Chengdu J-20 5th Generation Aircraft News & Discussions

[marshall]

...and the reason this idea of a canard stealth mode in the FBW even began.

It is an idea not worth the blood sugar spent in speculating about.

I guess those dummies who designed the Eurofighter were just total morons to be programming code for the FBW to make the canard as stealthy as possible then right? Hey, why don't you submit your resume to get those incompetent aerospace engineers fired, they deserve the whip! LOL

Prove me wrong.

Prove me wrong that WW I era bi-planes were practically negative stability designs...

Another red herring! LOL Your claim that the J-20 has canards solely to account for negative stability is a leap of giant proportions and as I said back-assward logic. Canards are usually part of a fighter design to add maneuverability in the absence of other measures like thrust vectoring and these decisions are done early on in the design, NOT to regain stability after the design is almost complete. In the case of the J-20 it's mostly a result of the historical development of China's indigenous fighter designs.

Conversely, if you have poor programming skills, then all the flight control effectors doo-dads in the world are not going to help you.
...
The J-20 -- without TVC -- have the same amount of 'control effectors' as the F-16. Canards are 'control effectors'. Limiting their movements in the hope -- HOPE -- of minimizing their RCS contributorships is asking for an in-flight disaster.

Yet another red herring. lol Obviously the FBW would set upper bounds to how much the canard movements could be minimized if the flight environment at any given specific moment warranted it. You claim it might crash? I claim you wouldn't make a very good programmer. Falsely repeating that I said the canards could be locked will get you nowhere.

I do hope the Chinese DO NOT exercise technical and operational common sense when they do give the J-20 this 'feature'. ...It will make the Americans' -- and possibly the Indians' -- job easier at shooting the PLAAF out of the sky.

This is ridiculous. Again, the Eurofighter already has this "feature" in the FBW for its canards. It's been around for over 10 years! I'm done with this thread. Go claim your victory. Yeehaw!

 

[amalakas]

I guess those dummies who designed the Eurofighter were just total morons to be programming code for the FBW to make the canard as stealthy as possible then right? Hey, why don't you submit your resume to get those incompetent aerospace engineers fired, they deserve the whip! LOL



Another red herring! LOL Your claim that the J-20 has canards solely to account for negative stability is a leap of giant proportions and as I said back-assward logic. Canards are usually part of a fighter design to add maneuverability in the absence of other measures like thrust vectoring and these decisions are done early on in the design, NOT to regain stability after the design is almost complete. In the case of the J-20 it's mostly a result of the historical development of China's indigenous fighter designs.



Yet another red herring. lol Obviously the FBW would set upper bounds to how much the canard movements could be minimized if the flight environment at any given specific moment warranted it. You claim it might crash? I claim you wouldn't make a very good programmer. Falsely repeating that I said the canards could be locked will get you nowhere.



This is ridiculous. Again, the Eurofighter already has this "feature" in the FBW for its canards. It's been around for over 10 years! I'm done with this thread. Go claim your victory. Yeehaw!

It isn't quite so. And it happens to step into an area of my expertise.

First of all, the canards are not added to the design for the reasons you mentioned. The aircraft is designed from scratch with canards.

Canards become the main control surfaces just as the tail planes are on other aircraft.
The addition of canards usually provides greatest control authority on the plane as they are usually affecting the shifting center of gravity of the plane to a greater extent than the traditional tail planes (eg. su 30, EF2000) would or are.

There is no stealth canard mode, at least not in the way you describe it. Control surfaces don't move based on programming alone.

the flight control laws for a particular aircraft are indeed programmed, but the control surfaces are governed by dynamic and adaptive control laws also.

if you attempt to use linear logic to a control surface actuators on a modern inherently unstable aircraft there is only one way you are going, and that is down and very fast too.

You cannot programme a "minimum amount" of movement for a control surface. I don't see how, that would mean that either the pilot would have to disengage the mode, or the mode is disengaged automatically when it detects there is a reason for it.. how would it ? based on control stick inputs? relative position and acceleration ? use the gyros ? But the system is already doing that.... the FCS will not use excessive deflection for flight path level correction anyway... not if it is decent anyway so what is the pioint ?

 

[marshall]

It isn't quite so. And it happens to step into an area of my expertise.

First of all, the canards are not added to the design for the reasons you mentioned. The aircraft is designed from scratch with canards.

That was actually what I was saying. He was suggesting the J-20 canards were solely designed and added to account for negative stability.

Canards become the main control surfaces just as the tail planes are on other aircraft.
The addition of canards usually provides greatest control authority on the plane as they are usually affecting the shifting center of gravity of the plane to a greater extent than the traditional tail planes (eg. su 30, EF2000) would or are.

There is no stealth canard mode, at least not in the way you describe it. Control surfaces don't move based on programming alone.

the flight control laws for a particular aircraft are indeed programmed, but the control surfaces are governed by dynamic and adaptive control laws also.

if you attempt to use linear logic to a control surface actuators on a modern inherently unstable aircraft there is only one way you are going, and that is down and very fast too.

You cannot programme a "minimum amount" of movement for a control surface. I don't see how, that would mean that either the pilot would have to disengage the mode, or the mode is disengaged automatically when it detects there is a reason for it.. how would it ? based on control stick inputs? relative position and acceleration ? use the gyros ? But the system is already doing that.... the FCS will not use excessive deflection for flight path level correction anyway... not if it is decent anyway so what is the pioint ?

I assumed excessive movements could trigger an instantaneous and temporary automatic override before switching back. I learned of the Eurofighter FBW programmed to maximize stealth with the canards but never really investigated it. Can you explain its principles? Sorry about the tirade, I like to have fun sometimes.

 

[amalakas]

That was actually what I was saying. He was suggesting the J-20 canards were solely designed and added to account for negative stability.



I assumed excessive movements could trigger an instantaneous and temporary automatic override before switching back. I learned of the Eurofighter FBW programmed to maximize stealth with the canards but never really investigated it. Can you explain its principles? Sorry about the tirade, I like to have fun sometimes.

I never investigated the EF2000 FCS controls in particular. I have no idea what it is supposed to do. I don't see how the canards of the EF2000 can be stealthy managed though. If you can find some source I would be more than happy to read it.

 

[gambit]

The IRST device is not properly stealth shaped. It's a front facing spheroidal shape providing specular reflection back to source. You do not have this with the canopy. That is the difference.

And what is that difference? How is the canopy's curvature DOES NOT produce specular reflections?

The context was talking about the IRST and you brought up the lambda rule suggesting a larger IRST would be more stealthy. The same IRST which you can see is not shaped to deflect radar away from the source and is spheroidal. On an untreated canopy, the cockpit is considered the 2nd worst contributor of RCS and the pilots helmut the worst within the cockpit. Guess what a front facing round IRST most resembles? Hmmm...and you think a BIGGER IRST could be better? Hey, why don't you patent your invention and present it as a stealth breakthrough?

This is exactly what I mean by you guys' failure to understand 'stealth' in general. EVERYTHING is a contributor, front facing or not, edge diffraction producer or not, specular reflections or not. If the IRST device's contributorship does not violate a certain threshold, the same concept that J-20 Chinese engineers adheres to but is disparaged by the clueless and inexperienced Chinese conscript rejects members here, then the IRST device does not pose a negative factor to final RCS. In nowhere did I even 'suggest' that when it comes to the 10-lambda rule, larger mean smaller in RCS. It seems for all your boasting of your edukashun, you have poor logical reasoning skills. So let me say this again: If the diameter is just large ENOUGH to be greater than 10 wavelengths, then there is no need to make that diameter ANY larger.

Btw, I've been arguing with that guy for years because he constantly posts questionable stuff. You're simply the flipside of your doppelganger. You and your bloodbrother are Internet cheerleaders to the max.

I do not major in 'Chinese physics'. So there is no 'flipside' to YOUR man here. In fact, by the ways you agreed with him in this IRST device subject, both of you are clueless allies. And wrong.

 

[gambit]

I guess those dummies who designed the Eurofighter were just total morons to be programming code for the FBW to make the canard as stealthy as possible then right? Hey, why don't you submit your resume to get those incompetent aerospace engineers fired, they deserve the whip! LOL

The Eurofighter is a 'stealth' aircraft? Yeah, if those engineers call it that, they do deserve my whip.

Another red herring! LOL Your claim that the J-20 has canards solely to account for negative stability is a leap of giant proportions and as I said back-assward logic. Canards are usually part of a fighter design to add maneuverability in the absence of other measures like thrust vectoring and these decisions are done early on in the design, NOT to regain stability after the design is almost complete. In the case of the J-20 it's mostly a result of the historical development of China's indigenous fighter designs.

Wrong. I said that fly-by-wire FLCS, not canards. In a FBW-FLCS system, IF the canards are intended to be active flight control surface, then any feature to 'lock' or minimize their movements to reduce dynamic RCS contributorship may have adverse flight control effects.

Yet another red herring. lol Obviously the FBW would set upper bounds to how much the canard movements could be minimized if the flight environment at any given specific moment warranted it. You claim it might crash? I claim you wouldn't make a very good programmer. Falsely repeating that I said the canards could be locked will get you nowhere.

Are you speaking here from experience or just baseless speculations?

This is ridiculous. Again, the Eurofighter already has this "feature" in the FBW for its canards. It's been around for over 10 years!

Source for this claim, please. I want to see a non-Chinese source that says the Eurofighter's canards can and WILL be 'locked' in place SOLELY for RCS purposes.

Under very specific conditions will any flight control surfaces will move to a preset position, as in how the Gripen's canards are so positioned. In the above image, those are landing/speedbrake positions for the canards. They would not be in those positions for take-off because they would produce the most drag.

I'm done with this thread. Go claim your victory. Yeehaw!

Your failed arguments and lack of logical thought processes rendered you 'done' with this thread a long time ago. So yeah...Yeehaw...

 

[gambit]

It isn't quite so. And it happens to step into an area of my expertise.

First of all, the canards are not added to the design for the reasons you mentioned. The aircraft is designed from scratch with canards.

Canards become the main control surfaces just as the tail planes are on other aircraft.
The addition of canards usually provides greatest control authority on the plane as they are usually affecting the shifting center of gravity of the plane to a greater extent than the traditional tail planes (eg. su 30, EF2000) would or are.

There is no stealth canard mode, at least not in the way you describe it. Control surfaces don't move based on programming alone.

the flight control laws for a particular aircraft are indeed programmed, but the control surfaces are governed by dynamic and adaptive control laws also.

if you attempt to use linear logic to a control surface actuators on a modern inherently unstable aircraft there is only one way you are going, and that is down and very fast too.

You cannot programme a "minimum amount" of movement for a control surface. I don't see how, that would mean that either the pilot would have to disengage the mode, or the mode is disengaged automatically when it detects there is a reason for it.. how would it ? based on control stick inputs? relative position and acceleration ? use the gyros ? But the system is already doing that.... the FCS will not use excessive deflection for flight path level correction anyway... not if it is decent anyway so what is the pioint ?

But if a Chinese on an anonymous Internet forum says so, then it is so. This is 'Chinese physics' at their best.

 

[marshall]

I never investigated the EF2000 FCS controls in particular. I have no idea what it is supposed to do. I don't see how the canards of the EF2000 can be stealthy managed though. If you can find some source I would be more than happy to read it.

double posted, sorry.

 

[marshall]

I never investigated the EF2000 FCS controls in particular. I have no idea what it is supposed to do. I don't see how the canards of the EF2000 can be stealthy managed though. If you can find some source I would be more than happy to read it.

There is mention of it in most descriptions of the Eurofighter but no specific details. The closest details I've read is that the canards work in unison with the elevons to realize a lower RCS. How that is done is never actually explained but since it was described as programmed adjustments to reduce the contribution of the canards, it sounded suspiciously like canard adjustments that are in turn compensated by elevon adjustments. The canards were a huge bone of contention when the J-20 was first unveiled.

Btw, on an unrelated note. I have a question concerning Greece that you might know about that I can't find in the history texts I've read. I know an Armenian who can't stand Turkish and he has been telling me an alternative history. He told me that western Turkey (Asia Minor) was once mostly populated by Greeks and eastern Turkey populated by Armenians and Kurds. Then the original Turks, who he claims actually came from central Asia, not vice versa, migrated to Turkey proper over centuries and after out breeding both the Greeks and Armenians, claimed all of present day Turkey. He was basically saying the present day Turks are actually Asians and that Turks are a mixture of Greeks, Armenians, Kurds and central Asian Turks?

 

[amalakas]

There is mention of it in most descriptions of the Eurofighter but no specific details. The closest details I've read is that the canards work in unison with the elevons to realize a lower RCS. How that is done is never actually explained but since it was described as programmed adjustments to reduce the contribution of the canards, it sounded suspiciously like canard adjustments that are in turn compensated by elevon adjustments. The canards were a huge bone of contention when the J-20 was first unveiled.

Btw, on an unrelated note. I have a question concerning Greece that you might know about that I can't find in the history texts I've read. I know an Armenian who can't stand Turkish and he has been telling me an alternative history. He told me that western Turkey (Asia Minor) was once mostly populated by Greeks and eastern Turkey populated by Armenians and Kurds. Then the original Turks, who he claims actually came from central Asia, not vice versa, migrated to Turkey proper over centuries and after out breeding both the Greeks and Armenians, claimed all of present day Turkey. He was basically saying the present day Turks are actually Asians and that Turks are a mixture of Greeks, Armenians, Kurds and central Asian Turks?

ohh... you are opening a can of worms here buddy. Let me put it this way. The present day turks, especially the ones who live now on near east (i.e. the Mediterranean basin) have very little in common (genetically) with the turks who invaded the land about 1000 years ago.

 

[no_name]

The ancient Turkic people are more like a confederation of nomadic tribes, They tend to migrate around asia and where ever they settled over time they become close in appearance to local populations since they tend to be the minority. Thus turkic people in eastward asia took on oriental features and those in Turkey took on caucasoid features, while those in central asia looks different to both.

 

[marshall]

ohh... you are opening a can of worms here buddy. Let me put it this way. The present day turks, especially the ones who live now on near east (i.e. the Mediterranean basin) have very little in common (genetically) with the turks who invaded the land about 1000 years ago.

Interesting, since it conflicts with some of the history you read concerning this yet what you just said is what I've heard from an Armenian and a few Greeks. This is related to something I'm debating about Xinjiang on another forum site.

The ancient Turkic people are more like a confederation of nomadic tribes, They tend to migrate around asia and where ever they settled over time they become close in appearance to local populations since they tend to be the minority. Thus turkic people in eastward asia took on oriental features and those in Turkey took on caucasoid features, while those in central asia looks different to both.

Yes, that's true, I was trying to get an accurate background about Turkey as it exists today because a group of Turkish nationalists are attacking me at a blog defending Uighur (turkic sub-group) machete attacks against Chinese civilians. It's interesting that what happened demographically to former Greek & Armenian territory is what also happened to Xinjiang, formerly ethnic Mongolian & Chinese areas where these Turkic sub-groups usurped the existing populations, mixed with them but still remained essentially Turkic.

 

[amalakas]

Interesting, since it conflicts with some of the history you read concerning this yet what you just said is what I've heard from an Armenian and a few Greeks. This is related to something I'm debating about Xinjiang on another forum site.


Yes, that's true, I was trying to get an accurate background about Turkey as it exists today because a group of Turkish nationalists are attacking me at a blog defending Uighur (turkic sub-group) machete attacks against Chinese civilians. It's interesting that what happened demographically to former Greek & Armenian territory is what also happened to Xinjiang, formerly ethnic Mongolian & Chinese areas where these Turkic sub-groups usurped the existing populations, mixed with them but still remained essentially Turkic.

This is a common theme throughout turkish conquests, the local indigenous populations are absorbed first through religion and then through the erasure of ethnic backgrounds slowly, indigenous populations forget their ethnic backgrounds and identify as turkic.

 

[ARSENAL6]

The ancient Turkic people are more like a confederation of nomadic tribes, They tend to migrate around asia and where ever they settled over time they become close in appearance to local populations since they tend to be the minority. Thus turkic people in eastward asia took on oriental features and those in Turkey took on caucasoid features, while those in central asia looks different to both.

Ah-ha
So inconclusion J-20s were kinda like normadic tribes that went around asia an became close appearnce in local populations. Therefore J-20s in eastward asia took on oriental features and those in Turkey took on caucasoid features, while those in central asia looks different to both. If you don't agree why bring it up. This is about j-20 5th gen stop going off topic.

 

[siegecrossbow]

Link to newest flight Video (March 10th). I think you need a CJDBY account to watch it.

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