Chengdu J-20 5th Generation Aircraft News & Discussions

[Deino]

I know the details of the aircrafts are very different. I just want to emphasize that they are optimized for high speed. So I expect the top speed of J-20 to approach Mach 3.

Oh no !!! Please ....

Even if I can't give my own calculation - simply since I can't do that - there is no reason to believe neither a +200 kN engine nor to reach Mach 3.

No modern fighter is able to reach this, it is not even a requirement to do so and if You look, what China has achieved so far, then is this step simply beyond any capabilities.

I really don't know what's You background, but in nature science - I studied Chemistry - and You notice something You don't understand or cannot explain at once and You possible have several different explanations it is most often the most rational one and surely never - at least in my experience - the most extreme unlikely option.

Therefore again: We are not sure what engine the J-20 uses and we do not know its capabilities, but a +200 kN engine or to reach Mach 3 is so much beyond that it even kills all Your credibility.
So IMO there must be another much more simple explanation ... and that is plain and simple You massively overestimate the climb-rate and manoeuvrability.

Just my two cents.

Deino

 

[Asoka]

Oh no !!! Please ....

Even if I can't give my own calculation - simply since I can't do that - there is no reason to believe neither a +200 kN engine nor to reach Mach 3.

No modern fighter is able to reach this, it is not even a requirement to do so and if You look, what China has achieved so far, then is this step simply beyond any capabilities.

I really don't know what's You background, but in nature science - I studied Chemistry - and You notice something You don't understand or cannot explain at once and You possible have several different explanations it is most often the most rational one and surely never - at least in my experience - the most extreme unlikely option.

Therefore again: We are not sure what engine the J-20 uses and we do not know its capabilities, but a +200 kN engine or to reach Mach 3 is so much beyond that it even kills all Your credibility.
So IMO there must be another much more simple explanation ... and that is plain and simple You massively overestimate the climb-rate and manoeuvrability.

Just my two cents.

Deino

Well Deino, you are a chemistry teacher, so elementary math should be well within your ability. Let me lay it down to you again as simply as I can, humanly.

To suspend a 20 tons plane (included fuel) in mid air, requires 20 tons of force to push it up. To make it climb vertically, it requires 20+ tons of forces. Faster it climbs or accelerate, greater the force is required.

Force = Mass x Acceleration

Now, if a plane has two engines, that means each engine must supplies 10 tons of force each.

Still following me, so far? 20 divided by 2 = 10. I hope everybody got it. If not use a calculator.

Now, a turbofan jet generates thrust by burning fuel and compressed air in the combustion chamber, this thrust is called Dry Thrust or military power. The pilot could also activate the afterburner and greatly increase the engine's thrust or power.

"Afterburning is achieved by injecting additional fuel into the jet pipe downstream of (i.e. after) the turbine. The advantage of afterburning is significantly increased thrust; the disadvantage is its very high fuel consumption and inefficiency, though this is often regarded as acceptable for the short periods during which it is usually used.

Pilots can activate and deactivate afterburners in-flight, and jet engines are referred to as operating WET when afterburning is being used, and DRY when not.

An engine producing maximum thrust WET is at Maximum Power, while an engine producing maximum thrust DRY is at Military Power". --Wikipedia

So DRY or Military Power is less than WET or Maximum Power. Dry thrust or military power is usually 50-60% of Wet or Maximum Power.

Now, if an airplane is able to climb vertically, without the use of the Afterburner, or seeing a long long blue flame from the exhaust, then it is using Dry or Military Power only.

That means 10 tons of thrust generated by each engine is solely Dry thrust. Now, we have said Dry thrust is usually 50-60% of Maximum Thrust. Supposed, its 50%, instead of 60%, I usually used. The F135's dry thrust is 67% of maximum Thrust. Very high.

That means Maximum Thrust is double of Dry Thrust,

Max. Power = Dry Thrust / 0.5,

20 = 10 / 0.5 , so the Maximum Thrust of each engine is 20 tons.

1 ton is 9.8 kilonewtons. So 20 tons is 20 x 9.8 = 196kN.

So this engine Maximum Power is at least +196kN, if Dry is 50% of Max. Power.

Now, we are assuming a plane to be weighting 20 tons including fuel.

-----------------------------------------------------------------------------------------------------------------------------------------------------------
The F-22 is weighting 19.6 tons empty. And J-20 is much bigger than F-22, in fact, it's body is at least 3m longer. So we need to add 2 tons of weight to make it more realistic and add 3 tons of fuels for the demo or testing.

So, now the weight of J-20 is 20 + 2 + 3 = 25 tons. It's two engines need to generate a total of 25 tons of Dry Thrust to lift it vertically, without afterburner.

Using the above calculation, I have arrived the figure of 25/2 = 12.5 tons of Dry Thrust for each engine. If the engine efficiency is 50%, we can find the Maximum Thrust by double the Dry Thrust, 12.5 x 2 = 25 tons. or 245kN.

Now, if the engine efficiency is higher than 50%, say, 60%. Then we can use the formula,

Max Thrust = Dry Thrust/0.60.

20.8 = 12.5/0.6

So, the Maximum Thrust of the engine required is 20.8 ton or 203.8kN, for a plane like J-20, weighting 22 tons plus 3 tons of fuel.

It all depends on how much J-20 actually weights, how much fuel it was carrying when it was doing the vertical climb, and its engine's efficiency.

I am guessing those numbers, by using F-22's weight (20 tons + 2 tons) as reference, and using a low fuel weight of 3 tons, and an engine efficiency of 50-60%.

Sounds clear?

Do you got it this time?

Show the math to someone, if you still have doubts.

This is the third or fourth time that I done the calculation. I don't think I can do it better.

 

[AlyxMS]

All predictions made from insufficient data are going to be inaccurate.

We know nearly nothing about WS-15 or J-20's actual specs and aerodynamic properties. How can you make so much assumptions and claim you are right?

It's like guessing a car's engine power by staring at its tail light, there's simply no logical pathway.

Also, the "efficiency" thing.
It's not efficiency, simply the dry to wet thrust ratio.
Afterburning thrust is not usually double the dry thrust, (in other words, the ratio being 0.5)
I did the calculation for D-30(for Mig-31) and AL-31F, both are higher than 60%.

 

[Asoka]

All predictions made from insufficient data are going to be inaccurate.

We know nearly nothing about WS-15 or J-20's actual specs and aerodynamic properties. How can you make so much assumptions and claim you are right?

It's like guessing a car's engine power by staring at its tail light, there's simply no logical pathway.

Also, the "efficiency" thing.
It's not efficiency, simply the dry to wet thrust ratio.
Afterburning thrust is not usually double the dry thrust, (in other words, the ratio being 0.5)
I did the calculation for D-30(for Mig-31) and AL-31F, both are higher than 60%.

Show me your calculations please. I love to see them.

I used 50% to make the calculation easy to see. I usually use 60%. F-35, F135 engine is rated at 67%. Outstanding, IMO.

As I have calculated, a plane weighting 20 tons including fuel, with 60% efficiency, will requires 165kN Maximum power to lift it vertically.

If we take J-20's empty weight as 22 tons (2 more than F-22) and 3 tons of fuel, and 60% efficiency, we will find the Maximum thrust to be 203kN. At 50% is 245kN.

Personally, I would prefer the engine to be more efficient at Dry thrust than having higher maximum power rating or Wet Thrust, since the afterburners burns several times more fuel.

 

[AlyxMS]

I do no have any calculations because there aren't any numbers to work with. Where did you get the specs of J-20? Calculations based on guess work is pointless.

By to lift vertically I assume it means thrust to weight ratio = 1. You also said it must be done with just dry thrust?

Why?
TWR >= 1 is standard for modern jet fighters, sure. But not with dry thrust, afterburning thrust is always used to calculate TWR.

Why would one need TWR>=1 with only dry thrust?
That's a absurd amount of excess thrust!

If Tdry = Twet * 0.6, the TWR when afterburning would be 1.67! One can build a much bigger plane, with much higher capabilities with such engines.

 

[Nadhem Of Ibelin]

1. via jobjed from sinodefence​

 

[Deino]

Well Deino, you are a chemistry teacher, so elementary math should be well within your ability. Let me lay it down to you again as simply as I can, humanly.
.....
Sounds clear?

Do you got it this time?

Show the math to someone, if you still have doubts.

This is the third or fourth time that I done the calculation. I don't think I can do it better.

YES, and Your analysis & calculation might be correct if it is a sustained climb to say somewhat 30,000 meters like the Streak Eagle or the P-42 Flanker did, but like I explained before and will do again: Your whole argumentation falls together like a house of cards simply the J-20 does not perform a sustain climb.

Yes, each and every type can climb vertically since this only depends on the velocity an aircraft has before climbing. Even when You do a simple loop, an aerobatics aeroplane climbs vertically for a brief time. The point is however how long can it climb and in all videos so far we've seen the J-20 is doing a split + a moderate climb but then the video stops or it accelerates in straight level and then climbs ... but again not comparable what You deem necessary for such a thrust requirement.

Therefore - like @AlyxMS already explained - any assumption or calculation made from insufficient data is going to be inaccurate.

So I would better leave all these guesswork since they are bare any rational foundation.

Deino

 

[Ultima Thule]

I know the details of the aircrafts are very different. I just want to emphasize that they are optimized for high speed. So I expect the top speed of J-20 to approach Mach 3.

No bro with DSI it can barely reach Mach 2, there are one more problem if it increases speed its become least agile and maneuverable and J-20 is air superiority fighter not interceptor like MIG-25, 31 they rely on their top speed not maneuverability and agility, their tactics were shoot and run,if J-20 want to become agile and maneuverable its Mach numbers should have been under or equal Mach 2.5

Well Deino, you are a chemistry teacher, so elementary math should be well within your ability. Let me lay it down to you again as simply as I can, humanly.

To suspend a 20 tons plane (included fuel) in mid air, requires 20 tons of force to push it up. To make it climb vertically, it requires 20+ tons of forces. Faster it climbs or accelerate, greater the force is required.

Force = Mass x Acceleration

Now, if a plane has two engines, that means each engine must supplies 10 tons of force each.

Still following me, so far? 20 divided by 2 = 10. I hope everybody got it. If not use a calculator.

Now, a turbofan jet generates thrust by burning fuel and compressed air in the combustion chamber, this thrust is called Dry Thrust or military power. The pilot could also activate the afterburner and greatly increase the engine's thrust or power.

View attachment 365263

"Afterburning is achieved by injecting additional fuel into the jet pipe downstream of (i.e. after) the turbine. The advantage of afterburning is significantly increased thrust; the disadvantage is its very high fuel consumption and inefficiency, though this is often regarded as acceptable for the short periods during which it is usually used.

Pilots can activate and deactivate afterburners in-flight, and jet engines are referred to as operating WET when afterburning is being used, and DRY when not.

An engine producing maximum thrust WET is at Maximum Power, while an engine producing maximum thrust DRY is at Military Power". --Wikipedia

So DRY or Military Power is less than WET or Maximum Power. Dry thrust or military power is usually 50-60% of Wet or Maximum Power.

Now, if an airplane is able to climb vertically, without the use of the Afterburner, or seeing a long long blue flame from the exhaust, then it is using Dry or Military Power only.

That means 10 tons of thrust generated by each engine is solely Dry thrust. Now, we have said Dry thrust is usually 50-60% of Maximum Thrust. Supposed, its 50%, instead of 60%, I usually used. The F135's dry thrust is 67% of maximum Thrust. Very high.

That means Maximum Thrust is double of Dry Thrust,

Max. Power = Dry Thrust / 0.5,

20 = 10 / 0.5 , so the Maximum Thrust of each engine is 20 tons.

1 ton is 9.8 kilonewtons. So 20 tons is 20 x 9.8 = 196kN.

So this engine Maximum Power is at least +196kN, if Dry is 50% of Max. Power.

Now, we are assuming a plane to be weighting 20 tons including fuel.

-----------------------------------------------------------------------------------------------------------------------------------------------------------
The F-22 is weighting 19.6 tons empty. And J-20 is much bigger than F-22, in fact, it's body is at least 3m longer. So we need to add 2 tons of weight to make it more realistic and add 3 tons of fuels for the demo or testing.

So, now the weight of J-20 is 20 + 2 + 3 = 25 tons. It's two engines need to generate a total of 25 tons of Dry Thrust to lift it vertically, without afterburner.

Using the above calculation, I have arrived the figure of 25/2 = 12.5 tons of Dry Thrust for each engine. If the engine efficiency is 50%, we can find the Maximum Thrust by double the Dry Thrust, 12.5 x 2 = 25 tons. or 245kN.

Now, if the engine efficiency is higher than 50%, say, 60%. Then we can use the formula,

Max Thrust = Dry Thrust/0.60.

20.8 = 12.5/0.6

So, the Maximum Thrust of the engine required is 20.8 ton or 203.8kN, for a plane like J-20, weighting 22 tons plus 3 tons of fuel.

It all depends on how much J-20 actually weights, how much fuel it was carrying when it was doing the vertical climb, and its engine's efficiency.

I am guessing those numbers, by using F-22's weight (20 tons + 2 tons) as reference, and using a low fuel weight of 3 tons, and an engine efficiency of 50-60%.

Sounds clear?

Do you got it this time?

Show the math to someone, if you still have doubts.

This is the third or fourth time that I done the calculation. I don't think I can do it better.

Too much none-sense we knows nothing about J-20 and WS-15

Show me your calculations please. I love to see them.

I used 50% to make the calculation easy to see. I usually use 60%. F-35, F135 engine is rated at 67%. Outstanding, IMO.

As I have calculated, a plane weighting 20 tons including fuel, with 60% efficiency, will requires 165kN Maximum power to lift it vertically.

If we take J-20's empty weight as 22 tons (2 more than F-22) and 3 tons of fuel, and 60% efficiency, we will find the Maximum thrust to be 203kN. At 50% is 245kN.

Personally, I would prefer the engine to be more efficient at Dry thrust than having higher maximum power rating or Wet Thrust, since the afterburners burns several times more fuel.

too much nonsense

 

[Asoka]

I do no have any calculations because there aren't any numbers to work with. Where did you get the specs of J-20? Calculations based on guess work is pointless.

By to lift vertically I assume it means thrust to weight ratio = 1. You also said it must be done with just dry thrust?

Why?
TWR >= 1 is standard for modern jet fighters, sure. But not with dry thrust, afterburning thrust is always used to calculate TWR.

Why would one need TWR>=1 with only dry thrust?
That's a absurd amount of excess thrust!

If Tdry = Twet * 0.6, the TWR when afterburning would be 1.67! One can build a much bigger plane, with much higher capabilities with such engines.

"Where did you get the specs of J-20? "

I get the estimate of J-20's weight by comparing J-20 to F-22, and found its body length (nose to nozzle) to be at least 3m longer. So I added 2 tons to F-22's weight of 20 tons, to get 22 tons for J-20. It's a reasonable guess. IMO. I need to make another guess, that is how much fuel J-20 was carrying when it did he demo. I guess is a low ball figure of 3 tons or 1/4 of a full tank. It could be more like 4 or 5 tons. So I guess it's flying weight is a total of 25 tons.

Another guess, I need to make is engine efficiency. Dry thrust is generally 50-60% of wet thrust for fighter engine. The AL-31F's Dry thrust (84kN) is 60% of Wet thrust (122kN). The F35's F135 is 67% -- very High.

I said J-20 must be climbing vertically with Dry Thrust at the China Air Show, because there was no long long blue flame shoot out of its nozzles.

"By to lift vertically I assume it means thrust to weight ratio = 1." yes, that's correct.

Many modern jet could climb vertically, but with their afterburner turned on. We can see the intense long blue flame when that happen.

"Why would one need TWR>=1 with only dry thrust?
That's a absurd amount of excess thrust!"

Yes, it's absurd amount of excess thrust, if one could climb vertically with only Dry Thrust. Not that absurd, if one consider the F-35's F135 engine is rated 190kN. And 200kN, is only 5% greater.

"If Tdry = Twet * 0.6, the TWR when afterburning would be 1.67! One can build a much bigger plane, with much higher capabilities with such engines."

Yes, that's true. A TWR of 1.67 with afterburning is huge. You can build a large, Supersonic Cruise, bomber with several powerful +200kN engines. I think that's what China is doing with its top secret H10 stealth bomber project.

No bro with DSI it can barely reach Mach 2, there are one more problem if it increases speed its become least agile and maneuverable and J-20 is air superiority fighter not interceptor like MIG-25, 31 they rely on their top speed not maneuverability and agility, their tactics were shoot and run,if J-20 want to become agile and maneuverable its Mach numbers should have been under or equal Mach 2.5


Too much none-sense we knows nothing about J-20 and WS-15


too much nonsense

"DSI it can barely reach Mach 2"
Not true. The DSI on J-20 is adjustable. It can go way beyond Mach 2.

"if it increases speed its become least agile and maneuverable"
That's definitely true with older generation of fighters. THE F-104 Starfighter can only fly basically in a straight line at Mach 2. With manual mechanical control of the plane, the plane needs to be aerodynamically stable so it won't be too difficulty to fly.

But with the invention of digital electro flight control system run by the computer, the stability can be relaxed. The plane can basically fly itself, making all the fly control decisions to maintain stability.

The fighter plane can be made highly agile and maneuverable with active canards, TVC, and all moving vertical tails, and leading edge extensions.

The F-22 can do 5G moves at Mach 1.6 at 30,000ft.

"too much nonsense"
It's nonsense to you because the idea that J-20 is running with WS-10 or AL-31FN got burned into your head. You can't get it out of your brain.

If I say, F-35 has a 190kN engine. No one would ever doubted me. But when I say J-20's has a 200kN engine (only 5% > than 190kN), all hell broke loose. You have to cry and cry and whine.

You have problem with the conclusion, not with the calculations I had made.

It's all because you and many fanboys and foreign intelligence agencies got successfully deceived by a brilliant campaign of deception by China's Bureau of Strategic Deception.

Anyone who enthusiastically supported the idea that J-20 was underpowered or using WS-10/AL-31FN, is, unwittingly, a part of China's brilliant DECEPTION campaign.

"we knows nothing about J-20 and WS-15"
Yes, you will stay that way, "know nothing", if you don't get your head out of the sand. You helped it. You got duped. Live with it. Get your head out of the sand.

The China's Strategic Deception has served its purpose, and ran its course. It has convinced US to cancelled its Supreme Air Dominant Machine, F-22, at 187 units, after entered service for 3 years, and made a massive poor bet on the underperforming F-35, with a production goal of 2400 planes.

There is no easy way out of this strategic quagmire, and gigantic mistake. US and its allies must live with this mistake for the next 30-50 years. Cancellation of F-35 is not an option anymore, perhaps never was one. Never had a Plan B, anyway. That was intentionally built into Plan A. Making sure, there was no other options.

Now, China has unmistakably demonstrated the true power of J-20, with an effortless vertical climb without afterburners, by flying over thousands of foreign spectators, who are mostly aviation professionals and spies.

If you still don't believe me, ask an aviation professional.

 

[Ultima Thule]

"DSI it can barely reach Mach 2"
Not true. The DSI on J-20 is adjustable. It can go way beyond Mach 2.

"if it increases speed its become least agile and maneuverable"
That's definitely true with older generation of fighters. THE F-104 Starfighter can only fly basically in a straight line at Mach 2. With manual mechanical control of the plane, the plane needs to be aerodynamically stable so it won't be too difficulty to fly.

The phyics don't changed whether jets have relax static stability like F-16 and F-22 without static stability like MIG-25, 31 and SR-71 you increases top speed you must lose agility and maneuverability its a natural phenomenon not man made @gambit, @Khafee, @Bilal Khan 777 please correct this guy

The F-22 can do 5G moves at Mach 1.6 at 30,000ft.

So what under 900 MPH

It's nonsense to you because the idea that J-20 is running with WS-10 or AL-31FN got burned into your head. You can't get it out of your brain.

No ones know that what engine is used by J-20 its maybe WS-10X, AL-31FN3, early versions of WS-15 or just other clean sheet interim design

If I say, F-35 has a 190kN engine. No one would ever doubted me. But when I say J-20's has a 200kN engine (only 5% > than 190kN), all hell broke loose. You have to cry and cry and whine.

This just your assumption and wishful thinking, no ones knows actual thrust of WS-15, are you in the team of WS-15 development project too much fanboy-ism is bad for your health best stated that WS-15 thiust is in between 18 to 19 tons on various sites including Chinese ones this is slightly inferior same thrust that F-135 have and i am not underestimating WS-15 or J-20

You have problem with the conclusion, not with the calculations I had made.

Too much FANBOY-ISM is bad for your health

It's all because you and many fanboys and foreign intelligence agencies got successfully deceived by a brilliant campaign of deception by China's Bureau of Strategic Deception.

Anyone who enthusiastically supported the idea that J-20 was underpowered or using WS-10/AL-31FN, is, unwittingly, a part of China's brilliant DECEPTION campaign.

"we knows nothing about J-20 and WS-15"
Yes, you will stay that way, "know nothing", if you don't get your head out of the sand. You helped it. You got duped. Live with it. Get your head out of the sand.

The China's Strategic Deception has served its purpose

And you are in this decption campaign
Too much FANBOY-ISM is bad for your health

 

[gambit]

Not true. The DSI on J-20 is adjustable.

Source ?

"if it increases speed its become least agile and maneuverable"

That's definitely true with older generation of fighters. THE F-104 Starfighter can only fly basically in a straight line at Mach 2. With manual mechanical control of the plane, the plane needs to be aerodynamically stable so it won't be too difficulty to fly.

But with the invention of digital electro flight control system run by the computer, the stability can be relaxed. The plane can basically fly itself, making all the fly control decisions to maintain stability.

The fighter plane can be made highly agile and maneuverable with active canards, TVC, and all moving vertical tails, and leading edge extensions.

The F-22 can do 5G moves at Mach 1.6 at 30,000ft.

You are partially true here.

On any aircraft body, there is a neutral point where the body is physically balanced. This neutral point is not the same, it varies from design to design. In order to create a relaxed stability body, center of gravity (CG) is moved aft of that neutral point. However, there is a point where too far aft and the aircraft becomes absolutely uncontrollable, computer assisted flight or not, and just like the variability of that neutral point, this 'too far aft' CG position also varies from design to design.

The laws of physics are absolute. So absolute that not even the PDF Chinese can change them, no matter how much they want.

The laws of physics states that as speed increases, aerodynamic 'clamping' forces on the aircraft reduces its maneuverability and agility. It does not matter if the aircraft was designed with relaxed stability. As the aircraft crosses the supersonic threshold, increasing aerodynamic forces will eventually reach a point where the aircraft cannot maneuver at all.

Q: What about air-air missile that can maneuver at double digits g at Mach ?

A: The air-air missile is an aircraft. But being a missile does not excuse it from the laws of physics. In fact, the tubular design of the missile reinforces those laws of physics. As the missile IS an aircraft, its body design allows a greater RANGE of neutral-to-aft CG re-position. The operative word here is RANGE or LATITUDE or FREEDOM on a sliding scale from that neutral point to that 'too-far-aft' CG position. The missile's tubular body allows that much greater range than on an aircraft. The behaviors of aerodynamic forces differs on a tubular body than it would on any planar-like body and that is for a completely different discussion.

What this mean is that if we are to re-design the F-104 today with keeping its original tubular body as foundation, moving the CG aft will create that range of controlled maneuverability. The new design may not have the agility and maneuverability of the F-16, but it would give some greater agility and maneuverability than the old design in the supersonic region.

It's all because you and many fanboys and foreign intelligence agencies got successfully deceived by a brilliant campaign of deception by China's Bureau of Strategic Deception.

The China's Strategic Deception has served its purpose, and ran its course. It has convinced US to cancelled its Supreme Air Dominant Machine, F-22, at 187 units, after entered service for 3 years, and made a massive poor bet on the underperforming F-35, with a production goal of 2400 planes.

Yeah...Sure...This is why you PDF Chinese are usually laughed at.

 

[Asoka]

Source ?


You are partially true here.

On any aircraft body, there is a neutral point where the body is physically balanced. This neutral point is not the same, it varies from design to design. In order to create a relaxed stability body, center of gravity (CG) is moved aft of that neutral point. However, there is a point where too far aft and the aircraft becomes absolutely uncontrollable, computer assisted flight or not, and just like the variability of that neutral point, this 'too far aft' CG position also varies from design to design.

The laws of physics are absolute. So absolute that not even the PDF Chinese can change them, no matter how much they want.

The laws of physics states that as speed increases, aerodynamic 'clamping' forces on the aircraft reduces its maneuverability and agility. It does not matter if the aircraft was designed with relaxed stability. As the aircraft crosses the supersonic threshold, increasing aerodynamic forces will eventually reach a point where the aircraft cannot maneuver at all.

Q: What about air-air missile that can maneuver at double digits g at Mach ?

A: The air-air missile is an aircraft. But being a missile does not excuse it from the laws of physics. In fact, the tubular design of the missile reinforces those laws of physics. As the missile IS an aircraft, its body design allows a greater RANGE of neutral-to-aft CG re-position. The operative word here is RANGE or LATITUDE or FREEDOM on a sliding scale from that neutral point to that 'too-far-aft' CG position. The missile's tubular body allows that much greater range than on an aircraft. The behaviors of aerodynamic forces differs on a tubular body than it would on any planar-like body and that is for a completely different discussion.

What this mean is that if we are to re-design the F-104 today with keeping its original tubular body as foundation, moving the CG aft will create that range of controlled maneuverability. The new design may not have the agility and maneuverability of the F-16, but it would give some greater agility and maneuverability than the old design in the supersonic region.


Yeah...Sure...This is why you PDF Chinese are usually laughed at.

I said: "Not true. The DSI on J-20 is adjustable."

Here is the source:
http://cqtimes.cn/?g=home&c=newsdetail&a=index&id=136029&inside=&uid=&deviceid=

"歼-20独创的“可调DSI进气道”，做出了新的创新，解决了DSI高速性能不佳的难题。歼-20进气口鼓包固定，但是进气道侧面有可调挡板，可有效随速度变化改变进气量，从而达到从低到高各个主要速度段的优秀的进气控制能力，令发动机更为澎湃地工作，也将意味着更好的加速性、爬升率和超巡能力。"

Here is my rough translation:

"J-20 has a unique feature called "adjustable DSI air intake". It solved the problem that DSI is not efficient at high speed. The "bump" is fixed, but inside the air intake, there is an adjustable surface that could effectively change the amount of air enter the intake according to the speed, thereby able to provide outstanding air intake control ability from from low to high speed. Thus enable the engine to have better acceleration, higher climb rate and superior supersonic cruise."

No details of how this adjustable control surface was accomplished.

How do I know J-20 could reach Mach 3.0? I just found this picture from a video clip recently.

The caption below says "Our company has successfully completed the mission given by PLAAF to produce China's first Large Caliber Supersonic Wind Tunnel Pressure Control Valve. Thereby broke the American and Russia technology blockade, provided our country the equipments to test rocket, large aircraft, spaceship, and especially enabled the J-20 stealth fighter to completed its Mach 3.0 wind tunnel testing.

I guess this video sneaked past the Chinese censors.

 

[gambit]

I said: "Not true. The DSI on J-20 is adjustable."

Here is the source:
http://cqtimes.cn/?g=home&c=newsdetail&a=index&id=136029&inside=&uid=&deviceid=

Here is my rough translation:

"J-20 has a unique feature called "adjustable DSI air intake". It solved the problem that DSI is not efficient at high speed. The "bump" is fixed, but inside the air intake, there is an adjustable surface that could effectively change the amount of air enter the intake according to the speed, thereby able to provide outstanding air intake control ability from from low to high speed. Thus enable the engine to have better acceleration, higher climb rate and superior supersonic cruise."

No details of how this adjustable control surface was accomplished.

Then you are wrong.

The DSI feature is the bump. Simple as that. Whatever mechanisms inside the inlet make the intake system no different than any other inlet air flow control system prior to the J-20.

How do I know J-20 could reach Mach 3.0? I just found this picture from a video clip recently.

The caption below says "Our company has successfully completed the mission given by PLAAF to produce the first large caliber supersonic wind tunnel pressure control door. Thereby enable the J-20 stealth fighter to complete Mach 3.0 wind tunnel testing.

I guess this video sneaked past the Chinese censors.

No, it does not mean the J-20 can reach Mach 3. It means the wind tunnel used was a supersonic wind tunnel...

https://en.wikipedia.org/wiki/Supersonic_wind_tunnel

...And the J-20, as a complete airframe, withstood that level of airspeed stress.

Have you ever been in a wind tunnel ? I have. It was a portable wind tunnel traveling around the country showing people what a hurricane can produce. My body withstood nearly nearly 100 mph before I waved off.

Here you go...

In no way does that mean I can, on my own power, reach speed of 100 mph.

This is why on PDF, it is ALWAYS entertaining to debate you Chinese on military related technical issues. None of you ever served. None of you ever been even second degree away involvement in the technical issues discussed. The results are that you guys consistently make declarations that are outright wrong. Worse, to date none of you ever admitted that he was wrong.

 

[Asoka]

Then you are wrong.

The DSI feature is the bump. Simple as that. Whatever mechanisms inside the inlet make the intake system no different than any other inlet air flow control system prior to the J-20.


No, it does not mean the J-20 can reach Mach 3. It means the wind tunnel used was a supersonic wind tunnel...

https://en.wikipedia.org/wiki/Supersonic_wind_tunnel

...And the J-20, as a complete airframe, withstood that level of airspeed stress.

Have you ever been in a wind tunnel ? I have. It was a portable wind tunnel traveling around the country showing people what a hurricane can produce. My body withstood nearly nearly 100 mph before I waved off.

Here you go...

In no way does that mean I can, on my own power, reach speed of 100 mph.

This is why on PDF, it is ALWAYS entertaining to debate you Chinese on military related technical issues. None of you ever served. None of you ever been even second degree away involvement in the technical issues discussed. The results are that you guys consistently make declarations that are outright wrong. Worse, to date none of you ever admitted that he was wrong.

"The DSI feature is the bump. Simple as that."
To you it is, who knows nothing about it. Tell that to the LockeedMartin engineers who invented and patented DSI. They will puke in your face.

Yes, sure, you are right, Gambit, in fact you are brilliant. China would go to all the trouble and expense to test J-20's airframe for MACH 3.0, that it will never able to reach. Makes a lot of senses to me.

In fact, why don't you tell Boeing and Airbus to test their planes for supersonic speed they will never reach like MACH 3, MACH 5 or even MACH 10? They might even give you a job, because you are so brilliant like the fanboys here PDF think you are.

Thank you for cracking me up.

 

[gambit]

In fact, why don't you tell Boeing and Airbus to test their planes for supersonic speed they will never reach like MACH 3, MACH 5 or even MACH 10? They might even give you a job, because you are so brilliant like the fanboys here PDF think you are.

The F-16's airframe was over engineered to handle double digits g, even though the FLCS restricts maneuvers to 9gs.

Thank you for cracking me up.

No...Thank YOU for cracking up the readers over and over again.