Reduced RCS question

I guess one of the big issues in stealth is, what exactly constitutes a "reduced RCS"? Reduced from what? I mean a Boeing 747 has a RCS 3 times smaller than a 2-ton Parcel truck, does that mean that it's RCS is "reduced"?

(by the way, I'm not really sure where to post this. I posted it here because when you think of RCS you normally think of airplanes, but the question really came about from a discussion of stealth ships mainly located here, but in other threads too.)

I believe the comparisons made are to what a similar radar return would be recieved from a metallic sphere.


Currently, the talk is of marble sized cross sectional area.

This is my personal take on it but I would say that a 'reduced' RCS would be one where measures had been taken to lower it specifically from a previous level. For instance the F-18E models have a reduced RCS by comparison with earlier models, the Typhoon has a reduced RCS because sp0ecific measures were incorporated into the design to lower it.

To use your own analogy, the 747 wouldn't have a 'reduced' RCS because it was 3 times less than the truck it would just be a 'lower RCS' to begin with, but if measures were taken to make the trucks RCS the same as the 747's, that would constitute a reduced RCS.

Reduced RCS is based on comparative value! Usually objects of the same size have a roughly simular Radar Cross Section. When an object produces a radar return Significantly lower than one would expect for an object of that size, it has reduced RCS. The Stealth aircraft are a more dramatic example of this:

Overall a B-52 and a B-2 are of a comparable size (The B-2 is smaller, but not drastically). Hense, you would expect the two bombers to have a comparable RCS based on size. However, while the B-52's RCS is about 1000 Square Meters, the B-2 has an RCS of LESS then 0.001 Square meters.

Given the simular size, you wouldn't expect the B-2 to be so much smaller on Radar (Except for the fact that the B-2 is a Stealth Bomber! )

Hope that helps!

Tim

[edit on 5/13/2007 by Ghost01]

What about sonar? I hear that, as far as ships go, they are attempting to reduce the sonar signature, is that the same?

Originally posted by SwitchbladeNGC
What about sonar? I hear that, as far as ships go, they are attempting to reduce the sonar signature, is that the same?

It's very similar in concept. Remember that both light and sound travel in waves, therefore they behave in similar ways. The principle difference is that Radar is electromagnetic in nature while sound isn't. This means that Radar is affected by a magnetic field, while sonar is not. Sound can be absorbed by rubber and other ordinary materials. Radar, being electromagnetic is a bit harder to absorb and dissipate.

However, the shaping concepts are similar in many ways.

Tim

Originally posted by kilcoo316
I believe the comparisons made are to what a similar radar return would be recieved from a metallic sphere.


Currently, the talk is of marble sized cross sectional area.

This sounds very logical in my ears because a sphere has an infinite ammount of points to return the radarwave back to the radar. Therefore it doesn't matter in which angle your radarwave hits the sphere, it will always be returned.