New J-10 thread II
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Dear Guys:
One of the things I noticed with the high-resolution pictures coming out of Zhuhai 2008 was just how conventional the external structure of the J-10 is. All over the aircraft one can see rivet heads, with flat-head philips screws on access panels and covers.
It reminded me of the MiG 29's construction when they visited the Philippines. There were poorly-fitting dimpled (dinked?) panels and many of the rivets weren't flush. The Soviets also displayed the Su-27 but the overall finish and workmanship of that aircraft was in a different class altogether.
It seems to me the J-10 is still very much an "iron bird". Now don't get me wrong, I have worked in tool and die and have some experience in metal-forming, making those 3-dimensional shaped panels is accurately and close fitting is no easy job, but I have to admit I was a little disappointed especially after a lot of talk of new 'advanced' materials (which I thought were composites) in the structure.
Still the Russian journalist's commentary still rings true, during the very short take-off run the J-10s flight control surfaces (flaps, slats and canards) barely moved. And the aircraft pulled almost effortlessly into a steep climb. Admittedly this for display this aircraft was in a light condition, but who doesn't do that in airshows?
I expected to see this on the J-8II, and the JH-7, but not on the J-10? Am I nit-picking, - you bet. The new-build J-10's should have a smoother structure with less riveting and greater use of radar-absorbing composites.
Best Regards,
Dusky Lim
One of the things I noticed with the high-resolution pictures coming out of Zhuhai 2008 was just how conventional the external structure of the J-10 is. All over the aircraft one can see rivet heads, with flat-head philips screws on access panels and covers.
It reminded me of the MiG 29's construction when they visited the Philippines. There were poorly-fitting dimpled (dinked?) panels and many of the rivets weren't flush. The Soviets also displayed the Su-27 but the overall finish and workmanship of that aircraft was in a different class altogether.
It seems to me the J-10 is still very much an "iron bird". Now don't get me wrong, I have worked in tool and die and have some experience in metal-forming, making those 3-dimensional shaped panels is accurately and close fitting is no easy job, but I have to admit I was a little disappointed especially after a lot of talk of new 'advanced' materials (which I thought were composites) in the structure.
Still the Russian journalist's commentary still rings true, during the very short take-off run the J-10s flight control surfaces (flaps, slats and canards) barely moved. And the aircraft pulled almost effortlessly into a steep climb. Admittedly this for display this aircraft was in a light condition, but who doesn't do that in airshows?
I expected to see this on the J-8II, and the JH-7, but not on the J-10? Am I nit-picking, - you bet. The new-build J-10's should have a smoother structure with less riveting and greater use of radar-absorbing composites.
Best Regards,
Dusky Lim
Aircraft don't use steel, they use aluminum, which lends to the "denty" appearance. A plane after a while gets all these hand made dents that is caused by hand pressure against thin aluminum. What you hang outside however isn't as important as the inside. Composites themselves are facing competition for lightness and strength against new forms of aluminum alloy, most notably aluminum lithium. it appears that aluminum lithium is in production in China, in fact for quite a while, and aviation is the most likely application for it.
Sample:
Composites themselves are not radar absorbing but they let radar through. But this is worst than radar reflecting metal because radar will only go through and reflect among internal structures. You want instead to properly harness this radar reflection ability by reflecting radar away from the emitting source. Generic composite are by themselves practically useless on this field. Microwave absorbing composite are specially designed for this purpose, because inside the composite, you must have honeycombs or cells that are structurally sized to match against the radar frequencies they are intended to be used. The same principle applies to frequency selective radome materials, this being used on the nose of aircraft covering the radar, or in another field, the round bulb like things that cover ship radars. You have to intentionally select which radar frequencies you want to let through, and which ones you want to absorb. Same thing with carbon fiber. Matrix structure, how you intentionally design that, determines the radar frequencies that are absorbed and which ones are let through, and these frequencies are deliberately selected.
So just adding any composite to aircraft does not necessarily lower its RCS just like that. RCS reduction requires a very deliberate design and approach.
Sample:
Composites themselves are not radar absorbing but they let radar through. But this is worst than radar reflecting metal because radar will only go through and reflect among internal structures. You want instead to properly harness this radar reflection ability by reflecting radar away from the emitting source. Generic composite are by themselves practically useless on this field. Microwave absorbing composite are specially designed for this purpose, because inside the composite, you must have honeycombs or cells that are structurally sized to match against the radar frequencies they are intended to be used. The same principle applies to frequency selective radome materials, this being used on the nose of aircraft covering the radar, or in another field, the round bulb like things that cover ship radars. You have to intentionally select which radar frequencies you want to let through, and which ones you want to absorb. Same thing with carbon fiber. Matrix structure, how you intentionally design that, determines the radar frequencies that are absorbed and which ones are let through, and these frequencies are deliberately selected.
So just adding any composite to aircraft does not necessarily lower its RCS just like that. RCS reduction requires a very deliberate design and approach.
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the rudder and flap,on Mig-29 and Su-27 uses super plastic,the fuel tank uses lithium aluminum.
J-7's use a composite tail rudder since the mid to late eighties. Ditto with the J-8II. The ventral tail fin of the J-8II that can be drawn back is also composite. The canard on the J-10 is composite but said to have a titanium spar on the leading edge.
If you note the common trend, the most common application of composite tends to be the control surfaces, like the rudder, elevator, wing control surfaces.
If you note the common trend, the most common application of composite tends to be the control surfaces, like the rudder, elevator, wing control surfaces.
you might have experience in manufacturing methods, but you seem to be misinformed about material knowledge. constructing an aircraft using steel is extremely heavy, despite which steel you use, with the same area and volume of steel used on the aircraft, alluminium is a much lighter material. and when bonded with another element such as lithium to aluminium, you get the goods of both materials into one.
ive never heard anyone said that composite lowers RCS, composite is mix of 2 or more elements to create a single element, that recieves the benefits from both elements. the end process is that you get a light, tough, mid-tough material. reflecting radar isnt always about materials, the thickness of the material being assembled on the airframe also counts to lowering your RCS. and also it depends of what frequencies you want your aircraft to reduce. not every frequency can be accounted for. even the B-2 can be detected with certain frequencies. nothing is invisible, it just media hype to make the aircraft sound more threatening then it really is.
Dear Sirs:
It seems my post attracted a lot of attention. There also seems to be a certain degree of misunderstanding. I never said that the J-10 was constructed of steel, (though I specifically mentioned I worked in metal-working and forming, not any particular metal).
When I said 'iron bird' I meant that it was mainly made of metal, not of composites - its an expression folks; like the bad Cold-War era movie 'Iron Eagle', ok? I did not literally mean it was made of iron.
I am aware that aircraft since the 1st World War are mainly made of strong aluminum alloys, like duralumin - which incidentally was formulated by Alfred Wilm in Duren, Germany in the early 1900's and was first used for airships, mainly the Zeppelins.
The Su-27 uses an advanced aluminum-lithium-titanium alloy in its structure for strength and lightness. Incidentally the deputy general-designer of the Sukhoi bureau, Konstantin Marbashov (and an interpreter) accompanied the aircraft.
I was lucky enough to talk to him and get his signature for my Air Forces magazine! I also bought the Russian aircrew a case of our local San Miguel beer - and I still have one of the mechanics Soviet Air Force cap!
As to the J-10's and MiG-29's appearance, that was made in contrast to that of the Su-27 which despite regular aerobatic displays at airshows around the world, (it had just come from Singapore) still had a smoother surface appearance than either of those two.
I even had a chance to walk around and touch the aircraft, (the tires were so worn down the cords were showing,) - the only thing they didn't permit was getting into the cockpit - see what a case of beer gets you!
What I had meant was that both the J-10 and MiG-29 reflect something like the ex-Soviets Frontal aviation philosophy, in that they are smaller, lower-cost, tactical fighters, and serve to complement the heavyweights like the Sukhoi Su-27, and MiG-31 which are PVO-Starny aircraft.
As such they are meant to have less maintenance and operate from unprepared airstrips, although the J-10 is much more sophisticated than its Soviet counterpart, it still is the cheaper, lower-cost, mid-weight, tactical fighter.
Best Regards,
Dusky Lim
It seems my post attracted a lot of attention. There also seems to be a certain degree of misunderstanding. I never said that the J-10 was constructed of steel, (though I specifically mentioned I worked in metal-working and forming, not any particular metal).
When I said 'iron bird' I meant that it was mainly made of metal, not of composites - its an expression folks; like the bad Cold-War era movie 'Iron Eagle', ok? I did not literally mean it was made of iron.
I am aware that aircraft since the 1st World War are mainly made of strong aluminum alloys, like duralumin - which incidentally was formulated by Alfred Wilm in Duren, Germany in the early 1900's and was first used for airships, mainly the Zeppelins.
The Su-27 uses an advanced aluminum-lithium-titanium alloy in its structure for strength and lightness. Incidentally the deputy general-designer of the Sukhoi bureau, Konstantin Marbashov (and an interpreter) accompanied the aircraft.
I was lucky enough to talk to him and get his signature for my Air Forces magazine! I also bought the Russian aircrew a case of our local San Miguel beer - and I still have one of the mechanics Soviet Air Force cap!
As to the J-10's and MiG-29's appearance, that was made in contrast to that of the Su-27 which despite regular aerobatic displays at airshows around the world, (it had just come from Singapore) still had a smoother surface appearance than either of those two.
I even had a chance to walk around and touch the aircraft, (the tires were so worn down the cords were showing,) - the only thing they didn't permit was getting into the cockpit - see what a case of beer gets you!
What I had meant was that both the J-10 and MiG-29 reflect something like the ex-Soviets Frontal aviation philosophy, in that they are smaller, lower-cost, tactical fighters, and serve to complement the heavyweights like the Sukhoi Su-27, and MiG-31 which are PVO-Starny aircraft.
As such they are meant to have less maintenance and operate from unprepared airstrips, although the J-10 is much more sophisticated than its Soviet counterpart, it still is the cheaper, lower-cost, mid-weight, tactical fighter.
Best Regards,
Dusky Lim
Dear Sirs:
By the way, there are a class of materials, (mainly composites) that by internal reflection and scattering are able to absorb EM energy. They are called Jaumann absorbers.
A self-taught, amateur German inventor, Klaus Nickel, has developed a paint that is one of the most-effective Jaumann absorbers around. Its effectiveness has been confirmed by the head Luftwaffe's radar test bureau.
One of the countries most interested in his invention is the People's Republic of China. You can read about this in Der Spiegel's archives.
Best Regards,
Dusky Lim
By the way, there are a class of materials, (mainly composites) that by internal reflection and scattering are able to absorb EM energy. They are called Jaumann absorbers.
A self-taught, amateur German inventor, Klaus Nickel, has developed a paint that is one of the most-effective Jaumann absorbers around. Its effectiveness has been confirmed by the head Luftwaffe's radar test bureau.
One of the countries most interested in his invention is the People's Republic of China. You can read about this in Der Spiegel's archives.
Best Regards,
Dusky Lim
That is still frequency dependent. Which means you cannot just put any material and expect a wide range of frequency absorbtion.
You need to determine first which frequencies you want to absorb and by doing this, you need to strictly define the mission role of the platform and its most likely threats. Then from the frequency requirements, you can determine the design of the material to be used. It still boils down to a very deliberate process. You also have to realize what works in one band won't work in another.
"Jaumann absorber
A Jaumann absorber or Jaumann layer is a radar absorbent device. When first introduced in 1943, the Jaumann layer consisted of two equally-spaced reflective surfaces and a conductive ground plane. One can think of it as a generalized, multi-layered Salisbury screen as the principles are similar.
Being a resonant absorber (i.e. it uses wave interfering to cancel the reflected wave), the Jaumann layer is dependent upon the λ/4 spacing between the first reflective surface and the ground plane and between the two reflective surfaces (a total of λ/4 + λ/4 ).
Because the wave can resonate at two frequencies, the Jaumann layer produces two absorption maxima across a band of wavelengths (if using the two layers configuration). These absorbers must have all of the layers parallel to each other and the ground plane that they conceal.
More elaborate Jaumann absorbers use series of dielectric surfaces that separate conductive sheets. The conductivity of those sheets increases with proximity to the ground plane."
You need to determine first which frequencies you want to absorb and by doing this, you need to strictly define the mission role of the platform and its most likely threats. Then from the frequency requirements, you can determine the design of the material to be used. It still boils down to a very deliberate process. You also have to realize what works in one band won't work in another.
"Jaumann absorber
A Jaumann absorber or Jaumann layer is a radar absorbent device. When first introduced in 1943, the Jaumann layer consisted of two equally-spaced reflective surfaces and a conductive ground plane. One can think of it as a generalized, multi-layered Salisbury screen as the principles are similar.
Being a resonant absorber (i.e. it uses wave interfering to cancel the reflected wave), the Jaumann layer is dependent upon the λ/4 spacing between the first reflective surface and the ground plane and between the two reflective surfaces (a total of λ/4 + λ/4 ).
Because the wave can resonate at two frequencies, the Jaumann layer produces two absorption maxima across a band of wavelengths (if using the two layers configuration). These absorbers must have all of the layers parallel to each other and the ground plane that they conceal.
More elaborate Jaumann absorbers use series of dielectric surfaces that separate conductive sheets. The conductivity of those sheets increases with proximity to the ground plane."
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