J-XX Fighter Aircraft

Re: J-xx

Indianfighter said:

Nevertheless, composites are used heavily in every modern 4.5 G combat airplane from Gripen, Rafale, Eurofighter, F-18 SH, Su-37 etc. Even the world's largest commercial aircraft A-380 has reduced weight by extensive composite use.

Purely metallic airframes are a really thing of the past and composites are here to stay. In fact, composites are one of the distinguishing features that define the transition from 4G to 4.5G.

Titanium alloys, aluminium alloys, steels, carbon-carbon composites and of course, plain metallic aluminium are all used on the same aircraft and are not used in isolation. The challenge is in determining their layout.

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We're using composites partly because its cheap. Its not necessarily better in many other areas such as battle damage and long term maintainability. And little of what you know about composites is that they already appearing in 3rd generation aircraft.

Though its true that canards on account of being smaller will have lesser RCS than wings or rudders, the fact is that in this age when we speak of 0.001 sq. m RCS (? figure), the tiniest reductions do matter hugely and critically.

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Lol then why don't we just get rid of variable camber slats because that will account for more RCS increases.

Also, J-10 has movable canards which will expose more surface area to the front often at times, something

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, thus unacceptably increasing the frontal RCS manifold.

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That's not very convincing especially if the canards are composite. And if you have canards positioned like that, you're landing in the first place. You won't see aircraft in combat with canards in that position.

Re: J-xx

crobato said:

We're using composites partly because its cheap. Its not necessarily better in many other areas such as battle damage and long term maintainability. And little of what you know about composites is that they already appearing in 3rd generation aircraft.

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Composite fabrication is actually more expensive, but its benefits far outweigh the disadvantage of costs.

Long term maintainability is better because there are a few thousand reduced small parts (atleast in case of a fighter plane from India). There is also drastic reduction in time taken for manufacture.

crobato said:

That's not very convincing especially if the canards are composite. And if you have canards positioned like that, you're landing in the first place. You won't see aircraft in combat with canards in that position.

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They are ultimately movable canards and are bound to deflect in varying positions during the course of J-10's maneuvers while in flight. They will thus expose more area to the front than when being just flat, and hence increase RCS. Moreover, this will be over and above the RCS of the wings, which will be separate due to their alignment in different planes.

challenge said:

according to Chinese open text,aircratt such as J-10, composite material makeup 25% airframe body.other material may be super plastic.

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25% is fine for J-10, a 4.5 gen aircraft, though I have no idea about what you mean by super plastics. If J-10's weight is reduced by that (and of course plastics are radar unfriendly), then even the current J-10 ought to have decent amount of stealth.

Re: J-xx

Indianfighter said:

The figure is from the

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. The J-10 uses composites, but as you said that if it is to be equivalent to EF, then it has to increase the use of composites to these levels.

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I don't know why you're talking this total nonsense here. So if a modified J-10 needs to be equivalent to Eurofighter, it has to have the exact same percentage of composites? Does it need to have the exact same weight too? And the exact same manufacturer?

Others have already corrected you on your mistaken belief that composites yield a significant stealth advantage. Trying to twist the issue to pretend you were really talking about T/W ratios is not convincing.

Re: J-xx

eurofighter is actually 40% composite overall, it clearly said that only the surface area is 70% composite. btw, this doesn't mean typhoon is stealthier. If you look at the intakes, you can actually see the upper part of the engine blade for typhoon, but you can't see that for J-10. If you look at the intake itself, the typhoon is just two big square openings. Whereas for J-10, you actually see see the side edges curve up.

And if we look at 22/35, they don't use nearly as much composite as the typhoon. Either way, no matter how "stealthy" you are, as soon as you start carrying external fuel tanks and missiles, the RCS will bump up. So, l'm waiting to see some J-10 with internal carriage, not sure if that will happen.

Re: J-xx

tphuang said:

eurofighter is actually 40% composite overall, it clearly said that only the surface area is 70% composite.

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Of course, overall composites have not exceeded 44% in any combat airplane the rest is composed of metallic alloys. However, the surface-area percentage is the one which determines the degree of stealthiness.

tphuang said:

And if we look at 22/35, they don't use nearly as much composite as the typhoon. Either way, no matter how "stealthy" you are, as soon as you start carrying external fuel tanks and missiles, the RCS will bump up. So, l'm waiting to see some J-10 with internal carriage, not sure if that will happen.

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That is correct, though the percentage of titanium is extremely high. That is probably due to the high strength required to hold weapons internally. Exposed weapons increase RCS significantly, but atleast the airframe that is 'plastered' with RAM and composites, contributes its share of providing stealth.

Challenge, I just searched and found that you might be refering to thermoplastics. F-22 has 1% composition of these but no informtion about J-10.

Re: J-xx

Indianfighter said:

That is probably due to the high strength required to hold weapons internally.

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Internal carriage has nothing to do with strength. And why you do drone on about irrelevant things when people point out your mistaken claims?

Re: J-xx

I don't doubt my fellow forum members translation ability, but just because it has been written in the Chinese press doesn't make it so. As with the US there would seem to be two reasons for stealthy aircraft; as a fighter to shoot down other aircraft, and as a strike platform.

If we are talking about the potential J-XX (this thread) being a stealthy aircraft (as opposed to an enhanced, Super, J-10), then it will need to have internal weapons storage, among other stealth features. If it is not an expeditionary aircraft (ie. purpose to defend Chinese airspace against the F-35), internal fuel capacity and heavy ordnance load will not be as important. Also a single engine should be sufficient, given either no or limited over water requirement, although this would suggest a high level of composites to reduce weight in order to provide the required power/weight ratios etc. A single engined aircraft generally means a smaller and cheaper aircraft (the philosophy behind the 22/35 mix). A Typhoon sized J-10 evolution would seem to represent the safest and quickest way to achieve a stealth fighter, even it is not comparable to an F-22.

This of course doesn't preclude a twin engined J-XX (the expeditionary or longer ranged strike aircraft). It would have different roles and take longer to develop.

Re: J-xx

Indianfighter said:

Composite fabrication is actually more expensive, but its benefits far outweigh the disadvantage of costs.

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I am not very convinced for safety and maintenance reasons that its benefits far outweigh its costs.

Long term maintainability is better because there are a few thousand reduced small parts (atleast in case of a fighter plane from India). There is also drastic reduction in time taken for manufacture.

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This is not proven in practice. Your saying drastic reduction in time taken for manufacture is in conflict with your statement of composite fabrication is more expensive, because time is the overlying factor for producing cost.

With metal you can weld, with composites, you have to replace the entire structure. Composites have more rigorous inspection procedures. Metals can be inspected for cracks, composite delamination can only be exposed by subjecting the part to X rays.

They are ultimately movable canards and are bound to deflect in varying positions during the course of J-10's maneuvers while in flight. They will thus expose more area to the front than when being just flat, and hence increase RCS. Moreover, this will be over and above the RCS of the wings, which will be separate due to their alignment in different planes.

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Wrong. In combat maneuvering the J-10's canards would never deflect like that. And its a non issue if the canards are made of carbon fiber which they would most certainly are. The J-10's canards, control surfaces, entire tail and double ventral fins are all composites except for the front edge is a titanium spar. Even if there is radar reflection, the direction of the reflection is not frontward.

You have no empirical data to prove what you are saying.

Re: J-xx

crobato said:

This is not proven in practice. Your saying drastic reduction in time taken for manufacture is in conflict with your statement of composite fabrication is more expensive, because time is the overlying factor for producing cost.

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I said that has been so atleast in case of an Indian fighter program (LCA). Manufacturing time was reduced from 11 to 7 months. The costs are because of equipment and running the equipment used for composite layout.

crobato said:

With metal you can weld, with composites, you have to replace the entire structure. Composites have more rigorous inspection procedures. Metals can be inspected for cracks, composite delamination can only be exposed by subjecting the part to X rays.

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All that is true, but the world's aircrafts including J-10 are decidedly adopting composites. Airbus A-380 has reduced weight because of massive composite fabrication.

crobato said:

Wrong. In combat maneuvering the J-10's canards would never deflect like that. And its a non issue if the canards are made of carbon fiber which they would most certainly are. The J-10's canards, control surfaces, entire tail and double ventral fins are all composites except for the front edge is a titanium spar. Even if there is radar reflection, the direction of the reflection is not frontward.

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Since they are movable canards, (and not fixed ones like those on Su-30), they are bound to deflect to some degree as they are responsible for not only vortex generation, but also for lift.

In effect canards are simply elevators affixed in front of the wings instead of behind. Leave aside deflection, their mere presence will increase the RCS no matter how small.
Now I'm aware that Gollevainen has asked us not to discuss other fighters, but just to give an example, I would ask that if canards were to be added on Mirage-2000 or LCA (both tail-less deltas), wouldn't their RCS show a marginal increase ?

Here we are talking of J-XX having enough stealth to counter JSF over Chinese airspace. The RCS in question is atleast of the order of 0.01 sq.m just on account of the airframe. I just do not see canards jutting out of the J-XX !!

Re: J-xx

They are only using a minority of percentage of composites not a majority for safety reasons. There has been accidents traced to delamination both military and civilian.

As for canards the rcs would be so small in comparison to the agility gain. Canards don't require as much deflection that elevons do to achieve the same control authority hence less drag n greater sustained turn rates. Not to mention superior pointabilty and high angle of attack.