China may have bought parts of US F-117 Nighthawk shot down over Serbia

S

sublight

Guest
FTA:
Chinese stealth fighter jet may use US technology. China may have bought parts of US F-117 Nighthawk shot down over Serbia in 1999, say experts.

http://www.guardian.co.uk/world/2011/jan/23/china-stealth-fighter-us-technology
 
sublight said:
FTA:
Chinese stealth fighter jet may use US technology. China may have bought parts of US F-117 Nighthawk shot down over Serbia in 1999, say experts.

http://www.guardian.co.uk/world/2011/jan/23/china-stealth-fighter-us-technology
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Well, if the aircraft has actually "disintegrated" maybe I could buy the story. But it didn't, and the disposition of most of the parts is known.
F-117 components would not particularly help anyone in developing or fabricating a VLO aircraft. It just does not work that way.

However, does the J-20 incorporate some advanced Western technology that is a bit suspicious? It does appear that way.
 
Perhaps the RAM? Perhaps the F404 engine? Although in the grand scheme of things evidence seems lacking for the proposition that anything they got made much material difference on how soon they could have made the J-20 fly.
 
seruriermarshal said:
RAM
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The RAM from an F-117 does not tell them much. RAM would be very difficult to reverse engineer for a number of reasons, and the F-117's RAM is designed for a set of threats the Chinese are unlikely to be concerned about. There is also very little about the F-117's RAM that is unique to the aircraft, it is not very different from materials available commercially. F-117 components would not even tell the Chinese much about how to detect an F-117.
RAM is also not a magical solution; it is only one part of a holistic approach to VLO design. If you coat a B-52 in RAM it does not become a B-2.
 
There's been speculation about the Chinese getting hold of parts from the F-117 for several years. It's interesting that a high level PLA delegation did pay a visit to the 250th Air-defence Brigade (the unit that shot down the F-117). The delegation apparently included officers who had never previously left China and came specifically for this visit.

Official photo op
 
At the ILA 2000 in Berlin, I remember seeing Chinese "tourists" looking closely at F-117, which was making its first appearance at an airshow outside the USA.
 
The story is probably right and quellish is also right. IMHO there is no doubt that America's enemies would have been drooling over getting their hands on pieces of the F-117 regardless of their inherent value or lack there of. Also we must remember that the Serbs were in desparate need of hard currency so would definitely would have sold the pieces (China has hard currency).

The question I would have for SP members is with the state of mass spectroscopy analytic tools could the Chinese have learned some of the material "makeup" of the coatings or other materials? They then have had close to 15+ years of brute force trail and error to make something work.
 
bobbymike said:
The question I would have for SP members is with the state of mass spectroscopy analytic tools could the Chinese have learned some of the material "makeup" of the coatings or other materials?
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I was also thinking along the lines of coatings and radar-absorbing/-deflecting materials. You don't need to own large pieces of an F-117 to be able to learn stuff. Of course reverse-engineering would not necessarily be easy, but it sounds more likely that this could be the part incorporated in the J-20, since the latter doesn't seem to have inherited any features of the F-117 from an aerodynamic viewpoint.
 
I've seen photos of the F-117 wreckage on a Polish language website. The aircraft came down inverted, tail and wings were shattered or separated, but fuselage appeared largely intact and easily recognizable. I don't see evidence of major fire. I suspect a vast amount of forensic information concerning the aircraft's construction, power and control system and mission equipment could be geathered from the wreckage.
 
If you look at the literature, quoting one reference,
"the two most practical ways to reduce RCS are shaping and absorption".

It is the same for everyone.
 
As we're speaking of China's possible gathering of intelligence on the F-117, it makes me wonder where this full-scale mockup of the Nighthawk done by the Chinese fits in...
 

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shockonlip said:
If you look at the literature, quoting one reference,
"the two most practical ways to reduce RCS are shaping and absorption".

It is the same for everyone.
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Radar detection range decreases with the fourth root of the radar cross section for a given frequency. This means that for an appreciable or militarily valuable decrease in detection range, the radar cross section has to be lowered a LOT (example: reducing RCS by half only gets you a 16% change in detection range). There are both practical and theoretical limits to what can be done with absorbers. While absorbers are certainly helpful, they are only one of many tools.
 
Does RAM refract in addition to absorb radar? If so, then shaping a wedge of RAM into places like the seam between the body of the plane and its moving control surfaces could help direct echo from those parts away from the radar if the shape of the underlying part itself can't be made to do the same.
 
chuck4 said:
Does RAM refract in addition to absorb radar? If so, then shaping a wedge of RAM into places like the seam between the body of the plane and its moving control surfaces could help direct echo from those parts away from the radar if the shape of the underlying part itself can't be made to do the same.
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I'll let you draw your own conclusions about that. However I will point you to a Rosetta Stone of information on this topic:
www.dtic.mil/mctl/MCTL/Sec18MCTLg.pdf

I am far, far more concerned about the appearance of a diverterless supersonic inlet on the "J-10B" testbed several years ago, leading to its incorporation on the "J-20". The dates and personalities involved are very concerning, but I would not want to comment on the particulars.
 
guy from (djcross at Key Forums) SW btw says that RAM applied to 22 is mostly the same sandwich used for 117
 
Diverter-less intake is hardly new, nor secret, having been publicly tested on a F-16 in the mid 1990s. The Chinese are unlikely to lack the talent, the expertise, and the resources to look at the photos, deduce the inspiration underneath, and work out how to implement their own version.
 
quellish said:
shockonlip said:
If you look at the literature, quoting one reference,
"the two most practical ways to reduce RCS are shaping and absorption".

It is the same for everyone.
Click to expand...

Radar detection range decreases with the fourth root of the radar cross section for a given frequency. This means that for an appreciable or militarily valuable decrease in detection range, the radar cross section has to be lowered a LOT (example: reducing RCS by half only gets you a 16% change in detection range). There are both practical and theoretical limits to what can be done with absorbers. While absorbers are certainly helpful, they are only one of many tools.
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Hi.

If I was detectable at 10 miles. But because of a 50% RCS reduction,
I am now detectable at 8.5 miles, it could still be very useful to me
in certain scenarios, a few of which follow:

1. Say, before, at 10 miles, the enemy can react in time to defeat my attack,
but now at 8.5 miles, due to the hypersonic speed of my missile, or the
speed of light of my electromagnetic beam weapon, they can't
react in time, so a 50% RCS reduction has worked well for me.

2. I just need to avoid detection and before, they could detect me at 10 miles,
but now, I am invisible until 8.5 miles. So a 50% RCS reduction has helped
give me more room to maneuver and still avoid detection.

In other words, it depends on what I'm going for.

And by the way, I didn't say only absorption.
 
one insider interview from 2009 that now seems to be guy that exactly knew he was talking about (he described aircraft pretty close to real stuff) says - several times - of adjustable DSI on J-20
bump is not movable, but seemingly intake lips are
 
flateric said:
one insider interview from 2009 that now seems to be guy that exactly knew he was talking about (he described aircraft pretty close to real stuff) says - several times - of adjustable DSI on J-20
bump is not movable, but seemingly intake lips are
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I've looked at all of my pics and I can see the leading edge of the intake, but it's so shallow, i.e.-not very long, I think it's just the RAM material. However, I could see them placing an adjustable ramp just inside the outside wall of the intake.
 
some think of rotating and extracting "teeth" from the intake cheek, thinking that it shows up on this photo exposing partially naked yellow primer
as I understand to adjust DSI for various speeds/optimal performance you need to change inlet throat area
not sure if "teeth" can do that ... whatever, DSI aerodynamics is complicated stuff for me
and technically I think that "teeth" is rather complicated idea
 

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chuck4 said:
Diverter-less intake is hardly new, nor secret, having been publicly tested on a F-16 in the mid 1990s. The Chinese are unlikely to lack the talent, the expertise, and the resources to look at the photos, deduce the inspiration underneath, and work out how to implement their own version.
Click to expand...

Well, look very closely at the JF-17, the J-10B, and the J-20. Draw your own conclusions, and we may disagree.

"I was scary stuff, radically advanced. It was shattered... didn't work. But it gave us ideas, It took us in new directions... things we would never have thought of. All this work is based on it."

shockonlip said:
And by the way, I didn't say only absorption.
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Of course not. With *just* an absorber, you can't hit a 50% reduction even with modern materials. Current commercial materials are reasonably close in performance to those in use by DoD. When DARPA initiated the XST program, their expectations were based on previous work by TR and other companies using very limited shaping, compressor hiding, and absorbers. It wasn't until advances were made in modeling, testing, and simulation that shaping was able to take signatures to much greater levels of reduction, levels that were militarily significant.

If you're only being detected at 10 miles to begin with, you're probably doing OK unless you are up against a (very powerful) MMW radar. But if you're against something like a Patriot battery, for example, that would mean your RCS is already *very* low in that band. And to reduce your RCS by 50% again would likely be expensive either in cost or capability.

But yes, if you are flying super fast and super high, a 50% RCS reduction DOES have different payoff than if you were a low flying stealth blimp.
 
flateric said:
some think of rotating and extracting "teeth" from the intake cheek, thinking that it shows up on this photo exposing partially naked yellow primer
as I understand to adjust DSI for various speeds/optimal performance you need to change inlet throat area
not sure if "teeth" can do that ... whatever, DSI aerodynamics is complicated stuff for me
and technically I think that "teeth" is rather complicated idea
Click to expand...
hmmm... could be for variable shock

adjusting the throat on a curved structure would be difficult...
 
quellish said:
seruriermarshal said:
RAM
Click to expand...

The RAM from an F-117 does not tell them much. RAM would be very difficult to reverse engineer for a number of reasons, and the F-117's RAM is designed for a set of threats the Chinese are unlikely to be concerned about. There is also very little about the F-117's RAM that is unique to the aircraft, it is not very different from materials available commercially. F-117 components would not even tell the Chinese much about how to detect an F-117.
RAM is also not a magical solution; it is only one part of a holistic approach to VLO design. If you coat a B-52 in RAM it does not become a B-2.
Click to expand...

Then RAM = Nothing ?
 
seruriermarshal said:
Then RAM = Nothing ?
Click to expand...

RAM is worthwhile on VLO aircraft, but in many cases is not on a LO aircraft or a conventional aircraft with some signature reduction in the design (such as the F-18E). That is the simplest way I can think of explaining it.
 
Those F-117 parts were really wanted souvenirs.
I remember a TV interview (BBC News?), where the Serbian paramilitary commander Zeljko Raznatovic, known as "Arkan", once presented a black covered piece for the shot down F-117.
The black piece was then zoomed in by the camera, and he said, it was his talisman for not being killed.
 
April 21 - An F-117A 86-0837/'OT' of the USAF 422nd TES "suffered extensive damage in an unspecified landing accident [at Aviano], details unconfirmed, but reported as a Class A accident." (Air Force Monthly, August 1999, p. 74)
 
flateric said:
April 21 - An F-117A 86-0837/'OT' of the USAF 422nd TES "suffered extensive damage in an unspecified landing accident [at Aviano], details unconfirmed, but reported as a Class A accident." (Air Force Monthly, August 1999, p. 74)
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Must have taken more than 'minor damage' from that encounter with the SA-3 if it cracked up on landing. Unless it was just the cover story to explain away the damage from the SA-3 itself.
 
flateric said:
April 21 - An F-117A 86-0837/'OT' of the USAF 422nd TES "suffered extensive damage in an unspecified landing accident [at Aviano], details unconfirmed, but reported as a Class A accident." (Air Force Monthly, August 1999, p. 74)
Click to expand...


F-117, serial 86-0837, was never in Europe at the time. All the F-117s in Germany and Italy during Allied Force are known. The aircraft enthusiasts were out in abundance noting the serials during the conflict. See website link for serials that took part in the conflict.

Aviano was never mentioned in the original Air Forces Monthly article. 86-0837 was part of test and evaluation and stationed in the US.

April 21 An F-117A 86-0837/'OT' of the USAF 422nd TES "suffered extensive damage in an unspecified landing accident, details unconfirmed, but reported as a Class A accident." (source: Air Forces Monthly, August 1999, p. 74)

The entry for the damaged F-117 appeared in Air Forces Monthly in July 1999.

An F-117A of the 49th FW was damaged during strike mission by a nearby explosion of an SA-3 SAM, "...causing loss of part of the tail section, but the aircraft was able to return safely to Spangdahlem air base, Germany." (source: Air Force Monthly, July 1999, p. 75)

Several groups and individuals tried to attribute 86-0837s landing accident to a combat loss/damage in Europe.

http://www.f-117a.com

Some images of 86-0837 post conflict.

http://www.airliners.net/search/photo.search?regsearch=86-0837

I've submitted a USAF Freedom of Information Act request in relation to the USAF historical timeline update in reference to the F-117. I can imagine it being turned down due to classification issues, but you never know?

TJ
 
TJ, thanks for clarification (feel ashamed)
 
::) Regarding this GE-spotted it seems most likely only a model ... and the one posted on page one seems to be from a company located in Chengdu and specialised in producing scale models of all kind (need to look for their HP).

Deino
 

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Cool thanks for posting

Speculation, if China used models such as this to develop counter Low Observable technology, (and the US had some knowledge of this) would it not make sense for the US to assess China's Counter Low Observable work on some of their own F-117's.... Haven't some re-activated Nighthawks been seen flying over Groom recently?
 
Deino said:
... (need to look for their HP).
Click to expand...

Here it is:

http://www.ymmx.net/products_detail/&productId=ca7ff126-5f95-4521-822c-355ba01efb36.html

Deino
 

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