Who cares how it works as long as america is the only to have it and use it in a war.

This thread is here for everyone. If you read the origional post, it has something for everyone. For newer member, it gives you a realistic, unbias look at how stealth technology works and a littie of why. For more experienced members, it is a reminder and a reallity check. The Pentagon and the Media have used years of Disinformation and Misinformation to hide the truth and twist public preception of Stealth. Wheather intentionly or not, Stealth Aircraft air often portraied as the Invisible Attackers of the night that are invernerable to air defenses. While this sounds nice, it's not true!

We often (me Included) want to think of planes like the B-2 Spirit and F-22 Raptor as the ultimate weapon, an Invisible attacker that can kill without warning and then vanish. The Loss of the F-117 Nighthawk in Kosavo a few years back was a shock and a huge mystery to most people, because we though it couldn't happen! It wasn't true.

Tim

Thanks for the answers to my query guys. Unfortunatly with three different explanations I am still no wiser. I can see elements I recognise to be true in each of the explanations but I can also spot things I am sure are wrong.

Certain facts we know to be true:
The F-22 is designed to give a small number of big reflections rather than lots of small ones - that also explains why stealth aircraft tend to have repeated angles throughout.

I understand "corner reflector" concept. Wikipedia in fact explains that quite well.

But the exact determination of stealthy curves is still above me. If any of you guys are highly QUALIFIED on radar then please shout out the correct answer.

The point with this post wasn't to learn anything... I didn't... but simply to put all togheter in on post... good job ghost...

Originally posted by planeman
OK, I think I understand basic deflection principle stealth on faceted aircraft, but I am at a loss on how they determine blended stealth.

Am I correct?
If someone could explain rounded stealth to me, it would be cool. Thanks.

Rounded stealth is very complicated, however, I will try my best to explain it without getting hopelessly technichal.

Electromagnetic waves flow. Given a smooth, gradually changing contor, they will bend and fallow the surface. The Math behind it is very complex and confusing (I'll admitt I barely understand it myself.) It is similar in principle to the Conuit Effect, the law of physics that allow flowing water to fallow a curved glass. The Idea is to bend the waves so they flow around the aircraft. The trick is the use of a continuious curve of a constantly changing radus.

When used correctly, the covers cause the radar energy to flow around the aircraft instead of reflecting form it. the main draw back of this method is that the surface of the plane needs to be smooth and unbroken! Any seems such as thoes on an access door will break the flow of the Radar wave and cause energy to be reflected back. This is why the B-2 has to be so carefully maintained, and inperfection on the surface of the plane can cause "Spikes" in the Plane's RCS.

I'm tight on time today, whick makes this harded to explane! If anyone else with sufficent knowlege of the science behind stealth has time and is willing to explain what I just said in better detail, I would welcome the help!

Tim

[edit on 11-5-2006 by ghost]

Ghost is right the waves bend around the aircraft the more rounded it is the better. The B-2 bends the radar whereas the Raptor both bends and deflects radar. If you watch stealth secrets on the Discovery Chaneel you wills see that when the B-2 get's hit with radar waves it flows over the top.

Thanks guys, that really helps. Does the extent to which the radar waves are bent around the aircraft dependant on what angle they are coming from?

To a degree, yes! Using the principles of electromagnetism, you can bend the radar wave without breaking it flow. However, in practice, there is a limit to how much the beam will bend. Remember, Radar is an electromagnetic wave just like visible light. Except for the wave length and the frequency, the basic properities of Radar and visible light are the same. Both can be bent to a degree, both can be focused using a lens of some type. They each travel in waves that exist within a defined range of lengths and frequencies.

Being elecromagnetic, Radar posses both electrical and magnetic properities. This
means that if introduced into a magnetic feild, a radar wave's energy will be absorbed and disapated. The ability of Radar energy to be absorbed in a polarized magnetic feild is another key to stealth technology. Scientists have created materials that have an internal magnetic field. These Materials are calls Radar Absorbing Materials or RAM. While the details of RAM are Secret, we know that it has existed since World War 2. RAM is complex and I will try to go into more detail in a future post.

Tim

OK, I'll assume EM waves work the same as acoustic waves. (So will go with the geometrical theory of diffraction)


When a wave passes over a surface, and meets a sharp edge, it will scatter (diffract) - and this degrades with a 2nd power relationship with frequency. Double the frequency, and you'll get a 3dB reduction in sound field power.

Going around a smoother corner (where the wave would meet the corner at a tangent, and leave at a tangent), it will creep - and it decays exponentially. The decay rate will be dependant on the wavelength and surface of the object.




So its best to have smoother surfaces, which can 'drag' the wave around and will degrade the strength of the wave more. Also, this is the reason that low freq (long wavelength) radars will detect a 'stealth' aircraft easier as the wave will scatter and not creep.

Originally posted by kilcoo316
OK, I'll assume EM waves work the same as acoustic waves. (So will go with the geometrical theory of diffraction)

That's pritty much correct! As a matter of fact, one of the critical peices of research in the development of steath was paper by Russian Physicist Pytor Yufimshev (I hope I spelled that right). He wrote a paper called the Method of Edge Waves and the Physical Theory of Diffraction. Understanding how geometric defraction worked was the key to calculating and ultimatly reducing RCS.

So its best to have smoother surfaces, which can 'drag' the wave around and will degrade the strength of the wave more. Also, this is the reason that low freq (long wavelength) radars will detect a 'stealth' aircraft easier as the wave will scatter and not creep.

Right again! The smooth surfaces cause the radar to flow around the plane. Also, the Low freq radar waves don't creep very well. The only way to counter them is with absorption (RAM). Also, they seem harded to absorbe. Supposedly, there is a way to coulnter them, but I'm not sure about the details. I'll see what I can Find. I suspect it might have something to do with Radar Absorbing Structures (RAS).

Tim

I say on stealth secrets on the discovery channel the waves flow completely over the top with the B-2. However I doubt the Raptor bends the waves this much since it uses deflection and bending.

Thanks ghost and kilcoo.

Re bending radar waves. I can visualise that if a radar wave hits the upper surface of a B2 it could be bent to have a similar effect to deflection(?) -see top image below. But if it hits the upper surface at a steep angle, can it really be bent around the B2?

Originally posted by planeman
Thanks ghost and kilcoo.

Re bending radar waves. I can visualise that if a radar wave hits the upper surface of a B2 it could be bent to have a similar effect to deflection(?) -see top image below. But if it hits the upper surface at a steep angle, can it really be bent around the B2?

no i mean head on with the front at a 180 base angle. Not the top.

Originally posted by planeman
can it really be bent around the B2?

Yes, but within limits! While a radar beam can be bent quite a bit, it's not unlimited. Under certine rare conditions, what you end up with is deflective scattering similar to what the F-117 does. It's rare, but it can happen.

Tim

As with everything in this world, Stealth Technology has drawbacks to it. Achieveing stealth is a trade off in design that is about striking a balance of Pro's and Con's. We all know what the Pro's of stealth are, now let's look at a few of the con's:

1. Stealth Teachnolgy is High Maintance- Yes new designs such as the F-22 Raptor and F-35 are getting better in this area, but they still require more maintance then their Non-stealth counterpart. ALL stealth aircraft need regular LO maintance. This consists of detailed inspections of the aircafts skin to look for and repaire dents, scratches and chips in the paint. While these things are not as huge of an issue as they were on the first F-117's, they are still very importante.

2. Stealth Adds weight to the aircraft- As before new designs and materials are helping, but this problem still faces today's engineers and scientists.

3. Stealth cuts Payload- To make stealth work everything need to be carried in internal bays. The need to carry everything inside means that the plane carries less paylode than a non-stealth combat aircraft of the same size and weight.

4. Steath complicates Battle management- Stealth doesn't discriminate between radar systems. Planes like the B-2 and F-117 make air traffic control more difficult for AWACS and Friendly Battle management systems as well as enemies, as they slip in and out of areas undetected.

Tim

[edit on 23-5-2006 by ghost]

i think theyve got more cons than pros

if you want a stealth aircraft, you want it to be completely undetectable . . . . if a plane is partailly stealth , its crap.

I dont want to be rude but . .you can have a plane completely soaked with RAM and have a RCS of a golfball . . but if the enemy can detect your, then its a complete waste . . . .

take the f117s . . the iraqis were able to detect them . . ( chinese radar . . they had was detecting the f117s but they were unable to transfer that info to other radar systems they had) (* cant expect much from iraqis . . ) . . . but the thing is that . . night hawk . . . (f117) . . could not do the thing it was made for . . it just becomes a ground attack aircraft with a very small RCS . . . .


you c what i mean . . . im sure the B2 too can be detected . . . we just dont have a scenario where its pitched against decent opposition

[edit on 25-6-2006 by srsairbags]

Originally posted by srsairbags
i think theyve got more cons than pros

if you want a stealth aircraft, you want it to be completely undetectable . . . . if a plane is partailly stealth , its crap.

I dont want to be rude but . .you can have a plane completely soaked with RAM and have a RCS of a golfball . . but if the enemy can detect your, then its a complete waste . . . .

you c what i mean . . . im sure the B2 too can be detected . . . we just dont have a scenario where its pitched against decent opposition

[edit on 25-6-2006 by srsairbags]

Well, actually it is not a complete waste! SAM's have what is called a minmum engagement range. This prevent the missile from destroying the launch site when it detonates. Also, the echo is much too weak for the missile to track. By the time the aircraft is visible, it's inside the minimum engagement zone.

Imagin of you were standing in the fog with a grenade. You know that someone with a gun is trying to kill you. However you can't see the person until they are 1 foot away form you. At this point, you are as good as dead! If you don't use the grenade, the person will shoot you. However, if you use a grenade so close to you, the explosion of your grenade will kill you. Either way you are dead!

You see how it works?

It similar to how camoflage works! A soldiure in camoflage isn't invisible, but by the time you are close enough to see him, he's already had plenty of time to shoot you! The idea is to attack before you can be seen!

Tim

[edit on 26-6-2006 by ghost]

well . .you never know to what degree . . .the plane is stealth . . .it may be stealth (completely invisible) to one type of radars and air defences . . and then again . . be very less stealth for another type of radar . . . you cant test your hardware against each and every air defence that the enemy has . . .now . . can you . . ? ? ?

the f117 were picked up by the chinese nanchang radar and by some australian low level turbulance detector . . who knows . . . what else may be sucessful in detecting it . .

awesome post dude . . . cleard up lotsa things . . .