J-XX Fighter Aircraft
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Re: J-xx
Or you can just apply RAM to it.
That's nonsense. There is no consistent theory why canards compromise stealth. Canards can be made into composite and RAM'ed. Canards does add a factor because stealth works by minimizing the number of angles of reflection, however by the same token, variable camber slats in the front edge of the wing of any plane would add more to that variance than any canard could.
Or you can just apply RAM to it.
That's nonsense. There is no consistent theory why canards compromise stealth. Canards can be made into composite and RAM'ed. Canards does add a factor because stealth works by minimizing the number of angles of reflection, however by the same token, variable camber slats in the front edge of the wing of any plane would add more to that variance than any canard could.
Indianfighter
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Re: J-xx
The figure is from the . 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.
I have heard about a future version of the J-10 that is slated to have TVC. Other than that and J-XX, at least I have not heard of other projects that China has undertaken of late.The "modified J-10" was never really a modified J-10. The PLA has a practice of understating its new projects. If it was Russia, for example, it would have been J-30 by now
Composites have the property to absorb radar emissions and have less reflectivity. It does not mean that RAM and composites cannot be used simultaneously. Both are leveraged on almost all fighter airplanes.
RAM and composites only minimize detection and not provide perfect evasion.
No this assertion is incomplete. Stealthiness is achieved by both, that is, absorption of as much incident radar waves as possible, and re-bounding the remainder in other directions. RAM and composites ensure the first part, whereas aircraft design ensures the latter one.
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Re: J-xx
All you need is to reduce your RCS to the same levels, which does not necessarily need you have to use composites.
Look at your picture again. The composites is on the body where the composites would hardly show against a frontal aspect, where engagement would be most common.
Only certain types of composite do, and they don't necessarily absorb the emission on the radar wavelength you wanted unless you specifically design the composite and the structure for it. For all you know, you're absorbing Y wavelength, where the radar's wavelength is at X.
RAM and composites are frequency selective. Which means they only absorbs certain bands, which you can adjust by design. There are RAM and composites that can absorb all frequencies, but they're not as effective in absorbing emissions of a certain wavelength compared to frequency selective materials. You have the principle of specialization vs. jack of all trades here.
What you don't seem to understand is that canards don't play that much of a factor. I mean where will the canards bounce the radar off to? Look at the angle of canards in most forms of flight. The emission would mainly radiate to the top or below. It makes no difference compared to biplanar elevators (where the elevators is not in the same plane as the main wing), or to wings which has variable camber slats or flaps, or to wing ailerons.
All you need is to reduce your RCS to the same levels, which does not necessarily need you have to use composites.
Look at your picture again. The composites is on the body where the composites would hardly show against a frontal aspect, where engagement would be most common.
Only certain types of composite do, and they don't necessarily absorb the emission on the radar wavelength you wanted unless you specifically design the composite and the structure for it. For all you know, you're absorbing Y wavelength, where the radar's wavelength is at X.
RAM and composites are frequency selective. Which means they only absorbs certain bands, which you can adjust by design. There are RAM and composites that can absorb all frequencies, but they're not as effective in absorbing emissions of a certain wavelength compared to frequency selective materials. You have the principle of specialization vs. jack of all trades here.
What you don't seem to understand is that canards don't play that much of a factor. I mean where will the canards bounce the radar off to? Look at the angle of canards in most forms of flight. The emission would mainly radiate to the top or below. It makes no difference compared to biplanar elevators (where the elevators is not in the same plane as the main wing), or to wings which has variable camber slats or flaps, or to wing ailerons.
Re: J-xx
Composite usage's first target is to reduce weight, not stealth.
For a stealth plane, composite usage is one of many ways used together to achieve the low RCS goal. That's why EF2000 is not a stealth plane, but F22, with lower composite usage, is a stealth plane.
For example, if you don't use composite carefully, you actually increase your RCS by letting radar waves pounding on all the metal stuffs inside the plane's body. Simply applying 70% of composite will not make any plane stealth.
Composite usage's first target is to reduce weight, not stealth.
For a stealth plane, composite usage is one of many ways used together to achieve the low RCS goal. That's why EF2000 is not a stealth plane, but F22, with lower composite usage, is a stealth plane.
For example, if you don't use composite carefully, you actually increase your RCS by letting radar waves pounding on all the metal stuffs inside the plane's body. Simply applying 70% of composite will not make any plane stealth.
Indianfighter
Junior Member
Re: J-xx
This allows more payloads, more range and more T/W ratio.
I hope we all agree that stealth is a matter of degree and not an absolute measure, like true-false or black-white.
But whatever be the case, in any composition or orientation, the radar reflectivity of composites will be lesser than an all-metal plane with protruding rivets. In effect, any degree of radar absorption is better than none at all.
What you mentioned is applicable to wings also. But wings have frontal RCS and so will canards, especially if they are not in the same plane as the wings.
Composites have to be used to reduce stealth. Even if not specifically aimed at reducing stealth, ultimately composites will still have to be used because their primary and most important advantage over rivetted metallic airframes is that they drastically reduce the weight of the airframe without any decline in the tensile strength (in fact it is increased).
This allows more payloads, more range and more T/W ratio.
I hope we all agree that stealth is a matter of degree and not an absolute measure, like true-false or black-white.
No. All carbon-fibre composites have the property of reducing radar signatures. However, they can be customized to absorb particular bands of frequencies, that are spaced far apart and arbitrarily so.
But whatever be the case, in any composition or orientation, the radar reflectivity of composites will be lesser than an all-metal plane with protruding rivets. In effect, any degree of radar absorption is better than none at all.
Any outward metallic extension from the main body in any direction, increases the RCS, be they canards or vertical tails. Vertical tails are indispensible, but canards are not used in any 5th G fighters in existence. US and Russia have tactfully avoided canards in not only their 5g airplanes, but in their older combat aircraft also.
What you mentioned is applicable to wings also. But wings have frontal RCS and so will canards, especially if they are not in the same plane as the wings.
Re: J-xx
Weight is the essential thing about using composites, but lately new alloys like aluminum lithium is rising to challenge this, as well as in using titanium.
The problem of composites however, is delamination. You just don't know when the layers will pull apart and the adhesives comes unglued. This requires rigorous and expensive inspection practices. No one is clear about the long term effects of stress against composite while the effects of this on metal is very well understood.
Composites are more than just carbon fiber. Hence, when you say composites, you mean composites in general.
On the other hand, composites blow against EMF because metal absorbs EMF, but composites will let it through, increasing your vulnerability to ECM or EMP.
Canards are much thinner than wings, and they simply don't have the same frontal RCS. Furthermore, they require a smaller deflection to exert authority, whereas elevators do, which in turn also increases RCS. Canards are also smaller than elevators in general. Canards still don't create RCS like a second tail rudder do.
Every design accepted even in the US and Russia is full of compromises. But once it is accepted, there is every attempt to justify the decisions in front of Congress and that means inventing canned responses that later form into dogma and bad mouthing the alternatives, and this happens in all different services from tanks to submarines but the spirit is the same. If you are to accept only what the defense industry wants to tell you with criticism of your own, you will for example, accept that nuclear subs are the only way to go, and there is no room for diesel subs, for example.
If you want to accept the marketing dish out (e.g. canards are bad for RCS) you might as well accept the entire banana being dished out, like the pretty uselessness of small fighters, as defense industries try to justify larger and larger planes.
Weight is the essential thing about using composites, but lately new alloys like aluminum lithium is rising to challenge this, as well as in using titanium.
The problem of composites however, is delamination. You just don't know when the layers will pull apart and the adhesives comes unglued. This requires rigorous and expensive inspection practices. No one is clear about the long term effects of stress against composite while the effects of this on metal is very well understood.
Composites are more than just carbon fiber. Hence, when you say composites, you mean composites in general.
On the other hand, composites blow against EMF because metal absorbs EMF, but composites will let it through, increasing your vulnerability to ECM or EMP.
Canards are much thinner than wings, and they simply don't have the same frontal RCS. Furthermore, they require a smaller deflection to exert authority, whereas elevators do, which in turn also increases RCS. Canards are also smaller than elevators in general. Canards still don't create RCS like a second tail rudder do.
Every design accepted even in the US and Russia is full of compromises. But once it is accepted, there is every attempt to justify the decisions in front of Congress and that means inventing canned responses that later form into dogma and bad mouthing the alternatives, and this happens in all different services from tanks to submarines but the spirit is the same. If you are to accept only what the defense industry wants to tell you with criticism of your own, you will for example, accept that nuclear subs are the only way to go, and there is no room for diesel subs, for example.
If you want to accept the marketing dish out (e.g. canards are bad for RCS) you might as well accept the entire banana being dished out, like the pretty uselessness of small fighters, as defense industries try to justify larger and larger planes.
Re: J-xx
according to Chinese open text,aircratt such as J-10, composite material makeup 25% airframe body.other material may be super plastic.
according to Chinese open text,aircratt such as J-10, composite material makeup 25% airframe body.other material may be super plastic.
Indianfighter
Junior Member
Re: J-xx
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.
Also, J-10 has movable canards which will expose more surface area to the front often at times, something , thus unacceptably increasing the frontal RCS manifold.
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.
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.
Also, J-10 has movable canards which will expose more surface area to the front often at times, something , thus unacceptably increasing the frontal RCS manifold.
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