I thought the claim was the plane had radar wave absorbing skin so that a stealth coating was unnecessary?
J-20... The New Generation Fighter II
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I thought the claim was the plane had radar wave absorbing skin so that a stealth coating was unnecessary?
airsuperiority
Captain
Your name is creepy..
Hendrik_2000
Lieutenant General
Did Shot-Down F-117 Aid J-20 Development?
Posted by Bill Sweetman at 1/24/2011 12:00 PM CST
Danger Room links to an AP story, reporting that Chinese agents scoured the crash site of an F-117 in Serbia in 1999, and speculating as to whether what they found contributed to the stealth design of the Chengdu J-20.
As with much in the world of espionage, it is hard to produce an exact answer, but possibly helpful to set some bounds to the benefits that might have been gained.
My own view is that with one exception, the Chinese would not have learned very much. The fundamentals of stealth start with shaping, and the Chinese could have learned all they wanted from a visit to a hobby shop
Materials are important - but most of the materials applied to the F-117, while state-of-the-art in the 1970s, are much heavier and thicker than anything you'd want to let near a supersonic aircraft. Better absorbers eventually made their way to the F-117 fleet, but under an upgrade program that had not delivered any jets by 1999. .
The devil of stealth is in the details - apertures, doors, inlets and exhausts and so on. However, an F-117 is not the best place to find out how to do that.
The designers solved the problem of radio-frequency antennas by not having any, at least in stealth mode. The only antennas were for basic communications and retracted when the jet needed to be invisible, and the "titanium tennis racket" covers for the infra-red sensors would not be used today.
The gridded inlets and high-maintenance tiled exhaust did their job but, again, have little relevance to a high-performance aircraft, and the same goes for the F-117's unique air-data system.
The one exception might be the edge structures. In unclassified briefings in the early 1990s, F-117 chief engineer Alan Brown said that the aircraft made use of high-performance, layered radar absorbent structures to reduce the RCS peaks associated with the long, straight wing edges. Details of those structures have never been revealed.
Comments (17) | Permanent Link
Posted by Bill Sweetman at 1/24/2011 12:00 PM CST
Danger Room links to an AP story, reporting that Chinese agents scoured the crash site of an F-117 in Serbia in 1999, and speculating as to whether what they found contributed to the stealth design of the Chengdu J-20.
As with much in the world of espionage, it is hard to produce an exact answer, but possibly helpful to set some bounds to the benefits that might have been gained.
My own view is that with one exception, the Chinese would not have learned very much. The fundamentals of stealth start with shaping, and the Chinese could have learned all they wanted from a visit to a hobby shop
Materials are important - but most of the materials applied to the F-117, while state-of-the-art in the 1970s, are much heavier and thicker than anything you'd want to let near a supersonic aircraft. Better absorbers eventually made their way to the F-117 fleet, but under an upgrade program that had not delivered any jets by 1999. .
The devil of stealth is in the details - apertures, doors, inlets and exhausts and so on. However, an F-117 is not the best place to find out how to do that.
The designers solved the problem of radio-frequency antennas by not having any, at least in stealth mode. The only antennas were for basic communications and retracted when the jet needed to be invisible, and the "titanium tennis racket" covers for the infra-red sensors would not be used today.
The gridded inlets and high-maintenance tiled exhaust did their job but, again, have little relevance to a high-performance aircraft, and the same goes for the F-117's unique air-data system.
The one exception might be the edge structures. In unclassified briefings in the early 1990s, F-117 chief engineer Alan Brown said that the aircraft made use of high-performance, layered radar absorbent structures to reduce the RCS peaks associated with the long, straight wing edges. Details of those structures have never been revealed.
Comments (17) | Permanent Link
I think the prototype will include weapon bay doors as it will have a effect on RCS of the aircraft even when closed due to a discontinuity on the aircraft surface however small, and they'll want to test that since the other prototype 2002 is for static test. It could be they only intends to have a big bay on the lowerside and for go the side weapon bays altogether.
If only we can find a flight picture with the gear bay closed we can have a rough comparison of how well the seal is.
If only we can find a flight picture with the gear bay closed we can have a rough comparison of how well the seal is.
maozedong
Banned Idiot
I saw chinese bbs that some body said J-20 body with radar wave absorbing material, but I think you are right.
airsuperiority
Captain
from the site of the article:
It made me laugh when he said the "that's it?" part. I think it's possibly quite true, if we piece speculations of the "if scenario" that Chinese did got hold of some materials with "J-20 independent design" theories. This might be the reasons why the Russians and the Chinese didn't go on to purchase anymore of the debris. To be honest, I don't doubt the Chinese really got their hands on some. After all, it doesn't hurt to take a look at it and see what they can get out of it. So maybe the debris did help, if the Chinese really did took some samples...but in such a subtle manner that it didn't matter.
And here is another poster's comments that I think was really interesting.
What he mentioned here implied that both the Russians and the Chinese were already making enough progress in their own stealth research, and that they already moved past the stage of the F-117 stealth. For the same matter(I won't be surprised the appearance of the YF-22, YF-23 last decade made it as their mark to achieve), they already knew how to beat the F-117 stealth technology by the time of the conflict, because it was obsolete and easy to go around. This was implied in the comment, as well in a way, somewhat matches the timeline that both countries rolled out their own prototypes this decade. Everything seem somewhat in place, but also an accurate picture of what both countries could achieve, based on what we know about their industries. (This also implicitly implied which countries were the lazy ones, and which ones think their technologies were really "all-that")
It made me laugh when he said the "that's it?" part. I think it's possibly quite true, if we piece speculations of the "if scenario" that Chinese did got hold of some materials with "J-20 independent design" theories. This might be the reasons why the Russians and the Chinese didn't go on to purchase anymore of the debris. To be honest, I don't doubt the Chinese really got their hands on some. After all, it doesn't hurt to take a look at it and see what they can get out of it. So maybe the debris did help, if the Chinese really did took some samples...but in such a subtle manner that it didn't matter.
And here is another poster's comments that I think was really interesting.
What he mentioned here implied that both the Russians and the Chinese were already making enough progress in their own stealth research, and that they already moved past the stage of the F-117 stealth. For the same matter(I won't be surprised the appearance of the YF-22, YF-23 last decade made it as their mark to achieve), they already knew how to beat the F-117 stealth technology by the time of the conflict, because it was obsolete and easy to go around. This was implied in the comment, as well in a way, somewhat matches the timeline that both countries rolled out their own prototypes this decade. Everything seem somewhat in place, but also an accurate picture of what both countries could achieve, based on what we know about their industries. (This also implicitly implied which countries were the lazy ones, and which ones think their technologies were really "all-that")
lol, yep, call sign on number of multiplayer game...
I don't wan't to forget it also... more easy with only a name ...
If they have radar absorbant skin it's awesome. In the US, they have headhache with the f-22 coating. For the JSF, they have radar absorbant skin panel that will cut a lot of works for maintenance.
Composite panel are good if all the structure beneath is composite too, for tails or canard it's ok but for the fuselage, wave hit the metallic structure,wire and engine behind it so it have to absorb radar wave somewhere or reflect it in another direction like the f-117.
The skin look soo smooth on the j-20, i don't know if it's color but it look like big surface are made in one piece or have coated joint(hard for maintenance), not easy to do big panel with multiple bend and curve in metal but far more easy in composite.
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What we saw, are pics taken by enthusiats and from quite a distance away from the plane. I do not believe any of them have any massive camera with super tele lens on. Plus Chengdu's weather is not exactly tiptop and extremely clear in winter. Coupled with the fact that when the aircraft flew, light condition, coupled with angles of the shoot would actually hide many details of the aircraft.
Unless anyone of us could actually get to stand very near the aircraft, we would know what the aircraft actually looks like up close and all the fine details.
Of course I am not dismissing the idea that the aircraft could be make of large single piece composite too... either way, it was too early to tell. This might only be a concept whereby the Chinese explored the actual feasibility of the technology and improved on its design for later introduction to the production J-20.
Beside, radar stealth is a good thing but with the use of more and more infra-red search and track (IRST) system you have to be aware that you can be detected without radar.
In the US they want a IRST on the superhornet because they see it's like a need on newer aircraft to counter stealth and identify treat.
On the later sukhoi , in clear weather, their IRST can detect an f22 like aircraft and guide missile to the target practically at the same times than the f22 can launch their missiles with passive radar, so it's a race on contermeasure quality more than range of detection...we see the system on the j-10B, Typhoon and others airplane.
This old system(seen on voodo, f14, etc) but with new technology in optic and camera, stealth have to evolve to counter that and not only with IR absorbing coating but probably with new camo design in the future.
In the US they want a IRST on the superhornet because they see it's like a need on newer aircraft to counter stealth and identify treat.
On the later sukhoi , in clear weather, their IRST can detect an f22 like aircraft and guide missile to the target practically at the same times than the f22 can launch their missiles with passive radar, so it's a race on contermeasure quality more than range of detection...we see the system on the j-10B, Typhoon and others airplane.
This old system(seen on voodo, f14, etc) but with new technology in optic and camera, stealth have to evolve to counter that and not only with IR absorbing coating but probably with new camo design in the future.
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