In article ,
(phil hunt) wrote:

On Thu, 18 Sep 2003 04:24:06 GMT, Chad Irby wrote:
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?

acquisition_range = k * rcs^0.25

So for every 1% you increase the RCS, you increase acquisition range
by 0.25%

Okay, I'll go with this. Sounds like a good bottom range.

At 100 miles that's still a couple of miles of extra time before
acquiring,

2.5 miles

Okay, a couple and a half. Noting, of course, that the F-22 has an RCS
in the 0.01 meter^2 range over most aspects...

The phrase you're looking for is "golden BB."

Never heard of it.

It's what a civilian would call a "lucky shot."

But with the number of
missiles around Baghdad in GWI and II, it easily qualifies.

Don't understand you.

Lots of missiles and radar = "heavily defended."

And since you're claiming that stealth isn't that important,

I don't recall ever making that claim -- perhaps you could vremind
me where I did.

By trying to show that it's not that effective, and imagining odd ways
of detecting a plane with non-radar techniques that won't work.

With pure visual, planes are pretty hard to find at anything like a safe
distance.

What do you mean by "safe distance"?

Far enough away so they won't kill you.

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.

I more had in mind an observer on the ground.

"Hey, a plane just flew over!"

"Great, where is it?"

"Uhhh... it went west..."

and pure IR is not very useful for very long ranges.

Why not? Is is more or less useful than visual? Does it make a
difference whether it is day or night? And what do you mean by "lonh
ranges"?

See the comment I made about long range above. Call it 100 miles, like
I mentioned earlier in the post. IR isn't good in atmosphere without a
*big* detector, for long ranges, for the same reasons as visual sighting.

I don't think so. Once something hase been detected, finding its
exact position should be relatively easy.

Exactly. But you have problems with detecting first, then with
identifying the target without having to resort to radiating or active
measures.

If we are using visual sensors, we could have several point towards
it and use parallax to get the exact position.

Each of which would then have to find the very tiny object. That's
covered below.

(Here I'm only considering using passive sensors in an air defence
system, since they are immune to anti-radar missiles and anti-radar
stealth. (Obviously they are not immune to making the aircraft
smaller, but there are practical constraints to doing that).)

You also lose them for 1/2 of the day (pure optical sensors are not too
good at night), on cloudy days, if there's smoke in the way, if the
sun's behind the target... and you need a *lot* of them. With the
curvature of the Earth in the equation, you're going to need a linked
ground observer station every 20 miles or so - at *best*.

Once the position is got, the defenses can fire a missile to
intercept, using ground-controlled mid-course guidance, and active
radar (or IR) terminal homing.

All of which are vulnerable to spoofing or jamming. Oops.

Identifying is fairly easy. Either use IFF or the known positions of
friendly aircraft to know whether it's hostile. If you know it's
hostile, use the size of sensor returns to guess more or less what
it is (cruise missile/ small fighter/ big fighter/ AEW), though the
precise nature isn't very important, since in all cases the response
would be the same.

So the other guys pop up a plane or two and get you to actively ID them,
or you target them with a long-range radar (that doesn't work because
they're too stealthy), because some guy saw something the couldn't
really identify... and then they kill you between reloads, because the
other "Wild Weasel" plane is at 50,000 feet, above the clouds, unseen by
your ground observers, watching where the missiles came from. Later
that night, they kill your launchers.

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.

Yes.

....and *that's* why people don't use visual acquisition and targeting.
A system with a useful "uptime" of a couple of hours a day is a loser in
so many respects...

And if you can manage to "detect" a 10 pixel object, you still have to
figure out what the heck it is.

Why? You only have to detect whether it's hostile or not.

And you don't even know what it is...

All the enemy has to do is toss up a few low-end decoys, and you spend a
half hour picking out the one that will kill you. If he wants you
crippled, he drops a few incendiaries on the surrounding terrain, and
you're blind for hours.

They used to have civilian ground observers in WWII, you know. They
stopped using them because it really doesn't work that well.

--


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