J20 Stealth Fighter

ARVION

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Why the J 20 is not the true Frontline's aircraft's.

Chengdu's made clear they want the J-20 to evolve into a family of aircraft. The biggest problem for the J-20 to be further upgraded is the lateness of the WS-15. We've heard nothing out of the rumor mill of late, and we have so-and-so aircraft engine manufacturer declaring they'll build around 5 WS-15 in the 2025 to 2030 timeframe, which is way too slow.

One big issue is the sizing of the J-20's current inlets. The airflow under the present DSI system is adequate for an Al-31 / WS-10X classed engine, but the airflow is insufficient for a F135 / WS-15 class engine. The easy solution is simply to adjust the DSI; i.e, reduce the size of the bumps (and possibly increase their length) to accommodate the greater airflow needed, but an alternative solution would be to enlarge the inlets, creating greater body space and potential for the engines to be shifted to enlarge the weapons bay.

The measurements of the J-20 inlets are roughly the same, perhaps a bit larger, than on the Su-27 series for the Al-31 engines. It's a bit of a pity, to an extent, since larger inlets would have guaranteed better high-altitude / high-speed airflow, sufficient to allow the J-20 to have at least sustainment (requires afterburners to break Mach barrier, but can supercruise around Mach 1.3 without afterburners) supercruise. But that'd compromise low-altitude maneuverability as you'd end up with spillage drag from overflowing the inlets. Consider how much the Su-27 has evolved. The Su-30 modification added canards, necessitating new actuators, and the Su-34 platform converted the Su-27 into a light bomber.

Biggest impediment, of course, is time. The Su-27 emerged and evolved at a time when the Russian armaments industry was wheeling from the collapse of the Soviet Union, meaning that there was limited funding for completely new designs. The Chinese plan to get a sixth-generation fighter up by 2035, and we're already at 2020 with the WS-15 very very late. Then again, as suggested, the J-20B might be significantly different from the J-20A given the 25-37% increase in thrust, allowing the aircraft to carry much more munitions and payload without sacrificing maneuverability. And the TVC expected of the WS-15 could allow the aircraft to conduct a substantial redesign as the tailfins are no longer needed for yaw control.

My basic issue is that the J-20 as a design is rather compromised to deal with the PLA's conflicting requirements and the limitations of Chinese engine technology. It's not as pure a stealth design as the F-22. The weapons payload, while better than the F-22, is roughly the same as on the F-35 so is inferior for a heavyweight stealth fighter. It's not designed for extreme maneuverability like the Su-57 is. And while the aspect ratio would imply that the aircraft is designed for and optimized for extreme speed, the J-20 is limited by the need to protect its stealth coating as well as the DSI inlets on the J-20. The only unique aspect the J-20 has going for it would be its lerx long-coupled canard lerx delta wing set-up, and even that has already been presaged by Rafale.

In other words, the J-20 is good against 4th generation fighters and in numbers adequate to 5th generation fighters, but it seems to lack its own advantages against competing 5th generation fighters. Where its advantages do lie are in the respective weaknesses of specific airframes (F-22 is only just getting upgraded with IRST, does not have EODAS, has an anemic weapons bay capacity, the Su-57 does not focus that much on stealth, the F-35 has poor agility), but it doesn't have anything world-beating. On the other hand, the J-20 has strong developmental potential from the basic design of the airframe. The limitation to the J-20 is constantly the engine, and if that limitation were lifted, the design could be modified to make it not simply a par aircraft, but something that could have a decisive advantage in one area or another.

Put another way, the J-10 is arguably better than a Block 50 F-16 or even a Block 60. The J-16 is arguably more capable than the F-15E. But all of these are last generation fighters. When it comes to 5th generation equipment, the Americans can tout their stealth and sensors on the F-35, the Russians can tout their kinematics on the Su-57, but what does China have? I mean, what do you want to talk about? I have the Song Weicong documents explaining why the J-20 layout was chosen. We have my discussion on how the J-20's weapons bay is crap.

The fact of the matter is, we can compare the J-20 to an F-22 and an F-35. The J-20 isn't an LO aircraft as China-bashers want to claim, but neither is it likely to have a stealth advantage over American warplanes unless China metamaterials design matures and the J-20 is refitted with metamaterials. Then American aircraft can also be refitted with metamaterials, and the advantage disappears. We can also compare it in terms of maneuverability. It has a 75 m^2 wing area for an empty weight range in 18000-22000 kg, I prefer the lower figures given known Chinese advances in 3D materials. This roughly puts it at a wing loading comparable to the F-22, but it doesn't give it advantages over the Su-57. We are aware that the lerx long-coupled canard lerx body lift delta planeform is superior to canard deltas (in the J-10-style configuration) by 20% in terms of lift, but this doesn't necessarily give it an advantage over lerx long-coupled canard lerx planeforms like the Rafale and Eurofighter, which have far superior wing loading compared to the J-20.

In terms of thrust-to-weight, it's competitive with 4th gens at 60% fuel and with missiles, but without the WS-15 it doesn't have a decisive advantage. In terms of weapons bay capacity and strike capability, it's better than the F-22, about the same as a Su-57, but significantly worse than the F-35 Joint Strike Fighter given that its loadout has no decisive advantage over the F-35 despite greater size. In terms of supercruise, while I've tried to argue that the air intake on the J-20 permit's very limited's supercruise, it's apparent from the volume of the intake that the J-20 intakes are comparable to Su-27 intakes and no further mass can be obtained. The Vtech drag diagrams say that total drag build-up for the J-20 at Mach 1 is 9 kt (metric), at Mach 1.1 this drops to 6.8 kt, assuming 35kft or 10.68 km. The Al-31 engine outputs about 2.65 kt of force at Mach 1.0 at 10km and about 2.85 kt at Mach 1.1. The dry thrust of the Al-31 is 7.6 kN at sea level, implying a 65% thrust reduction at altitude. At Mach 1.1, you'd need about 3.4 kt per engine and to break Mach 1 you'd need 4.5 kt per engine, or roughly you'd need a 20% increase in dry thrust to achieve pseudo-supercruise and a 70% increase in dry thrust to achieve true supercruise. Even the Al-41F-1S on the Su-57 can't achieve pseudo-supercruise on a J-20 platform without tweaking to high altitude dry thrust.

In terms of max speed, the DSI and stealth coatings on the J-20 prohibit it from having a strong max speed due to the let-off in engine thrust at high speeds and the need to preserve the engines. In terms of cost, the F-22 is out of production, the F-35 has seen massive cost reduction since its LRIP versions (around 80 million a pop these days), and the Russians are claiming they've gotten the Su-57 down to ridiculously low prices that can have you losing 2 Su-57s per F-35 and not bat an eye. The rumored J-20 price is 100 million (especially with exchange rate changes over the past few years). In terms of other subsystems, the J-20 has advantages in the operation PL-15 system, but the PLAAF lacks micromissile development as even the Russians are attempting such to fit their tiny Su-57 side weapons bay. The PL-21 can't fit on the J-20, the J-20 seems to lack an interceptor missile for very long-range interception against AEW&C and tankers, the J-20 seems to lack an anti-radiation strike missile for the SEAD mission. The Su-57 has a DIRCM that the J-20, to date, lacks, although as I've pointed out, the J-20 is very pod ready given its side weapons bay.

In short, one possibility that can be brought up is that the J-20 is going to be the Chinese 6th generation fighter. When you look at the J-20's development and design, it's clearly a J-10 derivative (and a key feature is that it inherits the anhedral-dihedral canard wing layout as the J-10 has a modified inverted gull wing from the inner section of its wing being dihedral). The ability to modify the basic J-20 design for other purposes and enhanced capabilities suggests that modding the J-20 can be how the PLAAF gets a sixth generation aircraft up by 2035 or even 2030. It could, in all honesty, be a 5.5th generation aircraft, but it's close enough to 6th generation to form a stop-gap. That also allows the PLAAF to develop more aggressive 6th generation designs that would be riskier than the PLAAF could support without a stop-gap fighter like J-20 derivatives.
 

ARVION

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One of the solutions for the J 20's would be this.

9iClole.jpg

I will explain later at a time why I prefer a Lambda wing over the current wing's of the J 20's and why I hate the DSI's not just of J 20's but of any aircraft's. I will explain's it in details in later post's.
 

ARVION

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One of the solutions for J 20's

Basically, fanboy position -> canards are better than tailed stealth aircraft. Fanboy-Moderate position: canards impose some penalty from an all-aspect perspective, but not to direct. Moderate position: canards impose penalties, but not prohibitively so. A paper was posted here a while back detailing canard design and treatment for a speculative canard delta stealth fighter. It stated that with exhaustive ram treatment on the interface between the canards and the main body, RCS contribution can be reduced to around -40 dBsm, but are aggressively treated with RAM.Canards are, of course, not an ideal set up for a stealth aircraft, but no stealth fighter is an ideal set-up for a stealth aircraft and as the ideal stealth shape looks something like this.

All stealth designs tries to reduce the amount of control surfaces to a minimum. Just look how clean and sleek the F-22 and F-35 are designed. Or look at all the various future concepts. The J-20 right now is like the anti-thesis to this. All kinds of control surfaces and aerodynamic elements, which can be easily attributed to, even contrary, goals and requirements. It's a weird plane.

The Possible solution's

One of the solutions for the J 20's would be this.

9iClole.jpg


Lambda wing's

Indeed, it is due to resemblance with Greek letter 'lambda', though not the capital one (ΛΛ), but the small one: λλ. With drawing a lambda over it. Typically, the wing has two taper ratios. The inboard wing tapers heavily, corresponding to legs of small lambda, and the outboard wing tapers slightly or do not taper at all.

Comparison-of-aerodynamic-coefficients-obtained-from-the-numerical-solution-with-the-wind.jpg

Comparison of aerodynamic coefficients obtained from the numerical solution with the wind tunnel results, Re=6×10 5

Comparison-of-turbulence-models-error-in-estimating-the-aerodynamic-coefficients.jpg


Comparison of turbulence models error in estimating the aerodynamic coefficients.

Sensitivity-study-of-turbulence-models-at-different-AOA.jpg


Sensitivity study of turbulence models at different AOA.


In later post's I will explain the Distance placement of engine's.
 

ARVION

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Now the J 20 B's is just a small bomber's, not even a fighter's. After looking at the bump in the air intake's, the fighter's capabilitie's is reduced's.
 

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The world’s third operational fifth-generation aircraft, the Chengdu J-20 “Weilong,” has entered mass production, according to insider reports. The Chinese People’s Liberation Army (PLA) Air Force has reportedly placed a large order, now that many of the jet’s early problems have been sorted out.
According to PLA insider reports, a new version of the J-20, the J-20B, is ready to be fielded by the Chinese military.
“Mass production of the J-20B started on Wednesday. It has finally become a complete stealth fighter jet, with its agility meeting the original criteria,” a military source close to the project told the South China Morning Post (SCMP) on Sunday.
“The launch of the J-20B means this aircraft now is a formal fifth-generation fighter jet,” said SCMP’s source, which noted Chengdu Aerospace Corporation (CAC) had received “heavy orders” from the People’s Liberation Army.
Just a handful of J-20As have been made - 50 by the end of 2019 according to SCMP, which noted in January the PLA would likely need between 100 and 200 to fill its needs. It’s estimated CAC can make four J-20s per month.
The source noted the new version of the stealthy jet is equipped with thrust vector control, a high-tech function on some newer jet fighters that allows them to change the angle their jet engines are pointing. This function makes an aircraft supermaneuverable.
Some other jets with the ability include the US’ F-22 Raptor, Russia’s Su-30-series fighters and Su-57 and China’s J-10C.
Chinese ground crew members inspect a J-20 stealth fighter in Chengdu, in southwest China's Sichuan province (File)

© AP PHOTO / COLOR CHINA PHOTO
Chinese ground crew members inspect a J-20 stealth fighter in Chengdu, in southwest China's Sichuan province (File)
Related to the matter of thrust on the J-20 is the development of its engines: Beijing has been attempting to replace the J-20’s underpowered WS-10 and AL-31 engines, the latter of which is built in Russia, with the domestically produced WS-15 high-thrust turbofan engine, but the work remains ongoing.
“The Chinese engine designed for the J-20s still failed to meet requirements, but its development is going quite smoothly, and it may be ready in the next one or two years,” the source told SCMP. “The ultimate goal is to equip the J-20B fighter jets with domestic engines.”
The report makes no mention of a rumored naval version of the J-20 that would complement or replace the staple of the PLA Navy’s aviation wing, the J-15. As Sputnik reported, a naval version of the J-20 would have to be much smaller than the present design in order to comfortably fit on an aircraft carrier.
The other aircraft under consideration is the Shenyang J-31 or FC-31 Gyrfalcon, a newer fifth-generation jet than the J-20, but for which the PLA has struggled to find an adequate use. However, the Chinese Aeronautical Establishment, the research and development branch of the Aviation Industry Corporation of China, said earlier this month it plans to begin testing a “new type of aircraft” for naval use in conjunction with Shenyang Aircraft Corporation, the maker of the FC-31.
 

ARVION

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According to the unoffical's account at least 72 J 20's are in operational Service's. They are stationed's at - Dingxin, Cangzhou and Wuhu Air Bases's.
 

Super lca

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According to the unoffical's account at least 72 J 20's are in operational Service's. They are stationed's at - Dingxin, Cangzhou and Wuhu Air Bases's.
If the j20s are faulty why do plaaf keep inducting them?
 

ARVION

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If the j20s are faulty why do plaaf keep inducting them?
Because of face saving and fill the gap appreant for a stealth aircraft till J 35 and SGFA enter service's. The J 20's would be improved's in development from basic to the next variant's like J 10's and J 11's
 

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I find J-31 more stealthy than J-20.
The chinese wants j31 to be solely a carrier based fighter but is it really feasible?Does j31 have any extra lift producing surface like Lerx,canards to take off from ski jump?
 

ARVION

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The chinese wants j31 to be solely a carrier based fighter but is it really feasible?Does j31 have any extra lift producing surface like Lerx,canards to take off from ski jump?
The F 31, is just a Technological demonstrator's, the J 35 would be the Naval Carrier's Fighter Aircraft's.
 

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Dilemma of J 20's for Role's

This is not to say that J-20 cannot be a viable and capable strike aircraft – for instance, the F-22 has demonstrated that even carrying a relatively light strike load of only JDAMs or SDBs, it is able to produce very potent strike capability by leveraging supercruise, sensor fusion and a very low observable design. But F-22’s primary role is that of an air superiority fighter, with a weapons bay designed to match that purpose, and it is most accurate to say F-22’s respectable strike capability arises despite the inherent limitations of the design of the actual airframe and its weapons bay dimensions rather than flourishing as a result of its design. In other words, if the Chinese Air Force truly desired a stealthy aircraft for strike and naval strike, there are a variety of other more sensible airframe designs and weapons bay configurations that could have been pursued first.

J-20 as an interceptor:

J-20’s other major role as speculated by mainstream defence media, is that of an interceptor. In such a role, it is suggested that J-20s would leverage their stealth, high speed, and long range to attack various United States airborne force multipliers such as vital tanker aircraft , airborne early warning and control aircraft, and electronic warfare aircraft .

Such actions, if successful, could cripple the ability of the United States military to conduct an effective air campaign in the western pacific, and the design of J-20 certainly does not rule out such a role for J-20 within an integrated offensive air campaign. However, as with the strike fighter debacle, the hard question which arises is whether J-20 is designed primarily (or in other words, “only”) as a long range interceptor aircraft or if its role as an interceptor is just one of many possible roles as a result of its design.

Dedicated interceptor aircraft were a common fixture of air forces during the early to mid Cold War, where the threat of massed nuclear bombers and the constant need to dissuade opposing reconnaissance aircraft required fighters which could fly at high altitude, with high speed with long range to reach and engage an opposing aircraft before it is able to launch its (potentially nuclear) payload. However, as the intercontinental ballistic missile succeeded the strategic bomber as a nation’s primary means of delivering nuclear weapons, the need of the interceptor also subsided.

Few air forces today operate dedicated interceptor aircraft, and those which do exist are typically increasingly obsolete and slated for replacement (such as China’s J-8 and J-8II interceptors), or feature unique speed and range characteristics allow them to cross vast distances for countries with expansive geography (such as Russia’s Mig-31s). Such examples of dedicated interceptors may be upgraded with newer avionics and weapons systems in the air forces they serve in, however such aircraft are a dying niche breed, and have been succeeded in the interceptor role by general air superiority aircraft, which are not only capable of aggressive air combat manoeuvring, but may also feature competitive performance in parameters such as speed, altitude and range.
 
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We immediately need a Stealth aircraft , J20 started mass production with TVC . If they are able to churn out 10 in a year in the next two years Number of J20 will be more than 40 . And we are waiting for Rafale😊.

Ghatak , AMCA MK1 /MK2 , F35 or Su 57 no matter what we need a Stealth aircraft . The Chinese aggression will continue and they won't hesitate to attack India.

A light stealth aircraft like Tejas RV will be very helpful . More importantly I won't think AMC A MK1 will come in near future, may be only in 2035. I m praying for an early induction. And J 31 in PAF will be the last nail on IAF air superiority.

We can develop ORCA as an antistealth Aircraft with advanced Avionics and long range Weapons. The airframe will be much simpler we don't need to worry about the stealth , and we don't need to put our time in Stealth profiling . ORCA with Stealthy Unmanned Wingman which can act as a EW support , Weapon carrier and as a sensor can protect ORCA from Stealthy adversaries. And using Unmanned Wingman in suitable formation and triangulation techniques , ORCA and its AI Wingman can give a tough time to intruders .

MWF can also do the same but a single engine MWF has limitations , Twin Engine ORCA with a superior Payload can do much better . We need to develop atleast MWF within 2025 , one or two Squadrons of F35 or Su 57 can hold our Airforce until AMCA arrive
 

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