Chengdu J-20 5th Generation Aircraft News & Discussions

[Cookie Monster]

Airbrake and speedbrake are used interchangeably, but the preferred is 'speedbrake'.

Now...Regarding the video. At timestamp 0:03, we see the J-20's canards are in what seems to be full deflection, but there is a crucial visual clue that most would miss: LEADING EDGE DOWN.

Whether it is leading edge (LE) down or up is important for the flight controls engineer. It depends on the MODE OF OPERATION or to put simply -- what the aircraft is doing at that moment in TRANSITION to what you want the aircraft to do.

What you want the aircraft to do implies a FUTURE mode of operation. So at the time of change, as the pilot changes cockpit switches, the jet will know how to deflect the flight control surfaces to make controls smoothly and safely.

So what is so significant about LE down?

If it is LE up, you would create a nose-up condition, which when you are moving on the ground trying to land in as short a distance as possible, a nose-up condition would be a very bad thing to do.

Further, we do not want this level of deflection while the jet is still flying. Leading Edge (LE) down is nose-down. Full LE down command while still in the air would mean a crash. So we install a safety condition call 'weight-on-wheels' (WOW). All aircrafts has WOW automatic switching. Another word is 'squat switch'.

http://www.askacfi.com/20020/squat-switch.htm

The F-16 has three WOW switches -- one per gear -- and there is a logic to this.

So if the J-20's flight controls engineer want to design a safe speedbrake system using the canards, how would he do this LOGICALLY?

If you have WOW on the main gear, that means the jet has only a PARTIAL touchdown condition. Whether the jet is in a take-off or landing mode, partial WOW means a partial ground condition. You want WOW on all three landing gear struts before the avionics fully reconfigure itself for landing.

So in general principles, the logic would be in this sequence:

- Cockpit switch activation (this essentially prepare the avionics to let the system know that you want to land)

- Main WOW switches active (this tells the avionics that the jet is partially on the ground)

- Nose WOW switch active (this tells the avionics that the jet is fully on the ground)

- Canards LE down

All three WOW switches must be active in order for the canards to deflect LE down. The avionics should not expect first main gear WOW, then nose WOW. The logic should not be a 'first-then-second' or sequential condition. The logic should be a simple 'and' condition because there will be times when a jet could land with all three landing gear making ground contact at the same time. It would not be a smooth landing but it is possible, so we just want to know when the jet is fully on the ground.

Now we come to the vertical stabilators and how they could be used as speedbrakes.

Note the F-18's vertical stabs, especially the rudders. And note that the vertical stabilator and the rudder are not the same thing, even though people uses the two words interchangeably. The stab CONTAINS the rudder. Or the rudder is a component of the stab.

The F-18 is clearly taking off as we do not see the arresting cable anywhere. The rudders are pointing inwards, or in a 'toe-in' condition. This condition assists the horizontal stabs in generating down force, which means nose-up, which assists take-off. This toe-in condition also exists on landing to generate additional aerodynamic drag.

What is the difference between 'toe-in' and 'toe-out' ? Certainly they generate some kind of forces but also certainly those forces are different in directions.

- If the vertical stabs are canted (angled) outward, rudders toe-in would generate downward force to assist nose-up. So to generate drag to slow down the jet, rudders should be toe-out.

- If the vertical stabs are canted (angled) inward, rudders toe-out would generate downward force to assist nose-up. So to generate drag to slow down the jet, rudders should be toe-in.

The above two rules are not absolute as the F-18's avionics uses toe-in and toe-out with different angle-of-attack.

So for the J-20, until someone post a video of the J-20 landing and showing from the rear perspective, we do not know for certain how the J-20's flight controls engineering staff uses the vertical stabs during landing. But we can have a high degree of confidence that the J-20's vertical stabs are used in some ways as speedbrakes. Even though the J-20 do not have rudders, the all-moving stabs can still be used in the same ways as the rudders.

This does not mean the J-20 can exhibit true S/TOL capability. Speedbrakes are used by the F-15, F-16, and F-22 and they do not have true reduced runway length landing capability. For that, we need thrust redirection, aka 'reverser'.

While the canards along with the all moving vertical stabilizers may not necessarily be enough(as speed brakes) to guarantee short landing ability...they would certainly be the biggest(together in terms of surface area) speed brakes on any fighter jet I've seen...including F15, F16, and F22.

I was just curious after seeing pictures/videos of the canards and vertical stabilizers in positions where they can serve as speed brakes. This in addition to J20 eventually having more powerful engines(for possible shorter take off) led me to think that STOL may be possible. Thanks for ur detailed explanation...much appreciated.

 

[gambit]

While the canards along with the all moving vertical stabilizers may not necessarily be enough(as speed brakes) to guarantee short landing ability...they would certainly be the biggest(together in terms of surface area) speed brakes on any fighter jet I've seen...including F15, F16, and F22.

Regardless of runway length, you always want to land in as short a distance as possible. Does not matter military or civilian, for any aircraft, the most vulnerable points of a flight are the take-off and landing. Get as fast as you can, then get as slow as you can. Whatever in between is the proverbial gravy.

I was just curious after seeing pictures/videos of the canards and vertical stabilizers in positions where they can serve as speed brakes. This in addition to J20 eventually having more powerful engines(for possible shorter take off) led me to think that STOL may be possible.

You are actually not that far off.

http://www.flight-mechanic.com/energy/

Potential energy is defined as being energy at rest, or energy that is stored. Potential energy may be classified into three groups: (1) that due to position, (2) that due to distortion of an elastic body, and (3) that which produces work through chemical action.

Note no. 2.

...a stretched bungee chord on a Piper Tri-Pacer or compressed spring are examples of the second group;

At end-or-runway (EOR) at take-off, you will do what pilots calls 'stands on the brakes', meaning you will apply maximum pressure on the brake pedals, then you will throttle up.

At this point, the combination of engine thrust and restraint via the brakes turned the entire jet into something -- as the laws of physics says -- similar to a coiled spring. Lots of potential energy.

If engine thrust is powerful enough, the jet will start to move forward while the wheels are still locked. Practically all jets can do this and it is a BAD condition to be in. You will learn to gauge when to release the brakes and each aircraft has its unique point. My aviation experience began in high school with a Cessna 152.

So is there a way to build up as much potential energy as possible to achieve as high a take-off speed as possible in as short a runway distance as possible?

Yes, an external restraint. In other words, have something hold the jet down while engine thrust go as high as afterburner. But this is actually an impractical idea for most situations.

The alternative is to have as large wing surface areas as possible and this is what the C-130 and C-17 can do. At take-off, engines runs up to maximum, pilots stands on the brakes, and flaps/slats fully extended. At the right moment, the pilot released the brakes and the ideal combination produced the desired short take-off capability. There are plenty of C-17 short take-off videos on youtube. Look them up.

Thanks for ur detailed explanation...much appreciated.

Yer welcome.

 

[Gomig-21]

Airbrake and speedbrake are used interchangeably, but the preferred is 'speedbrake'.

Now...Regarding the video. At timestamp 0:03, we see the J-20's canards are in what seems to be full deflection, but there is a crucial visual clue that most would miss: LEADING EDGE DOWN.

Whether it is leading edge (LE) down or up is important for the flight controls engineer. It depends on the MODE OF OPERATION or to put simply -- what the aircraft is doing at that moment in TRANSITION to what you want the aircraft to do.

What you want the aircraft to do implies a FUTURE mode of operation. So at the time of change, as the pilot changes cockpit switches, the jet will know how to deflect the flight control surfaces to make controls smoothly and safely.

So what is so significant about LE down?

lol. Don't get upset with me, I've know you for a long time so a bit of ball busting you should take lightly, especially coming from me yes? But this (below) is all you really needed to say looool!

If it is LE up, you would create a nose-up condition, which when you are moving on the ground trying to land in as short a distance as possible, a nose-up condition would be a very bad thing to do.

So it's always leading edge down when used as a speedbrake and leading edge up for take-off.

And I doubt that you'll see the deflection of the canards that drastic as in the taxiing video, as in almost vertical. They'll probably deflect about as much as the Gripen does when it uses them as speedbrakes.

 

[gambit]

And I doubt that you'll see the deflection of the canards that drastic as in the taxiing video, as in almost vertical. They'll probably deflect about as much as the Gripen does when it uses them as speedbrakes.

I am suspicious about that -- the highlighted -- based upon what I understand of flight control laws. Ninety deg is an extreme and in general we want to avoid extremes.

My guess is that the extreme deflection is based upon the combination of ground speed and that I think that extreme is unnecessary.

We know that surface deflection is based upon a combination of speed, gyro input, accelerometer input, air data, and pilot command. The lower the forward speed, the higher the deflection. But if the canards are used for speedbrake purposes, then WOW should replace pilot command. At taxiing speed, air data is irrelevant as the jet is moving too slow for any air pressure in the pitot-static system to have any significant effects. At ramp speed, meaning the jet is on the flightline ramp and not the runway, the brakes would have greater effects on the jet than the canards' deflection to assist in slowing down the jet.

So why the high deflection?

 

[Gomig-21]

I am suspicious about that -- the highlighted -- based upon what I understand of flight control laws. Ninety deg is an extreme and in general we want to avoid extremes.

My guess is that the extreme deflection is based upon the combination of ground speed and that I think that extreme is unnecessary.

We know that surface deflection is based upon a combination of speed, gyro input, accelerometer input, air data, and pilot command. The lower the forward speed, the higher the deflection. But if the canards are used for speedbrake purposes, then WOW should replace pilot command. At taxiing speed, air data is irrelevant as the jet is moving too slow for any air pressure in the pitot-static system to have any significant effects. At ramp speed, meaning the jet is on the flightline ramp and not the runway, the brakes would have greater effects on the jet than the canards' deflection to assist in slowing down the jet.

So why the high deflection?

That's what I was saying. I don't think you will see the canard deflect so drastically (as in 90 degrees) when used as speed brakes. Although conventional wisdom would make you think that putting them as flat up against the air is the optimal way to use them as speed brakes and that way you'd get the maximum air stoppage with them being in that position. But if I'm not mistaken, that probably goes against the wanted aerodynamics of airflow since they probably wouldn't want that much blocked air, but rather have a certain amount of airflow to still pass over the canards. If the canards went up to 90 degrees, you're blocking all the air that's hitting them and hence creating unwanted turbulence? Does that make sense? That turbulence will make the front of the aircraft unstable is my guess and so the deflection is not as drastic as 90 degrees in order to still have some airflow to reduce unwanted turbulence. That's just my guess.

 

[Cookie Monster]

That's what I was saying. I don't think you will see the canard deflect so drastically (as in 90 degrees) when used as speed brakes. Although conventional wisdom would make you think that putting them as flat up against the air is the optimal way to use them as speed brakes and that way you'd get the maximum air stoppage with them being in that position. But if I'm not mistaken, that probably goes against the wanted aerodynamics of airflow since they probably wouldn't want that much blocked air, but rather have a certain amount of airflow to still pass over the canards. If the canards went up to 90 degrees, you're blocking all the air that's hitting them and hence creating unwanted turbulence? Does that make sense? That turbulence will make the front of the aircraft unstable is my guess and so the deflection is not as drastic as 90 degrees in order to still have some airflow to reduce unwanted turbulence. That's just my guess.

I would guess the reason to not have them deflect at 90 degrees at high speeds(which is when it can be effective as a speed brake) might have to do more with the amount of stress it will place upon the joint(of the canard). Though the instability factor as u mentioned still would apply but I think it can be taken care of to some extent with the WOW(weight on wheels) thing as gambit mentioned. Once all the wheels have touched down and the aircraft is running flat on the runway, theoretically the instability(nose down) would no longer be the case with a flat 90 degree turn of canards as speed brakes.

 

[gambit]

That's what I was saying. I don't think you will see the canard deflect so drastically (as in 90 degrees) when used as speed brakes. Although conventional wisdom would make you think that putting them as flat up against the air is the optimal way to use them as speed brakes and that way you'd get the maximum air stoppage with them being in that position. But if I'm not mistaken, that probably goes against the wanted aerodynamics of airflow since they probably wouldn't want that much blocked air, but rather have a certain amount of airflow to still pass over the canards. If the canards went up to 90 degrees, you're blocking all the air that's hitting them and hence creating unwanted turbulence? Does that make sense? That turbulence will make the front of the aircraft unstable is my guess and so the deflection is not as drastic as 90 degrees in order to still have some airflow to reduce unwanted turbulence. That's just my guess.

I talked to a tire engineer once. Tire -- not tired.

He asked: "What slows down your car?"

Answer: Your tires, not your brakes.

So when I looked at the J-20's seemingly full canard deflection, any force on the canards would translate LONGITUDINALLY, meaning along the jet's body axis. It would work, but it would be not as efficient as some pressure on the nose wheel to increase contact pressure to the runway. Contact pressure equates to improved controllability.

But the counter-argument would be: "What about the drag chute upon landing?"

That is a fair question since the drag chute would impart force along the jet's longitudinal axis, slowing it down.

Which then begs the question: "Then what is the point of using the flight control surfaces in coordination with each other as speedbrake mechanism?"

Drag chutes are actually dangerous, especially in high and/or cross wind. The F-4 has a no drag chute rule if cross wind >= 20 kts.

The drag chute is in no way implies a S/TOL capability and the J-20 uses drag chutes on landing.

So at what ground speed does the J-20 pilot discard the two drag chutes?

If the J-20's ground speed after drag chutes deployment is slow enough, why the need to use speedbrakes in any manner?

This is why I find the J-20's canards in full LE down deflection at ramp speed -- curious.

 

[Gomig-21]

I would guess the reason to not have them deflect at 90 degrees at high speeds(which is when it can be effective as a speed brake) might have to do more with the amount of stress it will place upon the joint(of the canard). Though the instability factor as u mentioned still would apply but I think it can be taken care of to some extent with the WOW(weight on wheels) thing as gambit mentioned. Once all the wheels have touched down and the aircraft is running flat on the runway, theoretically the instability(nose down) would no longer be the case with a flat 90 degree turn of canards as speed brakes.

Would it, though? I'm not sure about that TBH. I completely understand what you're saying and I even thought about that but then realized that if the canards are not creating any airflow at all (meaning they're at 90 degrees) you lose that downward pressure on the wheels, hence negating the WoW. Now you don't have a stable front end of an aircraft. To me, it seems very important to still have that WoW and pressure on the front end to maintain control which the canards would create.

I also thought about the pressure on the canard hinge you mentioned, but I also think that's a non-factor. Reason being is that you don't have that much pressure on it at the point during the landing and the aircraft is slowing down since those hinges (or actuators whatever you want to call them) take a tremendous amount of pressure when the bird is flying and simply turning, or doing a barrel roll or going straight up from a level position.

When the aircraft is flying at let's say 350 knts (400mph) and then suddenly pitches up, the pressure and stress on those actuators is much greater than what they would endure when the aircraft is landing at 150 knts and slowing down. I'm also guessing that the J-20 pitches up and down and puts much greater stress & pressure on those canards at much higher speeds than 350 knts.

A lot of stress here.

And here.

Even during a high-speed minimum radius turn, I bet there is much more stress on those actuators than when it's landing at much slower speeds.

Or maybe it does deflect them to the max when landing?

 

[gambit]

That image does not tell us anything. At best, we can guess landing.

Where are the drag chutes?

If the drag chutes were discarded, what was the groundspeed at that time?

Those canards are practically 90 deg LE down. For what? The drag chutes were to slow the jet upon landing, but even once they are discarded, the jet's ground speed is still high enough that we need to use the flight control surfaces to act as speedbrakes?

 

[Gomig-21]

I talked to a tire engineer once. Tire -- not tired.

He asked: "What slows down your car?"

Answer: Your tires, not your brakes.

Makes total sense. Brakes are essentially ineffective if you don't have that grip from the tires.

So when I looked at the J-20's seemingly full canard deflection, any force on the canards would translate LONGITUDINALLY, meaning along the jet's body axis. It would work, but it would be not as efficient as some pressure on the nose wheel to increase contact pressure to the runway. Contact pressure equates to improved controllability.

That's what I was thinking. You need that downward pressure on the aircraft's nose to get that tire grip to get that deceleration while keeping control of the front of the aircraft.

I think it's the same principle in other designed aircraft with no canards; the same downward front pressure is achieved by lowering the trailing edge of the horizontal stabilizers? That essentially does the same thing as the canards, but I don't think it's as drastic since that would probably create too much downward pressure.

You can see how much those control surfaces impact the pitch of the aircraft in either direction as it doesn't take much. A simple, minor pull back on the stick during takeoff is all that's needed to lift the front end, and I'm thinking that the higher the airspeed, the less motion required on the stick, not factoring what the FBW system does on its own.

I remember seeing an instructional video on the MiG-15 take-off and the pilot was saying that you have to be really careful when you reach lift-off speed, to pull the stick back just a inch or so or you could get the aircraft to do a back flip! It seems the same applies even with these latest and greatest with FBW systems, you never see the pilot make much of a move on the stick to get the aircraft to respond.

This is why I find the J-20's canards in full LE down deflection at ramp speed -- curious.

It is a bit strange that it had its canards in full down like that when it was taxiing. Could it be the same thing that the F-22 does and even F/A-18 pilots do sometimes when they also taxi and check/move the control surfaces for whatever reason? You see that a lot, especially with the Raptor. The pilot seems to gyrate the stick and get all the control surfaces to crank to max positions etc. Kinda like this here.

 

[CrusherChamp]

Would it, though? I'm not sure about that TBH. I completely understand what you're saying and I even thought about that but then realized that if the canards are not creating any airflow at all (meaning they're at 90 degrees) you lose that downward pressure on the wheels, hence negating the WoW. Now you don't have a stable front end of an aircraft. To me, it seems very important to still have that WoW and pressure on the front end to maintain control which the canards would create.

I also thought about the pressure on the canard hinge you mentioned, but I also think that's a non-factor. Reason being is that you don't have that much pressure on it at the point during the landing and the aircraft is slowing down since those hinges (or actuators whatever you want to call them) take a tremendous amount of pressure when the bird is flying and simply turning, or doing a barrel roll or going straight up from a level position.

When the aircraft is flying at let's say 350 knts (400mph) and then suddenly pitches up, the pressure and stress on those actuators is much greater than what they would endure when the aircraft is landing at 150 knts and slowing down. I'm also guessing that the J-20 pitches up and down and puts much greater stress & pressure on those canards at much higher speeds than 350 knts.

A lot of stress here.

And here.

Even during a high-speed minimum radius turn, I bet there is much more stress on those actuators than when it's landing at much slower speeds.

Or maybe it does deflect them to the max when landing?

Baki gala chado tasweera kitni payyari ha........

 

[Brainsucker]

Not surprise, the stealth fighter is optimized to radar freqency that offer the highest possible resolution, whilst radar operates at other freqency may find the stealth fighter, the resolution is limited, thus they are not clear enough to locate it, maybe eventually with the aids of AI/machine learning/multi-source sensors, one can figure out a reliable way to track stealth fighters, or one may develop radar of new mechanism like China's quantum radar under R&D.

The US claims that The Northrop Grumman E-2D Advanced Hawkeye has been optimized to be able to detect a Fighter size Stealth Aircraft. Maybe it is not impossible to KJ-500 to be improved like the Hawkeye. But I doubt that it will be easy. And we don't know the effectiveness of the Hawkeye to detect J-20.

 

[52051]

The US claims that The Northrop Grumman E-2D Advanced Hawkeye has been optimized to be able to detect a Fighter size Stealth Aircraft. Maybe it is not impossible to KJ-500 to be improved like the Hawkeye. But I doubt that it will be easy. And we don't know the effectiveness of the Hawkeye to detect J-20.

The exercises details indicate how J-20 deal with AWACS: J-20 take full advantage of the problem with KJ-500 or E-2D whatever: their ceil limit, so J-20 will climb to high ceil to significantly reduce the detect range of AWACS and significantly increase their own detecting range against AWACS, so even if KJ500 have somewhat anti-stealth radar, it may still at disadvantage against J-20s.

So large, slow and high value AWACS is kind of outdated in the era of stealth fighters, they need low value high-ceil distributed UAV detecting nodes through datalinking to a network to deal with stealth fighters, SAC's new twin-body UAV is believed to serve such roles.

 

[gambit]

I think it's the same principle in other designed aircraft with no canards; the same downward front pressure is achieved by lowering the trailing edge of the horizontal stabilizers?

In principle, it seems workable. But I think there has to be a limit on deflection degree. You do not want too much pressure on the nose gear as that could induce some slippage on the main, but I do not know of any aircraft that uses the rear stabs as you suggested to reduce landing roll distance. Instead, when I was learning to fly back in high school, you can deflect the rear stabs as though for take-off, but not as fully needed for take-off, and with reduced throttle you have the rear stabs working as speedbrakes without the risk of taking off due to reduced throttle setting.

When I was on the F-111, the speedbrake is the main landing gear door, so when the landing gear handle is lowered, speedbrake deployment is inevitable. But the main gear door can be deployed by itself as a speedbrake function, meaning open without the main gear deployment. Once the jet has full WOW, and with full forward wing sweep, the wing spoilers pops up to kill lift and to serves as speedbrakes.

When I was on the F-16, this jet has unique landing characteristics -- it seemingly does not want to land. You almost has to do things to force it to land, even if the jet is loaded with externals. The F-16 has speedbrakes on the sides of the engine that are toggled on the throttle. Once full WOW, it is only these speedbrakes and the wheel brakes that slows the jet. Often I think the F-16 does not need the speedbrakes as usually the jet lands with almost empty tanks hence so light that the wheel brakes are enough. Sometimes I thought GD put the slim speedbrakes there as psychological devices and not as real functional devices.

I remember seeing an instructional video on the MiG-15 take-off and the pilot was saying that you have to be really careful when you reach lift-off speed, to pull the stick back just a inch or so or you could get the aircraft to do a back flip!

When I was on the F-111 stationed in the UK, I talked to a few pilots -- US and foreign -- who have flown the MIG-15 and in their opinions, it was the F-16 of its days. Revolutionary, touchy almost twitchy to handle even on the ground at beyond ramp speed. What you described is probably a function of flight controls responses and aerodynamics tendencies.

It is a bit strange that it had its canards in full down like that when it was taxiing. Could it be the same thing that the F-22 does and even F/A-18 pilots do sometimes when they also taxi and check/move the control surfaces for whatever reason? You see that a lot, especially with the Raptor. The pilot seems to gyrate the stick and get all the control surfaces to crank to max positions etc. Kinda like this here.

It is strange. Not a bit but a lot.

If a pilot 'cycle' the flight controls surfaces, either before or after a flight, it is to do his own personal checks of the flight controls outside of the standard automatic FLCS checks done in the chocks. Normally, the FLCS are not cycled thru the automatic checks after a flight, only before. Once the pilot returned the control stick to normal, all surfaces returns to default positions.

But with the J-20's canards, full deflection while on ramp speed is at least curious. With my understanding of flight controls laws, canard actuation SHOULD comes from the computerized FLCS. Whatever the pilot do in the cockpit, once he returned the control stick to normal, the canards should return to horizontal as default positions, just like the other FLCS surfaces with their default positions. Full vertical as the default? That sounds awfully strange.

Pilot (manual) control of a close-coupled canard system? That is dangerous.

The Wright Flyer was a canard-ed aircraft. But it does not fly at speed of today's jet fighters, so the pilot can have full manual control of the canard. When you learn to fly, you will learn to make 'coordinated turns' where you will have to pay close attention to how much turn of the yoke, how much pull back on the yoke, how much rudder pedal, and how much throttle increase, in order to turn the aircraft without losing altitude and airspeed.

With computer assisted FLCS systems, you do not need to do that anymore. With the F-111, there is a mechanical device on the backbone call the 'pitch-roll assembly' that combine appropriate pitch and roll degrees in conjunction with pilot command. The jet make the coordinated turn for you.

With computer controlled FLCS system, like the F-16 and the J-20, the flight control computer performs electronics pitch-roll combine and compensation signals and sends out appropriate deflection voltage commands to the surfaces. The jet make the coordinated turn for you.

Therefore...I find it difficult to envision the J-20's flight controls design team allows even partial pilot (manual) activation of the canards. Am NOT saying it is technically impossible. But just as we removed the need to make coordinated turns from the pilot to reduce his workload, why would the J-20's flight controls design team want to put the burden of canards actuation on the pilot?

The reason I went thru all this explanation is because manual pilot actuation of the canards is the best -- not the only -- way to explain the J-20's canards with their full vertical deflection at ramp speed. But that allowance even when full computer control when needed is still an additional pilot workload and possibly dangerous at critical times in flight, such as combat. And the J-20 is a single-seater.

 

[siegecrossbow]

More rumors about initial exercises of J-20 from reputable members in fyjs, this time J-20 is not equiped with lens so the RCS is not comprised:


http://www.fyjs.cn/forum.php?mod=viewthread&tid=1890684&extra=page=&page=1

Rough translation:

1 J20 vs 4 J-10 in dog-fight, the J-20 leave the rear end to 4 J-10s, but climb suddenly with afterburn, all J-10 lost tracks, the J-20 have not release any countermeasures at all.

2 J20 vs defence array consist of C300/HQ-16A SAM and KJ500 AWACS and several J-10, the first J-20 take down KJ500, the second J-20 take out all SAM batteries, then they finish the mission and leave, neither J-10 nor KJ-500 have any response during the exerise, the senior engineers of the AESA radar developer for KJ-500 is very impressed about J-20's performance.

2 J20 vs 4 J-10 and KJ500 as well as a electronic warfare plane, J-20 climb to 15,000 meter ceil, locate the KJ-500 and the EW plane, rush down to finish them and then take out the 4 J-10s, the whole fight last for 46 mins.

2 J20 vs 4 J-10 and KJ500 as well as a ground radar station, same story, the J-20s climb to high ceil and take out KJ-500, then finish off the J-10s, the whole combat last for 32 mins.

Like some senior scientist in China claimed once: stealth fighter is the nuke weapon in our time.

The poster admitted that he was joking in a following post. HOWEVER, it shouldn't be too hard for the J-20 to dispatch a squadron of Flankers or J-10s.