The Secrets of Stealth

[jduff]

Ever wonder how a stealth aircraft is made? I am going to share some of the secrets with you. First my disclaimer. I do not work for any government agency, nor subcontractor to a govt agency. What is said in this post is based off of common knowledge. Any similarity to the true process of our govts stealth technology is by calculated origin. No secrets were taken or a crime commited in getting this knowledge. I am just a common man who works in a warehouse.

 

Where to begin, well lets start with the physical structure of the aircraft itself. If you ever notice a stealth aircraft is oddly shaped compared to other aircraft. This is for a purpose. As the angles are designed to reflect or bounce radio, and or thermonic signatures away from the incoming source. This is common physics. While the physical structure helps in making the aircraft stealthy. The other applications truly make a stealth aircraft a marvel of genius.

 

Besides the physical structure a stealth aircraft has two very special coatings. One of the coatings is made of silica. Silca has a natural reflective property as well as thermonic dispensation. It is only obvious that a stealth aircraft would incorporate such a coating. It only goes to reason that silica is used. As the source of silica is plankton. Because silica in its normal state has alot of fractalization. Modern Stealth aircraft use strands across the plane that give out a small electrical current. This is done so a small electrical charge is given. To let the silica coating have a more soluable makeup. Thus leaving very little if any pockets for the coating to not cover. As well as making sure the coating stays in place.

 

The thermonic and radio reflective qualities of silica is incredible. But that is only the top coating. Underneath is a second coating which makes a stealth aircraft nearly invisible with the top coating over it. This undercoating is a carbon based coating that has been heated up. This coating is dark in nature. Looks like charcoal. This coating is designed to make even heat dispersion. The natural process for this carbon based coating is to keep heat to a minimal. In effect a heat shield. This coating when combined with the silica coating makes for a fantastic stealthy aircraft.

 

But we are not done.The stealth aircraft has a engine, which puts out alot of heat. If you ever notice. A stealth aircraft has dampeners that are at a 90 degree angle towards the bottom of the craft. You will also notice the dampener itself has a honeycomb or a buckminsterfullerine shape. This is to make sure heat is dispersed evenly. As we all know, heat rises. The intent of the dampener is to cause this effect. So that heat does not escape away from the aircraft.

 

After all these marvels of engineering are put together. You get one of the best weapons in the U.S arsenal. Hope everyone enjoyed the read.

 

 

Edited September 23, 2013 by jduff

[ADreamIveDreamt]

Heat itself doesn't rise,but I know what you meant. Also,the History of Stealth is a wonderful journey.

 

 

Enjoyed.

[Mr Monkeybat]

stealth planes have flat facets to avoid deflect signals away from radar stations. Does this mean that a stealth plane has to be careful in its manuevers to avoid lining one of its facets up square with an enemy radar.

[jduff]

stealth planes have flat facets to avoid deflect signals away from radar stations. Does this mean that a stealth plane has to be careful in its manuevers to avoid lining one of its facets up square with an enemy radar.

A stealth aircraft does indeed have to be careful when manuevering. A sharp turn or bank can cause a reflection back to the source. Vector and trajectory play a big role when a stealth fighter is on the move.

[ewmon]

Jduff, I suppose you mean well, and I rarely deconstruct someone's post, but just about everything you say here doesn't make sense.

 

Radio signature. Talking about "radio and or thermonic [sic] signatures" doesn't make sense. I'm sure you mean "radar signal". The term "thermonic signature" doesn't make sense. The word "signature" used with radio or thermonic in this manner doesn't make sense.

 

Thermonic. By "thermonic", which is not a real word, I think you mean "thermionic"; however, I don't know of any remote sensing device that uses thermionics ... that is, a remote sensing device that emits particles. If you meant "thermal signature", then that's what the engine exhaust emits, which does not involve reflections on the aircraft's structural angles.

 

Structural angles. Structural angles in stealth aircraft reflect incoming radar signals in directions other than back to the radar antenna, which anticipates receiving a reflection. Right-angled structures reflect signals back to their sources in the same way that a ball thrown into a right angle formed by a wall and the floor/ground returns to the thrower. See the diagram below. The right angle acts like a flat surface perpendicular to a radar signal regardless of the antenna's direction. So, stealth technology tries to avoid flat surfaces making right angles.

Coatings. It is not obvious that a stealth aircraft would use reflective coatings; just the opposite, so this statement doesn't make sense. And it's not obvious that the coating should be silica. You also use the term "thermonic dispensation", which doesn't make any sense at all. And you mention electric current and electric charge, which also don't make sense.

 

Invisibility. You mention that the two coatings on stealth aircraft make them nearly invisible, which is not only incorrect, but the photo you provide shows a very visible aircraft. And even if you meant that the carbon coating keeps heat to a minimum (instead of a "minimal"), this also doesn't make sense.

 

Engines. The description of "a 90 degree angle towards the bottom of the craft" doesn't make sense. You mention "a honeycomb or a buckminsterfullerine [sic] shape". Honeycomb is a flat, and buckminsterfullerene is spherical, so this doesn't make sense. The idea of the "dampener" causing the heat to rise so that it does not escape from the aircraft doesn't make sense.

 

I hope I'm wrong, but I don't know that you've provided anything useful here.

[jduff]

If you hope you are wrong then you would not have posted the post you did. While in my disclaimer I stated I did not work for any government agency. I did work for a corporation as a adhesives/bonds specialist for many years. The coatings on a stealth aircraft come after the coatings that are used on heat windows. As well as the heat shield on the space shuttle. I am not allowed to go into detail about that process(Classified). As that would actually get me in trouble. And in case you are wondering what corporation I worked for you can take a look here http://www.southwall.com/southwall/Home.html;jsessionid=916291DFB98A291B1E912CF6FB8882C9

 

As to the engineering of a stealth aircraft structure. It is complete common knowledge. And can be found here http://science.howstuffworks.com/question69.htm

 

As to the coatings(non classified), Here is a example of how they work for the general public. http://www.southwall.com/southwall/Home/Company/Technology.html

It is non permissable for me to use information that is classified or C/RE7 and above. This is also a non classified source in pdf: http://buildings.lbl.gov/sites/all/files/31616.pdf

 

Thanks for the interest. I posted this piece for entertainment purposes.

Edited October 1, 2013 by jduff

[Phi for All]

Thanks for the interest. I posted this piece for entertainment purposes.

 

You have to remember, this isn't Wikipedia and it isn't YouTube. This is a discussion site, and you should expect people to discuss what you post.

 

Most members of SFN are intellectually incapable of tacitly reinforcing misinformation. If we keep our mouths shut, PEOPLE COULD DIE!

[ewmon]

I anticipate that some sort of language difficulty exists here somewhere.

 

 

 

What does "radio signature" mean?

 

What does "thermonic" mean?

 

What does "thermonic dispensation" mean?

 

What does "a 90 degree angle towards the bottom of the craft" mean?

 

What does it mean that "The intent of the dampener is to cause [the] heat ... not [to] escape away from the aircraft."

 

What does "C/RE7" stand for?

[jduff]

I anticipate that some sort of language difficulty exists here somewhere.

 

 

 

What does "radio signature" mean?

 

What does "thermonic" mean?

 

What does "thermonic dispensation" mean?

 

What does "a 90 degree angle towards the bottom of the craft" mean?

 

What does it mean that "The intent of the dampener is to cause [the] heat ... not [to] escape away from the aircraft."

 

What does "C/RE7" stand for?

Ewmon , sorry for a bit of a delay, my time is very limited during the weekdays. I will do my best to answer your questions. And yes I do believe there may be some language difficulty. More with me than you. I also corrected thermonic to thermionic. As I have always usd thermonic throughout my life and was not corrected. Go figure!

 

 

Radio Signature: Is a individual or distinct mark or set of parameters that define a source. In radio it can be frequency, wavelength(Bandwidth). For instance a SA-300 radar array uses a specific telltale set of frequency and wavelength. Which gives it away. With a stealth fighter/bomber, the coating can be set to specific frequency and wavelengths. This can be altered even during flight. You can have a narrow set of parameters or a wider range depending.

 

As to thermonic. Yes, that is my fault. I have always used thermonic rather than thermionic.

 

Thermionic Dispensation: A arrangement that dispenses thermal emissions evenly throughout a area. In the case of a steath fighter/bomber. It is specifically done for absorbtion.

 

It is set to that angle from 45 degrees to 90 degrees(adjustable) so the engine exhaust gases(heat) will disperse evenly. And the heat from those gases can be absorbed.

 

The last question. Just security clearance levels. They differ depending on where you are at or what you do.

 

Hope that helps you. I will do my best to improve my communication skills when posting or replying to a article.

 

Also, please do not ask how certain things are done . As I cannot answer them publicly or directly. But you do have enough information to draw your own conclusion.

 

Just so you know!

Edited October 4, 2013 by jduff

[MigL]

Its funny that your illustrations of stealth aircraft always show F-117s, which is 1970s technology stealth. At that time the EM dispersion equations had to be solved rather simplistically with the available computing power, and the simplistic solutions involved facettung and angles such that the F-117 and its predecessor, HaveBlue, were nearly impossible to fly. With todays massive computing power, facetting and extreme angles are not the only option. The Northrop-Grumman YF-23 and B-2 , Lockheed F-22 and F-35 as well as Boeing's X-32 ( along with numerous UCAV designs ) show very little if any facetting and are among the most maneuverable current fighters.

 

EM waves such as radar are particularily fond of cavities like intake and cockpits. The X-32 used a screen in its large intake for this problem ( and may have used additional means to reduce RCS ) and ALL stealth aircraft have their cockpit glazing coated with a layer of gold to get rid of the cavity effect ( take a look at a picture of an F-22 for the telltale gold sheen ). Radar waves also creep over metallic structures and re-radiate from edges if long enough. Notice that ALL access panels and bays on the F-22 have serrated edges to minimise this effect.

There are manythings that have been tried over the years, including part wave reflectors, which reflect incoming radar twice such that the two reflections interfere with each other. Unfortunately this only works at one frequency and would be useless against modern frequency agile radars.

 

The first radar absorbent coating used was composed of ferrite particles embedded in paint and graphite is a variation on this. Stealth is not new and Lockheed's Skunk Works under Clarence ( Kelly ) Johnson was working on it in the 50s with the U-2 program, in the 60s with the A-12/SR-71/YF-12A program and in the 70s with HaveBlue. All of this is documented in any good book detailing the history of the Skunk Works or of the airstrips in the Mohave desert where all the nuclear testing was done and the Lockheed spy planes were developed for the CIA ( otherwise known as Area 51 ).

 

If your company's coating was so effective don't you think everyone would paint their planes with it and have instant stealth? Why are they still spending billions of dollars to develop new stealth designs? The best coatings available, applied to the intake ducts of the F/A-18E and the F-15 Silent Eagle ( they were not developed with serpentine ducts to hide the compressor faces ) only reduce the RCS by less than an order of magnitude, and if you know any physics, this only marginally shrinks detection range.

[Enthalpy]

Instead of part wave reflectors, one can spread the reflection continously, if possible as a Gaussian distribution. This works over a wide frequency range.

 

The true worry of stealth aeroplanes is that over-the-horizon radars (OTH, see Wiki) use low frequencies, with about half a wavelength fitting in the target's size. Facets and all shapes do nothing against that, and paints neither.

[MigL]

Historical Notes:

 

In the late 60s/early 70s, the US became interested in low-observables due to their Vietnam experience.
DARPA asked major aerospace contractors to submit proposals for a demonstrator program. Lockheed
wasn't even asked since they hadn't produced any fighters for the USAF since the 50s. Kelly Johnson
had to ask permission of the CIA to declassify their experience with L-O during the U-2/SR-71 programs
so that they could make a submission. This is the path they chose.

 

In the late 19th century, James Clerk Maxwell developed equations which describe Electromagnetic behaviour
and phenomena. In the early 20th century, the German EM expert, Arnold J. Sommerfeld, refined Maxwell's
equations to predict the manner in which a given geometric configuration scatters, or reflects,
EM radiation. The Russian physicist Pyotor Ufimtsev, developed an alternate approach to Sommerfeld, by
cosidering the EM currents along the edges of geometric shapes. This was still considered much too cumbersome
to be applied to anything other than simple geometric shapes and forms.

 

It is at this point that Lockheed comes in. One of their software engineers and a retired mathematician named
D. Overholser and B. Shroeder, used finite element analisyss to reduce complex aircraft shapes to a finite set
of simple 2D surfaces, using a program developed in five weeks, called ECHO 1. This is the origin of facetting where
simplified calculations allowed L-O to be modelled mathematically and predicted.
The first design was an unflyable diamond shape. This was modified with wings for HaveBlue, and further modified
for the F-117 Nighthawk.

 

The other candidate chosen for a demonstrator was from Northrop/Grumman and was more of a 'best guess' or 'shot
in the dark' design. It used no facetting. Its fuselage looked like an upside down bathtub with smoothly chined
sides and a dorsal intake, but it provided them with invaluaable experience to build on for their B-2 design.

 

Tchnological notes:

 

Electromagnetic radiation intensity falls off with the square of the distance ( the reason for this has been
explaned numerous times in the Physics Forum ). What this means is that the searching radar is always at a
disadvantage. It has to deal with twice the separation or a quarter strength return from the target while the
target sees the searcher at the original intensity. Radar is, in other words, unuseable in combat. Its like
searching for an armed enemy with a gun and a flashlight. You have to see his dim reflected light to shoot
at but he only has to see the beacon of your flashlight to shoot at.
Most new combat aircraft use passive detection systems like IRST and do not use active like radar in combat.

 

If, however, you are trying to penetrate an area for attack purposes where the defenders don't care that
you can 'see' them, it makes sense to be as stealthy as possible. One way of acheiving near invisibility
is by using massive computational power to analise the search radar's signal, then using the equivalent
of a ray trace program and an electronically scanned transmitter array ( as in current AESA radar sets ),
to transmit a signal which is equivalent to the search radar signal but 180 deg. out of phase. This will
interfere with the search signal making the return to the search radar zero. This should even work
with LED transmitters in the visible light spectrum such that camoflage is no longer required.

 

Note that the analisys of the incoming signal doesn't have to violate special relativity, it just needs
to be done faster by the target aircraft than the searching aircraft. This should not be a problem since
the target aircraft has a much more intense sighal to work with, while the searching aircraft has, at best,
a quarter strength return and is at a disadvantage as was previously discussed.

 

Note that this kind of attenuation system slready exists in inexpensive noise cancelling headphones for
sound waves. This technology will eventually migrate to EM waves.

Edited November 3, 2013 by MigL

[Enthalpy]

You can forget the noise cancellation adapted to radar. It works only in one direction, and anyway, it demands too much accuracy to attenuate the reflection by a significant factor. As on difficulty more, every part of the aeroplane reflects the radar wave: shall we cover the whole craft with antennas? In headsets, sound is cancelled at one location only, and 20dB is a good result: not the same difficulty at all.

 

"One direction only" is worse than it looks, because the craft receives many signals from many sources, not only the radar. As it tries to cancel out the echo from a TV transmitter, the active echo cancellation would reveal itself to a passive radar.

 

The signal of Over-The-Horizon radars also propagates over several paths. It's an annoyance for signal processing, but makes them immune against signal cancellation. The aircraft sending a signal cancelling the first propagation path reveals itself through the other paths, as much as a perfect reflector would - nothing stealth then.

 

About LED: this one is really fiction. They emit light fully uncontrolled, neither in phase nor amplitude. Plus, their wavelength isn't agile. Zero chance to cancel anything.

 

IRST and other optronics: from the ground, you want to detect arriving planes, but these emit little infrared from the front. Worse, passive IR detectors don't measure the distance. Provided two aircraft will again fight in flight some day (it did happen in 1991, but the conflict was so unequal that new technology wasn't required), passive IR won't do all the job. And missiles have their own radar, about impossible to replace.

 

The disadvantage of the radar receiver over the target is much worse than a quarter. It's easily like 80dB.

[Mr Monkeybat]

2 or more passive IR detectors could calculate distance by parallax, so a network of modern infrared cameras could make it very hard for a stealth plane to pass undetected. As Stealth planes are designed mainly to not reflect radar back to the sender but to the side, networks passive antennas could make stealth planes more vulnerable to radar also.

[MigL]

No Enthalpy, it can work in all directions, but only against one radar ( unless you have multiple steerable transmitter modules and immense computing power ). It works in all directions because the generated interference beam is electronically steerable and the whole plane doesn't have to be covered with antennae since at a detection range of about 50 mi. the whole target airplane appears as a point source. Radars don't discern features on the target aircraft after all, or there would be no need for IFF.

 

As for LED's frequency not being agile, is your LED TV black and white, or can it produce millions of colours ?

Also can laser diodes not produce phase differences ?

 

You are right that single radar engagements ( at least on our side ) don't occurr anymore since there are always multiple aircraft joined by Datalink and possibly even AWACS control.

Edited November 5, 2013 by MigL

[Enthalpy]

You have to read about Over-The-Horizon radars. See Wiki for instance. Their multiple paths arrive with varied angles at the target.

 

Check how a LED works, and a laser diode. They emit on a single frequency. Check how colours are made on TV. Lidars are not human eyes.

 

By the way, I did work on military radars some time ago. For bad reasons, and I'm not available for this.

 

-----

 

Stealth aircraft reduce the IR signature as well, at least in some directions. The engine exhaust uses to be above the wing, already well diluted, without a direct sight to hot parts, and there are additional rumoured tricks with static electricity. At least for the truly steath like the B-2, not for more agile aircraft.

 

Stealth aircraft also reduce the noise. I heard the B-2, it was surprisingly silent.

[MigL]

I'm discussing airborne radar, not ground based. No airborne radar uses multiple paths unless two are working in sync through a datalink.

I know exactly how LEDs work and semiconductor lasers and they do emit on a single frequency. But note that I was suggesting their use as

substitute to camouflage, ie to the human eye's detection. But at 50 mi. separation do you think it matters if the emitted three frquency peaks

are separated by microns as on an LED panel when detected by a dish 18" across?

And yes I agree all aspect stealth takes ALL emissions into consideration.

 

I did not understand your third line where you worked on radar systems and " For bad reasons, and I'm not available for this".

What do you mean by that ? Can you elaborate ?