Iran military downs US RQ-170 Sentinel spy drone

[UpForce]

It's likely that contact was lost, it flew until it ran out of gas, and glided to a rough landing in Iran. It may not have been operating over Iran at all, just pointed in that direction.

No failsafes then?

I.e. (bad, bad pseudocode) [IF contact=NULL for xx seconds THEN altitude=xx, heading=xx, speed=xx AT xxxx,xxxx,xxxx beacon=activate, flight pattern=default_circle] type of thing, or even just [IF contact=NULL for xx seconds THEN altitude=ceiling AT ceiling charges=arm, wait xx seconds AND charges=initiate]. The latter would seem even more likely, given that a wayward drone risks a collision and/or in circumstances like Afghanistan might compromise air support/operations for a given area (... a drone, might've been a Predator, was shot down at some earlier point by an F-16 after control was lost). Then again this drone might be a much more simple affair than the "stealthy" shape would suggest, with no autopilot/autonomy/intrinsic situational awareness to speak of. Not much to "hack" if it's such a crude affair.

It certainly is much smaller than I thought (Many commentators have noted on this ... or does the "RQ" come in different scales? Would be a neat trick. To me the earlier taxiing photos don't scale really well - especially in detail - to the thing the Iranians are parading around. Might just be a lack of clear scale of reference thing, or that those Iranians are 10 ft tall or something.) and the lack of crash damage could also suggest that of the kinetic energy variables the actual mass of the vehicle is not very significant - also pointing to a lack of sophistication and complexity. What kind of a turbine (at least ten years old) fits in that frame anyway? Fuel consumption/max volume/range?

What if it's covered in places (or someplace else on the jet is) with a mesh that appears solid from a distance or in a lower quality image, but is actually intended for air sampling? An air sampling platform would be far, FAR more valuable over Iran than any sort of traditional ISR platform.

I can only guess, but air sampling seems a good candidate; at least it was the first thing that came to my mind. The USAF has unique capabilities and decades of experience in the area of nuclear arms control flights (bespoke planes - can't remember type but large, passenger plane scale frames - and the Global Hawk was also deployed extensively at Fukushima) and the Homeland Security front also has some (purportedly) amazing sensors, picking up radiotherapy patients miles and miles away. Much information can be derived from minuscule amounts of isotopes, so why not have a moderately low observable thingy collecting samples pretty much routinely?

The worst that can happen is that a couple of buffoons get to prance around the thing while practically nothing of covert value (apart from the data from the run) is lost. And the missions can pretty much continue regardless because, hey, the sovereignty of their airspace in this regard is mostly nominal anyway. Not everything covert must be really, really complicated.

 

[Ian33]

The photo taken by Mr M Yon doesn't show this airframe. His photo clearly has different wing sensor array and also a series of what appear to be sensor windows along the right wing. This Iranian one does not.

What the Iranian variant is identical to in both color and rough finish is those photos that appeared in combat aircraft magazine. Could it be that the USAF have one variant and the CIA a smaller fleet of the earlier airframes? Bit like the CIA when they had the Predator fixed with Hellfires way way before the 'recce' variant became officially armed.

 

[tacitblue]

A part of me really wonders if this just isn't part of an elaborate counter-intelligence exercise. Something along the lines of deliberately allowing the Chi-Coms to down a decontented airframe for the purposes of plugging leaks and probing the capabilities of the people across the pond.

Beers and Migs!

 

[Eagle2009]

Abraham/Quellish,

Except those kind of crashes still had a pilot at the controls did they not? IF the Sentinel did run out of fuel and therefore its autopilot shut down (because no engine means no power), there would be nothing controlling it and it would be simply "glide" to the earth. Even the Horten's gliders had pilots at the controls. What I am saying is its hard for many (including myself) to believe a flying wing can remain that stable with no control at all and make that good of a landing. If someone could provide a clear example of an aircraft falling from at least medium altitude with no control whatsoever (aka no pilot, no hydraulics, nothing) and land THAT well it would help me better understand it.

As to the question of it's altitude, 50,000 feet is the most often mentioned ceiling and it's high enough there would be no contrails correct? Considering their apparent habit of flying the Sentinel in broad daylight at times I would think you would want to fly higher than an airliner so the enemy couldn't simply see you with their own eyes.

Personally I am still very conflicted as to what happened. I have a hard time believing it simply glided to earth and sustained that little of damage. Then again, Iranian cyber units being able to hack the command systems is equally hard to imagine (at least on their own, with China's help it becomes much more realistic).

 

[Ian33]

dreamlandresort.com have linked hi-res pics of the craft in a thread.

Steve Douglas also has played around with one photo contrast and it indeed has an engine behind that grill. So no shell. The wing and damage is also evident as is the repairs to make it presentable.

 

[Machdiamond]

Eagle,
There is this notorious case of an F-106 that made a gentle belly landing after the pilot ejected, landed intact and returned to service.
http://www.f-106deltadart.com/71fis_PilotlessLanding_580787.htm
A flying wing is no different, it can be statically stable without spiral instability and can glide straight ahead trimmed at low speed, which is a trim position similar to loiter speed.
You do not need ot fly at 50000 ft to avoid leaving contrails.

 

[quellish]

No failsafes then?

It doesn't quite work that way. At point there is a probability of loss of control.
This paper covers that and other topics using Tier II+ as a case study:
http://www.nps.edu/Academics/Institutes/Meyer/docs/A%20study%20of%20reconnaissance%20surveillance%20UAV.pdf
Pages 10, 70, and 77-78 cover how this works in Tier II+.

Because of interest in flying UAVs within civilian airspace, there are a number of studies and models for these scenarios, often including data on UAV accidents.

Here is a breakdown of UAV accidents by type, with a focus on human factors:
http://www.dtic.mil/cgi-bin/GetTRDoc?Location=U2&doc=GetTRDoc.pdf&AD=ADA460102

I can only guess, but air sampling seems a good candidate; at least it was the first thing that came to my mind. The USAF has unique capabilities and decades of experience in the area of nuclear arms control flights (bespoke planes - can't remember type but large, passenger plane scale frames - and the Global Hawk was also deployed extensively at Fukushima) and the Homeland Security front also has some (purportedly) amazing sensors, picking up radiotherapy patients miles and miles away. Much information can be derived from minuscule amounts of isotopes, so why not have a moderately low observable thingy collecting samples pretty much routinely?

Because for air sampling, you don't fly OVER the target, you're flying wherever the wind is taking the output of the target. So if you're collecting on a target in Florida, you might be sampling in North Carolina, or Boston. The need for a VLO platform isn't really there, since you can usually find a way to sample in a permissive environment.

Jeffrey Richelson's "Spying On the Bomb" has several good accounts of air sampling missions.
http://books.google.com/books?ei=54riTvrVJ5TaiQL31ZTJBg&ct=result&id=gJcgAQAAIAAJ&dq=spying+on+the+bomb&q=sampling#search_anchor

Abraham/Quellish,

Except those kind of crashes still had a pilot at the controls did they not?

No.
http://www.pilotfriend.com/aeromed/medical/uncon_landing.htm

This is more common than you would think.

The photo taken by Mr M Yon doesn't show this airframe. His photo clearly has different wing sensor array and also a series of what appear to be sensor windows along the right wing. This Iranian one does not.

Why would there be a sensor array on/in the wing?

 

[blackstar]

Because for air sampling, you don't fly OVER the target, you're flying wherever the wind is taking the output of the target. So if you're collecting on a target in Florida, you might be sampling in North Carolina, or Boston. The need for a VLO platform isn't really there, since you can usually find a way to sample in a permissive environment.

Jeffrey Richelson's "Spying On the Bomb" has several good accounts of air sampling missions.
http://books.google.com/books?ei=54riTvrVJ5TaiQL31ZTJBg&ct=result&id=gJcgAQAAIAAJ&dq=spying+on+the+bomb&q=sampling#search_anchor

That was air sampling of nuclear bomb blasts, when a huge amount of material is tossed into the atmosphere. That's not what the CIA would be looking for in this case. If they can do this with an aircraft, they would be seeking out much much smaller amounts of material, and trying to localize where it is coming from (i.e. secret manufacturing facilities) would be a major goal.

 

[quellish]

That was air sampling of nuclear bomb blasts, when a huge amount of material is tossed into the atmosphere. That's not what the CIA would be looking for in this case. If they can do this with an aircraft, they would be seeking out much much smaller amounts of material, and trying to localize where it is coming from (i.e. secret manufacturing facilities) would be a major goal.

I believe Richelson's book also covered sampling of noble gas byproducts of Pu reprocessing, but I could be mistaken. It's been a few years since I read it. Nonetheless, the same basic principles for air sampling apply. Air sampling can be made to work for detecting Pu reprocessing, but to detect U enrichment is much, much more difficult.

This paper outlines the current state of the art in detecting clandestine nuclear programs, including air sampling.
http://esarda2.jrc.it/internal_activities/WC-MC/Web-Courses/01-Background/09-Environmental-Kalinowski.pdf

 

[kcran567]

If this is a legitimate detection/control/landing does this bode well for any of our stealth systems?


This drone "should" be stealthier than a larger fighter.


I doubt it was a visual detection, with some crazy Iranian in a white van getting a WiFi connection and landing it.


If this is legit it doesn't bode well considering the vast amount of money the West has spent on these systems. The west will collapse like the old soviet empire because we are spending ourselves into oblivion.


The only other option is it was a failed dead-end technology plant given to the Iranians, and that seems far fetched.

 

[GEF110]

A photographer and aviation writer I know has this site, best coverage for this sort of thing beyond the back and forth on the message boards which is also great. Real in depth, so much junk out there on this topic right?
www.Aviationintel.com
Check this out:
http://aviationintel.com/?p=4322
New to posting on this forum, some great thoughts here.

 

[Grey Havoc]

The photo taken by Mr M Yon doesn't show this airframe. His photo clearly has different wing sensor array and also a series of what appear to be sensor windows along the right wing. This Iranian one does not.

What the Iranian variant is identical to in both color and rough finish is those photos that appeared in combat aircraft magazine. Could it be that the USAF have one variant and the CIA a smaller fleet of the earlier airframes? Bit like the CIA when they had the Predator fixed with Hellfires way way before the 'recce' variant became officially armed.

You may be on to something there.

 

[quellish]

This drone "should" be stealthier than a larger fighter.

Why? RCS is independent of size.

 

[Abraham Gubler]

The only other option is it was a failed dead-end technology plant given to the Iranians, and that seems far fetched.

Iranians hack the drone or an intentional white ant operation? They are your only two options? Ever heard of aircraft having problems and crashing? If not may I suggest you catch up on a few episodes of Air Crash Investigation.

http://natgeotv.com/uk/air-crash-investigation

The If this is legit it doesn't bode well considering the vast amount of money the West has spent on these systems. The west will collapse like the old soviet empire because we are spending ourselves into oblivion.

UAV crashes in Iranian desert equals the end of the western countries? While the EU and USA (which is not ALL of the west) may in some ways resemble the financial troubles of the Soviet Union the difference is still several significant figures. The ‘west’ is having trouble with cash flows and over imaginative medias feeding the fears of ignorant fools. The Soviet Union suffered a complete societal, political, technological and economic collapse. Saying they are the same is like saying a toy boat a baby plays with in the bath is the same as MS Oasis of the Seas.

 

[sublight]

If this is a legitimate detection/control/landing does this bode well for any of our stealth systems?

This drone "should" be stealthier than a larger fighter.

I doubt it was a visual detection, with some crazy Iranian in a white van getting a WiFi connection and landing it.

If this is legit it doesn't bode well considering the vast amount of money the West has spent on these systems. The west will collapse like the old soviet empire because we are spending ourselves into oblivion.

The only other option is it was a failed dead-end technology plant given to the Iranians, and that seems far fetched.

I think it was pointed out earlier that this platform was designed from the get go to be sacrificial. While there is some secret sauce in the hardware, the best secret sauce is in the software. If the software is loaded into volatile ram before each flight then the software goes poof when the power goes poof, and the power goes poof when the engine stops spinning.

Aside from some of our other bazillion dollar bad investments, this seems like a good one.

 

[bipa]

This drone "should" be stealthier than a larger fighter.

Why? RCS is independent of size.

While I understand what you mean, this statement is slightly inaccurate at best. Size is one major factor that greatly "shapes" RCS of any object... just not in a monotonic way... and of course there are several other major factors.

To take a guess at its RCS vs stealth fighters, we would need to see the underside of this beast. Please please Iranian soldiers: remove those camouflage nets, shoot more high-res pictures, and post back with a nice walkaround. ;-)

But anyway, judging by what's visible on top, I wouldn't exactly expect this thing to appear like a "Christmas tree" on a radar scope.
No wonder: if the (supposedly skilled) LM ADP people went into the trouble of removing the tail, installing such an inlet blocker and taping all the joints, I trust them for not leaving fancy "Christmas balls" anywhere else, especially on the underside.

Apropos Christmas ornaments: has anybody already posted a theory about those two odd black strips (clearly visible on the right leading edge)?

Regarding the circumstances of the crash/hijacking/landing: anybody knows what's the policy of US UAVs in the event of their datalink getting jammed? Loiter/climb and try to recover the link (until it runs out of fuel)? Return to base?

 

[GEF110]

He just put up more evidence, some pretty cool details. I am going to send him that video the Global Hawk spinning.
www.aviationintel.com

 

[quellish]

While I understand what you mean, this statement is slightly inaccurate at best. Size is one major factor that greatly "shapes" RCS of any object... just not in a monotonic way... and of course there are several other major factors.

No, RCS is really independent of size.
http://books.google.com/books?id=0WuGjb8sqCUC&lpg=PP1&dq=radar%20cross%20section&pg=PA294#v=onepage&q=size&f=false
"Thus, the radar cross section of those shapes is not dependant on their size, and large versions of such shapes have the same RCS as small ones"

Size matters as it affects shaping for the relevant frequencies, but the size of an object has no correlation to its RCS. If the wavelength of the targeted frequency is longer than the size of the object, that is a different problem.

This:
http://en.wikipedia.org/wiki/ADM-20_Quail
Has the same RCS as:
http://en.wikipedia.org/wiki/B-52_Stratofortress

To take a guess at its RCS vs stealth fighters, we would need to see the underside of this beast. Please please Iranian soldiers: remove those camouflage nets, shoot more high-res pictures, and post back with a nice walkaround. ;-)

Why take a guess when there is enough information out there now to model it?

No wonder: if the (supposedly skilled) LM ADP people went into the trouble of removing the tail, installing such an inlet blocker and taping all the joints, I trust them for not leaving fancy "Christmas balls" anywhere else, especially on the underside.

Apropos Christmas ornaments: has anybody already posted a theory about those two odd black strips (clearly visible on the right leading edge)?

Yes.
http://goo.gl/iqtCV
Higher resolution photos of the vehicle in Iranian hands clearly shows where it was taped together for show, as well as scratches, stains, etc. along the underside indicating a wheels up landing.

Regarding the circumstances of the crash/hijacking/landing: anybody knows what's the policy of US UAVs in the event of their datalink getting jammed? Loiter/climb and try to recover the link (until it runs out of fuel)? Return to base?

It varies, but this was discussed in the previously cited papers on UAVs in the national airspace system, etc.

 

[kcran567]

The only other option is it was a failed dead-end technology plant given to the Iranians, and that seems far fetched.

Iranians hack the drone or an intentional white ant operation? They are your only two options? Ever heard of aircraft having problems and crashing? If not may I suggest you catch up on a few episodes of Air Crash Investigation.

http://natgeotv.com/uk/air-crash-investigation

The If this is legit it doesn't bode well considering the vast amount of money the West has spent on these systems. The west will collapse like the old soviet empire because we are spending ourselves into oblivion.

UAV crashes in Iranian desert equals the end of the western countries? While the EU and USA (which is not ALL of the west) may in some ways resemble the financial troubles of the Soviet Union the difference is still several significant figures. The ‘west’ is having trouble with cash flows and over imaginative medias feeding the fears of ignorant fools. The Soviet Union suffered a complete societal, political, technological and economic collapse. Saying they are the same is like saying a toy boat a baby plays with in the bath is the same as MS Oasis of the Seas.

You left out the part where I said IF the drone was successfully hacked. But it seems more likely it crashed or its failsafe was to make a landing, or it was a software malfunction.


Since the Iranians have the habit of back engineering and copy/improving older systems (ie- Northrop f-5)
What are the chances of the Iranians copying the RQ-170 and using it as an OFFENSIVE weapon to carry a small nuke or something along those lines?

 

[Demon Lord Razgriz]

Well, reading on Key Publishing.com(which I sadly can't post on) that the photo enhanced image which showed the engine through the inlet grill was from a guy who was a questionable source, I did some magic of my own with GIMP and got what I've attached below.

Seems the guy's enhanced image is the real deal. If someone could repost it over there, I'd be happy.

 

[bipa]

Size is one major factor that greatly "shapes" RCS of any object... just not in a monotonic way... and of course there are several other major factors.

No, RCS is really independent of size.
http://books.google.com/books?id=0WuGjb8sqCUC&lpg=PP1&dq=radar%20cross%20section&pg=PA294#v=onepage&q=size&f=false
"Thus, the radar cross section of those shapes is not dependant on their size, and large versions of such shapes have the same RCS as small ones"
Size matters as it affects shaping for the relevant frequencies, but the size of an object has no correlation to its RCS.

Fine... If it makes you feel wiser to take a random sentence out of Knott (relating to a theoretical reasoning about specific shapes under specific illumination conditions) and reformulate it as a general truth... I'm not going to beat a dead horse on this most trivial topic, but just in case you didn't catch my first post: I agree with you, though, that this drone "should" not necessarily be stealthier than larger fighters (at least not just because of its smaller size, as kcran567 seemed to imply).

This: http://en.wikipedia.org/wiki/ADM-20_Quail
Has the same RCS as: http://en.wikipedia.org/wiki/B-52_Stratofortress

Given adequately sized radar reflectors ;-)... and better with a little help from an active radar repeater...

Why take a guess when there is enough information out there now to model it?

Have any decent picture of the underside then?
Or is the RCS of any object also uncorrelated to its underside? (Knott citation needed ;-) )

two odd black strips (clearly visible on the right leading edge)

Higher resolution photos of the vehicle in Iranian hands clearly shows where it was taped together for show, as well as scratches, stains, etc. along the underside indicating a wheels up landing.

That's what I first thought, but on the very same high-res pictures those strips really don't look at all like duct tape to me, and there is something either side of them that looks like a mechanical interface blended into the airframe.

 

[Stargazer]

RCS is really independent of size.

I would imagine so... But still, I wonder: if a B-2 has the RCS of a bird, would a B-2 shaped, bird-sized R/C model have the RCS of a fly? Or keep that of a bird? I'm not so sure that RCS reduction is that effective in smaller scales. Any thoughts?

 

[bipa]

RCS is really independent of size.

I would imagine so... But still, I wonder: if a B-2 has the RCS of a bird, would a B-2 shaped, bird-sized R/C model have the RCS of a fly? Or keep that of a bird? I'm not so sure that RCS reduction is that effective in smaller scales. Any thoughts?

Keep in mind that RCS behaviour is highly dependent on the size / wavelength ratio. If you were able to downscale everything (including some very tiny details, as well as material properties, which is generally impossible), it would have exactly the same dimensionless RCS pattern shape at the downscaled wavelength (or, in other words, upscaled frequency, which won't lie in the same radar band). However, its absolute RCS magnitude (in square meters) would be lowered according to the square of your scale factor.

Bottom line: given all these assumptions, you may end up closer to the RCS of a fly (but only at the upscaled frequency).

There is no way to tell the RCS of a scaled object at the same (not upscaled) frequency. Usually though, by downscaling your object, you will get closer to low frequency resonant regime, at which stealthy shapes tend to become (a lot) less stealthy.

 

[Hobbes]

If this is a legitimate detection/control/landing does this bode well for any of our stealth systems?

Stealth does not mean that an aircraft becomes completely invisible. It just reduces the detection range. Get close enough and detection is still possible.

Also, a radar, IR or visual detection is not necessary to gain control of the aircraft (if that's what happened). I'd be difficult to insert yourself in the middle of the radio link, but again not impossible. I.e. controlling the aircraft is possible without it meaning that its stealthy design was flawed.
It would mean that its radio link was flawed.

 

[flateric]

via st_Paulus

 

[quellish]

Bottom line: given all these assumptions, you may end up closer to the RCS of a fly (but only at the upscaled frequency).

No, you would have the same RCS as the original object. This is how pole testing scale models works.

 

[quellish]

Fine... If it makes you feel wiser to take a random sentence out of Knott (relating to a theoretical reasoning about specific shapes under specific illumination conditions) and reformulate it as a general truth... I'm not going to beat a dead horse on this most trivial topic, but just in case you didn't catch my first post: I agree with you, though, that this drone "should" not necessarily be stealthier than larger fighters (at least not just because of its smaller size, as kcran567 seemed to imply).

It's hardly random, it's part of a larger section, which was the target of that link, which explains why RCS is independent of size. The quote was a summary of that.
Rather than using a tone like "If it makes you feel wiser...", why not cite relevant peer reviewed source material?

Given adequately sized radar reflectors ;-)... and better with a little help from an active radar repeater...

The RCS of the ADM-20 was approximately the same as that of the B-52 from several aspects without the ECM system.

Have any decent picture of the underside then?
Or is the RCS of any object also uncorrelated to its underside? (Knott citation needed ;-) )

There are good photos of it out there, yes. There is certainly enough out there to build a high fidelity model. There are even enough photos of the underside to show the vehicle with different payloads.

That's what I first thought, but on the very same high-res pictures those strips really don't look at all like duct tape to me, and there is something either side of them that looks like a mechanical interface blended into the airframe.

There is visible peeling of the tape in several areas, and it covers clearly defined cracks and seams. If you were to measure the tape in the photos, you might find that the width is exactly the same as commonly available duct tape or gaffer's tape.

 

[Abraham Gubler]

On RCS perhaps it might help if people think more about the geometrical alignment between the aircraft and the radar. To grossly simplify things what matters are those surfaces which are at 90 degrees to the radar beam. Even a big straight side of an airframe is only going to offer a very small part of its area at 90 degrees to the antenna. This is the part that will reflect radar waves back at the antenna. It doesn’t matter if this surface is 1m long or 1,000m it will still only offer one point on it at 90 degrees to the radar beam. Big aircraft however tend to have a larger number of surfaces offering more chances for reflections; especially with rounded edges (a circle always offers a 90 degree surface to any angle). However if you build a very big aircraft (like a B-2) with a very small number of different angled surfaces you will have a very low RCS. RCS is associated with size no determined by it.

 

[Steve Pace]

If you look very closely at the leading-edges of the B-2's wings - lol, you'll see minute curvatures as on it's trailing edges. - SP

 

[Eagle2009]

Gents,

I recently ran into something interesting on Wikipedia's page of the RQ-170, namely in the Discussion section. IN said section, an author makes the argument that one of the stated dimensions for the Sentinel is WAY off, while the other two are fairly accurate. He/she did so by imagery analysis and I think they make an interesting argument.

He/she also includes an image that helps to illustrate the issue he is raising, here is the link to the discussion page:
http://en.wikipedia.org/wiki/Talk:Lockheed_Martin_RQ-170_Sentinel#Specifications.

Thoughts?

 

[quellish]

Thoughts?

The commenter is closer than anyone else has been. I believe essentially the same process was covered in the deleted thread

 

[Abraham Gubler]

If you look very closely at the leading-edges of the B-2's wings - lol, you'll see minute curvatures as on it's trailing edges. - SP

Curves are not circles.

 

[AeroFranz]

I recently ran into something interesting on Wikipedia's page of the RQ-170, namely in the Discussion section. IN said section, an author makes the argument that one of the stated dimensions for the Sentinel is WAY off, while the other two are fairly accurate. He/she did so by imagery analysis and I think they make an interesting argument.

I'm glad somebody picked up on that. It looks like the span measurements were off by a factor of two!
I wonder if whoever wrote down the figure either:


1) thought the measurement was the semi-span and multiplied it by two
2) measured span parallel to the leading edge and not tip to tip. That still does not account for the disparity.


curious that the other two figures are accurate...

 

[bipa]

Bottom line: given all these assumptions, you may end up closer to the RCS of a fly (but only at the upscaled frequency).

No, you would have the same RCS as the original object. This is how pole testing scale models works.

No, sorry to disturb with this off topic debate (moderators feel free to create another topic if necessary), but this should not be left unanswered, because this is definitely not how it works.

"RCS 101": Absolute magnitude RCS (in square meters) of object at scale 1 and frequency f is equal to s^2 times the RCS of object at scale 1/s and frequency s.f.

Stargazer, I stand by my explanation: it will definitely be closer to the RCS of a fly (but only at the upscaled frequency). So does Knott btw (peer reviewed I guess):
http://books.google.fr/books?id=0WuGjb8sqCUC&lpg=PP1&dq=radar%20cross%20section&hl=fr&pg=PA257#v=onepage&q=scale&f=false

To make it perfectly clear: since this compares RCS at well distinct wavelengths, this fact has (almost) nothing to do with the other debate on whether

RCS is really independent of size.

... or not (sigh).

There is visible peeling of the tape in several areas, and it covers clearly defined cracks and seams. If you were to measure the tape in the photos, you might find that the width is exactly the same as commonly available duct tape or gaffer's tape.

We are not talking about the same thing: I have seen this tape, but it lies further along the wing. I was referring to the short black strips, kindof shiny, on the right leading edge. There is no peeling and no sign of crack or seam. They seem to be built into the platform somehow. Maybe some kind of binocular sensor?

 

[quellish]

I'm not sure where the confusion is coming from. The very page you are linking to echos what I said:
http://books.google.com/books?id=0WuGjb8sqCUC&lpg=PP1&dq=radar%20cross%20section&pg=PA257#v=onepage
from Knott, Shaeffer, Tuley.

My post:

No, you would have the same RCS as the original object. This is how pole testing scale models works.

In response to the earier post:

Keep in mind that RCS behaviour is highly dependent on the size / wavelength ratio. If you were able to downscale everything (including some very tiny details, as well as material properties, which is generally impossible), it would have exactly the same dimensionless RCS pattern shape at the downscaled wavelength (or, in other words, upscaled frequency, which won't lie in the same radar band). However, its absolute RCS magnitude (in square meters) would be lowered according to the square of your scale factor.

Knott's "Radar Cross Section Measurement" has a chapter on scaling laws, as applied to measuring scale models as RCS targets. For example, if you are testing a 1/48 scale model the test frequency must be 48 times the "real world" frequence (i.e. if you designed for a 1GHz radar, you test with a 48GHz radar on your 1/48 model). To take the result of that scaled testing and apply it to your real world vehicle, multiply the test result by the square of the scaling factor (i.e. 48^2).
If I am not mistaken, this is what was being described in the above post.

We are not talking about the same thing: I have seen this tape, but it lies further along the wing. I was referring to the short black strips, kindof shiny, on the right leading edge. There is no peeling and no sign of crack or seam. They seem to be built into the platform somehow. Maybe some kind of binocular sensor?

There are two types of tape. A wider tape at the wing root, and black gaffer/duct tape covering cracks in the leading edge. There is peeling on both types of tape. In the attached images, RED indicates a specular reflection. GREEN indicates a projection (peel or tear) in the tape. BLUE indicates a measureable feature under the tape detected underneath (crack/seam). In the video these are easier to detect using automated methods, but for the sake of simplicity I used perspectives available in public photos.

I hope that clears things up.

 

[Stargazer]

So it's tape after all?? Watching the video I wrongly assumed these must be some glazed parts, hiding some optical sensors.

 

[Trident]

I do not intend to snipe from the sidelines or barge in, but I CAN see where confusion came from.

I'm not sure where the confusion is coming from. The very page you are linking to echos what I said:
http://books.google.com/books?id=0WuGjb8sqCUC&lpg=PP1&dq=radar%20cross%20section&pg=PA257#v=onepage
from Knott, Shaeffer, Tuley.

My post:

No, you would have the same RCS as the original object. This is how pole testing scale models works.

Arguably that looks more like it echoes what bipa said - your comment did not make any mention of the requirement to scale.

In response to the earier post:

Keep in mind that RCS behaviour is highly dependent on the size / wavelength ratio. If you were able to downscale everything (including some very tiny details, as well as material properties, which is generally impossible), it would have exactly the same dimensionless RCS pattern shape at the downscaled wavelength (or, in other words, upscaled frequency, which won't lie in the same radar band). However, its absolute RCS magnitude (in square meters) would be lowered according to the square of your scale factor.

Knott's "Radar Cross Section Measurement" has a chapter on scaling laws, as applied to measuring scale models as RCS targets. For example, if you are testing a 1/48 scale model the test frequency must be 48 times the "real world" frequence (i.e. if you designed for a 1GHz radar, you test with a 48GHz radar on your 1/48 model). To take the result of that scaled testing and apply it to your real world vehicle, multiply the test result by the square of the scaling factor (i.e. 48^2).
If I am not mistaken, this is what was being described in the above post.

Well, if you were agreeing with what bipa said there, responding with what amounts to "No, you're wrong" when taken at face value seems like a patently unhelpful way of expressing your agreement.

 

[Ian33]

Tape?

So an LO airframe flies about for years with two strips of uncovered tape? And not into undefended airspace but highly defended as well?

Do LM not have a repairs facility? is this tape so supreme that it can replace LO skin on such a vulnerable area? I am skeptical to say the very least.

Days, maybe. Years? No way.

 

[Ian33]

'Dear Pakistan - all your airspace belong are to us!'

'Dear Iran - bbwwhahahahaha'

A very nice turn out and it will be very interesting to say the least to see if this is followed by its stretched and heavier armed brethren.

 

[Michel Van]

a other US Drone has crash
"MQ-9 Reaper" just impact on runway of international airport, of Mahé.
The main island of the Seychellen,
the MQ-9 try to land after a mission (to spy on Somalia pirates ?)
Source in german
http://www.spiegel.de/politik/ausland/0,1518,803549,00.html