Originally posted by kilcoo316
That was what... 25 years ago? No doubt improvements to the concept exist.

You don't think ram has improved enough in 25 years from the time of the F-117 to allow it to be under 7cm thick? Also who's saying the entire coating has to be 7cm?

Awesome discussion guys and gals this is when I try to learn a bit and ask half educated questions.

Originally posted by C0bzz

Is it really that inconceivable for 7cm thick foam to be mounted to the outside of a subsonic, medium payload bomber?

I must agree C0bzz as I wasn't even aware till you posted that we where talking about subsonic speeds.

[edit on 26-11-2008 by Canada_EH]

I really don't know how much can be said about stuff without a bunch of retro research, but think about this little story from back in the 80s or 90s:

B-52s practicing runway approaches at a military base sometimes lined up on a local commercial runway by accident. The tower operators at that runway had to be informed in advance, and had to watch constantly for an occasional B-52 trying to land on their runway by accident. Why? Because the B-52s do not show up on commercial airport radar. Makes that transponder rather important, but the tower operators relied on binoculars. Think about it.

The DARPA project will probably try and make some progress in aural and visual stealth. It is hard to hide from listening devices, and anyone can build one that will "find" an aircraft's vector at fairly great range (20-30 miles). Two or more listening devices and you have the range. Time to launch.

Stealth is great at night, but how do you hide in the daylight? Eyeballs and Binoculars can find an aircraft in clear skies. Again, time to launch. It's hard to hide even a stealth aircraft when you put an surface-to-air missile right there in the same spot in the sky. The closer it gets, the better the seeker works.

Also, one reason stealth aircraft are mostly sub-sonic, is to keep the infra-red signature down to a minimum. Supersonic gets hot, and modern seekers don't have to find that hot engine, they can target the mid fuselage of an aircraft regardless of whether it's hot or not. Hot just makes it worse.

In case you are wondering, what a surface-to-air missile isn't very good at is a head-on shot, from the front. Usually it's an "oops, I missed", and detonates. The warhead is designed to fire up and out like a shotgun, in hopes of getting something into the air intake, mostly, to ruin an engine.

Laterz

Originally posted by C0bzz
Is it really that inconceivable for 7cm thick foam to be mounted to the outside of a subsonic, medium payload bomber?

Yeap.

Besides - the material needs to contain conducting materials... i.e. metallics - if it doesn't it won't interfere with the electromagnetic (radar) waves.



There is a difference between radar absorbent, and radar transparent material.

Originally posted by Canada_EH
You don't think ram has improved enough in 25 years from the time of the F-117 to allow it to be under 7cm thick?

See:

Me
But the trick is then getting the wavelength into the skin, and not bouncing off it - back to that RAM depth problem.

That was what... 25 years ago? No doubt improvements to the concept exist.

Originally posted by Canada_EH
Also who's saying the entire coating has to be 7cm?

See:

ZPE StarPilot
And for anyone that thinks that things like 7cm of RAM absorbent material is impractical, I say nonsense. It's been done long ago, you just don't know about it.

Sorry for any confusion caused.

Ok, we're missing the big picture here. It's a combination of shapes, Radar Absorbent Materials, and absorbent/reflective paints. Plus other materials for other purposes. And various trick combinations of all of the above for special purposes. This is just the passive systems. Even the fit, finish, and assembly of parts is critical. The active systems don't get discussed much. The paint alone will do most of the job. It's not cheap, and it's hard to put on and repair later. It's not very thick. Where it won't work well enough, the other methods are used, by design. Not added on after, like paint on a B-52.

did you know that one of the bigger reflections on a car, when hit by police radar, is from the driver's face? The radiator, of course, is a big reflector as well. At least that's what I've read. I've never confirmed that one.

Originally posted by C0bzz
Is it possible to make foam conductive?

Well, you could simply run copper lines through the foam to make it carry current.

The B-2 is supposed to use a copper mesh on its skin. But it is a slightly different approach to absorbing radar in comparison to iron ball paint.


In it:

EM energy => Electrical energy => Heat

I reply to the OP, since I only read the first post.

Intelgurl, I highly respect you and your posts are always interesting, but I read an information (can't remember where), that DARPA is currently financing only projects that can somehow help soldiers in Iraq and Afghanistan. Is this information false, or I just can't see how such all aspect stealth project could help soldiers in those deserts (in pretty short time, since the wars won't last for decades).....


greets