied Electrical Engineering in University. I worked as a software engineer with US Defense Company in all my working life in US. We make Communication, Control, Intelligence, and Command equipments for Pentagon. While I don't have a Ph.D, all my colleagues have at least a Master and Ph.D in various fields.

Well, if my upper bound is too high, please use method of estimation I have shown to come up with your own estimates.

I would love to see you and Deino and others to do the same and see what values you would come up.

Not very hard at all. You can use a calculator to do the simple math.

 

[Asoka]

Tell me, who else is not guessing in here?

But there are ways to decipher the mystery. The slimest tell tale indications that China deliberately gave away as a clue.

1. Sound of the engine (Which they cannot hide anyway)

2. The vertical thrust without utilizing AB. (This is done deliberately)

However if one stick to an argument for a credible source as a form of verification then it will probably not happened until China offer the J-20 for export.

Right now, it remains TOP SECRET.

And for those F35 fanboys who believe that the single engine F35 is all it takes to counter the J-20, think again.

Even the experts can the Pentagon is in a state of trepidation as this point as they expects the J-20 to be in service only after 2020 and more like 2015. The F-35 fanboys will be in for a big surprise but I won't be.

That is why I find Asok postings very interesting.

Thanks bro. Asok.

Why is the Pentagon planning to revive the production of the F-22 Raptor if the F35 Lightning is such a superior stealth fighter?

Thanks Bro, @CAPRICORN-88. Truth sometimes stare in our face. But we are so ingrained in our out dated thinking, that we can not change. Someone has said that "Science advances by one death at a time". Because the old timers simply have trouble accepting the new theory, despite mounting evidences.

China will never release the true performance figures of J-20 to the public. It's TOP SECRET.

We can only guess. Nothing wrong with that. I am just having fun. My life is not depend on whether I am right on the number or not.

1.) The sound of the engine was a big indicator that J-20, version 2001 has a new engine that is neither WS-10 nor Al-31FN. That was obvious to a lot of people.

2.) The white nozzles J-20, version 2001 was another indicator, but was ignored by most people.

3.) I didn't catch on the fact that J-20 could climb vertically with Dry Thrust alone, until someone pointed out at the China Air show. If we look at the old videos, J-20 has done that before.

4.) I also didn't catch on to the fact, until recently, that neither WS-10X nor AL-31FN could enable J-20 to do Supersonic Cruise and thus has Supersonic Maneuverability. That these two requirements are part of the 4S requirements of a 5th generation fighter that J-20 is aim for.

Without a engine that is sufficiently powerful enough to enable Supersonic Cruise, a big part of J-20 flight envelope is missing. It's structural strength will not be able to be sufficiently tested to the maximum, and its highly complex digital Flight Control System will not be able to test the Supersonic Maneuverability at all.


5.) If you think that is no problem, one could always test that later, when WS-15 is available, by loosen a few screws and pop in the new engine. And in the meantime, lets produce several hundreds of J-20. Then, I really think you have no idea what you are talking about.

6.) All of the above could be easily missed by outsiders, who are not informed about aeronautical engineering. This is not an indication of having low IQ, just an indication that we don't have the experiences.

7.) The vertical climb, without AB, at the China Airshow is an unmistakable sign that the engine CANNOT be WS-10X nor AL-31FN.

8.) There is only three candidates that China could use to power J-20, namely, WS-10X, AL-31FN, and WS-15.

9.) Now, that WS-10X, AL-31FN has been eliminated by the vertical climb demo, we have only the WS-15 left.

10.) There is no evidence that this engine could not be WS-15. Evidence or reports like it's canceled, its delayed, it's unreliable, its performances failed to meet the requirements, etc . . . are entirely absence.

11.) Now, if there are such strong and persistent reports that those negatives are true. Then, we have to also left out WS-15. But there isn't any.

12.) So, now, that we have eliminated the other two possibilities, we have got the only choice left, that J-20 is running WS-15.

"Once you eliminate the impossible, whatever remains, no matter how improbable, must be the truth." - Sherlock Holmes.

 

[Deino]

Guys ... can we stop this ???

Deino

 

[ptldM3]

A little friendly comparison between J-20 and T-50

What are you trying to compare exactly? One of the first pak-fa prototypes with no paint to one of the latest J-20 prototypes with pain?

If you want to passive aggressive insult the pak-fa atleast compare the latest painted prototype.

As for @Asok, you don't need afterburners in an underpowered aircraft with a thrust to weigh ratio under 1:1 to go vertically. The kenetic energy alone will be enough.

 

[Asoka]

What are you trying to compare exactly? One of the first pak-fa prototypes with no paint to one of the latest J-20 prototypes with pain?

If you want to passive aggressive insult the pak-fa atleast compare the latest painted prototype.

View attachment 367061


As for @Asok, you don't need afterburners in an underpowered aircraft with a thrust to weigh ratio under 1:1 to go vertically. The kenetic energy alone will be enough.

"you don't need afterburners in an underpowered aircraft with a thrust to weigh ratio under 1:1 to go vertically. The kenetic energy alone will be enough."

Really? Show me an example, with a video clip, please.

 

[ptldM3]

"you don't need afterburners in an underpowered aircraft with a thrust to weigh ratio under 1:1 to go vertically. The kenetic energy alone will be enough."

Really? Show me an example, with a video clip, please.

Here are gliders with zero thrust.

Here is a 757

 

[Asoka]

Here are gliders with zero thrust.

Here is a 757

Thanks for the beautiful videos!
Let me give my opinions of them.

The glider is impressive. It is using its own kinetic energy for the loop. But its not like a sustained vertical climb demonstrated by J-20.

The 757 is climbing at an impressive 70 degree angle, but not vertical. It is using its kinetic energy and lifting force from the wings to do the climb, not just the raw engine thrust.

When you are vertical, the wings don't contribute upward lifting force. And when you are vertical for even just for a few seconds, the plane's entire body acts as a giant wind brake, dropping your horizontal speed quickly to below stall speed.

So you would have to rely on your engine's raw power to lift you up vertically, like a rocket, after a few seconds. That means your Thrust to Weight Ratio must be > 1 in an extended vertical climb.

This sudden pointing the nose vertically is known as the Super-cobra maneuver, made famous by the Flankers. Notice how fast its horizontal speed drops.

Notice too, this Flanker is not climbing up much, its just hanging there in mid air. Probably, the pilot did not push the throttle to make thrust greater than the weight.

 

[Deino]

...
As for @Asok, you don't need afterburners in an underpowered aircraft with a thrust to weigh ratio under 1:1 to go vertically. The kenetic energy alone will be enough.

Exactly what I try to say since pages !!!

Again: that brief blurred video shows simply nothing, not a sustained climb nor anything impressive. Simply nothing at least to assume such calculations.
I'm sure these guys at CAC are still laughing ...

As such this whole assumption on vertically climbings, thrust to weight ratio and that calculation up to +210 kN is simply wrong since the basic statement on which all this calculation is based on is wrong.

Deino

 

[ptldM3]

The glider is impressive. It is using its own kinetic energy for the loop.

Yes, it never went vertically for long but nevertheless, it was going vertically with zero thrust.

But its not like a sustained vertical climb demonstrated by J-20.

By those standards the J-20 never had a sustained vertical climb either, a true sustained vertical climb would be until the aircraft could not climb anymore and every aircraft has its altitude limit. The point is any aircraft can go virtually even if it has horrible thrust to weight ratios, granted it has enough airspeed when attempting a vertical climb.

The 757 is climbing at an impressive 70 degree angle, but not vertical.

At the very end of the video it went full virtical.

It is using its kinetic energy and lifting force from the wings to do the climb, not just the raw engine thrust.

Yes, that's what I said in the very beginning. Forward moment can make any aircraft go virticall.

When you are vertical, the wings don't contribute upward lifting force. And when you are vertical for even just for a few seconds, the plane's entire body acts as a giant wind brake, dropping your horizontal speed quickly to below stall speed.

This move is known as the Super-cobra manuever, made famous by the Flankers.

Going virtically does not act as "giant wind break". A Cobra and virtical flight are two different things. The Cobra is due to a high angle of attack and a quick jerk of the centre stick. A 757 obviously can not do a Cobra, so it gradually goes virtically, just as a Flanker can also choose to gradually go virtical.

 

[Asoka]

Yes, it never went virtually for long but nevertheless, it was going vertically with zero thrust.

By those standards the J-20 never had a sustained vertical climb either, a true sustained vertical climb would be until the aircraft could not climb anymore and every aircraft has its altitude limit. The point is any aircraft can go virtually even if it has horrible thrust to weight ratios, granted it has enough airspeed when attempting a vertical climb.

At the very end of the video it went full virtical.

Yes, that's what I said in the very beginning. Forward moment can make any aircraft go virticall.

Going virtically does not act as "giant wind break". A Cobra and virtical flight are two different things. The Cobra is due to a high angle of attack and a quick jerk of the centre stick. A 757 obviously can not do a Cobra, so it gradually goes virtically, just as a Flanker can also choose to gradually go virtical.

"The Cobra is due to a high angle of attack and a quick jerk of the centre stick"

That's what the J-20 did, a cobra by going suddenly vertical and then push the throttle to do a sustain climb. When you are vertical, your body will slow you down quickly like a brake. That's the purpose of a Super Cobra. It's actually not very useful in air combat, because it bleeds your energy too fast and too much.

If your enemy catch you doing that, he could loop over you like that glider and get behind you, without losing too much energy.

"a true sustained vertical climb would be until the aircraft could not climb anymore and every aircraft has its altitude limit."

This I disagreed. A sustain vertical climb could be done, long enough to demonstrate its Trust to Weight Ratio is > 1. No need to climb to maximum altitude.

In fact, if your maximum altitude is 60,000ft, you could climb vertically far lower than that, because you are not using lifting force from the wings, your accumulated kinetic energy, to help with the climb, just your raw engine power.

You will go up like a rocket, not like an airplane, and use up a lot of fuel and reach lower altitude.

Exactly what I try to say since pages !!!

Again: that brief blurred video shows simply nothing, not a sustained climb nor anything impressive. Simply nothing at least to assume such calculations.
I'm sure these guys at CAC are still laughing ...

As such this whole assumption on vertically climbings, thrust to weight ratio and that calculation up to +210 kN is simply wrong since the basic statement on which all this calculation is based on is wrong.

Deino

Starting at 1:03, It climbed vertically for at least 7 seconds and then disappeared into the cloud. We don't know its still climbing, since it disappeared into the clouds. The speed before the climb was very slow.

In this video, the vertical climb starts at 0:40, it also quickly disappear into the cloud after 5-6 seconds.

http://www.bilibili.com/video/av6668356/