Photos and analysis of China's J-20 fighter as it nears first flight

[Sundog]

The views from above show that the entire main wing is behind the C. of G. (which has to be ahead of the mainwheels)

I agree with you the main wing is positioned well behind the center of gravity, this has to make the aircraft quit stable and not as maneuvrable as the other two fifth generation fighters, the F-22 and T-50, this aircraft starts to look more and more like an interceptor.

This is actually quite false as I demonstrated in my explanation. It's not about the main "wing" it's about the aerodynamic center. The same could be said of the Typhoon, Rafale, and Gripen and they are all unstable designs.

 

[PAK FA]

This is actually quite false as I demonstrated in my explanation. It's not about the main "wing" it's about the aerodynamic center. The same could be said of the Typhoon, Rafale, and Gripen and they are all unstable designs.

The main wing center of lift has to be closer of the center of gravity, a fighter like the AJ-37 or Kfir has the wing placed well behind the center of gravity.
compare the AJ-37 with the JAS-39 or the Mirage III and Kfir with the Mirage 2000.
the JAS -39 places the wing well ahead so the jet pipe nozzle and aft fuselage are free of clutter, the Mirage 2000 does the same.

On the J-20 the delta is very close to the aft fuselage, the nose wheels almost at the root of the wing, then the canard has to be a second lifting force.
Delta canard aircraft are usually neutral or near neutral to avoid extra trimming having a tail heavy aircraft or in other words an aircraft with a high pitch up tendency.
a conventional aircraft with tailplanes when is made statically unstable has a higher longitudinal unstability but also it frees the tailplane because it allows the now tail heavy aircraft to requiere less downforce to trim and therefore more lift at the tail is available

by making it more stable or neutrally stable a canard delta wing aircraft becomes easier to fly at supercrusing speeds.
The aircraft also has canards that can not be placed upon the small forebody because it will disrupt the inlet work, also the DSI inlet works better if the forebody is small and generates a weaker boundary layer, thus by being shorter, the DSI can work better, so the canards are positioned already well behind the forebody, also the aircraft uses a delta meaning it will have a long wing chord and the delta already has a LERX that adds length to the wing chord this is forcing the wing to be placed well behind the nosewheels
The LERX of the wing also moves the aerodynamic center ahead having a positive effect.

 

[Deino]

Huuuu ... it sems as if it's only minutes from "GO" ... and reportedly two prototypes are taxiing on the runway in front of the VIP-stand.

Deino

 

[overscan (PaulMM)]

That would be very interesting....

 

[Deino]

Latest news ... flight has been cancelled for today !!!! ???
Reportedly due to "bad" weather.
Deino :'(

 

[rousseau]

I bet there may be some error, there is no clouds covered the place where the a/c would making its maiden flight. B)

 

[F-14D]

I think PAK FA makes some good points. Like the Typhoon, this aircraft does not appear to have a close coupled canard. Unlike the Typhoon, which uses its more forward canard for extreme maneuverability, this seems (from what little we've seen from overhead, to be a case where the canard is being used for extra lift as well as control, which might imply greater flexibility in payload at the expense of some manueverability. I suppose we'll all see when the time comes.

BTW, US Defense Secretary Robert Gates is due in Bejing on Sunday. As political theater goes, what better weekend for a first flight, eh? Or they could be leading us all around by the nose...

 

[Deino]

Via =GT from CDF .... and again those exhausts are more WS-10A like !!! ;D

 

[Mike Pryce]

The views from above show that the entire main wing is behind the C. of G. (which has to be ahead of the mainwheels)

I agree with you the main wing is positioned well behind the center of gravity, this has to make the aircraft quit stable and not as maneuvrable as the other two fifth generation fighters, the F-22 and T-50, this aircraft starts to look more and more like an interceptor.

This is actually quite false as I demonstrated in my explanation. It's not about the main "wing" it's about the aerodynamic center. The same could be said of the Typhoon, Rafale, and Gripen and they are all unstable designs.

In my original post I took other sources of lift into account:

I think that, even with lots of canard/forebody lift, that would still make it a less than ideal dogfighter

However, the wing is still the largest source of lift, and with it being so far aft it will mean the aerodynamic centre is unlikely to be far forward. On Typhoon, Rafale, Gripen the wing is relatively further forward than on J-20, with the canard often not being used as a lifting surface but as a trimming surface, and in subsonic flight the trim force is downward. At supersonic speed, as the centre of lift on the wing moves aft, the canard becomes a positive, lift adding, trim surface. However, on J-20, the wing is so far aft that even at subsonic speed I think the canard will be directly adding to lift (unlike Typhoon etc).

Still, flight test will reveal all. Hopefully!

 

[Deino]

Again regarding the different exhausts ... still not convinced that these are different engines !!!!??

 

[Otaku]

I think PAK FA makes some good points. Like the Typhoon, this aircraft does not appear to have a close coupled canard. Unlike the Typhoon, which uses its more forward canard for extreme maneuverability, this seems (from what little we've seen from overhead, to be a case where the canard is being used for extra lift as well as control, which might imply greater flexibility in payload at the expense of some manueverability. I suppose we'll all see when the time comes.

BTW, US Defense Secretary Robert Gates is due in Bejing on Sunday. As political theater goes, what better weekend for a first flight, eh? Or they could be leading us all around by the nose...

Clearly, the many thousands of hours of wind-tunnel testing of the 1.44 have been put to good use.
Hu Jintao phoned the US DoD and asked "will you be long Bill?...just that I've got to be in Chengdu for tea-time..." ;D

Again regarding the different exhausts ... still not convinced that these are different engines !!!!??

Maybe they're nozzle 'covers'?

 

[saintkatanalegacy]

wow... they actually polished them

but go check the last pic where it's an aft view.

seems that the "covers" aren't placed

another thing i've observed: if you overlap the petals of both picture... they're actually aligned - coincidence?

 

[rousseau]

That's funny, one of my friend told me there are two prototypes has been rolled out, each equipped its own engine, but both of those are similar specifications. We care too much of difference of those powerplant without any idea about what superiority it impossible to be.

 

[Deino]

wow... they actually polished them

but go check the last pic where it's an aft view.

seems that the "covers" aren't placed

another thing i've observed: if you overlap the petals of both picture... they're actually aligned - coincidence?

Maybe we should simply wait and see ... at least for me the thing's are as clear as they are to You. So let's wait.

That's funny, one of my friend told me there are two prototypes has been rolled out, each equipped its own engine, but both of those are similar specifications. We care too much of difference of those powerplant without any idea about what superiority it impossible to be.

Yes ... and the differences are not only the engines but also some yellow, unpainted parts esp. around the front fuselage ... one has them, the other one not. And I really can't think that thes has to "polish" the pedals that often and replace parts between each test.

The one with those yellow parts has the AL-31FN ... and the completely grey one these "siverish" exhausts.

Deino

 

[fightingirish]

http://pic.yupoo.com/emfire/AKTe1WPW/k7EjX.jpg

http://pic.yupoo.com/emfire/AKT846j6/116uml.jpg
http://pic.yupoo.com/emfire/AKTa2H1W/141KLN.jpg
more fence party
http://pic.yupoo.com/emfire/AKT846j6/116uml.jpg

all from FYJS

http://www.fyjs.cn/bbs/read.php?tid=...toread=&page=2

1st pic resized as attachment.

 

[Sundog]

This is actually quite false as I demonstrated in my explanation. It's not about the main "wing" it's about the aerodynamic center. The same could be said of the Typhoon, Rafale, and Gripen and they are all unstable designs.

The main wing center of lift has to be closer of the center of gravity, a fighter like the AJ-37 or Kfir has the wing placed well behind the center of gravity.
compare the AJ-37 with the JAS-39 or the Mirage III and Kfir with the Mirage 2000.
the JAS -39 places the wing well ahead so the jet pipe nozzle and aft fuselage are free of clutter, the Mirage 2000 does the same.

On the J-20 the delta is very close to the aft fuselage, the nose wheels almost at the root of the wing, then the canard has to be a second lifting force.
Delta canard aircraft are usually neutral or near neutral to avoid extra trimming having a tail heavy aircraft or in other words an aircraft with a high pitch up tendency.
a conventional aircraft with tailplanes when is made statically unstable has a higher longitudinal unstability but also it frees the tailplane because it allows the now tail heavy aircraft to requiere less downforce to trim and therefore more lift at the tail is available

by making it more stable or neutrally stable a canard delta wing aircraft becomes easier to fly at supercrusing speeds.
The aircraft also has canards that can not be placed upon the small forebody because it will disrupt the inlet work, also the DSI inlet works better if the forebody is small and generates a weaker boundary layer, thus by being shorter, the DSI can work better, so the canards are positioned already well behind the forebody, also the aircraft uses a delta meaning it will have a long wing chord and the delta already has a LERX that adds length to the wing chord this is forcing the wing to be placed well behind the nosewheels
The LERX of the wing also moves the aerodynamic center ahead having a positive effect.

Being an Aero Engineer, I'm quite familiar with all of that. Anyone designing a modern fighter that is naturally stable has already missed the boat. It's obvious this isn't designed to be just a supercruiser, otherwise it wouldn't need the high AOA features. My math shows this is an unstable design, but I won't be able to be sure until I have a good planform view.

BTW, your logic fails, because both the Typhoon and the Rafale have their wings at the end of the fuselage. It isn't as simple as where the wing is on the fuselage. A lot of that also has to do with boat tail drag and area distribution.

 

[saintkatanalegacy]

hence the dorsal fins

 

[Desert Dawn]

INTERSTING NEWS on I TELE (CANAL PLUS +)
J-20 hunter bomber will not be operational before several years.(French experts one french TV).
Probably did they forget the number of persons on the tarmaks?
They have spys and THALES net filters and a lot of retroenginiery.
For to their space program to launch their russian rocket there were 65000 persons with russians and french engineers in the first and second shot. (and their space quest is a question of marketing and communication not space research, in "France" for launching ARIANE V, 500 people are nesessary.said experts and Jean-François Clervoy on ARTE (c'est dans l'air).
To meditate!!!!!!

But for the experts they still excavate the dustbins and are still unable of ratraper the knowledge of the SNECMA of Rolls-Royce or of ONERA.


** Hi Bruno, i agree with you, pretty much what i was saying in essence on another forum, but sadly nationalistic pride and such got in the way. They are bringing their first stealth fighter behind 3 generations of US stealth fighters, drones, bombers and helicopters and 30 years after HAVE BLUE, and not so long ago were still trying to lay their hands on any F-16 engine they could find (a 35 to 40 year old design) to fix the development problems they had with making their own homegrown fighter jet engine (some illegal importer got caught trying to smuggle one of these a few years ago).

Stéphane.
Stratosphere Models.

 

[Foxglove]

wow... they actually polished them

but go check the last pic where it's an aft view.

seems that the "covers" aren't placed

another thing i've observed: if you overlap the petals of both picture... they're actually aligned - coincidence?

Maybe we should simply wait and see ... at least for me the thing's are as clear as they are to You. So let's wait.

That's funny, one of my friend told me there are two prototypes has been rolled out, each equipped its own engine, but both of those are similar specifications. We care too much of difference of those powerplant without any idea about what superiority it impossible to be.

Yes ... and the differences are not only the engines but also some yellow, unpainted parts esp. around the front fuselage ... one has them, the other one not. And I really can't think that thes has to "polish" the pedals that often and replace parts between each test.

The one with those yellow parts has the AL-31FN ... and the completely grey one these "siverish" exhausts.

Deino

Deino's right. The funny thing though is that both the all-grey and the yellow-marked airframes bear the same 2001 number. Possible reasons: it's the same aircraft, only the yellow parts have been painted over and engines replaced or there are two aircraft with the same number( to mislead the spies?).

 

[flateric]

Hui Tong says that second prototype has one of advanced FSW10 mods

 

[Deino]

My most favourite for today !!! :-*

 

[PAK FA]

BTW, your logic fails, because both the Typhoon and the Rafale have their wings at the end of the fuselage. It isn't as simple as where the wing is on the fuselage. A lot of that also has to do with boat tail drag and area distribution.

When did i say the aircraft is stable? i said most canard delta configuration are close to the neutral or near neutral position, they can be unstable but the degree they are unstable is lower than an aircraft with tailplanes.
The canard already is a distabilizing force, excesive pitch up tendencies will render the aircraft difficult to fly and trimming will induce more drag, already the canard is killing lift on the main wing, canard deflections also will increrase radar signature.

Both Eurofighter, and Rafale position their nosewheel deeper into the wing, in the Rafale the main landing wheels are not near the LERX but a bit deeper into the wing, on the J-20 the main landing wheels are almost at the LERX wing junction, this is achieved because on the Rafale the canard is above the inlet and the Rafale `s wing LERX begins at the inlet lip, this saves longitudinal space and makes for a compact fighter in the Rafale`s case, on the J-20 due to stealth considerations, the canard starts at the inlet lip and the LERX of the wing after the canard also the Eurofighter and Rafale are smaller in size implying they are also lighter, lighter aircraft will suffer less structurally, lighter aircraft can pull more Gs.

 

[Sundog]

Both Eurofighter, and Rafale position their nosewheel deeper into the wing, in the Rafale the main landing wheels are not near the LERX but a bit deeper into the wing, on the J-20 the main landing wheels are almost at the LERX wing junction, this is achieved because on the Rafale the canard is above the inlet and the Rafale `s wing LERX begins at the inlet lip, this saves longitudinal space and makes for a compact fighter for the Rafale, on the J-20 due to stealth considerations, the canard starts at the inlet lip and the LERX of the wing after the canard also the Eurofighter and Rafale are smaller in size implying they are also lighter, lighter aircraft will suffer less structurally, lighter aircraft can pull more Gs.

I think you're confusing weight with wing loading. Or you're trying to talk about wing loading in a round-a-bout way. The aircraft with lower wing loading will pull more g's, regardless of weight, all else being equal.

 

[PAK FA]

i think you're confusing weight with wing loading. Or you're trying to talk about wing loading in a round-a-bout way. The aircraft with lower wing loading will pull more g's, regardless of weight, all else being equal.

Let me explain when you have fighters of similar sizes and weights of course the aircraft with lower wing loading will have better turning ability that will happen even withing the performance of any fighter at different weights.
But heavy aircraft in example MiG-31, are only rated to 5Gs and even heavier aircrat like the Tu-160 are rated at 2Gs at most why?
Simple heavier the aircraft you have to multiply their weight by the Gs, this means a very heavy aircraft has loads that are stronger than a lighter aircraft.
If you want to built a good dogfighter you need to make it fly low and make it light, this contradicts the modern tendecies in aircraft design,a Su-27 is heavier than most WWII bombers, a Spitfire lighter than a LCA

 

[lastdingo]

i think you're confusing weight with wing loading. Or you're trying to talk about wing loading in a round-a-bout way. The aircraft with lower wing loading will pull more g's, regardless of weight, all else being equal.

Let me explain when you have fighters of similar sizes and weights of course the aircraft with lower wing loading will have better turning ability that will happen even withing the performance of any fighter at different weights.
But heavy aircraft in example MiG-31, are only rated to 5Gs and even heavier aircrat like the Tu-160 are rated at 2Gs at most why?
Simple heavier the aircraft you have to multiply their weight by the Gs, this means a very heavy aircraft has loads that are stronger than a lighter aircraft.

This is more about size (side load!) than weight, and the use of a flat fuselage as with T-10 and T-50 reduces the problem a lot because the fuselage is strong and the span of the wings themselves doesn't need to be extraordinary.

Btw, the MiG-31 is a bomber interceptor based on another bomber interceptor design. The max load is in both cases small because there was no intent to ever do dogfighting with them. There was also no intent to dogfight with a Tu-160.
On the other hand, the F-15 was rated to 9 G while many smaller designs were rated to 7 G or less.


Modern combat aircraft can be developed to tolerate 11 or 12 G - the 9 G limit was used in the 70's because humans weren't able to go farther with pneumatic anti-g suits without lying or being in a water tank. The hydro-based Libelle anti-g suit has addressed this issue and allows for two more Gs. Future combat aircraft designs may very well be designed for 11 or 12 G - especially if they're meant to be optionally piloted.

 

[kcran567]

i think you're confusing weight with wing loading. Or you're trying to talk about wing loading in a round-a-bout way. The aircraft with lower wing loading will pull more g's, regardless of weight, all else being equal.

Let me explain when you have fighters of similar sizes and weights of course the aircraft with lower wing loading will have better turning ability that will happen even withing the performance of any fighter at different weights.
But heavy aircraft in example MiG-31, are only rated to 5Gs and even heavier aircrat like the Tu-160 are rated at 2Gs at most why?
Simple heavier the aircraft you have to multiply their weight by the Gs, this means a very heavy aircraft has loads that are stronger than a lighter aircraft.

This is more about size (side load!) than weight, and the use of a flat fuselage as with T-10 and T-50 reduces the problem a lot because the fuselage is strong and the span of the wings themselves doesn't need to be extraordinary.

Btw, the MiG-31 is a bomber interceptor based on another bomber interceptor design. The max load is in both cases small because there was no intent to ever do dogfighting with them. There was also no intent to dogfight with a Tu-160.
On the other hand, the F-15 was rated to 9 G while many smaller designs were rated to 7 G or less.


Modern combat aircraft can be developed to tolerate 11 or 12 G - the 9 G limit was used in the 70's because humans weren't able to go farther with pneumatic anti-g suits without lying or being in a water tank. The hydro-based Libelle anti-g suit has addressed this issue and allows for two more Gs. Future combat aircraft designs may very well be designed for 11 or 12 G - especially if they're meant to be optionally piloted.

I 100% agree with PAKFA, Lighter for a true fighter/dogfighter.

This aircraft J-20 is as big as an F-111 and being 60,0000 to 80,000 lbs range when fully loaded this is the largest of the new stealthy fighters by FAR.

Speculated that is a long range interceptor with some strike capability seems the most clear choice. It is clearly not built for dogfighting. And don't forget that unless the Chinese have built an engine that SURPASSES the ones in the t-50 or f-22, with higher thrust, how can the J-20 compete in the thrust/weight ratio category, let alone wing loading while having the largest design among them, and using (at best) engines with parity to the other designs. Even with engine parity to the f-22 and T-50, the J-20 will be heavier, and thus underpowered to the other two designs. Its a hard row to say the j-20 is going to be anything but a long range interceptor with strike capability, and air to air dogfighting given the least priority. The Chinese could have another (unbuilt) aircraft for that role, or just rely on the j-10's.

 

[rousseau]

Finally it is easy to estimate how large this monster is.
presume the black stick scaled as 1.5 meter, now for your calculation

http://postimage.org/image/z2o14t0k/

 

[Steve Pace]

Finally it is easy to estimate how large this monster is.
presume the black stick scaled as 1.5 meter, now for your calculation

Can't see anything. -SP

 

[PAK FA]

. Future combat aircraft designs may very well be designed for 11 or 12 G - especially if they're meant to be optionally piloted.

I agree with you but what i am trying to say is simple, a F-16 at 10tonnes has less need for a stronger wing than a MiG-31 at 24 tonnes at empty weight.
Bombers like the Tu-22M or like the B-1B are too heavy, it means to make them fly at 9Gs their complete structure is not as strong as the one of the F-16, the load of 15 tonnes multiplied 9 times is much lower than 130 tonnes multiplied by 2Gs.
heavy aircraft have weaker structure and can not fly like a fighter.
Small and light aircraft are always better suited for dogfights.
Even the Su-27 or Su-30 fly better at a weight of 23 tonnes, the combat weight is not the same that max take off weight.
Ideally the T-50 will fight a enemy fighter at 23 tonns after it has burn some fuel.
Another problem is wing span, as the wing gets longer gets heavier and weaker, to make it stronger you need tobeef it up but this bring more weight in example the An-124 wing.
In my opinion the J-20 is not a fighter well suited as a dogfighter it is bigger than the F-22 and very likely heavier and its aerodinamic configuration limited, the T-50 is a better fighter i see it more like a F-35 type of aircraft more A than F

 

[rousseau]

Not each words you posted I agreed with but the position of J-20 you set is about right.
It is really hard to convinced an aircraft with 22 meters long without power over which F-22 fitted could possibly be air-superiority fighter.
This is a mini-b-70 IMPO ;D

 

[sferrin]

Not each words you posted I agreed with but the position of J-20 you set is about right.
It is really hard to convinced an aircraft with 22 meters long without power over which F-22 fitted could possibly be air-superiority fighter.
This is a mini-b-70 IMPO ;D

Not B-70 (no Mach 3 performance). More like what Boeing wants us to think their F-15 "Silent Eagle" would be.

 

[PAK FA]

Not each words you posted I agreed with but the position of J-20 you set is about right.
It is really hard to convinced an aircraft with 22 meters long without power over which F-22 fitted could possibly be air-superiority fighter.
This is a mini-b-70 IMPO ;D

i understand you

 

[F-14D]

http://www.aviationweek.com/aw/generic/story_generic.jsp?channel=awst&id=news/awst/2011/01/10/AW_01_10_2011_p26-280386.xml&headline=What%20China%27s%20Stealth%20Fighter%20Means

 

[DFC]

This aircraft exhibits some of the philosophy that went into strategic interceptor projects during the closing stages of the USSR.
I won't be surprised if it has a high ceiling and decent range.

As far as the secondary ground attack role is concerned, I wonder if the canards can come into play there..

 

[PAK FA]

As far as the secondary ground attack role is concerned, I wonder if the canards can come into play there..

As far as i know the only aircraft that uses exclusively canards as an strike aircraft of the size of the J-20 is the Su-34, the Su-34 uses the canards as a turbulance dampers at low flight, this allows it to fly low and fast as the Su-24 with its VG wing.
The B-1B uses its small nose canards in a similar way.
The Su-34 with its large nose and smaller LERX than the original Su-27, needed the canards to restablish some of the lift lost by reducing the LERX size and making a bigger cockpit with side by side seating.
The Eurofighter is not a dedicated striker niether the Rafale they use their canards also for air to air combat and turning, The Su-34 uses the canard as vortex generators, vortex control, turbulance dampers, reduce landing speed and restablish longitudinal unstability lost by the increase of forebody size and weight.
Its canards alows it to regain some of the agility lost by making it heavier than the original Su-27.

 

[bobbymike]

How about one mission and one mission alone - with frontal stealth, high, clean (internal weapons storage), long range anti-access air interdiction fighter firing many long range BVR missiles and returning to base to fight another day?

Targets any and all US long range bombers plus the possibility of targeting (with the right missile technology and range) even tankers and AWACS?

This is my amateur opinion of course.

 

[DFC]

PAK -FA,

the Su-30 MKI also uses canards for terrain following. But of course it is a multi-role plane.

 

[saintkatanalegacy]

How about one mission and one mission alone - with frontal stealth, high, clean (internal weapons storage), long range anti-access air interdiction fighter firing many long range BVR missiles and returning to base to fight another day?

Targets any and all US long range bombers plus the possibility of targeting (with the right missile technology and range) even tankers and AWACS?

This is my amateur opinion of course.

well, that's a very good possibility

certainly more accurate than those of *some* "experts"

 

[DFC]

well some derivative of the K-37 LRAAM may certainly end up in this plane...

or Chicom may use an air to air derivative of the YJ-91.

so then the anti-tanker/ ISR asset role certainly becomes viable.

Plus for air to air action the PL-12 family is evolving .. the South africans have had a role to play there along with the Pakistanis who are probably going to induct the A-darter as well.

I am sure just like the focus on terminator Chicom will also seek to create a marriage between anti-radiation and AAM action.

 

[kcran567]

This aircraft exhibits some of the philosophy that went into strategic interceptor projects during the closing stages of the USSR.
I won't be surprised if it has a high ceiling and decent range.

As far as the secondary ground attack role is concerned, I wonder if the canards can come into play there..

A very large, (not optimized for dogfighting) aircraft, long range interceptor to patrol those vast Chinese borders. And, to make up for their lack of a large Navy/Carrier presence, a strike role to attack ground and surface targets...I would suggest a very strong anti-carrier and anti-ship role for this big airplane. Possibly needs a large bay to be big enough to fit some very large solid rocket + ramjet powered anti ship missiles.