World's 5th gen fighters - relative strengths and weaknesses

P

Pmichael

Junior Member
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.
 
I

Inst

Captain
Lockheed_Martin_F-22A_Raptor_JSOH.jpg


Hey look, the F-22 has forward elevators on its wings! Why can't they delete that?

As far as the J-20 goes, it's not a fully stealth optimized design. When you think about it, even the F-35 isn't a fully stealth optimized design because it has various bumps on its bottom to enhance body lift in certain flight environments.

I mean, I agree with you that the J-20 is not an "elegant" design because of the way it incorporates so many devices; and I sincerely doubt it'd be fully competitive with the F-35 in terms of stealth, not least because it's a larger fighter. But, you know, the F-35 at its peak RCS reduction is considered stealthier than the F-22. The F-35 is a light/mediumweight stealth fighter, whereas the J-20 is a heavyweight stealth fighter. They aim at different purposes, and if the J-20 can match the F-22 on some aspects of practical stealth it's viable.

The Chinese do attempt stealthier aircraft; the J-31 is quite similar to a knock-off of the F-35, but it's also in some ways a derivative of the JF-17, which is an attempt to upgrade a MiG-21 to a F-16 standard, which the F-35 can be considered a derivative of.

Moreover, if you compare the J-31 to the F-35, the J-31 is arguably stealthier than the F-35 given that it lacks the bumps on the underside of the F-35.
 
PiSigma

PiSigma

"the engineer"
Inst said:
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.
Click to expand...
J20 is not a derivative of j10. I have gone over the design history and decisions that arrived at the j20, you should dig it up and read it. I don't car if a plane is 4.99++++, it is still not a 5th gen, so it is 1 generation behind j20, f22 f35 end of story. Not Rafael is 4.5 so half a generation behind, that is just marketing.
 
I

Inst

Captain
PiSigma said:
J20 is not a derivative of j10. I have gone over the design history and decisions that arrived at the j20, you should dig it up and read it. I don't car if a plane is 4.99++++, it is still not a 5th gen, so it is 1 generation behind j20, f22 f35 end of story. Not Rafael is 4.5 so half a generation behind, that is just marketing.
Click to expand...

We're talking about this as though the F-22 were also a derivative of the F-16 and F-15 designs, and it shows. Like the F-15 and F-16, the F-22 uses LERXes as its main aerodynamic device, and carries over the side intakes of the F-15. In the same way, we can see the design concepts that were trialed on the Su-27 and MiG-29 were carried over to the Su-57; the Su-57 carries the distinctive underbody engines of the Su-27 and MiG-29, with the spacing between the engines naturally leading to an in-between engine weapons bay.

IIRC there used to be a proposed concept called the Super-10, which was intended as a twin-engine J-10 in the J-11 class. Evidently, the design and research for that went into the J-20, which not only inherited the anhedral-dihedral canard delta layout of the J-10, but also the ventral strakes of the J-10.

===

@localizer: as I've stated repeatedly, the J-20 layout can delete its all-moving tailfins and ventral strakes without a significant aerodynamic penalty once TVC W-15s are found reliable. The main drawback of doing so would be compromises in the J-20's IR stealth, to which the fins contribute. But with the fins removed, the strakes and tailfins no longer contribute to RCS, easily making the J-20 layout as stealthy or more stealthy than its American competitors in the radar dimension, as well as extending the J-20's range by reducing drag. However, some other solution would need to be found to conceal the J-20's IR signature.

The only current evidence for this is a satellite image of a J-20 without its tailfins. This is quite possibly a fan-model J-20, as people do produce such mock-ups, or alternately a J-20 in the progress of maintenance. But it is a promising sign.
 
J

Japhethsdecendent

New Member
Registered Member
ougoah said:
F-22 and Su-57 are both competent dogfighters probably in many flight envelopes but dogfights generally almost always trend towards lower speed and altitude as time progresses. So supersonic dogfighting isn't really a thing (depends how you define it) but supersonic agility to position yourself is key to winning dogfights if it's guns only. There's plenty of indication that the J-20 is quite a capable dogfighter, perhaps only let down by its size if anything. Watching its turns in the most recent showing where the PLAAF really still held back, is enough to know. Long arm canards, high thrust to weight with WS-15 (assuming net mass around 18 tonnes), extremely high lift generation, and low drag, no known aerodynamic shortfalls = at least a decent dogfighter. Anyway it's all on the pilot when it comes to WVR.

The short range missiles on 5th gens are really a last ditch in case they somehow get into a dogfight. They're also mildly capable of shooting down air to air missiles apparently. At least approaching that level. PL-10 also has pretty long range for a SRAAM. Sneaking up on targets as a stealth fighter is possible. There's a lot of cloud covering visual ID chances so it's not exactly out of place at all for 5th gens to carry at least 2 SRAAMs.
Click to expand...
I feel like j-20s strengths are hit and run tactics mainly against tankers and awacs and less capable jets. It's range and however good that pl-15 is suite it and whatever stealth it has makes it harder for picket defenders to find easily. If we are talking about fighting other stealth fighters that seems like even more of a last resort than with other fighters. However agile j-20 is there doesn't seem to be indication it can equal or better the others in that regard and it's lack of gun and datalinked sraam is glaring. J-20 excels at range and if the pl-15 is on the high end of some estimates also reach.
 
J

Japhethsdecendent

New Member
Registered Member
Inst said:
Biggest problem for a strike J-20 would actually be the JH-XX Xian is rumored to be developing.

What happened with the Su-34 as a modification was that the Russians needed a replacement for the Su-24, and as Sukhoi already did the Su-27, they found that it would be simpler for them to just modify the Su-27 for the attack role. With the JH-XX, the attack role would be filled and there'd be less need to modify the J-20.

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, as I've stated repeatedly, 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?
Click to expand...
F-22 doesn't have eodas but has its' unique strengths to make of for it. Not sure where you are getting the idea of a weak weapons bay it holds 6 full sized AAMs. The trope about f-35s poor agility is tabloid stuff from years ago at this point it has matured beyond that. One of the design goals was to be comparable agility wise to an f-16 or f-18. I don't think it's an f-22 or su-57 which seem to have emphasised agility more but I don't see why it wouldn't hold it's own against a j-20, it also has a gun, and a towed decoy.
 
O

ougoah

Brigadier
Registered Member
Japhethsdecendent said:
F-22 doesn't have eodas but has its' unique strengths to make of for it. Not sure where you are getting the idea of a weak weapons bay it holds 6 full sized AAMs. The trope about f-35s poor agility is tabloid stuff from years ago at this point it has matured beyond that. One of the design goals was to be comparable agility wise to an f-16 or f-18. I don't think it's an f-22 or su-57 which seem to have emphasised agility more but I don't see why it wouldn't hold it's own against a j-20, it also has a gun, and a towed decoy.
Click to expand...

If the Americans could upgrade the F-22 with tech and equipment that's already available on the F-35, then they've got a perfect 5th gen. I recall reading the Americans wanted to build such a fighter for Japan which would also restart their own production line and if there is scale, they can actually buy a decent number of these new F-22s. Japan didn't go for that option or rather hasn't decided to commit and it's doubtful the US would allow Japan to have a superior or even equal version to them. But the F-22 would benefit from some upgrades. Obama shut the production presumably because the F-35 is overall a better value option and they decided all the way back then that fighting China will be with carrier delivered and supported fighters since regional airbases don't stand much chance. Even if airfields can be repaired, the F-22s flying from those bases will need to land in other civilian or military fields in Japan if US airfields are being repaired after missile strikes. Nearly 200 F-22s is still plenty enough. They've actually planned and timed this well considering where PCA probably is in development.
 
siegecrossbow

siegecrossbow

General
Staff member
Super Moderator
ougoah said:
If the Americans could upgrade the F-22 with tech and equipment that's already available on the F-35, then they've got a perfect 5th gen. I recall reading the Americans wanted to build such a fighter for Japan which would also restart their own production line and if there is scale, they can actually buy a decent number of these new F-22s. Japan didn't go for that option or rather hasn't decided to commit and it's doubtful the US would allow Japan to have a superior or even equal version to them. But the F-22 would benefit from some upgrades. Obama shut the production presumably because the F-35 is overall a better value option and they decided all the way back then that fighting China will be with carrier delivered and supported fighters since regional airbases don't stand much chance. Even if airfields can be repaired, the F-22s flying from those bases will need to land in other civilian or military fields in Japan if US airfields are being repaired after missile strikes. Nearly 200 F-22s is still plenty enough. They've actually planned and timed this well considering where PCA probably is in development.
Click to expand...

Money for upgrading raptor is better spent developing a sixth gem.
 
B

Biscuits

Major
Registered Member
Adding so many different aerodynamic devices on it screams dedicated short range fighter vs fighter plane. Similar to J-10C and Typhoon.

It could probably lob missiles long range as good as any other stealthy platform.

As long as there aren't many J-20 total, they will probably be geared towards interception role. They would fly against enemy stealth fighter and bomber formations. Near the Chinese homeland, there are radars and awacs drones which could be used to give them a signficant edge while hunting enemy stealth planes, which would add up combined with the fighters' own advanced electronics and aerodynamic capability.

Once the enemy stealth aircraft get decimated, J-20 could be used for normal multirole duties, but compared to its rivals its bomb bay is small for its size and there aren't many of them, in terms of aggressiveness the J-20 seems suboptimal.
 
You must log in or register to reply here.
Top