J-20... The New Generation Fighter III

getready said:

Turning the j-20 to a strike version seems abit ambitious at this stage. Does PLAAF have this kind of experience? I mean they just embarked on a new challenging journney with her first stealth fighter, i reckon better not to take detours right now.

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You forget that the chinese aerospace industry has great experience in modifying existing designs
Obviously developing a strike J-20 will be years away, but it's certainly not unfeasible and will likely be cheaper than designing a completely new fighter ground up, if PLAAF ever has the need for a stealthy, fast/high theatre striker. Maybe SAC's 4th gen aircraft can fill that role but I'm not very confident it will have space for a large weapon bay.

MiG-29 said:

not indian at all, but if you want to know my ethnicity is Mexican, with family in Russia, Poland, Israel and of course Mexico.

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yes i believe that, without a doubt in my mind

just like i believed all your posts on j-20, particularly the one abt not coming here again.

Guys ... please stay on target, ähhm topic !

All personnel attacks, insults or insisting on leads to nothing. We had this so often; it's a free forum and everyone can post his opinion (within the rules), argue with others even 2-3 times forth and back, but there's no need to take the own opinion as the only truth and even more no need to persuade all others to the own one. As such ... let's leave it.



Deino

MiG-29 said:

interesting the same document is indiandefence but i never saw you gave a better counter argument, and by the way, that paper is 10 times much more proffessional than any thing i have seen here, see you in Indian defence, if you want to discuss it with me see you.

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lol! If that's your definition of 10x better than your scale is obviously inverse with that of reality.

The analysis is fundamentally flawed because it uses AVL model, which can't realistically represent a fighter. From :

A vortex-lattice model like AVL is best suited for aerodynamic configurations which consist mainly of thin lifting surfaces at small angles of attack and sideslip.

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Fighter aircraft don't satisfy this assumption since they can and do fly at large angle of attack and side-slip. If you constraint the simulation to small angle-of-attack and side-slip, then of course the plane can only fly with small angle-of-attack and side-slip. But using this to argue that this is all the maneuverability that the plane has is obviously circular argument, and is a logical fallacy.

AVL provides the capability to also model slender bodies such as fuselages nd nacelles via source+doublet filaments. The resulting force and moment predictions are consistent with slender-body theory, but the experience with this model is relatively limited, and hence modeling of bodies should be done with
caution.

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Here, the author of the software tells you that the model is untested and might not produce the correct results. The author of the presentation shows you two pictures of his AVL model, which does not model the fuselage. He obviously followed this suggestion:

If a fuselage is expected to have little influence on the aerodynamic loads, it's simplest to just leave it out of the AVL model. However, the two wings should be connected by a fictitious wing portion which spans the omitted fuselage.

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The author just assumed the body doesn't play any role in the aerodynamic loads. As pointed out many times in that 100+ pages of debate, one can't make an assumption like that. This is especially true when all parts of an aircraft interact with one another as is the case on a fighter aircraft.

DATCOM would be better than AVL because one at least have control over the shape of the fuselage model. However, both of these software suffer from the fact that they can't model what's not programmed in form of equations (ie. cannot model vortices from chine and LERX). Again, from that same page:

AVL assumes quasi-steady flow, meaning that unsteady vorticity shedding is neglected.

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Of course, I don't expect you to know any of these, since you've only talked the talk but haven't showed that you actually walked the walk.

MiG-29 said:

Optimized for use as a long-range interceptor and air-to-surface attack platform

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And no reason was given. The results weren't even compared against other aircraft for anyone to see the difference/similarities. This is only a statement at best, not a conclusion. I would expect people in university to do better than this.

omg look who's back.
can someone send me what he wrote? oh i mean seige, not the other guy who just came back from the banned.

airsuperiority said:

can someone send me what he wrote? oh i mean seige, not the other guy who just came back from the banned.

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http://www.sinodefenceforum.com/mem...-chinese-military-article-take-look-5679.html

An edited version of that article can be found over here with others that siege, noname and others have been translating.

Russian T-50 easy, medium, and hard fixes (topside)


China's J-20 Mighty Dragon stealth fighter


J-20 Mighty Dragon has no gaps between rear part of engines and fuselage. Notice the frameless one-piece bubble canopy. The continuous-curvature upper-body design of the J-20 is obvious to an untrained eye.


Russian T-50 or Pak-Fa "stealth" fighter

Easy fixes

The first of many non-stealthy features, which are immediately noticeable about the Russian T-50, is the metal-framed cockpit canopy. Also, the protruding IRST probe in front of the cockpit needs to be recessed.

Medium fixes

Thirdly, the gaps between the engines need to be filled to eliminate a stronger radar echo. Fourthly, unlike the J-20, there is no RAM coating over the gleaming Russian T-50 engines on the entire exposed upper-body surface. The T-50 designers may have to resolve cooling issues with its engines if they are covered with RAM material.

Hard fix

The fifth problem with the top-side design of the T-50 is the lack of continuous-curvature. On the Chinese J-20, there is a nice round curve to the entire upper-body fuselage. On the Russian T-50, there are sharp and oblique angles, especially behind the cockpit. The Russians need to obtain a supercomputer and fix the design problem.

[Note: Thank you to "MwRYum" for the J-20 pictures and Aimarraul for the Russian T-50 pictures.]

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I tried looking for the old "Discussion of J-20 and Pak-Fa" thread, but I couldn't find it. If a moderator knows where it is, please move this post. Also, this is a clinical and objective post to contrast and compare stealth design features. This is not a "versus" comparison. If Sukhoi doesn't like what I'm pointing out, they should fix the problems.

MiG-29 said:

really? well in Indian defence they usually give thanks for the articles

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It was a joke.

^^ What's the point of this comparison?

You again proved yourself just a fanboy

We are all fanboys at heart Martian, but behaving maturely is what you need to learn to do

Re: Russian T-50 easy, medium, and hard fixes (topside)

Martian said:

China's J-20 Mighty Dragon stealth fighter

J-20 Mighty Dragon has no gaps between rear part of engines and fuselage. Notice the frameless one-piece bubble canopy. The continuous-curvature upper-body design of the J-20 is obvious to an untrained eye.

Russian T-50 or Pak-Fa "stealth" fighter

Easy fixes

The first of many non-stealthy features, which are immediately noticeable about the Russian T-50, is the metal-framed cockpit canopy. Also, the protruding IRST probe in front of the cockpit needs to be recessed.

Medium fixes

Thirdly, the gaps between the engines need to be filled to eliminate a stronger radar echo. Fourthly, unlike the J-20, there is no RAM coating over the gleaming Russian T-50 engines on the entire exposed upper-body surface. The T-50 designers may have to resolve cooling issues with its engines if they are covered with RAM material.

Hard fix

The fifth problem with the top-side design of the T-50 is the lack of continuous-curvature. On the Chinese J-20, there is a nice round curve to the entire upper-body fuselage. On the Russian T-50, there are sharp and oblique angles, especially behind the cockpit. The Russians need to obtain a supercomputer and fix the design problem.

[Note: Thank you to "MwRYum" for the J-20 pictures and Aimarraul for the Russian T-50 pictures.]

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I tried looking for the old "Discussion of J-20 and Pak-Fa" thread, but I couldn't find it. If a moderator knows where it is, please move this post. Also, this is a clinical and objective post to contrast and compare stealth design features. This is not a "versus" comparison. If Sukhoi doesn't like what I'm pointing out, they should fix the problems.

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No offense, but Martian you probably know well by now that I collect models. While PAK-FA failed to impress me with almost everything from its looks to even its name, the flaws you've pointed out made me double-reconsider if I still want to buy a PAK-FA and build it to include into my future fleet of gen4+gen5. I still don't quite get why RuAF can produce something like this after so many years of R&D.