Chengdu J-20 5th Generation Aircraft News & Discussions

[BoQ77]

AL-31FP, of course !!!

 

[Deino]

AL-31FP, of course !!!

Surely not !

THE FP is a special Indian-MKI-taylored version ... can't think the Russians would sell this version to China too. However my point was that all AL-31's share the same or at least very similar internal features ...

 

[BoQ77]

Surely not !

THE FP is a special Indian-MKI-taylored version ... can't think the Russians would sell this version to China too. However my point was that all AL-31's share the same or at least very similar internal features ...

You're right. China need more powerful engines with thrust vectoring
That's an improvement from Al-31FP, maybe AL-31F M2

==========
According to the Salut Gas Turbine Research and Production Centre’s Director General Vladislav Masalov, the company manufactured about a hundred AL-31F turbofans in several variants in 2011. Over 75% of them, in the AL-31FN version in the first place, were exported. The rest were made for the Russian Defence Ministry. To fit the aircraft in service with the Russian Air Force, the company has for several years supplied AL-31F Series 42 engines upgraded by the in-house design bureau and known as AL-31F-M1.

The AL-31F-M1 passed its official trials in 2006 and has been ordered by the Defence Ministry since 2007 to equip Sukhoi Su-27SM fighters. Last year, Salut shipped another batch of engines of the type, which were used for fitting the Su-27SM(3) fighters delivered to RusAF under the contract signed in 2009. A decision in principle was taken to fit the RusAF-ordered Sukhoi Su-34 bombers with Salut-built AL-31F Series 42s. Unlike the baseline AL-31F, the upgraded engine has an advanced enlarged-diameter fan (924 mm) and an automatic control system with a digital integrated governor, which has increased the thrust up to 13,500 kgf and extended the service life.

The next stage of the Salut-conducted upgrade is to become the AL-31F-M2 engine, which thrust in special mode will increase to 14,500 kgf and the service life to 3,000 h or more.

Early this year, Salut hosted a meeting of the scientific and technical board attended by personnel of the Sukhoi design bureau, Lyulka scientific and technical centre (an affiliate of NPO Saturn JSC), United Aircraft Corporation and United Engine Corporation. The board met to consider the results produced by the development work on upgrade the second-stage AL-31F (AL-31F-M2). All work pertinent to the second stage of the engine’s upgrade is on schedule. To date, the engine has completed its special bench tests in Central Institute of Aviation Motors thermal vacuum chamber, which have proven the feasibility of a static thrust of 14,500 kgf and the manufacturer’s performance ratings. The upgraded engine has a 9% increase in thrust in flight modes over the AL-31F-M1.

“The upgrade of the AL-31F engine does not involve modifying its dimensions and is aimed at retaining the feasibility of re-engining the whole of the Su-27 aircraft fleet without extra modifications to the airframe or engine nacelles”, Salut General Designer Gennady Skirdov said.

Until year-end 2012, the special bench and endurance test programme is to be completed and the special flight test programme is to begin. The flight trials of the AL-31F-M2 are supposed to involve using a Su-27SM the Sukhoi company may provide or Gromov LII’s Su-27 flying testbed used for testing the AL-31F-M1.

 

[j20blackdragon]

The J-20's nozzles are too short to be a thrust vectoring engine.
AL-31F M2 is impossible because the gearbox is in the wrong location.

I'm well aware the black engines 'look' like the AL-31FN.
But looks don't tell the entire story.
The J-11D looks like a Flanker.
The H-6K looks like the Tu-16.
The J-10C looks like the Lavi.

 

[BoQ77]

The J-20's nozzles are too short to be a thrust vectoring engine.
AL-31F M2 is impossible because the gearbox is in the wrong location.

I'm well aware the black engines 'look' like the AL-31FN.
But looks don't tell the entire story.
The J-11D looks like a Flanker.
The H-6K looks like the Tu-16.
The J-10C looks like the Lavi.

Colors don't tell.

 

[j20blackdragon]

The engine mystery continues. Why are the nozzles black and now painted silver?

 

[Deino]

Is 2016 still at CAC or again ? I thought it was transferred to the CFTE already ?

 

[Taygibay]

To get back to a prior discussion :

I don't remember who said the J-20 was a MiG 1.44 extrapolation when in fact it resembles most
a stealthy evolution of the 31.

Bigger wing with swept aligned rear edge, corrections to the landing gear positioning,
awesome intake re-design job, twin vertical tails and canards added, etc.

Just like with the J-31, at some point, if your copy improves on everything from the original,
it's just not a copy anymore; is it?

As a long-range bomber interceptor with stealth, this bird has potential ... and it's rather pretty!

Good day all, Tay.

 

[neytirilover]

To get back to a prior discussion :
View attachment 279869

I don't remember who said the J-20 was a MiG 1.44 extrapolation when in fact it resembles most
a stealthy evolution of the 31.
View attachment 279870
View attachment 279871

Bigger wing with swept aligned rear edge, corrections to the landing gear positioning,
awesome intake re-design job, twin vertical tails and canards added, etc.

Just like with the J-31, at some point, if your copy improves on everything from the original,
it's just not a copy anymore; is it?

As a long-range bomber interceptor with stealth, this bird has potential ... and it's rather pretty!

Good day all, Tay.

It is highly unlikely that you can deduce technological origin based on mere eye-balling of such scarce, if not none, similarity between these two aircrafts.

I can judge, by eyeballing, that all fixed-wing aircraft are merely copies and/or evolutions from Chinese Kites--they both had a body and wings, it's great that modern Homo-Sapiens redesigned the system to remove the tethering line.

 

[rational]

The engine mystery continues. Why are the nozzles black and now painted silver?
View attachment 279866 View attachment 279867

Holly s*** damn that look awesome

 

[Taygibay]

It is highly unlikely that you can deduce technological origin based on mere eye-balling of such scarce, if not none, similarity between these two aircrafts.

Actually, one can! Not necessarily anyone as the you in your sentence implies
and of course, applying knowledge of a domain and its tools ( schematics, etc ).

There are such family ties in aircraft design. The Rafale's a clear follow-through
from the Mirage 2000 even if pushed so far that an untrained eye won't register it.
As a fan of both, it always strikes me as evident?

Over 40 years, thousands of images with live access and decent understanding,
one ends up able to shape an informed opinion.

I can't guess the RCS however! Good evening, Tay.

 

[slng]

this beast look solid except too much hidden card.
would like to see the perf

 

[neytirilover]

Actually, one can! Not necessarily anyone as the you in your sentence implies
and pf course, applying knowledge of a domain and its tools ( schematics, etc ).

There are such family ties in aircraft design. The Rafale's a clear follow-through
from the Mirage 2000 even if pushed so far that an untrained eye won't register it.
Fan of both, it always strikes me as evident?

Over 40 years, thousands of images with live access and decent understanding,
one ends up able to shape an informed opinion.

I can't guess the RCS however! Good evening, Tay.

With whatever evidence and analysis you have provided, it remains highly dubious of what you are claiming. If you insist on your opinion, you can certainly provide solid evidence and fact-based logic behind your conclusion (aka "applying knowledge of a domain and its tools", are you familiar with aerodynamics, CFD, avionics or any professional subject that even remotely relates to fighter aircraft design??), so as to back up your claim. I'm a PhD in a similar field, I do aerodynamic/hydrodynamic numerical modeling and design optimization, yet NO ONE in my field who is knowledgeable ever dare to claim that they know the performance and technological origin of a specific design by mere eyeballing. Now if you are a well trained PhD, I just might put a little bit of credibility in you.

Unfortunately, what you have claimed is totally wrong, the design of J-20 has nothing to do with a Mig-31. They do not share any similarity in terms of aerodynamics and virtually every other aspect, other than those features that serves a common purpose, such as making sure that the aircraft can fly, and optimization for high speed. Basically, with the highly non-linear and chaotic turbulence features in aerodynamics, outcome of any difference in aerodynamic design is hardly estimated with bare eyes, you need a wind tunnel and advanced compressible N-S equation-solving CFD tools to get an understanding about a specific design, then you move on to work on the FBW controls.

 

[General Observer]

With whatever evidence and analysis you have provided, it remains highly dubious of what you are claiming. If you insist on your opinion, you can certainly provide solid evidence and fact-based logic behind your conclusion (aka "applying knowledge of a domain and its tools", are you familiar with aerodynamics, CFD, avionics or any professional subject that even remotely relates to fighter aircraft design??), so as to back up your claim. I'm a PhD in a similar field, I do aerodynamic/hydrodynamic numerical modeling and design optimization, yet NO ONE in my field who is knowledgeable ever dare to claim that they know the performance and technological origin of a specific design by mere eyeballing. Now if you are a well trained PhD, I just might put a little bit of credibility in you.

Unfortunately, what you have claimed is totally wrong, the design of J-20 has nothing to do with a Mig-31. They do not share any similarity in terms of aerodynamics and virtually every other aspect, other that those features that serves a common purpose, such as making sure that the aircraft can fly, and optimization for high speed. Basically, with the highly non-linear and chaotic turbulence features in aerodynamics, outcome of any difference in aerodynamic design is hardly estimated with bare eyes, you need a wind tunnel and advanced compressible N-S equation-solving CFD tools to get an understanding about a specific design, then you move on to work on the FBW controls.

Respect! One question, why only compressible. If one wants to test for ranges <M 0.3, I believe an incompressible model would be required also?

In addition, then there is the transition zone or trans sonic region if you will, where turbulent flow really don't get represented well by the compressible model. What assumptions to the model would you add to this region?

 

[neytirilover]

Respect! One question, why only compressible. If one wants to test for ranges <M 0.3, I believe an incompressible model would be required also?

In addition, then there is the transition zone or trans sonic region if you will, where turbulent flow really don't get represented well by the compressible model. What assumptions to the model would you add to this region?

Even for low Mach numbers, sometimes compressible flow still has to be considered. In fact, in one of my projects, I use compressible models for an air chamber with velocity as low as 10cm/s, because I need to consider the phase difference between the motion of the liquid phase and the air. I use incompressible models for liquid phase only. Sometimes compressible model gets way too time-consuming, that's when I have to use incompressible models for high Reynolds number air flow.

I don't deal with high speed flows in my research, the largest velocity that I deal with is within Mach 0.1. So I'm sorry I cannot answer your second question based on my own experience. But in trans sonic region ppl use shock capturing and shock fitting methods for flow characterization, but this carries inviscid flow assumption. AFAIK, Reynolds Averaging and especially LES based compressible N-S solution is capable in capturing most of the transonic-supersonic turbulence details(tho not very accurately), with the cost of huge computational demand, provided that a proper Sub-grid Scale (SGS) viscosity model, a proper computational domain and a proper numerical scheme is used. Assumptions to such modeling, mainly being the assumptions carried in interpolation and schemes, as well as the assumption of parameterized SGS viscosity. A big issue being the characterization of the turbulence variation at the root of a shock wave, since the turbulence boundary layer is disrupted by the shock wave here. Research is still on-going in this area and they appears to be making progress.