Army has high expectations for smart artillery rounds.

• Author: Erwin, Sandra I.

Past unsuccessful attempts to field precision-guided munitions have serves as hard lessons to U.S. Army developers, who are now trying re bring to fruition a new generation of smart weapons.

Among the new weapons expected to enter service in 2008 is the Excalibur, a satellite-guided artillery round that was drastically redesigned after several test failures. To fix Excalibur, the Army joined forces with Sweden, which already, had developed a successful smart projectile. The U.S. contractor Raytheon and the Swedish firm Borers merged their designs, resulting in the current XM982 Excalibur.

Excalibur made headlines two years ago when the Defense Department cancelled the high-tech Crusader 155 mm howitzer, intended to replace the aging Paladin. At the time, Pentagon officials said advanced munitions such as Excalibur were more important than the guns themselves.

"The accuracy touted for Crusader really comes from Excalibur and not from Crusader," Deputy Defense Secretary Paul Wolfowitz told reporters in 2002. Many artillery experts disagree, however, claiming that no matter how precise a round might be, artillery units need a fast vehicle that can keep up with the tanks and infantry carriers. A source of continuing debate within the Army is whether artillery should serve in a "precision strike" role, as opposed to its traditional "area suppression" function, for which pinpoint accuracy is not as important.

In the absence of Crusader, the Army will fire Excalibur from a towed 155 mm howitzer now in development for the Army and the Marine Corps. The Paladin--with 1970s technology--may be too costly to upgrade for precision-guided rounds.

The Excalibur always was viewed as a complex technology, because its sensitive electronics must survive a gun launch 15,000 times the force of gravity and guide the projectile to a designated target with a 10-20 meter accuracy from ranges of about 40-43 Kilometers. By comparison, me accuracy of conventional artillery shells is about 270 meters.

The original design ran into trouble because the fins could not deploy properly, making the round instable in flight. The Army then asked Raytheon to change the weapon by incorporating the body and fin design of the Swedish "trajectory correctable munition."

The revamped Excalibur, to be purchased both by the U.S. and Swedish armies, has been flying in tests.

"It appears to be working. The body is stable in flight." said Franklin Y. Hartline, Raytheon business development...