Chengdu J-20 5th Generation Aircraft News & Discussions

[gambit]

Still can't supercruise,but yes as low observable strike aircraft why not. @gambit
How does thrust work for 2 engines?Just addition of 2 thrusts?I doubt it.

Essentially -- yes.

Patent US5480107 - 3x multi-engine jet configuration - Google Patents

2x Conventional Jet. This represents modeled data based upon a popular entry level business jet in current use, and generally depicted in FIG. 6. The 2x conventional Jet uses twin WILLIAMS/ROLLS ROYCE-manufactured engines (32 and 34 with reference to FIG. 6) of 1,900 pounds thrust each. The engines are mounted on the left and right rear of the fuselage and will be referred to as 1x (left) and 1x (right). The 2x conventional jet will develop a total (2x) thrust of 3,800 pounds.

But there are many factors that affect the attainment of a desired speed.

Two aircrafts comes to mind: SR-71 and F-104. Both have shapes that are optimized for acceleration (which is not the same as speed), speed, then the sustainment of said speed.

For multi-engine aircrafts, asymmetric thrust affects acceleration, speed, and sustainment of achieved speed. This is simple for the fact that the aircraft should present the least drag profile to the airstream. Asymmetric thrust, especially for the SR-71 with its wide engine spacing, will probably prevent Mach, let alone sustain it. The F-104 would not have this potential problem.

Another factor is drag from the engine itself. A ramjet have no moving parts and therefore the least drag loss to affect net thrust. On the other hand, a turbo-whatever have plenty of moving parts, especially the fan stages that must be exposed to incoming airstream in order to have air to create the air-fuel mixture and burn it.

Then add in airframe design which give aerodynamics, and weight and we have plenty of variables that can prevent an aircraft from attaining supercruise despite being multi-engine.

 

[jhungary]

Supercruise is a testament to the aircraft's aerodynamics and somewhat thrust to weight ratio, but pragmatically speaking such a feat is not useful in actual combat. Supercruise is the ability to maintain supersonic flight without engine reheat, which is barely fast enough when compared with modern maximum speeds. Kinetic energy can be maintained by supercruise or by engine reheat, sometimes with the latter being more useful since it can provide rapid variation of thrust in a short time period. In fact there has been no case in history where aircraft maintained their cruise speed during a high intensity dogfight. In such dogfights one can be guaranteed that afterburners will be used to propel the aircraft to its highest speed, at which point preservation of kinetic energy is no longer a concern since the aircrafts' speed in a fight will outstrip that of cruise speed.

It can somewhat "preserve" the IR stealthiness of an aircraft but that is no different if the aircraft simply went in at subsonic speeds. In fact level flight at subsonic speeds tend to save a lot more fuel.

Your talk of two fighters going head on is impractical. It takes two to tango and if one aircraft goes supersonic, then it will too have to face the threat of closing in on the enemy fast; it is the combined relative velocities of the two aircraft that matter, not just one. And none of that has any effect on the early detection and shoot capabilities of the parties.

That's where you are wrong.....

In Aerial combat, the most important thing regardless of dogfight or BVR is "Energy" you have to have the energy to perform certain task, dogfight for one, evading a missile is another.

Super-cruise translate to Aircraft that get more energy without the need to turn on "afterburner" thus saving fuel.

The longer you dogfight, the more fuel you will use, and you will WANT THE LAST DROP OF IT TO LAST, WITH THE MOST ENERGY AS YOU COULD GET. Hence super-cruise is important for any aerial engagement.

Unless you claim J-20 can hold "unlimited" amount of fuel so it will never ran out during dogfight, then super cruise is quite important.

Ausairpower is truly one of the most sensationalist websites and relies on dumping of misrepresented information to try and make their point. Which is why .. NO. and NO western air force, or respectable think tank wants to be associated with them.
The idea by them is to fool laymen by dumping numbers and statistics so that the general populous that is not aware or did not bother to look up the theory is fooled by them. Actual expects will see past these engineering "accountants".

That being said, non supercruisng or otherwise has little to do with obtaining a lock.. It has to do with reducing the IR signature and fuel efficiency. Dogfighting at supersonic speeds is possible but the pilot is the weak factor here.Moreover, the airframe as to have enough low drag and sufficient thrust so that it is able to maintain speed within a turn.

What supercruising essentially allows is faster Time on Target due to the ability to maintain a higher speed for a longer time AND the ability to use that higher speed to provide greater Kinematic energy to weapons released. If one looks at the shapes of fighters such as the J-20 and PAK-FA.. it comes to pass with the design of the J-20 that it is much more suited to flight in the supersonic regime as compared to other platforms(after all, the long thin delta has been the holder of speed records and offers the lowest drag as such.. but here it may be different). Hence, the J-20(if given the right engines or equal T/W ratio as the PAK-FA or the F-22 might have less difficulty slipping into the supersonic region as compared to the rest.
http://www.flightglobal.com/blogs/the-dewline/2011/02/j-20-chinas-ultimate-aircraft/

The article states the same.. so in essence the J-20 may be designed for an ENTIRELY different purpose than the F-22 and PAK-FA.. and may be more comparable to the FB-22 concept. Its shaping would allow it to get close enough and at supercruise to American High Value Air Assets like the E-3 or otherwise and attack them in a pass and GET OUT as fast as well. Perhaps , it is purposefully designed to avoid the dogfight and is more like the Mig-31 than a F-15; except that its a very stealthy Mig-31 and that is in itself a very deadly platform.

Because if you look at it, spotting something like the F-22 will be very very difficult for even something like the J-20. And for it to engage it in A2A combat is also folly. However, if such an aircraft can simply slip past the F-22's and other assets to strike at the main keystone like AWACS or Carriers.. then it sort of solves the problem for the Chinese in a way.
There were recent reports that US Navy ordered some panic upgrades to their naval ECM systems.. which means that something was developed which they found out about that caused them to panic; could the J-20 be part of that mix?
After all, the Chinese are smart learners and they are learning. Perhaps they figured that instead of fighting the Americans pound for pound.. why not find a way around them? Asymmetric warfare to their approach.

everybody knows Aus Air Power is just a shame media created by Carlo Kopps (Psuedo-Aviation expert) that have a real stain against the RAAF, and Ausairpower was the media to let out those rant. It have 0 value toward any actual aviation science nor technology.

It's just a ranting publication coming out of the mouth of self-proclaime over zealous aviation expert who only have a PhD in Computer Science and been in a simulator 3 times.......

It's a shame of Australia really......

 

[gambit]

Which brings another question into my mind.. What is more important? Shaping or Coatings.. or rather.. how much can you achieve with coatings alone or shaping alone.

See those gray-ish areas at the edges? Those are absorbers. For the F-22 and F-35, the dominant method for RCS control is shaping, and much much less than the F-117 in absorbers. The edges are treated with absorbers to control and reduce, not eliminate, the edge diffraction mode of radiation. We have to do this because an aircraft is a finite body and surface traveling waves must exit some time somewhere. For now, shaping is more important, more like 90% of the endeavor.

The 'stealth' community as a whole, and that includes allies and potential adversaries, is still facing serious technical hurdles in active cancellation at the material level. The US is quite ahead of the rest of this community but that does not rule out the chance that someone somewhere may have an accidental discovery in composite formulation that will propel his country into the lead. The SPECTRA method is active cancellation at the signal level and there are far too much lag times in threat signal analyses to make this method a viable 'counter-stealth', especially when the threat is wielding AESA.

Active cancellation at the material level is the Holy Grail of 'stealth'.

The above is passive cancellation and is not useful against what is bandied around as 'long wavelengths'. More accurately should be 'longer' than X-band wavelengths. The thicker the absorber, the greater the weight penalty, so most absorber destined for airborne applications are limited to the high centimetric (X-band) wavelengths. Put the F-22 inside a meters length radar, HF or UHF, and it will lit up like fireworks.

Active cancellation at the material level would render all wavelengths ineffective. The pulse's leading edge would be electrically cancelled the moment it penetrated the material and that cancellation signal would continue to exist until the pulse's trailing edge completed its entry. The threat signal would be the trigger so essentially, these 'smart' absorber would be EM silent, giving nothing away of its nature. With active cancellation at the material level, even the spinning prop of a prop jobber would be undetectable.

It would be great if you could answer that here
http://www.defence.pk/forums/air-warfare/73549-fundamentals-stealth-design-concepts-rcs-reduction-3.html

I contributed a post hinting at the necessary computational power to predict and verify if one's shaping achieved a certain RCS goal.

 

[Akasa]

Bullsh1t. If supercruise have no utility in combat, which begins at the moment of adversary detection and not ACM, then why is China trying to achieve supercruise in the new J-20?


And that is why supercruise is so useful -- fuel quantity available for those rapid throttle movements. You get to the fight with as much maneuvering fuel as you can.

The important factor is fuel quantity, then, not the fact that supercruise itself somehow helps during dogfights.

Ausairpower is truly one of the most sensationalist websites and relies on dumping of misrepresented information to try and make their point. Which is why .. NO. and NO western air force, or respectable think tank wants to be associated with them.
The idea by them is to fool laymen by dumping numbers and statistics so that the general populous that is not aware or did not bother to look up the theory is fooled by them. Actual expects will see past these engineering "accountants".

That being said, non supercruisng or otherwise has little to do with obtaining a lock.. It has to do with reducing the IR signature and fuel efficiency. Dogfighting at supersonic speeds is possible but the pilot is the weak factor here.Moreover, the airframe as to have enough low drag and sufficient thrust so that it is able to maintain speed within a turn.

What supercruising essentially allows is faster Time on Target due to the ability to maintain a higher speed for a longer time AND the ability to use that higher speed to provide greater Kinematic energy to weapons released. If one looks at the shapes of fighters such as the J-20 and PAK-FA.. it comes to pass with the design of the J-20 that it is much more suited to flight in the supersonic regime as compared to other platforms(after all, the long thin delta has been the holder of speed records and offers the lowest drag as such.. but here it may be different). Hence, the J-20(if given the right engines or equal T/W ratio as the PAK-FA or the F-22 might have less difficulty slipping into the supersonic region as compared to the rest.
http://www.flightglobal.com/blogs/the-dewline/2011/02/j-20-chinas-ultimate-aircraft/

The article states the same.. so in essence the J-20 may be designed for an ENTIRELY different purpose than the F-22 and PAK-FA.. and may be more comparable to the FB-22 concept. Its shaping would allow it to get close enough and at supercruise to American High Value Air Assets like the E-3 or otherwise and attack them in a pass and GET OUT as fast as well. Perhaps , it is purposefully designed to avoid the dogfight and is more like the Mig-31 than a F-15; except that its a very stealthy Mig-31 and that is in itself a very deadly platform.

Because if you look at it, spotting something like the F-22 will be very very difficult for even something like the J-20. And for it to engage it in A2A combat is also folly. However, if such an aircraft can simply slip past the F-22's and other assets to strike at the main keystone like AWACS or Carriers.. then it sort of solves the problem for the Chinese in a way.
There were recent reports that US Navy ordered some panic upgrades to their naval ECM systems.. which means that something was developed which they found out about that caused them to panic; could the J-20 be part of that mix?
After all, the Chinese are smart learners and they are learning. Perhaps they figured that instead of fighting the Americans pound for pound.. why not find a way around them? Asymmetric warfare to their approach.

Honestly I think the J-20 is specifically designed for close range dogfights, knowing that its stealth probably won't be as great as the F-22. They wouldn't be putting 180 kN engines and a canard delta design if that wasn't the case. High speed was also an emphasis, but much less so.

 

[Akasa]

But thats exactly what it is. It does not have to close into the AWACS.. it simply has to get within employment range of weapons that can track and take down the AWACS. Which its low frontal RCS allows it to do.. the J-20 is not all aspect LO especially with those canards and Chinese patents allude to algorithms that compute the lowest RCS with the Canards for the aircraft based on a target or direction(the Eurofighter and Rafale use similar algo's)

IMHO canards don't contribute much energy return at all. They are essentially a pair of airfoils that are parallel to the planform during interception missions. Only when they actuate do they generate some RCS, by which time the aircraft would probably be in close range and stealth would not matter much anyways. The F/A-XX proposal had canards in the same style as J-20.

Either way, the problem is with people trying to compare oranges and apples. The J-20 is perhaps not even in the category of aircraft that the F-22 and PAK-FA are.. and so trying to compare a interceptor/strike with air dominance fighters is ... Stupid.

The J-20 is not an interceptor. If it was they wouldn't be putting 180 kN engines for thrust to weight ratio as well as the proven canard delta design for high AoA. The Chinese military insiders stated that the J-20 sacrificed some of its VLO for agility.

 

[ptldM3]

The important factor is fuel quantity, then, not the fact that supercruise itself somehow helps during dogfights.

And with supercruise an aircraft consumes less fuel and stays in the fight longer, which also translates to longer range, range that can be exploited to achieve longer strike missions or penetrate further to engage enemy aircraft. Consider that during both interception missions as well as dogfights the afterburner is often used.

From an enemy stand point an opponent with supercruise will pose enormous challenges to opposing aircraft that try to intercept or engage the aircraft with supercruise. One story that comes to mind was the YF-23 test pilot and his admission that the chase aircraft that was tasked with flying along side the YF-23 was struggling to keep up with the YF-23 so much so that the chase aircraft had to engage afterburners while the YF-23 was casually cruising. The YF-23 pilot was not even aware that the chase plane was struggling.

 

[ice bomb]

No, Mr. Amnesia. It is you. Here, let me help you.



And bringing up j-20 in a thread titled j-20 is wrong?LOL.
I also brought up raptor and pak-fa not only j-20.All 5 were brought up as these are the only 5th gen fighters revealed atm.
I also remember u from the other discussion where u ran away.

Nothing wrong with that except you were talking about j-31 as an air superiority fighter which is plain wrong.
Yah, I did run away from you. When you lack basic knowledges like that. Why should I waste my precious time on you?

It does. It will be equipped with the 180 kN WS-15 engine. The engine core was completed in 2006 and was rumored to be tested in 2009.



The J-31 as of now does not need those engines since it is still in flight testing phase. The picture that's in front of you is already from an official release.

Dont need them or dont have them? You tell me they will say no to the engines if there were ready? They are using russian engines just like J-20 for one simple reason. Chinese engines are not yet ready for flight testings. Period.

Btw there is no more updated official release than the one I presented to you. Read it again. It is from 2013.

 

[ice bomb]

I contributed a post hinting at the necessary computational power to predict and verify if one's shaping achieved a certain RCS goal.

I will assume it is more a software issue than raw computerpower. You need to know what to put into the computers. After all both India and China got supercomputers. It cant be just about computerpower.

 

[Beast]

But thats exactly what it is. It does not have to close into the AWACS.. it simply has to get within employment range of weapons that can track and take down the AWACS. Which its low frontal RCS allows it to do.. the J-20 is not all aspect LO especially with those canards and Chinese patents allude to algorithms that compute the lowest RCS with the Canards for the aircraft based on a target or direction(the Eurofighter and Rafale use similar algo's)



Either way, the problem is with people trying to compare oranges and apples. The J-20 is perhaps not even in the category of aircraft that the F-22 and PAK-FA are.. and so trying to compare a interceptor/strike with air dominance fighters is ... Stupid.

It is appalling moderator of PK forum flying a pakistan flag don't even have the slightest knowledge of what J-20 intent to do. Perhap you shall keep your comment straightly on Pakistan military affair.

J-20 is a interceptor?
J-20 is not even in the league of PAK FA?

is it some kind of joke?

 

[ice bomb]

It is appalling moderator of PK forum don't even have the slightest knowledge of what J-20 intent to do. Perhap you shall keep your comment straightly on Pakistan military affair.

J-20 is a interceptor?
J-20 is not even in the league of PAK FA?

is it something of joke?

Apart from the comment that J-20 is an interceptor, he is basically right.
J-20 as of now with russian engines isnt gonna match PAK FA or even T-50 for that matter.

 

[Beast]

Apart from the comment that J-20 is an interceptor, he is basically right.
J-20 as of now with russian engines isnt gonna match PAK FA or even T-50 for that matter.

No bro. j-20 shaping is far superior in terms of stealth compare to PAK FA. Even Russian general admit PAF KA stealth is inferior to F-22, of cos Russian will stop short of calling their T-50 inferior to Chinese. If you think just having a superior engine will mean everything then why shall we called those thing 5th generation fighter?

 

[SQ8]

It is appalling moderator of PK forum flying a pakistan flag don't even have the slightest knowledge of what J-20 intent to do. Perhap you shall keep your comment straightly on Pakistan military affair.

J-20 is a interceptor?
J-20 is not even in the league of PAK FA?

is it some kind of joke?

It is appalling that a citizen of a generally sensible nation has little to show for his posts other than pointless attacks, perhaps it is then best to keep such citizens off their own threads to ensure that they dont insult their own country.

I stand by my opinion on the J-20's role.. It may be a good dogfighter but in a turning fight it will lose to the PAK-FA or F-22...where it may beat them is within supercruise.

 

[Argus Panoptes]

It is appalling that a citizen of a generally sensible nation has little to show for his posts other than pointless attacks, perhaps it is then best to keep such citizens off their own threads to ensure that they dont insult their own country.

I stand by my opinion on the J-20's role.. It may be a good dogfighter but in a turning fight it will lose to the PAK-FA or F-22...where it may beat them is within supercruise.

What is the likelihood that an F-22 will be ever drawn into a dogfight against any opponent? Slim to none. BVR technology will win.

 

[SQ8]

What is the likelihood that an F-22 will be ever drawn into a dogfight against any opponent? Slim to none. BVR technology will win.

Which is why the J-20 seems to be focused on avoiding getting seen by or getting into a brawl by the F-22 or PAK-FA..
Its a sneaky aircraft designed to slip through and hit the enemy where it hurts the most.

 

[Argus Panoptes]

Which is why the J-20 seems to be focused on avoiding getting seen by or getting into a brawl by the F-22 or PAK-FA..
Its a sneaky aircraft designed to slip through and hit the enemy where it hurts the most.

That is the future of nearly all frontline aircraft. The next major step would be networked swarms of smaller drones controlled by sneaky F-22/J-20/PAK-FA developments acting as area nodes, backed up by large AWACS and satellites.