CLEARANCE: Top Secret
- Jun 13, 2007
- Reaction score
Thanks - she'll look great when fully restored! Mark
Agreed. In some places it could look like a real article to the undiscerning eye.Sundog said:Thanks Mark, I had no idea the mockup had so much detail.
Sundog said:Nice pics as well Bill, thanks. BTW, do you guys know Orion Blam Blam has the A-12 details drawings with cross sections that he got while he was visiting the Jay Miller collection? I think they're available on his site.
Moving the A-12 Avenger II mockup, 8 April 2003
After the A-12 Avenger II development contract was cancelled, the aircraft's prototype model was moved from its hangar at Fort Worth's Air Force Plant 4 to the former Carswell Air Force Base for temporary storage.
RadicalDisconnect said:So how were they planning to address the straight trailing edge? If I understand correctly, wouldn't creeping wave diffraction contribute to a rather large frontal RCS?
RadicalDisconnect said:So how were they planning to address the straight trailing edge? If I understand correctly, wouldn't creeping wave diffraction contribute to a rather large frontal RCS?
I realize actual RCS figures are usually classified, but it would be interesting to see the RCS comparison of the Northrop submission versus the GD A-12. You know, like, a marble versus a water melon or something like that.quellish said:They were planning to address it with - wait for it, wait for it...
No joke. GD was under the belief that the RAM developed for SENIOR TREND and the B-2 were key to meeting the LO standards. GD really had no idea just how big the reductions Lockheed and Northrop were, just that they were better than the previous state of the art (A-12 would have been previous state of the art as well). GD was unaware of how much shaping played a part, and assumed that RAM was making a huge contribution to signature reduction.
And that's why GD was crying foul when RAM and composites processes were not handed over to them by USAF. There were assumptions made that if GD had the RAM technology that was developed for other programs their aircraft would meet the signature requirements. The reality was that even with the best RAM *physically possible* the A-12 signature would not be able to compete with aircraft designed using the methods developed for SENIOR TREND or SENIOR ICE.
GD dramatically undervalued the role of shaping, and because of that shaping did not drive their configuration.
Sundog said:I realize actual RCS figures are usually classified, but it would be interesting to see the RCS comparison of the Northrop submission versus the GD A-12. You know, like, a marble versus a water melon or something like that.
It's _always_ safer to attack from height. An AK or flung rock could do for you at low level. So can an SA-2 at 25,000ft. It's just that there's a lot fewer Guidelines than Kalashnikovs. Or Iglas.Also, IIRC, the USAF wasn't that interested in low alt high speed penetration at the time. The reason was, they had experience with the F-117 and with the advent of stealth, they knew they could attack from 20k ft and up relatively safely.
Here is where you hit problems. Stealth buys you altitude. Altitude buys you standoff. By the time you're in their midst, trying to 'penetrate' to deliver shortrange ballistic ordnance with blinker/sectored lightoff from remote (longwave) cuers, you're at a distance which will get you locked up and dead with any modern EPAR and most planar arrays (see: Eurofighter with Captor-PS tracking F-22 from 20nm in).That's why the USAF version of the A-12 was to have the exhaust nozzles above the wing.
The USAF told the Navy squat all.I believe they even told this to the Navy, but the Navy lacking the USAF's stealth experience still believed they would have to fly on the deck to attack, which is why they had their exhaust nozzles on the bottom of the airframe.
The Navy committed fraud in the inducement phase and refused to notify GDMD that NorGrumman had walked away and they were essentially competing against themselves to reduce their costs when DFAR or Defense Federal Acquisition Rules _require_ that if a contract is not competitively biddable, it has to be resubmitted and relet as a newly funded effort. When BAFO (Best And Final Offer) became BARFO (Best And REALLY Final Offer), NavAir broke all the rules.But the Navy was kind of stupid on this, as the book reference by F-14D points out. Especially when a company like Northrop, the company that had just built the B-2, told them they couldn't do it for the price they wanted and had the better design, IMHO.
An F-22 with specific excess power measured in the high hundreds if not low thousands of feet per second can afford the SC&M (Supersonic Cruise And Maneuver) regime at altitude. A subsonic jet cannot generate the same kinds of new-flightpath + progress along same energy to displace from the seeker cube and proximity blast radius. It's a differerence of 6-7G at 800knots and 3-4G at 400.However, for a subsonic attack aircraft, the A-12 was going to be quite maneuverable. Well, theoretically anyway.
Aside from the 'just one landing gear down' element (converted RCS mockup?) notice the weapons bay and particularly the -two part door-.flateric said:for the record: full-scale A-12 mockup was donated to HAA museum at FW in summer of 1994
first mockup photos have appeared on July, 1994, issue of CodeOne
the same two photos were accompanying famous A-12 article in February, 1995 issue of Koku Fan
LEG said:Here is where you hit problems. Stealth buys you altitude.
LEG said:One of the reasons why the F-117 was a failure waiting to happen was because it took the approach of 'going down town' on an increasingly narrowed bearing lane of possible route-around approaches to the target rather than lofting a weapon with a glide kit and DAMASK seeker.
LEG said:What people don't realize is that the public brief on VLO is only half of it. There are things that you do, internally, to cancel the signal and that is where the real ability to read the incoming pulsetrains very precisely for bearing, elevation, carrier and imbedded signal characteristics comes in.
LEG said:It _has to_ be this way because if it is not, then there is no real means of knowing whether there is an SA-21 under your ground track that simply isn't emitting until the NEBO 100nm further back tells it to. BAM. Locked up and dead. If you are using simply a shape+passive materials system.
LEG said:But in trade, you still have to deal with the resonant scattering mode which builds up huge impedance charges on the large skin area as surface/travelling waves move about with effects somewhere between St. Elmo's Fire and Coanda Effect. If you don't dissipate those charges at some level, the will hit a surface discontinuity or opposed edge and retroflect back out. And a digital radar whose signal processor is programmed with the design signatures of a Finite Elements Studied model, will 'See' that resonant return scatter and...your screwed.
LEG said:And conventional, passive, band-select ('shallow channel') RAM doesn't do it. But we haven't been using passive RAM since Gen-1.
LEG said:If you're subsonic, you have to be able to defeat the threat at the acquisition level of search and tracking illumination from ALL aspects, to avoid providing a composite trackfile which can have missiles shot into the seeker cube, blind at launch.
LEG said:The USAF solution to this is active loading through or along the skin lines and they only told the USN about that, in conjunction with the issues around the A-12 nose and inlets, at the very last, to keep the program limping along and avoid the tacair trainwreck which would result if I the Navy threw up it's hands and requested a lot of money for a new program startup account.
Altitude increases the number of radars viewing you and the aspect lines, especially in elevation, from which a simple 2D plot return becomes 3D off a billboard. To fly at height requires sophisticated VLO engineering but it is not a guarantor nor even requirement to stealth. As cruise missiles prove.No, altitude buys you stealth. That was true in the 1950s and is true today. The laws of physics have not changed.
Nope. Because the closer you go in, the more you open up your rear quarter to flash aspects which are less protected. Having a 67` sweep angle, like a B-1 may help limit FQ return bearings but it does nothing to aid against radars in sectored look-back along or across your bearing and indeed, as you change course to thread the needle around one threat, you can open yourself up to others.Actually this is one of the reasons the F-117 was a success. It highlighted the importance of mission planning to make full use of the observables of an aircraft. The F-117 was *designed* to "go downtown" to attack fixed targets within defended airspace while presenting the most survivable aspect to threats. Every US low observable aircraft since then has also made mission planning and presenting the best possible aspect to threats a primary means of survivability.
I mean the mantra that shape is everything and RAM is plastered onto jets like linoleum or built into it's skin as simple ferrite absorbers when ferrites have low structural load strength, high weight, the potential for galvanic activity and are _narrow band_.I am not sure what you mean by the "public brief on VLO". RF observables follow the rules of electomagnetics. They are an application of Maxwell's equations, which are public knowledge. There is no other half of it.
I seem to be alluding to the ZSR-62 which was indeed on the B-2 at this time and is likely still there, 'just undiscussed' under the signal characterization element of the ZSR-63.You seem to be alluding to an "active stealth" system being available in the early to mid 1980s - a system that would collect the incoming signal and emit a cancellation signal. There are many, many problems with this approach, and some of the bigger problems did not have solutions within this timeframe.
As I pointed out, if you go to the heart of an unreduced IADS the threat will see you based on your operating depth in their backyard and the sophistication with which they sector (narrowed scan angles, done initially to eliminate ground clutter) and blink (hold their systems in dummy load status, waiting for long wave, or observer corps or acoustic track cuing) their radars.As you yourself pointed out, not all low observable aircraft are designed for a mission that includes persistence. The F-117, for example, was designed to spend as little time as possible exposed to threats. Known, largely fixed threats. The B-2, in contrast, was designed to persist in a high threat environment, working with other platforms to find and strike mobile targets. This is a huge difference in terms of observables requirements, and is why the B-2 has an integrated defensive management system to locate threats and route around them. Similar systems exist on other persistent platforms.
Fighter level RAM isn't deep enough to absord L-Band and below. It's use on the later Lockheed jets is limited to a 'stealth ribbon' or tape to control edge glints from the leading edges of the airframe. Especially vs. high elevation angle systems, that doesn't change the reality of the majority of the return area being flat, planar, surfaces.Dissipating surface wave energy is what RAM/RAS is used for. Shaping is a tool that allows the engineer to collect that energy in a physical location where it will be advantageous. This can mean it is directed into a place where it can't create a scattering source, or into an area where the materials have been specifically tailored to absorb that energy.
Yes, but that is not the half of it. Radar wastes a lot of time and power as varied PRFs looking through space trying to get a ping off of 'anything' (height, range, speed) which a given combination of pulsetrains might not see but which interleaved PRI/PRF can.Surface waves are a problem when the threat radar wavelength is close to the size of the aircraft (or edge, wing, etc.) (this means lower frequencies, like search radars). They can manifest as travelling waves, creeping waves, or edge travelling waves. The incoming energy is received by the structure, flows over it, and becomes a scattering source when there is a large enough impedence change. This can be due to air gaps (panel seals, etc.), conductivity gaps (panel seals, etc. again), changes in materials, or reaching the end of a structure (edges, wingtips, etc.). Note that what matters here is the abrupt impedence change. Impedence can be controlled through materials - RAM, RAS, etc.
Low wavelength fraction treats the entire airframe as an impedance model dipole with resonant effects, not optical ones.Again, surface waves are a dominant scattering source at longer wavelengths (lower frequencies). At shorter wavelengths they are typically a minor source - they only become a concern when your RCS at those frequencies is around -60dbsm. At that point surface waves are a dominant scattering source even at those wavelengths.
The F-35 is covered with panels that have blatanly obvious edge gaps and this, for a jet whose RAM is supposedly 'baked right in' as an aid to materials reliability is inexplicable.That is, unless the vehicle's configuration is such that all energy received by the aircraft is directed to one area, and that happens to be a discontinuity that is between one and five times the size of the wavelength. Then that edge becomes a big antenna, potentially reflecting right back at the emitter.
No. The principle of _dielectric_ RAM grew out of experiments on the Windecker Eagle in the early-mid 70s when the ability to partially penetrate skin panels and trap the signal within varied layers of absorber back paneling first was explored via structural inserts.While RAM has certainly evolved since the 1950s, the principals remain the same, as previously stated. RAM is useful for a limited number of things - it is not magical cloaking paint - but for those things it can be very important. Passive RAM has been in use for a long time, continues to be, and will be for the forseeable future.
No. Because while you may know fairly well where the big, fixed, search radars are, you cannot know where the acquisition/engagement systems are, particualrly using the Soviet model when a divisional level equivalent to the (say) the Big Bird to provide separate cueing.No. You only need to defeat the aspects that have an observer and/or emitter.
No. The stealth bra which would have been used on the production airframe to _solve weight issues_ endemic to the airframe's supposedly not meeting stipulated performance conditions (a failure known from the start and ultimately a continuation of a fraud that Navair and DOD should have paid for) and yet which _The Five Billion Dollar Misunderstanding_ mentions only casually in passing, at the very back of the book's footnotes, could only have functioned because it allowed removal of a concommitant quantity of heavy, conventional, RAM coating. Whether tiled or paint.The Navy asked about RAM. They got a response about effective use of RAM. The "active loading" you are referring to in this case is the use of RAM to eliminate abrupt changes in impedence, as described above.
The USN could not possibly have failed to ask once they or one of their designated experts from each company 'had had the tour' of the B-2 production bay with the wingshape laid out before them. The USAF would be incredibly arrogant to risk a potential 30 billion dollar aircraft investment as the national security to fail to disclose issues like the straight trailing edge and the combination of multiple apertures and active EW (see the cutaway drawing for the ALQ-165 ASPJ emitter) if they knew how bad the A-12 was. That's borderline treason which is a very serious offense indeed in the military.The A-12's problems started and ended at it's outer mold line. USAF provided no guidance on this, and the Navy and GD probably didn't ask.
LEG said:Altitude increases the number of radars viewing you and the aspect lines, especially in elevation, from which a simple 2D plot return becomes 3D off a billboard.
LEG said:To fly at height requires sophisticated VLO engineering but it is not a guarantor nor even requirement to stealth. As cruise missiles prove.
LEG said:I mean the mantra that shape is everything and RAM is plastered onto jets like linoleum or built into it's skin as simple ferrite absorbers when ferrites have low structural load strength, high weight, the potential for galvanic activity and are _narrow band_.
LEG said:I seem to be alluding to the ZSR-62 which was indeed on the B-2 at this time and is likely still there, 'just undiscussed' under the signal characterization element of the ZSR-63.
quellish said:Every US low observable aircraft since then has also made mission planning and presenting the best possible aspect to threats a primary means of survivability.
LEG said:Fighter level RAM isn't deep enough to absord L-Band and below.
LEG said:To which I will add that if simple shaping were what does the job, we would not be seeing nearly cruciform target bodies on the F-22 and F-35. Nor would we see 'large air gaps' on applied VLO edge surrounds to the extent that the panels look like window frames with their poor fit.
LEG said:No. Not just the Ufimtsyev theories but the _engineering_ knowledge that makes up VLO design is occulted behind a bodyguard of lies.
LEG said:The F-35 is covered with panels that have blatanly obvious edge gaps and this, for a jet whose RAM is supposedly 'baked right in' as an aid to materials reliability is inexplicable.
LEG said:The principle of _dielectric_ RAM grew out of experiments on the Windecker Eagle in the early-mid 70s when the ability to partially penetrate skin panels and trap the signal within varied layers of absorber back paneling first was explored via structural inserts.
LEG said:Ben Rich whose experience on the F-117 and predictions for the A-12 proved right in so many other areas, is on the books as having had the RCS model brought to him at a 3-4 and exiting his RATSCAT facility at a 10-11. This is not possible if Denys Overholser's rules about 'shape, shape, shape and materials' were all that applied. Indeed, the Skunk Works was given an independent contract for VLO consultancy on the A-12. Did they 'fail to mention' VLO throughout their period of contribution?
LEG said:Stealth is active and it likely began with the A-12 which took systems knowledge from the B-2.
LEG said:Believe what the bodyguard tells you and you know only half of what VLO is about and particularly how it is generationally advancing.
No. It is the aspect which counts because if you are LOS with an emitter, your aspect -change- is visible throughout the period of tangential or direct flyby.If the aircraft is flying higher it may be within line of sight to more emitters, but it is farther from them. The farther from an emitter the aircraft is, the less likely it is to be detected for a given RCS.
Where IADS have always (SAGE, UKADGE, the Soviet Markham derived systems) been 'networked', there is no way to 'out turn' a radar beam because what you show to the threats beside and behind you is just as important as the target off your nose.I can only assume you are trying to assert that for an aircraft flying higher, that the resulting aspect or grazing angle to the emitter would increase the RCS enough that the benefit of the greater range to the emitter would be negated. Again, the increased RCS would have to be very large for that to occur. Even a small increase in altitude will result in a large increase in range to the emitter and received power decreases with the fourth power of the range.
Unless you are using ground wave radar and possibly even then, the clutter features ALL have a dipole size larger than the wavelength of the missile airframe and thus it is hidden within their overarching feature presentation as a jumbled background event. Extremely complex STAP modelling that works like SAR can break down some of these feature composites using E-pulse techniques but it still isn't a complete fix because the target is moving faster than you can track it and of course, anything up can be shot down, particularly if it is running around with an S-band aperture ontop of it.Cruise missiles have a very different mission and thus very different design requirements than manned penetrating or persisting aircraft. They have physical size constraints and face different threats than manned penetrating aircraft. In general their physical size relative to threat frequencies limits the degree of RCS reduction that is obtainable when compared to a larger aircraft. Sadly, there has not been a B-2 sized cruise missile program since the 1980s, and that was designed to fly at high altitude.
It is entirely appropriate for illustrating what protects the CM is indeed 'routable' because it is the entire earth LOS to various emitters and thus you can set your 'best side' towards the threat of greatest interest. There is no such protection at altitude.Comparing the RF survivability of cruise missiles to manned aircraft is not wise.
No. It can isolate maximum return pathways along narrow azimuth lines but it can do very little to prevent backscatter in elevation. RAM is everything here and it is not enough against more than 1960s era systems of the early SA-2/3/5/6.Shape *is* (nearly) everthing. This is an application of Maxwell's equations. You can only absorb so much, you can reflect much more.
It doesn't matter what the material is, if it's not creating an active electrical field, phase and wavelength tuned to impingent radar's -exact- operating frequencies, it is not going to do more than take 'a tenth off the top' of the impedance loading."Ferrites", for better or worse, has become something of a generic for the elements in materials that alter their electrical properties for the purpose of radar cross section reduction. Modern RAM/RAS does not use iron ferrites as the primary absorber and has not for a very long time.
Ahhhh, but the ZSR-62 was 'cancelled', everyone knows /thaaaat/. The easiest way to not talk about 'Stealth Jammers' is to deny they are on the airframe. No jammer suite = no active stealth.The ZSR-62 was and ZSR-63 is part of the B-2 Defensive Management System. I will repeat myself:
Quote from: quellish on July 15, 2014, 12:05:26 am
Every US low observable aircraft since then has also made mission planning and presenting the best possible aspect to threats a primary means of survivability.
And how long does it take for the S-300V to displace and move within one of the sanctuary bastions where it might be protecting roadmobile Topol? Fifteen minutes? Five?The DMS detects pop up threats and allows the crew and aircraft to present the best possible aspect to the threat. This can mean altering course using the autorouter, altering flight controls to minimize scattering sources, etc. Most persisting VLO platforms (and one not so VLO) have a similar capability.
WHO is providing the EOB mapping of these deep target areas in the middle of a nuclear war?
Oh, so the B-2 is _not_ primarily a strategic mobile ICBM sniper is it? Then the problems get worse because the threat densities become larger and the abiltiy to drop GBU-31/38 from the same height you would a B83 is minimal. Which means that even less than stellar kinematic threats like the SA-6 are now real problems because the B-2 cannot do a 7G split ess at 1,100 knots like an F-22 to spoil the shot.
And if you fly right over the site and something a long ways off snaps on to look at you on a blink schedule, all's he has to do is use his secure microwave comms to that SA-17/21 etc. and again:
You. Are. Dead.
I would like to know why small plastic ribbons around the F-22/35 provide the same degree of protection as the fully planform aligned YF-23. I would like to know HOW these narrowXshallow little bands, often buried in the control surfaces, are labeled 'deep channel RAM'. I would also like to know WHY, if late F-22 and all F-35 RAM is 'baked right in' there is such a marked difference in _smooth skin panels_ between non-LO treated early EMD F-35 prototypes and full LO treated LRIP models with thick RAM panels sufficient to change the contours of the jet's outline.You are saying (I believe) some active counter radar emitter exists and is in use operationally on the B-2. I would certainly like to know where the antennas for this emitter are, where it gets it's power from, and how this system is maintained and tested for readiness.
The B-2 has similar features in the surrounding frisbee curl on the wing LE.
It also has a deep enough body to support a secondary system, built into/under the skin.
At lower wavelengths, including L-Band, composites, even those which are RAM laminate stacks, are naturally dielectric-It doesn't have to absorb it. It has to prevent the energy from being sent back to the emitter.
It also does not have to be deep if it has a large attenuation constant.
The Russian approach has been to invest in the further development of low band radars, especially operating in the VHF band. With wavelengths of the order of a metre or more, only very large stealth aircraft (e.g. B-2A) satisfy the physics requirement for geometrical optics regime scattering. A fighter sized aircraft such as the JSF will see most of its carefully designed shaping features fall into the resonance or Raleigh scattering regions, where shaping is of little or no import, and skin depth penetration of the induced electrical surface currents defeats most absorbent coatings or laminates.
Another less frequently discussed consideration is that L-band frequencies typically sit below the design operating frequencies of stealth shaping features in many fighter aircraft and UAV designs. Shaping features such as engine inlet edges, exhaust nozzles, and other details become ineffective at controlled scattering once their size is comparable to that of the impinging radar waves. This problem is exacerbated by the skin effect in resistive and magnetic materials, which at these wavelengths often results in penetration depths incompatible with thin coatings or shallow structures.
It was therefore not surprising that during the 2000/2001 Australian media debate over the Wedgetail AEW&C aircraft, US participants were quick to vocally argue the “counter-stealth” capability of the Wedgetail's L-band AESA radar design.
Recently performed Radar Cross Section modelling and simulations performed on key shaping features of the F-35 Joint Strike Fighter show a pronounced degradation of shaping effects below the design's optimal X-band operation.
If there was no need for more than a surface constant loading value-
(Hitler's Stealth Fighter, Time Index 26:40)
You would not see these NOT building a stealth fighter, certainly not like the Horten brother's did, with it's layered carbon and bonded plywood design. Germany had no advanced composites for the engine shrouds nor does it speak well to build a steel cockpit tubular frame out of plastic rather than steel. But most importantly, the jet is being coated with a paint that treats all these mistake zones as an integrated body of METALLICIZED return and thus prevents the radar from intruding into the dielectric RAM stack for attenuation purposes. It instead forms a unified surface loaded skin, like a mirror.
I believe that, in fact, a similar approach is taken on the F-22 and F-35 and that whatever is not scattered on neutral bearings is deliberately dealt with as a surface wave by active cancellation.
Which is your way of sawing that the surface junctions whose angular intersections cannot be stealthy 'don't count' because the inverse correlate is that if the shape doesn't work and the design is still stealthy then _either_ there is a massive fraud going on. OR stealth includes measures of which you are either not aware or are aware of and are deliberately dissembling to cover for.The F-22 and F-35 are complex shapes. The F-117 (and X-47, and X-45) is simpler.
I do not see how you are drawing the conclusion that a more complex shape means that shaping is not the most significant contributer to RCS reduction.
I really don't care which it is, the proof is that jets which cannot survive a modern, _integrated_ air defense system because they lack the performance to do so, cannot be depending on shape considerations alone to protect them when they are NOT invisible to long wave lengths and CANNOT use mission planning to route-around multiple emitter threats whose location is apt to random change during the interval between stepping to the jet and possible overflight of a displaced battery system.
Either you will fly over a gap which isn't. Or you will get caught turning to avoid one threat and catching a bad aspect from another.
And then: You. Are. Dead.
And yet, this is exactly what the B-2 is supposed to do, with the nominal excuse that half the Soviet IADS would be shattered by previous SIOP ICBM/SLBM/Cruise hits. And the A-12 was supposed to match in the tactical realm where the threat density is even higher.
These being shape optimized flying wings with narrow bow ties lines off each tip and the F-117 and A/FX following the alternative path of darth shaped (supersonic potential) equivalents, the reality then must be asked: WHY (if shape is everythign) are two cruciform shaped, low sweep angle, F-22 and F-35 jets considered 'stealthy' at all?
And there's the bodyguard, looking you right in the face, caught in the headlamp of truth: stealth is not what they say it is.
Your prevaricative tongue or my lying eyes? :-]Again, PTD is an application of Maxwell's equations. There are no lies there. No one is changing physical laws.
You said 'air gaps' I believe. Look at an oblique angle which catches RAM surrounds on things like the lateral avionics bays or the large 'step' around the DVI with it's enormous glossy dielectric plastic shield.Physical, or electrical gaps? It is the electrical discontinuities that matter, as pointed out in my previous post.
These are surface discontinuities which, by whatever EE law you care to quote, should be disrupting the surface flows of EM current across the body of the jet. Why are they there on a jet whose composite tolerances are much finer than even the F-22? Why are they there if RAM is 'baked right in' (a sure and certain recipe for disaster in the face of things like Gallium Nitride emitters whose power and operating bands are likely to shift constantly, making a fixed RCS control scheme worthless if it is, essentially, structural in nature).
Thanks to the commercial telecomms revolution (I-Phones and the like), we can now buy phase shifters at ridiculously cheap prices whose tailored MMIC/VLSI features and operating characteristic are both individually tailored and highly efficient. It is these which drive modern AESAs.Um, what? All materials have dielectric properties. This is a measure of how electrically permissive a material is and is expressed in comparison to the permissivity of a vacuum. Metals are good conductors. Other things, not so much. All RAM is engineered to have dielectic properties that are favorable for whatever application the RAM is intended for. This was the case even for "WWII U-Boat periscope stuff".
There is no reason to assume that stealth cannot make use of these too, _if_ it knows, pulse to pulse, what the incoming target wavelength is and can be energized to match with a surface charge that is of an exactly polar opposed level.
The Windecker Experiments shows the direct that stealth designers were thinkign _before_ Ufimtsyev. Dielectrics, not surface coatings. Skin penetration happens anyway and is one of the big reasons why fighter LO should be impractical on anything not a flying wing.What you seem to be attempting to express is the idea of the outer surface of an object having a dielectic constant much closer to free space than would be the case for metal, and putting an absorber behind that outer surface. This would be an outer surface "transparent" to radar. The Windecker Eagle was constructed of plastic and fiberglass, which are materials used for radomes for the same reasons. Of course, if you make the outer surface of an aircraft "transparent" to radar, all of those unavoidable shiny metal bits under the skin are still reflecting. This was nothing new, and the experiments with the Windecker Eagle did not advance the state of the art in RCS reduction or absorbers. Nor were they particularly successful in achieving a very low signature.
Then everything related to LO went black, and the Russian Angle became the cover story.
Fixing this issue is one of the principle reasons why stealth brings such a huge weight and performance hit (the other being closed loop cooling) in 'linoleum' covered jets like the F-117.
Because you are literally building up the functional RAM applique on the outside of an aluminum airframe.
Now imagine you are dealing with something that is both composite skinned to the extent that you build the exoskeleton and fit the metallic airframe to the inside. And that has to be 9G @ 700knots+ capable.
You cannot afford a huge weight deficit, you cannot accept a large structural impingement, because strength of the airframe will suffer, as will wingloading and T/Wr.
Oh, 'and by the way', the skin is naturally dielectric so if there is nothing buried in it or beneath it, the metallic components will be seen anyway. While the nature of this radar-proof lining is both band and powerloading sensitive such that you cannot guarantee that what works today will continue to be effective in 10 years. What you CAN say is that adjusting the VLO scheme via replacement of 'baked right in' absorbers is not as cheap as adjusting a software driven cancellation system that works on the principle of active phase shifters whose performance is a known and will remain viable so long as the emitter characterization system can keep up with the wavefore codings on things like LPI and UWB.
Hence the huge and continuing investments on the ASQ-239.
The idea of making this absorber have active, broadband, charge states that capture the signal crush the life out of it, in the skin or along it's surface is most asuredly more than Oxcart or Senior Crown did.The idea of putting a lossy absorber inside an outer surface or structure that was "transparent" was not new. It had been used successfully and operationally on the A-12 (OXCART).
Doesn't change the spirit of what I said a bit. If the Skunk Works made the RCS model (for indeed it would have to be so if it was tested at RATSCAT) go from a 2 to a 9, it was most certainly stealthy, even if we are talking orders of magnitude incrementation between steps.> We interviewed them and found their level of stealth was, on a rating of [1 to] 10, where 10 is best, at about a level of 2.
> There were two finalists, but before the final decision [was made] we took their model to the Skunk Works, rebuilt it, tested it at RATSCAT, and raised them from a factor of 2 to a factor of 9. And they had a good design, believe me it was a good design. But it was not stealthy...
And so again: Who is defrauding the government? Lockheed or the USAF? Who is committing treason? I want to know because, for five billion dollars and the security of the U.S. at stake, they should still be eligible for life before a firing squad.
Unless. There was no massive fraud. And the A-12 was indeed progressing exactly as planned. The Skunkworks was fired because they couldn't make weight or cost on the nozzles. Not because they failed with the external signature characterization testing.
Been to RATSCAT have you? Tell me more so that I can place you.It's important to note that this should not be taken verbatim: Lockheed did not take a model back to the Skunk Works, and it was not a full scale model. The model work was performed at RATSCAT (significantly, using the older pole and rotator).
As a result of this consulting work Lockheed was given a portion of the construction work on the A-12, specifically the trailing edges and exhaust. But it was not long before that contract was cancelled, and the product of Lockheed's *design* work was discarded. Lockheed's stealth changes did not actually make it into the A-12.
No. Rich would have had to have known how bad the jet was when he called up Elberfeld and told him he was underprice by at least 60% (forgive, I have lost all my resources, and am going by memory here). You can't make cuff calls like that without a working knowledge of what would be needed to fix the problem.
Nor is it definite that Lockheed was off the program. As I recall, Rich told the GD president that if he wanted the work done again, it would cost him four million for the reach-back because the engineering drawings had all been trashed due to security constraints. He _did not_ say that this data had not been recovered.
What is known however is that serious RCS redesign and improvement was undertaken as that 'mere analyst' states in his interview with the Two Star AF Big Wig. "These people don't grant audiences to the peons unless they want to 'convey an idea' which was specifically that the A-12 signature problem was _just fine_, a matter of differing perspectives between USAF and USN modeling techniques."
And how did the period USAF system differ from the USN pole model equivalent?
It's digital, based on finite elements computer modeling.
Now here, Stevenson made himself a mistake. Because he assumed that the USN version was the 'real deal' because it used real world measurements. But that's not the case. Because, even though it's based on a physical vs. virtual measurement system an RCS pole model can never match the NUMBER OR INCIDENT ANGLE variations that a computer model can.
And that's critical when you are flying a high altitude mission, being hit from several aspects with multiple bands of radar emission, all of which tickle the RAM differently, some of which (so called 'omicron' emissions) are specifically phase polarized designed to foil the absorber mechanics.
The USAF modeling system was more sophisticated even though it as 'just' computer based because it did not attempt to use physical models to representatively model a high density, sophisticated (blink on, blink off), sectored, emitter environment.
And what was the result of this? One paragraph in Stevenson's book. A 'Stealth Bra'. Which, if you look at subsequent models and tie pins of the A/FX (the flying wing version) visible on this very forum in fact totally alters the front end of the jet to more of a cranked arrow appearance.
That is how much the A-12 would have changed, had it been fixed through FSD.
Now we get into the nitty gritty of the legal case, whereby there were TWO men from each company cleared into the F-117 and B-2 programs -at some level- of compartment access. We also have the Cold Pigeon and Sneaky Pete designs which the lead engineer (again, it's in the _The Five Billion Dollar Misunderstanding_) at GD says never flew. But which the government insists represents his 'special knowledge' of VLO which obviates their having to prove that they needed to give him squat.Lockheed was not permitted to discuss the products of other programs with GD or the Navy. So no, they did not mention that the "VLO" threshold was much lower than the A-12 would ever be able to achieve. They did provide more general input on reducing the RCS through both shaping and materials. This included suggesting significant shape changes to the inlets, wing thickness, and trailing edges.
The implication being that this was national security essential stuff which was exchanged between the various companies _before_ the A-12 (and possibly before the F-117) so that each and all could compete. Which would also go a long ways towards explaining why the team of GD and MD were allowed to work together to begin with.
My own contention is that the recent SCOTUS ruling that the USG cannot use a national security restriction to refrain from providing proof that the GDMD was in fact given the technology base access which would have let them complete the A-12 FSD on time, with prototypes. It wasn't that the government backed out on a VLO promise. It wasn't that the USAF didn't want to share it's TDP on the B-2. It's that _the nature_ of that B-2 technical data package was so extremely sensitive that it could not be admitted into any record of law.
Stevenson got himself one end of a very long snake tail. But he didn't pull near long or hard enough to get more than the teasing fragments that the case shows and even that is only revealed in that one quote, in the addendum, at the back.
What he did get was a crucial admission, by the USN, that VLO -as they knew it- did not work at altitude. You can see the nature of this in the design of the A-12 without tails and with very large inlet bypass ducts above the main engine installational envelope, feeding that giant ejector plenum where it is exhaust mixed through the serpentine before exhausting.
This is the kind of trickery that you resort to when you _know_ that you have an overweight (stealth + carrier) design that has no SEP to get to altitude (shades of the F-105) with a useful warload and have to work both the threat radar and his lower hemisphere (MiG-23, MiG-31) IRST systems as a result.
What Stevenson did not have the brains to ask was: "How did you go from an overweight, thin winged, short ranging, no-VLO knowledge, airframe to a thick wing, long radius, and 'solved RCS problem' design with improved SEROC and cruise speeds if LO is such a massive driver on program expenses and ultimately a serious part of the weight issue (or the Stealth Bra would not have played such a large role in the two companies defense against the weight analyst's generalizations about being over the limit on takeoff).
Again, this can only be true if someone, somewhere, likely to preserve their own pet program (F-22, C-17, whatever) coughed on some very significant weight tradeable stealth technologies that took the A-12 from the Gen-1 era of the F-117's linoleum towards the 'best there was at the time' which would have been the B-2.
The B-2 for which the 'cancelled' ZSR-62 is known to have been a major element of an active loading/cancellation scheme.
Your problem is that you are hiding behind detail rules and ignoring the main one which is that the data doesn't match the theory. This contradiction principle is a key element of logic as scientific reason and the F-22/F-35 are not what they seem if the shape-shape-shape-materials rule is true.Denys Overholser's "Shape, shape, shape and materials" is only restating the prinicples governing how fields intertact with a physical object in free space. There is no lie here, only math.
See Above.The A-12 (Avenger II) apparently did not receive any significant input from the B-2 program. I do believe there was a lawsuit about that.
Dunno. I'm not a radio frequency electrical engineer. I simply do not trust people to ever tell me the truth and so I look at things from a skewed perspective that assigns weighting values to contradiction based on historical data I have read from other system commentaries.What do you mean by "Stealth is active"? That there are components on VLO aircraft that contribute to signature reduction, such as "active" gap sealing that requires power? Or are you asserting that "active cancellation" using emitters on the VLO aircraft are operational, were pioneered by either the A-12 (Avenger II) or B-2, and contribute more than shape to the RCS reduction of the aircraft?
Again, if you ARE an EE doctoral (the level at which they start to explain how it really all works), you should admit it and name the field under which you participate so that we can all understand your potential bias when you explain how what I have said is not possible from within the established rules of EM theory as you know it.
I'm stunned sir. Winning Winston's famous quote about the truth needing a bodyguard of lies for it's own protection as Britain's and yet a presumably British subject not knowing it? What is the national school system coming to?As you may have guessed, I believe in physics. I have no idea what you mean by "the bodyguard". The physical laws that govern how fields interact with physical objects in free space *is* the whole of what VLO is about. That is difficult to argue with.
Shocked I say. :-]
What better way to send the Russians and Chinese down a merry path for 30 years than to let them in on a secret which is incomplete or subtlely warped? Why not assume that among a scientific principle's selection criterion is the certainty of knowledge as to not only it's direct countermeasure but several generations of exploitable measure/counter down the road so that you can plan beforehand how to stay 2 steps ahead?
Stealth is not what it seems. It is admitted but the existence is not the method and the method stated, when pressed for details, is a lie. War is Deceit but what people don't get is that we are always at war. Is that a good thing? When you don't know why the lie is being used, you can only assume that the person stating it is a liar. That condition breeds poisonous separations of trust, even when the underlying protected truth is in fact beneficial.
That's all I got. Last word is yours.