J20 Stealth Fighter

[trackwhack]

that looks sexy.:thumb:

when is our amca coming?

 

[J20!]

As of September 25, a new test pilot has joined the test pilots team:

 

[J20!]

On September 26, J-20 #02 gave a demonstration for VIPs.

 

[J20!]

Sept 26 flight tests. J2002 is said to have flown 3 different times on the 26th:

 

[J20!]

J-20 #2001 at CFTE

Apparently J2002 has also moved on to Yanliang, J2003 must be almost done.

 

[p2prada]

Hmm, which helicopters are those?

I am pretty sure people have already done it, but this gives a proper scale to measure the J-20's dimensions.

 

[W.G.Ewald]

Hmm, which helicopters are those?

I am pretty sure people have already done it, but this gives a proper scale to measure the J-20's dimensions.

The J-XX/J-20 is a large fighter, similar in size to an F-111 (Chinese Internet).

Chengdu J-XX [J-20] Stealth Fighter Prototype / A Preliminary Assessment

 

[J20!]

Hmm, which helicopters are those?

I am pretty sure people have already done it, but this gives a proper scale to measure the J-20's dimensions.

That looks like a Z8 considering its size.

 

[J20!]

Chengdu J-XX [J-20] Stealth Fighter Prototype / A Preliminary Assessment

The J20 isn't that large Ewald. It's actually shorter than a PAK FA in length but longer than an F22. I'd find you the pics but I'm dozing off bro, gotta hit the hay... J20! Out!

 

[AprilLyrics]

most people agree that J-20 is about 21.5m long

 

[nefory]

most people agree that J-20 is about 21.5m long

20.3M

 

[J20!]

Good Photos Came Out During The Holidays...

 

[p2prada]

Good Photos Came Out During The Holidays...

Maybe because all the patrols near the airstrip fence may have stopped due to the holidays.

 

[p2prada]

Pic for comparison with a Flanker.

Nearly as long as the Flanker but with a smaller wingspan.

 

[ersakthivel]

Hi! Is it possible to post Song's paper here? If it is on this thread I think I missed it. TIA.

IMO, J-20 is a multirole fighter, and not simply dedicated to one role or another.

I am positive it has small wings that make it a very good dog fighter, a long body for supersonic dash and a decent balance between high altitude and low altitude performance like the MKI or Rafale.

So in your opinion any fighter that has long body and small wings is a very good one!!!

Is that all to the aerodynamics.I'm mesmerized.The poor thing does not have a proper engine, so nobody knows it's TWR .Also what are it's wingloadnig figures and sustained turning radius?

I'm sure without a proper engine even it's developers won't know that.

Looking at PAKFA and J-20 it seemsif you fly some airframe without final engine configuration, avionics, asea radar and call it stealth if you put some black paint on it!!!!!!!!!!!!!

Poor guys in ADA should follow this same phony trick and put black paint over LCA with some fancy shaping and they should claim it as their top secret stealth as soon as possible.

This circus called 5th gen is getting stranger these days!!!!!!!!!!

People who cannot develop engine ,radar,avionics,for JF-17 leaving the pakistanis begging all over the world for the same have suddenly become 5th gen stealth makers.

In my opinion ADA and DRDO have atleast finished a decent MMR with air to air mode,truly modern FBW and mission computers and avionics in much better way than the chinese.The chinese even now haven't finished WS engine.

.So if they put two kaveri engines that are now generating 150 kn with an airframe larger than LCA having the same aerodynamic features, incorporating internal bomb bays, and stealth shaping features,with canted tail fins, they are much closer to true 5th gen stealth than chinese and Russians.

But the NAPOLEANS and ALEXANDERS IN IAF wont allow it.They can swallow any russian junk with both eyes open but will set goals so high for AMCA ensuring it's delay as much as possible.

 

[ersakthivel]

How do you copy this:

And come up with this?:

.

And second:

http://www.-------------------/2011/09/mig-denies-stealth-technology-transfer.html

Mig state that no such transfer ever took place.

The 1.44 is far from a stealth aircraft, the stealth shaping on the J20 far exceeds that of the 1.44. If you had bothered to read Dr. Song's paper, or even analysed the J20's aerodynamic configuration, you'd find that the J20 utilized, canards, large LERX's, body lift and its inner wings to produce most of its lift, and is designed mainly for supercruise, whereas the 1.44 has no LERX and mainly uses its larger wing surface area, as well as canards and thrust vectoring control to achieve super maneuverability. It is considerably less oriented towards supercruise than the J20 is.

Not to mention that their intake designs are completely different. The 1.44 has rectangular intakes under its fuselage whilst the J20 uses chin mounted diverterless supersonic intakes, an intake design first tested in China on the J10B. Its like saying the Rafale and the Eurofighter are the same aircraft simply because they use the same aerodynamic configuration, (ie canard delta). The Korean KFX utilized the same configuration, maybe its a 1.44 copy too?

Super cruise is achieved by having higher power engine not by having LREX lift and lifting body implementation.The grippen NG claims super cruise because putting a higher power engine on a same weight plane allows the plane to cross sound barrier without using after burners thats all.

 

[ersakthivel]

I don't say anything. It looks like you've already made up your mind, arguing with you would just be a waste of both our time. But if you really want to know about the J20's design process, here's an excerpt from Dr. Song Wencong's paper on its design:


This paper analyzes the main design conflicts of the future fighter's stealth, high maneuverability, and supercruise characteristics while proposing specific design solutions for trans-sonic lift to drag characteristics, low speed high AOA characteristics, and supersonic drag characteristics. The author believes that in-depth study of fluid dynamics, exploration of the full practical potential of current aerodynamic designs, development of new design concepts, employment of corresponding systematic and control measures, and necessary compromise among numerous design proposals will allow us to achieve our design goals.

1. Introduction:
The future fighter, aside from satisfying low and mid-altitude maneuverability performance of modern 4th gen. fighters, must have the capability to supercruise and perform unconventional maneuvers such as poststall maneuvers. As a result, the aerodynamic configuration of the future fighter must not only satisfy the design constraints of RCS reduction but also lower supersonic drag, improve lift characteristics, and improve stability and controllability under high AOA conditions whilel accounting for trans-sonic lift to drag characteristics. The high number of design requirements provide new challenges to the aerodynamic layout. The design must employ new aerodynamic concepts and approaches, take necessary systematic and control measures, and compromise amongst the numerous design points in order to obtain the necessary design solution.

But what is employed in J-20 is exactly the same as any other modern 4.5gen fighters with canards and LREX. while naval LCA employs LREX for low speed handling, grippen employs canards for the purpose.The J-20 claims to employ both ,but the problem is it will make things complicated in relation to WHITCOMb's area rule which advocates smoother and gradual increase in cross section from nose to wing root and then smoother reduction of cross section from wing root in the shape of coke bottle.

This is evident in F-22 , first nose , then lrex like air intakes and then wings. But in J-20 all increase in cross section are sudden Lrex and canards jut out so near the nose cone , so it will be a high drag combination in low altitude supersonic speeds.Tejas hopes to overcome this problem by higher power engine in the same way as J-20 hopes.So I don't see any new design ground broken.Just employing high thrust engine to overcome this wave drag is no design break through.

If you have any doubt you can refer CEMILAC report by S.K.Jebakumar on how lengthening the fuselage and making cross sectional increase gradual will reduce supersonic drag at sea level.IS ther any lift to drag cross sectional area curve published for J-20?

,

2. Main design conflicts:

The design requirement for stealth brings new difficulties to the aerodynamic design. Frontal stealth capability imposes new restrictions on both the sweep angle of the leading edge and air intake configuration. Lateral stealth requires the proper alignment of the aircraft's cross sectional shaping and the vertical stabilisor configuration. These restrictions and requirements must be considered during the earliest phase of designing the aerodynamic configuration.

What are the restrictions imposed on sweep angle of leading edge by frontal RCS stealth?

How did J-20 solved it?

To me the leading edge sweep angle of J-20 doesn't seems radically different from fourth gen fighters.If there are any specific points please post.
The first non complaint design aspect of stealth are canards, but we don't find any mention of this, and the report suggests leading edge sweep angle as main challenge in frontal RCS.

World over the view is operation of frontal canards are in direct conflict with frontal RCS stealth wich goes against the concept of planform arrangement and deflection of RADAR waves from the source.Surely with canards, elevons, tail fins all swivelling in different directions at the same time is supposed to compromise stealth.

There is no way in the world that you can operate all of them simultaneously and remain stealth even to X band.If stealth compliant operation of these control surfaces are imposed by FCS then the effectiveness of these controls significantly decrease..

Trans-sonic lift to drag ratio and supersonic drag are traditional design conflicts. Modern Fourth gen. fighters successfully solved this dilemma by relaxing aircraft stability and employing wing bending mechanisms. Future fighters, however, have stricter requirements for supersonic drag characteristics. At the same time, conventional design maximizing low speed lift characteristics contradicts the pursuit for lower supersonic drag. Since current aerodynamic measures don't offer satisfactory solutions to these conflicts the design team must explore new design paths.

No one can get around these design conflicts imposed by basic aerodynamics other than having higher thrust engines.ANd if J-20 employed any different ways the report doesnot speks about it.

Post stall maneuvers require the aircraft to have good controllability and stability. After the plane enters the post stall region, however, the decrease in stability and control efficiency of conventional rudder surfaces become irrecoverable. One must carefully design an aircraft to enable sustained controllability at high AOA. Although it is possible to solve the problem of post-stall controllability through the use of thrust vectoring nozzles, the aerodynamic configuration itself must provide enough pitch down control capability to guarantee the aircraft to safely recover from post-stall AOA should the thrust vectoring mechanism malfunction. As a result, it is vitally important to study unconventional aerodynamic control mechanisms for high AOA flights.

These are all general design conflicts that are present since the advent of modern aviation.If you employ so many unconventional aerodynamic control surfaces and mechanisms to overcome this you will end up with an RCS of 5 sq meter for clean configuration like SUKHOI,which is the very antithesis of stealth requirements imposed by 5th gen stealth.

3. Trans-sonic lift to drag characteristics

Trans-sonic lift to drag characteristics determine an aircraft's maximum range and sustained turn capability. The future fighter's demands for these characteristics will exceed those of modern 4th gen. fighters. Modern fighters employ the strategies of relaxing longitudinal stability, adapting wings with medium sweep and aspect ratio, twisting the wing, and adding wing-bending mechanisms to greatly improve the lift-to-drag characteristics. Due to the future fighter's requirement for supercruise, supersonic drag characteristic is a critical design point and designers must avoid using aerodynamic measures that may potentially increase supersonic drag. As a result, the wing shape and wing twist coefficient can't be selected based on trans-sonic lift to drag characteristics alone. It is necessary to employ wing-bending mechanisms but its aerodynamic efficiency has already been exhausted.

5th gen fighters too have to employ the strategies of relaxing longitudinal stability, adapting wings with medium sweep and aspect ratio, twisting the wing, and adding wing-bending mechanisms to greatly improve the lift-to-drag characteristics like 4th gen .Can there be any difference?Once again super cruise comes with higher thrust engine only overcoming the high drag canard delta combination.it doesn't come by employing lifting body or LREX.Super cruise refers to stright line supersonic speeds without after burners.

Employing lifting body concept and LREX will generate lift which will help the fighter achieve higher STR in knife edge position , and all modern fighters use lifting body and LREX for this, surely the J-20 is neither the first or the last one to do that.LREX is suggested on naval LCA to improve low speed handling of deltas .Not for supercruise

Further decreasing the aircraft's longitudinal relaxed stability is an excellent solution to this problem. Diagram 1 shows how the variation tendency of trim-drag coefficients against longitudinal instability of a conventional fighter aircraft in a tight, sustained turn. Modern fighters fix their longitudinal instability at 3% the average aerodynamic chord length. The future fighter could enjoy a significant improvement in lift-to-drag if the longitudinal instability could be increased to a magnitude of around 10%.

Further relaxing the longitudinal instability could not only enhance trans-sonic lift to drag characteristics but also improve super sonic lift to drag capabilities, increase take-off and landing characteristics, and maximize low-speed lift characteristics. This is akin to killing three birds with a single stone. Yet a increase in longitudinal instability will also increase the burden on high AOA pitch down control and subsequently increase flight control complexities. As a result the design team should not "over-relax" the longitudinal stability.

These concepts apply to all fighters

4. Low speed high AOA characteristics

4.1 Lift-body LERX Canard configuration

Advanced modern fighters utilized research on detached vortices from the 1960s and 70s to gain excellent lift characteristics with their max lift coefficient peaking at around 1.6. They either employ conventional LERX configuration or canard configuration to accomplish this. The future fighter has higher requirements for max lift coefficient and the situation is further complicated by the fact that the use of twin vertical stabilizers is detrimental to lift (see figure 4.2). As a result the design team must raise the max lift coefficient to a whole new level. It will be difficult to realize this goal simply employing conventional LERX configuration or canard configuration.

It is beneficial to choose canard configuration from a high AOA pitch down control stand point(see figure 4.3). Blending lift body LERX characteristics with the conventional canard configuration to form a "lift body LERX canard configuration" will greatly enhance the max lift characteristics. Exploration of the lift body LERX canard configuration will solve three important technical issues. The first problem is the aerodynamic coupling between canards and medium sweep, medium aspect ratio wings. The second problem is the coupling between the canards, the LERX, and detached vortices generated by the wings. The third problem concerns the gains and losses of employing body lift on a canard configuration aircraft.

But the problem is it will greatly reduce the 5th gen touted stealth charecteristic of the aircraft.Once your position is detected by radar when you us LREx+CANARDS +all moving TAIL surfaces it's gonna rain BVrs on these costly small store carrying 5th gens,either with L band radar searches or IRST measures.

Traditionally close coupled canard configuration aircraft utilize constructive coupling between the canards and detached wing vortices to enhance the max lift coefficient. Only wings with large back-sweep angle and small aspect ratio could generate detached vortices that are powerful enough for the task. As a result most modern canard configuration fighter aircraft have a leading edge backsweep angle of around 55 degrees and an aspect ratio of around 2.5. For these aircraft, the canards could generate around a 3 to 4 times increase in max lift coefficient with respect to their wing areas. Ideally we hope to employ wings with medium leading edge backsweep angle and medium aspect ratio in order to improve lift characteristics over the entire AOA range. This wing shape, however, could not effectively generate leading edge detached vortices. Could the canards still attain their original lift enhancing effects? The answer is yes according to wind-tunnel tests. As the slope of the aircraft's lift curve increases, the lift enhancing capabilities of the canards are the same as those on traditional close coupled canard configuration aircraft (see figure 2). The key influence on aerodynamic coupling between the canards and medium back-sweep, medium aspect ratio wings should not be interference among detached vortices. Preliminary studies indicate that down-wash on the wings generated by the canards play a far greater role.

It is a well known fact that LERX could improve the max lift characteristics on medium back sweep, medium aspect ratio wings. In order to obtain even better lift characteristics, we should consider using both canards and LERX to create a canard-LERX configuration. Study shows that employing both canards and LERX not only retain the lift enhancing effects of the two mechanisms when they are used separately but also help achieve higher lift-coefficient (see figure 3). This means that there is beneficial coupling among the canards, LERX, and the wings.

Blended wing lift body configurations could utilize lift generated by the aircraft's body to increase internal load and enhance stealth characteristics at relatively low costs to drag. Lift-body configurations have been adapted by many conventional configuration aircraft and achieved excellent results. Yet until now now canard configuration fighter utilized lift-body configuration. This isn't because aerodynamic experts failed to realize the tremendous advantage of the lift body configuration but the result of a canard configuration aircraft's need to place the canards above the aircraft's wings. It is difficult for lift-body configuration aircraft to satisfy this demand. Our experimental results indicate that although the canards on a canard-LERX configuration aircraft employing lift-body suffered a decrease in lift-enhancing effects, the overal lift characteristic of the aircraft was still superior to that of a canard-LERX aircraft not employing lift-body (see figure 4). Figure 5 shows the vortex generation on the wings and body of a lift-body canard configuration aircraft observed using laser scanning. It demonstrates that planes employing this configuration derive excellent lift characteristics not only from coupling among the canards, LERX, and detached vortices but beneficial interaction between the left and right detached vortices. The latter contribute to significant lift on the body of the plane and greatly contributed to the enhancement of lift characteristics. Figure 5 also indicates that the detached vortices primarily contribute to lift on the body and inner portions of the wings. Consequently, most of the lift produced under high AOA conditions are generated in the corresponding areas.

All modern fighters strive to employ blended lift body configuration for enhances RCS reduction and better lift.Lift is not generated by coupling of canards and wing.Any increase in wing area or canard ,and Lrex area will automatically generate more lift.SO using canard configuration along with lifting body concept seems to be the new achievement in J-20 .but it will lead to sudden increase and decrease in cross section through out the aircraft resulting in higher supesonic wave drag as implied by WHITCOMB'S area rule.How is this problem resolved in J-20.If you look at F-22 or PAKFA or RAFALE or LCA the increase in crss section from cockpit to the wing root is gradual and there are no decrease in between. But J-20 goes against this principle by employing a combination of canards and LREX to gether.In this case are ther no problems in complying with whitcomb's area rule for reduction of supersonic wave drag?If this problem is resolved by simply higher thrust engines there is nothing ground breaking about it.

4.2 Canted vertical stabilizers

Vertical stabilizer design is an important consideration when it comes to future fighter configuration design. From a lateral stealth stand point, the vertical stabilizers should cant inward or outward to reflect incoming radar waves in other directions. The future fighter must be long and thin to accommodate for supercruise and as a result, the space between the vertical stabilizers couldn't be too wide. The twin stabilizers should cant outward in order to decrease destructive interference between the vertical stabilizers. Since the future fighter will fully utilize detached vortices to improve max lift coefficient, forward vortices will generate relatively high outward facing velocity airflow on the vertical stabilizers. Figure 6 shows the calculation results of a type of lift body LERX canard configuration fighter using n-s time average function. It indicates the limiting flow rate on the aircraft's rear once the vertical stabilizers are removed. The results indicate that the regional side slip angle at the location where vertical stabilizers are usually installed reaches around 15 degrees when the AOA is 24 degrees and the side slip angle is 0 degrees. If the back-sweep angles of the vertical stabilizers are sufficiently large, the enormous regional side slip angles could generate leading edge shed vortices on the external faces of the stabilizers and form low pressure regions. Regional sideslip angles will also increase the static pressure on the inner portions of the vertical stabilizers. As a result, the vertical stabilizers will become highly efficient lateral force surfaces which direct the lateral forces outwards. The lateral forces are projected in the direction of lift, with respect to the outward canting vertical stabilizers, and generate negative lift. Negative lift acting on the vertical stabilizers and rear body will both contribute to the undesirable pitch up torque. The high pressure region between the vertical stabilizers will form adverse pressure gradients on the body of the plane and negatively impact the stability of leading edge detached vortices. Since the vertical stabilizers are already highly loaded at 0 degree side slip angle, the yaw/roll stabilization efficiency of the vertical stabilizers will be decreased.

The negative impacts of vertical stabilizers as described above are closely associated with lift-enhancing measures and are, as a result, difficult to root out. Yet adjustment of the vertical stabilizer's area, position, cant angle, and placement angle and improvement measures such as making slots on the rear body can minimize the negative impact of the vertical stabilizers. Ordinarily, the max lift reduction coefficient generated by the vertical stabilizers could reach around 0.4. We've managed to successfully lower it below 0.1 through experimentation.

Decreasing the vertical stabilizers' area or even employing tailless configuration are directions worth studying. Their significance not only include improving low speed high AOA performance but also help improve stealth characteristics, lower drag within the entire flight envelope, decrease weight, and reduce cost. Implementing the tailless configuration requires the tackling of three major technical difficulties: replacing the stabilizers with another yaw control mechanism, installing sensitive and reliable side slip sensors, and implementing new flight control technology. As of now, these difficulties are being tackled one at a time. Relatively speaking, decreasing vertical stabilizers' area and relaxing static yaw stability are more realistic options. Generally speaking, the relative size of the vertical stabilizers is around 20% to 25%. In or studies, utilizing all moving vertical stabilizers with 10% to 13% could still maintain basic yaw stability while retaining the vertical stabilizers' function as yaw control mechanisms.

4.3 Aerodynamic control mechanisms

The requirement for high AOA pitch down control capability is closely related to the longitudinal static instability requirement. The greater the longitudinal static instability, the higher the demands for pitch down control capabilities. As described in chapter 3, the future fighter will hopefully increase its longitudinal static instability to around 10% its average aerodynamic chord length to enhance the trim's lift to drag and lift characteristics. As a result there should be a corresponding improvement in the pitch down control capability. We can categorize two types of control surfaces based on the relative position of the pitch control surfaces with respect to the aircraft's center of mass: positive load pitch down control surface and negative pitch down control surface. Control surfaces placed behind the center of mass, including the vertical stabilizers and trailing edge flaps, generate pitch down control torque by increasing lift. They are considered positive load control surfaces. Control surfaces placed in front of the center of mass, like the canards, are negative load control surfaces. Since the main wing's ability to generate lift tends to saturate under high AOA conditions, the positive load control surfaces' pitch down control capabilities tend to saturate under high AOA as well. Therefore it will be wise to employ negative load control surfaces for pitch down control under high AOA conditions. Figure 7 compares the pitch down control capabilities of the canards and horizontal stabilizers. From the high AOA pitch down control stand point, it will be wise to use canards on the future fighter. Canards on close coupled canard configuration aircraft have relative short lever arms. Employing the LERX canard configuration can increase the canards' lever arms while retaining the benefits of positive canard coupling. Considering the overall lift enhancement effect and pitch down control capabilities, we can set the canards' maximum relative area to around 15% and the maximum canard deflection to 90 degrees.

Yaw control ability under high AOA is another noteworthy problem. Control surface efficiency deteriorate rapidly with an increase in AOA for tailless and even conventional configuration fighters. Therefore it is necessary to consider control mechanisms other than conventional control surfaces. Studies on differential LERX, drag rudder, differential wingtips, and all moving vertical stabilizers indicate that differential LERX and drag maintained relatively high yaw control efficiency under high AOA conditions (see figure 8).

5. Supersonic drag characteristics

The key to lowering supersonic drag is to minimize the max cross sectional area of the aircraft.Accomplishing this requires excellent high level design skills. Placement of the engines, engine intakes, landing gears, cartridge receiver, weapons bay, and main structural support all influence the max cross sectional area of the aircraft. Attention to details and careful considerations are necessary to design decision making.

The key to reduce supersonic drag is to follow the whitcomb's area rule,not reducing the ross section of the fighter ,perhaps.

It is quiet natural this point is glossed over with a small paragraph because after providing for excellant lift in the form of lifting body+canards+Lrex all at the same time resulting in excellant low speed charecteristics, you can never hope to achieve matching low drag requirement in supersonic speeds that will arise from higher wave drag, which arises due to the uneven and abrubt changes in cross section throughout the fuselage.You can't have your cake and eat it too.

Wingshape has profound effects on supersonic drag characteristics. Small aspect ratio wings with large backsweep have low supersonic drag but are detrimental to low speed lift and trans-sonic lift to drag characteristics. If we select the liftbody LERX canard configuration we can expect to retain relatively good lift to drag characteristics while using medium backsweep wings. Under high AOA conditions, liftbody LERX canard configuration aircraft concentrate lift on the body and inner portions of the wings so moderately lowering the aspect ratio will not only not lower the max lift coefficient but raise it (see figure 10). Because of this, employing small aspect ratio wings on a lift-body LERX canard configuration aircraft will settle the conflicts among supersonic drag characteristics, low speed lift characteristics, and trans-sonic drag characteristics.

6. Air Intake design

Air intakes are one of three major sources of radar scattering. In order to lower intake radar reflection area, the design team must place a series of limitations on intake design due to stealth considerations. These limitations will significantly influence intake aerodynamic design.

Caret intakes have oblique intake openings and fixed intake ramps and could effectively lower radar cross section and structural weight. The future fighter may implement this technology. Preliminary studies indicate that when compared with conventional adjustable intakes, Caret intakes' total pressure recovery coefficient surpasses its conventional counterpart in supersonic and trans-sonic regimes and is only slightly lower in the low-subsonic regime. It also offers excellent total pressure distortion performances. Radar absorbing deflectors minimize the air-intake's radar reflection and could significantly improve its stealth characteristics. Aerodynamically speaking, the radar absorbing deflectors would slightly decrease the overall pressure recovery and flow coefficients but have no ill-effects on static or dynamic distortion coefficients.

7. A comprehensive study of a design example

The design team made a future fighter proposal based on the points raised by this article. The proposal employs lift-body LERX canard configuration. It is unstable in both the lateral and yaw directions. The proposal employs small aspect ratio wings with medium back sweep angle, relatively large dihedral canards, all moving vertical stabilizers far smaller than those on conventional fighter aircraft, and S-shaped belly intakes. According to our assessment, the proposed aircraft will have excellent supersonic drag characteristics, high AOA lift characteristics, high AOA stability and controllability, and excellent stealth characteristics.

8. Conclusion

The aerodynamic design for the future fighter, compared with that of advanced modern fighters, will require more design features and subsequently pose greater challenges. Only in-depth study of fluid dynamics, exploration of the full practical potential of current aerodynamic designs, development of new design concepts, employment of corresponding systematic and control measures, and necessary compromise among numerous design proposals will allow us to achieve our design goals.

Source: http://www.-----------/forums/chine...20-article-dr-song-wencong.html#ixzz23KnrN5yf

The original text is in Chinese, this is the only English text I could find.

First of all no new groundbreaking invention is announced in this article regarding the revolutionary design of J-20,which will make J-20 super manouverable and super stealth at the same time.The article outline the principles behind the design of J-20.

 

[ersakthivel]

The Invisible Bird

China's earlier-than-expected test flight of the fifth-generation J-20 stealth fighter has caught the world defence establishment napping. Bravado aside

Hours before American Secretary of Defense Robert Gates was to meet Chinese President Hu Jintao at the Great Hall of the People in Beijing on Tuesday, 11 January, an aircraft took off from an airfield in the southwestern city of Chengdu. The flight lasted barely 15 minutes, but it was a clear message that the strategic balance of global air power was set to shift inalterably. The fifth-generation Chinese stealth fighter, the J-20, which took off on that day, was a signal that the end of American technological dominance of the skies may no longer be a question of decades but years.

The timing itself shows it is just to shock .with no engine no asea and no avionics it is just a chinese toy airframe at present.

Denis Roy, senior fellow at the East-West Center in Honolulu, notes, 'The unveiling of the new Chinese stealth fighter, which the US press is characterising as a rival to the US F-22, reinforces two general US perceptions about the Chinese military. The first is the sense that the PLA (People's Liberation Army) is modernising more quickly than expected and catching up with US capabilities. The second is anxiety about Chinese intentions, and the fear that Beijing plans to challenge the accustomed US role and US interests in the Asia-Pacific.''

Typical speech to start production of F-22.

For weeks before the flight, pictures of the stealth fighter had been making their way to several Chin-ese websites. The very fact that they were not pulled out and the websites left free to operate was a signal that the world was meant to know of the existence of this fighter. The photographs were impressive, displaying the kind of technology that the world had suspected the Chinese were a decade away from developing. For this very reason, there was no shortage of sceptics, among them Robert Gates.

In July 2009, in a speech at Chicago, he had said, ''Consider that by 2020, the United States is projected to have nearly 2,500 manned combat aircraft of all kinds. Of those, nearly 1,100 will be the most advanced fifth generation F-35s and F-22s. China, by contrast, is projected to have no fifth generation aircraft by 2020. And by 2025, the gap only widens.''

Now, on his way to China, he admitted that US intelligence had underestimated the Chinese. He told reporters aboard his plane, which arrived in Beijing on Sunday, "I think what we've seen is that they may be somewhat further ahead in the development of that aircraft than our intelligence had earlier predicted." But even then he said he remained unsure of how 'stealthy' the plane was.

The flight that took off from Chengdu was the Chinese answer. This time the news did not filter out through grainy photos on the Web. It was Kanwa Asian Defence magazine (an East Asian military journal) editor Andrei Chang, a long-time observer of the PLA, who confirmed this in a report from Hong Kong. He said the J-20 took off at 12:50 pm local time, and this was the report the Chinese state-run media picked up to confirm the flight.

John J Tkacik Jr, Chief of China Intelligence in the US Department of State during the Clinton Administration and now part of the right-wing Heritage Fou-ndation, tells Open, ''Obviously, we don't know the technical specifications of the J-20 aside from what we see in the videos, but it appears from the videos that the engine nozzles are for a Chinese-manu-factured engine, and that they show very little exhaust, which indicates that they are quite well advanced, not relative to the US, but to most other countries."

''The Chinese also indicate that they have Russian-made engines as well, and this could mean the fighter will be available before 2017. Photos of the underside of the test aircraft don't reveal any lines for weapon bays, so either the test aircraft doesn't have weapon bays, or they are very tightly incorporated into the fuselage, and hence signal quite acceptable stealth characteristics. I could not see whether the thrust vectoring [the engine's ability to change altitude and velocity] was performing well in the test flight videos, but it seemed to be part of the design. I could not see whether supercruise—supersonic cruising spe-eds—were tested.''

The characteristic indicated by Tkacik are indicators of the advancements the Chinese have managed. Stealth characteristics, the ability to remain concealed from enemy radar, are what distinguish fifth-generation fighters from all other serving fighters around the world. Supercruise is the ability to reach supersonic speed without the use of afterburners (used on most military jets to achieve extra thrust by injecting additional fuel into the jet pipe), which show up on the radar.

So far only one fifth-generation fighter, the US Air Force's F-22 Raptor, is in active service, but its performance in air exercises demonstrates a vast superiority vis-à-vis the US F-15 and F-16. As Tkacik notes, ''The J-20 appears to be about two metres longer than the US F-22, and this could mean that it could hold more weapons, and hence each J-20 could shoot at more targets. Or it could mean that the J-20 will hold more fuel, and therefore be able to fly longer distances and/or loiter longer in target areas. One F-22 is said to be able to shoot down as many as twelve fourth-generation fighters before exhausting its air-to-air missiles and turning to on-board cannon. The purpose, of course, is to deploy effective fighter cover with the least number of aircraft. A J-20 would nullify or erode that advantage.''

The possibility that these aircraft could be deployed in the next few years is one that should worry not just Americans. Says Tkacik, ''India has the most to lose with this new Chinese capability, especially as the J-20 could be based in Tibet and Xinjiang, and it will be able to support significant Chinese ground-troop operations all along India's Himalayan borders—and those of Sikkim, Bhutan and Kashmir (not to mention Nepal).''

[QUOTE

THE INDIAN RESPONSE

Indian defence officials have taken note of the potential of this aircraft in reshaping the strategic context over the Himalayas. The stealth characteristics of the aircraft and the relatively thin deployment of Indian radar cover ''can potentially mean a pre-emptive running attack by the PLA air force,'' says a senior air force planner requesting anonymity.

It is not that India has been unaware of the threat, but, like Robert Gates, it has been labouring under the illusion that it still lies in the distant future. The Indian response was planned in conjunction with Russia. The air force planner adds, ''We have jointly developed fifth-generation aircraft from Russia joining in around the same time [as the J-20 becomes operational]. It's too early to tell in this dogfight." Harsh V Pant of the Centre for Defence Studies at King's College, London, agrees: ''By the time the J-20 becomes operational, the joint India-Russia response will be ready, and it will add complexity to the South Asian theatre. Do not underestimate the Russians in aircraft technology."

The russians atleast are showing a real test bed and they are 100 times more mature than chinese when it comes to ASEA and engine tech.

The aircraft they are talking about is the T-50. Just a month ago, India signed an agreement with Russia for joint development of a fifth-generation aircraft. Russia has already flown a few sorties of the platform on which the T-50 is to be built.

According to Air Marshal (Retd) Kapil Kak of the Centre for Air Power Studies, a think-tank that tracks strategic developments in aerospace: "The Chinese have this seeming headstart with the new prototype, but the Indians have a credible answer. We are not buying the next plane. We are co-developing it. And Russians are to aircraft what Germans are to motorcars. The T-50 platform will develop and outmatch the Chinese for the simple reason that it's a few steps ahead already. India will be in an easy position, come 2020, with its 124 new fourth-generation multi-role aircraft contract well on the way, and add to that the Tejas (a third-generation fighter) to take on the MiG-21 workload."

THE PROBLEMS

It is this mention of the Tejas that makes most strategic affairs experts pause on India's ability to develop a credible alternative, even in partnership with Russians. The Tejas has been 23 years in the making, and as Kak says, it is a third-generation aircraft. India now hopes to skip a generation and do as much work in the next five years as it was unable to do in the past two decades or so.

Typical bullshit.All fighters took 30 years to develop.funding for tech demo released in 1993 ,lca TD-1 flew in 2001.Even this delay of 12 years from 2001 is due to the fact that the two tech demos are supposed to validate all the tech after 4 years of flight trials. And only after the successful completion of this phase the PVs started rolling out from 2006

The idea behind Tejas was to develop an aircraft and its engine from scratch. The Kaveri engine was to be a gas-turbine engine, but the programme ran into trouble soon. The Gas Turbine Research Establishment (GTRE) could find neither the right talent nor the parts to put it together. Then, it was hit hard by sanctions. Finally a semblance of an engine was readied three years ago with a little bit of reverse engineering. After failing several cold-weather trials in Russia, the Government finally decided to invite a foreign manufacturer as a partner in the development of the engine, which is still underway. Meanwhile, the GTRE is proud to present the failed LCA engine as one fit for ships.

The authors expose that they are writing this articles from their ass not their brains.All engine developmental efforts have 25 year time frame.GTRE atleast has a worrking original engine with 75 kn thrust at the first try at hand. Does the jackass authors of this report recognize this significance. All problems were solved originaly by GTRE.
The engine already underwent 22 flight trials in high altitude trials and it is working successfully.The next step is developing single crystal blades for the engine through Jv, not by reverse engineering as the authors are pulling out their claims from their ass.
The navy evinced interest in the marine version no even dumped it on them as they produce 12 MW of power for their ship.Little did the JACKASS authors recognize what is the meaning behind this.

The GTRE engine is in working conditions and it has successfully produced about 75 kns in recent high altitude test in Russia.The JV is for a higer thrust variant.The article is so typical of stupid indin defence journalists who dont have a clue to what they are writing.

It was then decided that the initial versions of the aircraft would use the American GE404 engine. The pace of the programme was hit by American sanctions, and so far only 12 GE404 engines are available to power the first squadron. The radar that HAL, DRDO and ADA were developing ran into problems as the radar units developed by these entities ''did not talk to each other'', meaning the on-board radar was dysfunctional. The Government was forced to requisition Israeli radars.

Another bud headed claim .every claim in this para is false.more than 100 ge engines are ordered.And the proposed GTRE -snecma deal will deliver 100 kn version.Even snecma did the study and said it will be possible in 3 years,negotiations underway.
it is stupid to say the radar is dysfunctional.the air to air mode was ready long before, but the challenging air to ground mode was overcame with israeli processor help according to ADA.Meanwhile no one knows which chinese radrs any chinese fighter carries.
The radar is ready with isralei signal processor and already up and running in LCA.The asea miniaturisation is in progress.And it is an achievable goal for teajs mk_II.
I don't where he invented the term 'THEY didnot talk to each other".

The Tejas is touted as a fly-by-wire system; that is, one that uses sophisticated computer electronics to make it as foolproof as possible. A fly-by-wire aircraft normally has four circuits for each connection, meaning even if one circuit to the landing gear fails, three others will still operate. But in reality, the Indian Tejas has only two such circuits, not four. Technically it does not qualify as a fly-by-wire aircraft. And guess what India is handling in the fifth-generation fighter project it is planning with Russia—the fly-by-wire system.

The guy is quite literaly a fool quadreplex means four redundant channels thats all.He is literally blabbering some gibberish.There is no big tech challenge in quadreplex channel fly by wire.Only one channel is use in practical,while other channels are for redundancy.Does the author understands this?.

THE CHINESE PAST

Ranged against India's faltering attempt is the Chinese past, which has made a virtue of reverse engineering. A Wall Street Journal report recently summarised how China was able to build its current generation of fighters—the J-11B. In 1996, Russia agreed to supply 200 SU-27s to the Chinese. In 2004, China abruptly cancelled the contract after 104 such planes were developed. In three years, a Chinese version of the SU-27 was shown flying on state television.

The author proves himself a bloody fool once again.india atleast has one 75 kn flat rated KAVERI engine successfully undergoing high altitude tests in russia.But the chinese have none.The pratt and whitney has examined the engine and said it is already an world classs engine with much room for improvement .Snecma too conducted a technical audit and certified that in 3 years by employing SNECMA's hot section the engine can generate 95 kn power compared to 75 kn each fro RAFALE's engine.The snecma wants a minimum production run of atleast 250 engines for this jv.Tragically IAf has jumped in with a discovery that the proposed co operation wont produce a 90 kn engine!!!!!!
Then A.K.Antony the defence minister constitued a joint committe of GTRE and IAF to study the JV and now the JV between gtre and snecma is approved as per ANTONY's statement in parliament.

People are ready to do JVs with INDIA because india doesnot do reverse engineering.The foolish report says the GTRe reverse engineered the engine,contrdicting even PRATT &WHITNEY ,AND SNECMA!!!!!!!!!!!!!!!!

The J-11B is a fourth-generation aircraft and its rapid development is what has, in all likelihood, given China its ability to look at a fifth-generation fighter. Far too often, Western firms have ignored the Chinese ability to develop cheap imitations only to find that within years China has upgraded its design and capability to be more than a match for Western firms. History is now being repeated with the technology of war.

It is a copy of sukhoi.The chinese airforce will discover their true strength only when their inferior avionics J-11B comes into combat with sukhoi-MKI

Tkachik is clear that ''this test flight was designed to be provocative, in the sense that it will provoke the United States to reassess its ability to challenge China's rise as the pre-eminent power in Asia. I think the Chinese military believes that once the US sees how rapidly China has modernised, and how much disarray its own economy, industry and financial structure has fallen into, the US will quietly back away''.

It is a photo opp no test flight.Chinese havent made an engine for JF-17,radar for JF-17,How are they going to make engine and LPi ASEA radar for J-20.Infact even indian AMCA is almost ready with engines in the form of working KAVERI.Where is the chinese working engine?/

This may not be the most likely option, but it remains a real possibility. If so, India will be left to fend for itself. For the moment, it has no choice but to place more faith in Russian scientists than its own.

This stupid situation has arisen because IAf is once again aiming for the sky with ADA's AMCA ,instead of evolving LCA's design.The IAF will accept whatever RUSSIAN junk and live with crashing planes forever,but when it comes to MCA they have already set the world's most advanced ASR.

With reports from Adam Mathews, Anil B Lulla and Ninad D Sheth

The Invisible Bird | OPEN Magazine[/QUOTE]
Reporters like these are bud headed fools who don't know head to tails of aviation or they are motivted parties aimed at discrediting indian LCA program.

 

[ersakthivel]

Re: make your conclusion on the truth, not on your imagination

Mr. Bhramos and Singh,

Even Mr. Gates didn't know the J20 before he arrived Beijing airport, and he blamed his CIA partner underestimated chinese military progress, so how come, a senior lawmaker, suddenly got so undoubted conclusion, J20 copied from Russian? CIA suddenly know everything? sound so rediculous.

Chinese have never had illusion about American, American are not enemy naturally, they just want whole world be tamed and knee in front of him. Chinese don't want to be and can not be american tamed puppy sucking american finger, so chinese spend 60 years effort to build their independent military industry, the spine bone can make them stand like man. Military industry is not any commerical bubble, that's 3 generation chinese hard working result.

I am not sure whether Indian are tamed puppy or not, maybe you like to be russian or american puppy, not chinese puppy, that's fine, at least you are puppy, chinese don't have to worry about you.

If you don't want to be anyone's puppy, then shut up the big mouth first, wear glove, work harder and harder. You can not buy a modern military industy, without an indepentant military industy, you can never be a real independant country. 30 billion dollars is definately not enough to compete with either of China, America and Russian, my question is: do you indian want to suffer the pain to pay more? No pain no gain, that is always true.

Even russian give you indian the whole blueprint of T50, can you make one? ask yourself, you know the answer!!!! Chinese is about 15~20 years behind American, about 5~10 years behind Russian, Chinese know it clearly, but you indian don't know you are behind chinese at least 10 years!!!

Why doesn't that great famous spine shows in engine and radar of JF-17?

HAvent you heard of HAl's first home built sukhoi from raw material stage?

Here ADA wont be allowed to fool people with flying a kite like airframe with engines meant for another plane as prototype by indian government.If they fly LCA it has to be with the engines meant for Lca.

 

[ersakthivel]

China and America are the only two giants have the roleof windy tunnels, superhydropress and super computer, all three toys to design 5G jet fighter.
Russia, Japan, Great India, unfortunately, not in the list. No better sources, no connection or information for that, who believe what believe, who don't believe what don't believe.

what is a windy tunnel and in which mountain is it located?