In article ,
(phil hunt) wrote:

On Wed, 17 Sep 2003 21:26:04 GMT, Chad Irby wrote:

Unless there's some exteme qualifiers, you have to assume it's a fairly
general average. With even moderately ambitious stealth, you can get a
good reduction in cross section across the board (even a 10% reduction
gives you several extra miles of "shoot first" at long ranges).

To be precise, 1 mile at 40 miles range.

What sort of formula are you using for this? I don't consider 40 miles
"long" when we're looking at airborne missiles with ranges of over 100
miles. 40 miles is "medium." At 100 miles that's still a couple of
miles of extra time before acquiring, and you're probably really looking
at closer to ten miles at long range.

Consider the old-tech F-117. They fly it through some of the most
heavily-defended airspaces, *ever*,

Oh? Did Serbia and Iraq have modern AA systems? I think not.

The phrase you're looking for is "golden BB." But with the number of
missiles around Baghdad in GWI and II, it easily qualifies. And since
you're claiming that stealth isn't that important, we should have lost
them on a regular basis. We didn't.

How detectable is the F-117 (and F-22) using visual or IR sensors?

With pure visual, planes are pretty hard to find at anything like a safe
distance. If you're in a plane, you're not going to be using image
magnification to find the other guy, unless you know right where he's
coming from in the first place. Even with that, you have camouflage for
the human optical frequencies, and pure IR is not very useful for very
long ranges.

A quick BOTE calculation suggests that with clear air conditions, a
F-22 would in principle be detectable at 100 km with the sort of
digital equipment you can buy in a high street shop (a 10 m wide
object would produce an image 10 pixels across, assuming a 1000 mm
lens and a focal plane with 100 pixels/mm) though I'm sure in real
life conditions wouldn't be good enough to spot it in daylight.
Spotting the exhaust at night might be easier, especially for IR
sensors.

"Detecting" versus "acquiring and identifying," I'm afraid. Narrowing
down the field of view enough to make visual ID makes for a lot less
coverage per sweep. If you know where the target is, it gets fairly
easy, but you have to look in the right direction first, and hope
there's no clouds or haze in the way.

And if you can manage to "detect" a 10 pixel object, you still have to
figure out what the heck it is. I just took a photo of an F-22 (from
below, against a high-contrast light background - pretty much the ideal
ID angle) and shrank it to a 10 by 10 image. It looks like someone
squashed a very tiny bug. You can't even tell that it's an aircraft,
much less what sort of plane it is. With lower-contrast photos, it's
just one 10 x 10 pixel gray blob.

--


Remember: Objects in rearview mirror may be hallucinations.
Slam on brakes accordingly.