J-20:long range naval strike aircraft?

[SlowMan]

I think we can assume j-20 would also get a low bypass engine eventually for the same reason.

No, the J-20 is a long-range naval strike aircraft and not a fighter(Think F-111), so the fuel efficiency matters more than the higher cruise speed because it needs to make a 4000 km round trip on its US CBG strike missions.

 

[SlowMan]

So f-22 has internal bleed that exits through dorsal bleed doors. J -20 probably doesn't as there areno visible doors. That ought to mean j-20's maximum thrust is more tightly constrained by inlet dimension than f-22. No?

The J-20 doesn't need to supercruise. Its internal fuel capacity is large enough to sustain afterburning for an extended period.

 

[overscan (PaulMM)]

So f-22 has internal bleed that exits through dorsal bleed doors. J -20 probably doesn't as there areno visible doors. That ought to mean j-20's maximum thrust is more tightly constrained by inlet dimension than f-22. No?

The J-20 doesn't need to supercruise. Its internal fuel capacity is large enough to sustain afterburning for an extended period.

I'm presuming you measured the fuel capacity when one filled up at a service station near you?

 

[TaiidanTomcat]

So f-22 has internal bleed that exits through dorsal bleed doors. J -20 probably doesn't as there areno visible doors. That ought to mean j-20's maximum thrust is more tightly constrained by inlet dimension than f-22. No?

The J-20 doesn't need to supercruise. Its internal fuel capacity is large enough to sustain afterburning for an extended period.

Define "extended period"

 

[2IDSGT]

So f-22 has internal bleed that exits through dorsal bleed doors. J -20 probably doesn't as there areno visible doors. That ought to mean j-20's maximum thrust is more tightly constrained by inlet dimension than f-22. No?

The J-20 doesn't need to supercruise. Its internal fuel capacity is large enough to sustain afterburning for an extended period.

Just like the Concorde eh? ;D

 

[sferrin]

So f-22 has internal bleed that exits through dorsal bleed doors. J -20 probably doesn't as there areno visible doors. That ought to mean j-20's maximum thrust is more tightly constrained by inlet dimension than f-22. No?

The J-20 doesn't need to supercruise. Its internal fuel capacity is large enough to sustain afterburning for an extended period.

Just like the Concorde eh? ;D

He's probably thinking of the Mig-31 but the Foxhound is just a tad larger.

 

[chuck4]

So f-22 has internal bleed that exits through dorsal bleed doors. J -20 probably doesn't as there areno visible doors. That ought to mean j-20's maximum thrust is more tightly constrained by inlet dimension than f-22. No?

The J-20 doesn't need to supercruise. Its internal fuel capacity is large enough to sustain afterburning for an extended period.

Just like the Concorde eh? ;D

Actually, concord is a supercruiser that sustains Mach 2 without afterburner. It only use afterburner to get past draggy transonic region get to its economical supercruising speed faster.

 

[chuck4]

So f-22 has internal bleed that exits through dorsal bleed doors. J -20 probably doesn't as there areno visible doors. That ought to mean j-20's maximum thrust is more tightly constrained by inlet dimension than f-22. No?

The J-20 doesn't need to supercruise. Its internal fuel capacity is large enough to sustain afterburning for an extended period.

Just like the Concorde eh? ;D

He's probably thinking of the Mig-31 but the Foxhound is just a tad larger.

Mig-31 is also a supercruiser. The only aircraft I know that is actually designed to cruise in afterburner is the sr-71/a-12

 

[sferrin]

So f-22 has internal bleed that exits through dorsal bleed doors. J -20 probably doesn't as there areno visible doors. That ought to mean j-20's maximum thrust is more tightly constrained by inlet dimension than f-22. No?

The J-20 doesn't need to supercruise. Its internal fuel capacity is large enough to sustain afterburning for an extended period.

Just like the Concorde eh? ;D

He's probably thinking of the Mig-31 but the Foxhound is just a tad larger.

Mig-31 is also a supercruiser. The only aircraft I know that is actually designed to cruise in afterburner is the sr-71/a-12

The Mig-31 cruises in afterburner. It doesn't do supersonic dry. The XB-70 and XF-108 were also designed to cruise at Mach 3 in afterburner.

 

[SlowMan]

I'm presuming you measured the fuel capacity when one filled up at a service station near you?

The J-20's size is a telling sign.

 

[TaiidanTomcat]

I'm presuming you measured the fuel capacity when one filled up at a service station near you?

The J-20's size is a telling sign.

Of what?

 

[chuck4]

Of its size. In fact J-20's size is such a telling sign of its size that it tells almost half of everything there is to tell about its size.

 

[SlowMan]

Of what?

It's fuel capacity, range, and its intended mission.

The USAF didn't send out the F-111s to dog fight.
Likewise the PLA didn't intend to send out the J-20 to dogfight against the F-22s.

 

[Grey Havoc]

Of what?

It's fuel capacity, range, and its intended mission.

The USAF didn't send out the F-111s to dog fight.
Likewise the PLA didn't intend to send out the J-20 to dogfight against the F-22s.

You're forgetting long range/endurance interceptors like the Tu-28.

 

[TaiidanTomcat]

Of what?

It's fuel capacity, range, and its intended mission.

Whoa! I'm going to stop you right there. The J-20 is longer in profile than two other aircraft so it must carry more fuel? : How do we know that internal space isn't filled with bulky avionics? or giant weapons bays? or big extra curvy intakes? Did you really just judge fuel capacity on length and comparative size!? how do we judge volume on that?

If all things are equal the aircraft with more fuel will have engines that run longer, however we don't know how aerodynamically efficient the J-20 is, nor its weight nor how economical its engines are etc. so it having more fuel (assuming it even does) really doesn't mean anything. Except on planet slowman, where one detail grasped from nowhere is used to rewrite the rules of aviation.

If I have a giant brick filled with more fuel and a thirsty engine, and it competes against a pure aerodynamic design with less fuel and an economical engine, you are telling me the plane with more fuel will always outlast the other aircraft?

That stubby plane must have no range compared to the other, longer aircraft who's fuselages are clearly filled with fuel, thus increasing range.

Of its size. In fact J-20's size is such a telling sign of its size that it tells almost half of everything there is to tell about its size.

very big of you to say. ;D

 

[chuck4]

Of what?

It's fuel capacity, range, and its intended mission.

The USAF didn't send out the F-111s to dog fight.
Likewise the PLA didn't intend to send out the J-20 to dogfight against the F-22s.

You're forgetting long range/endurance interceptors like the Tu-28.

It's fuselage is longer than F-22, but it's engine is placed much further back, so its intake would be much longer than in the F-22, and the total volumn taken up by the intake inside the fuselage is likely to be much higher than in the F-22. So I think while it's useable internal volumn is probably bigger than the F-22, but nowhere nearly as much bigger as it's length might suggest. So I don't think it's an long endurance patrol interceptor. It's substantially smaller than Tu-28, also smaller than Mig-31 or Su-27. It's weapon bay seems very similar to F-22. It is probably not designed to carry any thing much large than AMRAAM, nothing like very long range A2A missiles like those on Mig-31, much less heavy A2G ordinance. Its long fuselage is suggestive of supercruising being a very high design priority, higher than in F-22 or T-50. Its canard layout, large control surfaces, and good pilot visibility suggests considerable thought to close air combat within the context of other sacrafices made for supercruising. This certainly does not suggest to me an aircraft optimized for strike or interdiction.

So the design seem to be more sharply focued on the role F-22 is likely to actually play - using stealth and high cruising speed to maneuver into position to make BVR a2a attacks; and less focused on the role for which F-22 has been highly tauted, but less likely to actually play - WVR dog fighting. But it probably isn't helpless if caught in one.

 

[kaiserbill]

Of what?

It's fuel capacity, range, and its intended mission.

The USAF didn't send out the F-111s to dog fight.
Likewise the PLA didn't intend to send out the J-20 to dogfight against the F-22s.

Why bother with the canards and other control surfaces the J-20 has, then?

 

[chuck4]

They are there for shaking off the water, dog style, in case the J-20 went in for the drink. ;D

 

[Deino]

I'm presuming you measured the fuel capacity when one filled up at a service station near you?

The J-20's size is a telling sign.

Sorry of WHAT !??? ... especially if You use a completele useless artwork drawn at a time when nearly no images were available ....

Honestly, but I really don't understand why over and over again the J-20 is mis-seen as a huge, oversized interceptor. It is actulally - and all images confirm that - not longer than a Flanker, actually even a bot shorter.

Deino

 

[chuck4]

Admitting the J-20 might be a supercruising G5 air superiority fighter flying 10 years before 2020 would be very awkward for his cherished fantasies about what the G4.5 KFX can do for Korean greatness after 2020, and whether Korea could make do without buying something more respectable from abroad.

 

[chuck4]

Yet somehow Su-27 flew at 60 AOA without canards. F-22 alledgedly also.

Regardless, I thought the J-20 was designed to pull some very high AOA from the fact that its canards are photographed pitched down 80 - 85 degrees.

Has any drawings of the tri-surface SAC design ever appeared? I assume it is a unique design and not the basis of the J-31?

 

[siegecrossbow]

Yet somehow Su-27 flew at 60 AOA without canards. F-22 alledgedly also.

Regardless, I thought the J-20 was designed to pull some very high AOA from the fact that its canards are photographed pitched down 80 - 85 degrees.

Has any drawings of the tri-surface SAC design ever appeared? I assume it is a unique design and not the basis of the J-31?

Amateur drawings of the "tri-plane" design did surface a while back (2006 or 2007) on the Chinese internet along with a fairly accurate J-20 amateur drawing. The "tri-plane" design was completely different from the J-31 and was eliminated due to the fact that the aircraft was even longer and heavier than J-20 (think Su-47 size).

 

[kcran567]

The f-22 is purely air to air. The j-20 will be multi-role with air to air, and air to ground/ship capability. That is my opinion. Anything to back this up?

Also, is the j-20 a competitor to the j-31? The j-31 looks like a medium fighter, and the j-10b will fill the light role.

 

[chuck4]

The f-22 is purely air to air. The j-20 will be multi-role with air to air, and air to ground/ship capability. That is my opinion. Anything to back this up?

Also, is the j-20 a competitor to the j-31? The j-31 looks like a medium fighter, and the j-10b will fill the light role.

I don't see anything in the J-20 that would be indicative of major design compromises to facilitate a stealth carriage of heavy air-to-ground or air-to-ship ordinance for a strike role, such as long and deep weapon bays similar to those on f-35. J-20 weapon storage arrangement seems to be a carbon copy of those on the F-22, which indicates to me the j-20 is primarily an air superiority fighter just like the f-22. To my eyes the main design difference between f-22 and j-20 is the j-20 perhaps prioritized supercruising aerodynamics higher, and WVR dog fighting lower, than the f-22.


Another difference may be, I am certainly not sure of it, j-20 was designed with an eye towards being useful even if stuck with weaker engine than f-22's f119. The Chinese are not exactly highly experienced in designing state of the art fighter engines, at the time when j-20 was being designed they haven't put a single domestic fully modern fighter engine into service yet. I think they must have some fall back plan in j-20's design in case the WS-15 doesn't work out.


J-31 looks to be much smaller than j-20, maybe about as much as mig-29 was smaller than su-27. So it seems to me j-31 wasn't designed to meet the parimary requirement that spawned j-20. So I am very intrigues by what SAC did offered to compete with j-20.

But that doesn't preclude some derivative of j-31 from later competing with some derivative of j-20 for some other role, like f-16XL competing with f-15e for the strike interdiction role.


Some say j-31 is a pure company sponsored export venture, with no substantial backing from Chinese government. If that is the case, j-31 may have no role in the Chinese military.

 

[SlowMan]

Well, hints that the J-20 is a strike platform and not an A2A fighter.

1. DSI inlet has a speed limit of Mach 2. A2A fighter jets fly faster, be it F-15, F-22, Flanker, PAK-FA, and even China own J-11 etc.
2. An unusually large size for carrying lots of fuel and weapons.
3. A poor weight to thrust ratio even with an 117S upgrade.
4. J-20's large single-piece weapons bay doors are not suitable for high supersonic weapons release because of high-stress put on them. Internal weapons bay doors intended for high Mach weapons release are two piece doors. Even J-20's IR missile door is single piece. The F-35's having trouble with supersonic weapons release because of the stress put on the large A2G weapons bay door.

J-20's single-piece weapons bay doors.

F-22's two-piece weapons bay doors.

Silent Eagle's two-piece weapons bay doors.

 

[overscan (PaulMM)]

Yet somehow Su-27 flew at 60 AOA without canards. F-22 alledgedly also.

Regardless, I thought the J-20 was designed to pull some very high AOA from the fact that its canards are photographed pitched down 80 - 85 degrees.

Has any drawings of the tri-surface SAC design ever appeared? I assume it is a unique design and not the basis of the J-31?

Su-27 has never flown at 60 degrees sustained AOA. It passes through 60 degrees AOA transiently.


The ability to do a Cobra is a side-effect of the Su-27's LERX/tail configuration and was also demonstrated by the YF-17 some years earlier and the MiG-29 later. It has precise entry requirements and has no real relation to real world situations. A great, entertaining airshow trick.


Su-27 can manage about 30 degrees AOA sustained.

 

[Deino]

Well, hints that the J-20 is a strike platform and not an A2A fighter.

1. DSI inlet has a speed limit of Mach 2. A2A fighter jets fly faster, be it F-15, F-22, Flanker, PAK-FA, and even China own J-11 etc.
2. An unusually large size for carrying lots of fuel and weapons.
3. A poor weight to thrust ratio even with an 117S upgrade.
4. J-20's large single-piece weapons bay doors are not suitable for high supersonic weapons release because of high-stress put on them. Internal weapons bay doors intended for high Mach weapons release are two piece doors. Even J-20's IR missile door is single piece. The F-35's having trouble with supersonic weapons release because of the stress put on the large A2G weapons bay door.

Would You please do at first Your hopework instead of again posting BS based on model-images and assumptions which are simply wrong !

1. Can't say much on this but even a speed of M2 would bu sufficent ... it does not need to push that beyond M2.5 or anything more. How often does a Raptor fly faster than that ???

2. "Usually large size": Again do Your homework; a Flanker is larger than the J-20 ... it looks only that huge, since it is so flat and slim !

3. "poor weight to thrust ratio": that's surely a point with the current engines, but why - given its size and ost likely wieight-estimations similar to or even lover than a Flanker - would it be underpowered even with the 117S ??? Simply accept as stated, the current engine si only an interim engine.

4. "J-20's large single-piece weapons bay doors": what a BS again ... to take a fan-boy's model as a basis for such an assumption ! Simply do Your homework ... it has the same inward folding inner part as the F-22 has ... and I don't think it's relevant for the small side bays !

...

Has any drawings of the tri-surface SAC design ever appeared? I assume it is a unique design and not the basis of the J-31?

This is all known - at least from the latest iteration - of SAC's submission.

Deino

 

[overscan (PaulMM)]

Well, hints that the J-20 is a strike platform and not an A2A fighter.

1. DSI inlet has a speed limit of Mach 2. A2A fighter jets fly faster, be it F-15, F-22, Flanker, PAK-FA, and even China own J-11 etc.

So F-16 and Typhoon weren't designed primarily for A2A then? F-15's rarely break Mach 1.5 let alone hit that theoretical Mach 2.5 speed.

2. An unusually large size for carrying lots of fuel and weapons.

Its smaller overall than an Su-27. Su-27 was designed for AA.

3. A poor weight to thrust ratio even with an 117S upgrade.

Given you don't know how much it weighs or the thrust of the engines, hard to say. Probably won't be worse than, say, an Su-27.

4. J-20's large single-piece weapons bay doors are not suitable for high supersonic weapons release because of high-stress put on them. Internal weapons bay doors intended for high Mach weapons release are two piece doors. Even J-20's IR missile door is single piece. The F-35's having trouble with supersonic weapons release because of the stress put on the large A2G weapons bay door.

Not sure you are correct about J-20 bays but even if you are - Northrop didn't get that technical memo then, (Y)F-23 had one piece weapons bay doors. Or maybe that was secretly A2G optimised too?

 

[TaiidanTomcat]

2. An unusually large size for carrying lots of fuel and weapons.

3. A poor weight to thrust ratio even with an 117S upgrade.

Wait a second, just last page we saying that its large size (still sticking to that?) gave room for more fuel which meant more range and now you are saying it has poor T/W ratio, so how is that extra fuel being used to extend range? ???

Slowman you don't usually have your contradictions in the same post, let alone right next to each other. Are you feeling OK? Looking forward to your next red herring.

 

[SlowMan]

Would You please do at first Your hopework instead of again posting BS based on model-images and assumptions which are simply wrong !

Still smarting over from the incident where I have shown you that you do not understand the politics and the organization of the PLA?

1. Can't say much on this but even a speed of M2 would bu sufficent ...

Against what, the PAK-FA? the F-22? the F-3?

it does not need to push that beyond M2.5 or anything more.

We are talking about the Mach 2 limit of DSI.

How often does a Raptor fly faster than that ???

When it needs to make the kill in BVR combat and escape, of course.

2. "Usually large size": Again do Your homework; a Flanker is larger than the J-20

Not really. A Flanker is 0.5 m longer than the J-20 because of its "tail", otherwise is less bulkier.

The J-20 is one bulky jet, comparable to F-111.

3. "poor weight to thrust ratio": that's surely a point with the current engines, but why - given its size and ost likely wieight-estimations similar to or even lover than a Flanker - would it be underpowered even with the 117S ???

1. Bigger and heavier than the F-22.
2. 117S doesn't make as much thrust as the F119.
3. The AL-41 is not for sale.

Simply accept as stated, the current engine si only an interim engine.

The current engine is AL-31 and the possible upgrade is 117S. Neither is good enough.

4. "J-20's large single-piece weapons bay doors": what a BS again ... to take a fan-boy's model as a basis for such an assumption !

Well, the side weapons bay door is single piece in spy shots, isn't it?

and I don't think it's relevant for the small side bays !

It is relevant because that determines the weapons release speed. The J-20 as it is currently designed cannot release weapons at a high Mach speed. What is designed to do is to release weapons at transonic or low supersonic speed, like the F-35.

So F-16 and Typhoon weren't designed primarily for A2A then?

The F-16 was initially designed to intercept Soviet bombers, while the F-15 battled Mig escorts. The F-16 needed a redesign to take on the Flanker itself, and it is the Agile Falcon.

As for the Typhoon, it was Europe's Agile Falcon which would battle transonic Flankers while the F-15 chased higher speed targets. Remember it was in the middle of Cold War during which the Typhoon was planned.

Its smaller overall than an Su-27. Su-27 was designed for AA.

And much slimmer too.

Given you don't know how much it weighs or the thrust of the engines, hard to say. Probably won't be worse than, say, an Su-27.

Worse because the J-20 is bulkier and heavier.

Wait a second, just last page we saying that its large size (still sticking to that?) gave room for more fuel which meant more range and now you are saying it has poor T/W ratio

T/W ratio has nothing to do with fuel capacity weight, but the engine thrust.

so how is that extra fuel being used to extend range? ???

Yes, because the J-20 is a long-range naval striker.

 

[Sundog]

The reason the F-22 main weapons bay doors fold isn't because of loads at supersonic speed. It's because it's designed to sit low to the ground to enable maintainers to perform as much work as possible from the ground. As a result, main weapons bay doors that didn't fold would have struck the ground if they tried to open them. Customers don't like it when weapons bay doors strike the ground; it damages them and prevents the customer from loading the aircraft.

 

[TaiidanTomcat]

The reason the F-22 main weapons bay doors fold isn't because of loads at supersonic speed. It's because it's designed to sit low to the ground to enable maintainers to perform as much work as possible from the ground. As a result, main weapons bay doors that didn't fold would have struck the ground if they tried to open them. Customers don't like it when weapons bay doors strike the ground; it damages them and prevents the customer from loading the aircraft.

precisely

 

[chuck4]

What this CG depicts maybe close to your heart, even if the CG is not from the right country. But that doesn't make it evidence for anything. Please don't invent bullshit or echo other bullshit just to convince yourself what this CG depicts will happen on your terms.

 

[TaiidanTomcat]

The F-16 was initially designed to intercept Soviet bombers,

The F-16 was designed as an interceptor? : Thats a good one, keep em coming

 

[TaiidanTomcat]

What this CG depicts maybe close to your heart, even if the CG is not from the right country. But that doesn't make it evidence for anything. Please don't invent bullshit or echo other bullshit just to convince yourself what this CG depicts will happen on your terms.

IS that a model kit box? ;D

Wait a second, just last page we saying that its large size (still sticking to that?) gave room for more fuel which meant more range and now you are saying it has poor T/W ratio

T/W ratio has nothing to do with fuel capacity weight, but the engine thrust.

uhh, realizing that more overall weight, requires more thrust, that thus requires more fuel? no free lunches.

And how exactly does a fully fueled aircraft not increase in weight? and change the T/W ratio? Is the fuel weightless?

Failing at the basics again.

 

[mz]

This forum has more and more nasty back and forth. It would be great if you could keep arguing the facts and not get so personal.

(For example, I don't see the inconsistency as argued. A plane can have lots of fuel and a not good thrust to weight ratio. Maybe you could reword your argument.)

Maybe there's no information to go around so all this speculation could just as well be pruned.

 

[SlowMan]

The reason the F-22 main weapons bay doors fold isn't because of loads at supersonic speed. It's because it's designed to sit low to the ground to enable maintainers to perform as much work as possible from the ground.

Sorry, wrong answer.

What this CG depicts maybe close to your heart, even if the CG is not from the right country.

There is no right/wrong country.

Each country does what they deem to be necessary for their national defense against the J-20.

This forum has more and more nasty back and forth. It would be great if you could keep arguing the facts and not get so personal.

It's the ones on the losing end of debates turning into nasty and offensive comments.

 

[sferrin]

The reason the F-22 main weapons bay doors fold isn't because of loads at supersonic speed. It's because it's designed to sit low to the ground to enable maintainers to perform as much work as possible from the ground.

Sorry, wrong answer.

Actually, he's exactly right. Speed has nothing to do with it, location does.

 

[SlowMan]

An interesting info was posted today at the SDF regarding the J-20's flight requirements and esp. a comparison to its competitor from Shenyang (posted by "Engineer"):

Wrong. The J-20's FBW is obviously based on the J-10's FBW, which CAC received help from the Israelis. Accordingly, the J-20 shouldn't be able to do things that the J-10 couldn't, such as the 60 degree AOA.

The fact is that the CAC's FBW system isn't stable enough to remove the ventral fins, and this is why the J-20 has ventral fins for a supposed stealth jet.

Both J-10 and J-20 have ventral fins, because the J-20 FBW is an adaptation of the J-10's FWB.

 

[SlowMan]

Actually, he's exactly right. Speed has nothing to do with it, location does.

Wrong again.