"Harry Andreas" wrote in message
...
In article , "Kevin Brooks"
wrote:


Eh? The E-8 is operating at that range--you think that the range error
of
the E-8's ISAR itself increases significantly through the depth of its
coverage? The platform doing the weapons release would have to be about
on
top of the target. This configuration, using AMSTE, was credited with a
successful strike in its first test drop, from what I have read.

What weapon was used? A 2000lb bomb with it's large blast radius is easy
to use to claim a kill. Doing the same thing with the 500 lb version is
much
more difficult and requires higher accuracy and better systems.
See the point? The reason for developing AMSTE and other systems of the
type is to use smaller weapons so more can be carried, or the a/c has
longer
range. That requires the development of high accuracy GPS, INS, and
targeting systems.

I'd think a three meter miss would likely be good enough for the 500 pound
variant; an inert 2000 pounder achieved that level of accuracy in a test
with a single E-8 providing the targeting fix:

"In the July 24 test, an Air Force E-8C Joint Surveillance Target Attack
Radar System (Joint STARS) provided target data to an F-16 equipped with an
inert, 2,000-pound, seeker-less, data link-equipped JDAM. The F-16, flying
at 20,000 feet, released the weapon nearly six miles away from the target.
Joint STARS directed the JDAM to a point where it engaged the truck, which
was traveling at 23 mph, shortly after the truck passed another vehicle at
an intersection. The weapon struck within three meters of the target, well
inside the lethal zone of a live JDAM."
www.capitol.northgrum.com/press_releases/ ngpress081203.html

Using two separate SAR inputs (one from an E-8 operating some one hundred
klicks away, the other from a JSF radar mounted on a test airframe some
thirty-five klicks distant), a 2000 pound live munition acheived a direct
hit on a moving M60 MBT target in a cluttered environment:

www.spacedaily.com/news/gps-03zzh.html

Av leak indicates that the reason for using the two radars is not related to
ranging problems:

"The reason Amste uses two radars is that Ground Moving Target Indication
Radars produce very accurate range estimates, but less precise estimates in
azimuth. By overlaying two simultaneous radar observations, a process called
bi-lateration, accuracy of azimuth is improved."
www.aviationnow.com/content/publication/ awst/20021202/avi_stor.htm

And I disagree with you as to why AMSTE was developed. While it will allow
the use of smaller weapons, it mainly was developed to give JDAM a
capability against moving targets, which the vanilla JDAM does not really
have.

It's like deer hunting. If you're a really expert shot you can use a .223
and
take head or spine shots. If you're not so good you use a cannon and try
to hit him wherever you can. (not good sportsmanship though)

No, in this case the program is designed to give you an assurance of hitting
and killing a running deer--while the vanilla approach is more like having
your rifle set in a fixed mount which is fine for killing Bambi while she is
motionless but not-so-fine for killing her while she meanders around or
bounds for cover.


Of interest
would be how much the E-8 "sees"--can it also pick up the aircraft
dropping
the munition (regular JDAM in this case)(as I believe the follow-on E-10
will be able to do)? If so, then it would appear to offer the dropping
aircraft the same accuracy enhancement that its own SAR would
afford--the
E-8 would have the target and the delivery platform in the same frame of
reference, so any ranging error would be largely negated?


Seeing something is not good enough for targeting.
Resolution matters, and resolution is linear with distance.

Seems to have worked OK during that E-8 only test. I believe that Av leak
source indicates the resuloution on the E-8 as is is some 12 feet, and the
folks at Northrup have supposedly tweaked it a bit via the software to have
an even lower resolution.

Brooks


There are a lot of variables to consider, and frankly, due to my job,
I'm not comfortable running through the whole thing in an open forum.

--
Harry Andreas
Engineering raconteur