Ground War Puts Some Exotic New Weapons Systems to Test : Technology: From copters to compasses, the performance of controversial high-tech arms is being closely watched.

WASHINGTON —  While the air war showcased the awesome capabilities of modern missiles and warplanes, the ground campaign represents an even tougher challenge to America’s massive defense investment, testing exotic new weapons that will more directly determine how many U.S. soldiers live and how many die in the Persian Gulf War.

Initial reports indicate that the opening phase of the ground war is going far better than U.S. commanders might have hoped and that at least some American weapons systems are functioning with devastating effectiveness.

But it also appears that the Iraqi army--so far, at least--is not putting up the massive defense that had been feared, and allied commanders remain well aware that ground combat could still produce serious casualties.

As a result, much may yet depend on the performance of ground weapons systems that have never faced the test of full-scale combat and--in some cases--were the subjects of substantial controversy during their development. For one thing, experts say the U.S. ground arsenal has serious deficiencies in terms of its ability to counter threats from Iraqi tanks at short and medium range.

There were no reports of major problems with these weapons in the early hours of ground fighting, and only scattered problems in the practice assaults and artillery exchanges that preceded the ground war. Many troops went into battle saying they had absolute confidence in their new high-tech weapons.

Leading the way were the deadly--and controversial--AH-64 Apache attack helicopters. Early footage from the Apaches’ night-vision gun sights showed ghostly scenes of Iraqi infantrymen fleeing their bunkers and being cut down by fire from an adversary they could not even see.

Thus, they seemed to bear out the assessment last week of Maj. Lee Stuart, executive officer of an attack battalion for a paratrooper division: “The Apaches rule the night.”

The new ground weapons waiting to prove their worthiness in battle range from 62-ton tanks to a two-pound, high-tech compass that gets its readings from satellites rather than magnetic poles.

Most of these weapons were designed for a more fearsome conflict that never happened--a war against Soviet forces in Europe.

“NATO realized they could never match the Soviets tank for tank, plane for plane, artillery piece for artillery piece,” says Jeff Shaffer, a military analyst with the Center for International and Strategic Studies. Unable to beat the Soviets with sheer firepower, the Western alliance put its money on speed and maneuverability.

So while allied ground weapons may not produce television pictures as breathtaking as those of Tomahawk missiles slamming through doorways and Patriot missile batteries knocking Iraqi Scud missiles out of the nighttime skies, “this will be a test of that entire strategy,” Shaffer said.

Further, many of the weapons themselves have provoked intense political battles over the past decade, with opponents insisting they are overpriced and unreliable. The ground war is not likely to put an end to the debate, but it will certainly provide the combat test that many critics have said has been lacking.

Supporters of these arms believe they will perform well enough to earn the rave reviews that helped overcome skepticism about many new air weapons in the early weeks of the war.

Chief among the new ground weapons is a $2.5-million armored behemoth: the M-1 tank, which along with its upgraded and more deadly version, the M-1A1, makes up almost half the total U.S. tank force in the Persian Gulf.

Given a flat terrain, the M-1 can speed across a battlefield at 40 m.p.h., more than twice as fast as its predecessors. Its high-tech aiming system, coupled with a state-of-the art suspension, will, for the first time, make it possible for tank gunners to hit targets without having to stop.

Before the Vietnam-era M-60 tank could fire a round, its crew had to find cover, pause for a few moments and line up the target. Even with all that preparation, the chance of a direct hit at 2,000 yards was “pretty nil,” said Ralph Hallenbeck, a defense consultant who had a quarter-century of experience in mechanized infantry. “You couldn’t see jack-diddly, especially at night, when you had no depth perception,” he said.

Today’s M-1 crew, by comparison, probably has a 90% chance of hitting an object at that distance, thanks to night-vision devices, lasers, and computers that automatically adjust for everything from wind velocity to heat, Hallenbeck said. “When you push the button and it goes bang, you’re pretty much done.”

The M-1’s frontal armor, made from a special alloy that includes depleted uranium, is expected to make it almost invulnerable to most antitank weapons, although its flanks and rear are less secure, said James F. Dunnigan, author of a book called “How to Make War.” Like all tanks, he said, it may also fall victim to mines, which can account for more than half of tank kills.

The M-1’s heavy armor also is its chief liability, because it brings the total weight of the vehicle to more than 60 tons in some versions. As a result, it can guzzle more than five gallons of fuel per mile--that’s gallons to the mile. By some estimates, one armored division equipped with M-1 tanks will consume more than 600,000 gallons in a single day, which is more than double the amount that Gen. George S. Patton Jr.’s entire 3rd Army used in World War II.

As a result, critics have noted, these tanks cannot operate without a huge supply effort, a particular problem in the barren desert.

“You have these voracious consumers of fuel out in the middle of nowhere. You’re operating in an area where you have to bring everything with you. There’s no fuel, no food, no water. It’s a logistic nightmare,” said military analyst Jeffrey Record.

Even if the supply line operates well, it will slow the tanks down; if it does not, it will leave them useless.

To deal with that problem, the Army has apparently sent supply units leapfrogging ahead to set up refueling stations that are ready and waiting when the tank columns arrive. While this might not be possible in all future situations, it has apparently been feasible in the Gulf because allied air supremacy has kept the Iraqis pinned in their bunkers, and vast areas of the desert are empty and undefended.

Working in tandem with the M-1 will be the controversial Bradley Fighting Vehicle, the Army’s most advanced armored personnel carrier. Undaunted by eight-foot trenches or three-foot-high obstacles, it plays an integral role in the modern concept of maneuver warfare.

But it shares a weakness with earlier personnel carriers: To obtain its impressive mobility while ensuring it will float during amphibious operations, its designers had to keep its armor relatively light. Also, critics say the aluminum in its undercarriage makes it particularly flammable.

While the Bradley Fighting Vehicle is probably strong enough to withstand the artillery fragments that are a major cause of ground war casualties, it could prove vulnerable to hand-held Iraqi weapons that can burn a hole through armor in microseconds, Record said. “I’m kind of pessimistic about it,” he said.

New concerns arose earlier this month after factory tests showed that up to 300 of the 2,000 Bradleys deployed in the Gulf may have a transmission problem that could limit their maximum speed to 12 miles per hour, less than a third of the speed they were designed to reach. The Army rushed to inspect all of its Bradleys and declared that it had fixed all of those with faulty transmissions.

The Apaches, though they dazzled analysts during early ground clashes in the Kuwaiti theater, got far less glowing reviews in their only other battle test to date. They drew blistering criticism for frequent breakdowns during the 1989 invasion of Panama. However, Shaffer said the helicopter proved then that it can take small-arms fire and return to base safely. “Here, we’ll see how it fares on a much higher-density battlefield,” he added.

In the early fighting, U.S. forces also were relying heavily on a weapon that represents one of their highest hopes to avoid casualties: the multiple-launch rocket system. The self-propelled MLRS can fire as many as a dozen rockets that burst in midair, raining 644 grenade-sized bomblets in a killing zone the size of four football fields. Troops call it “steel rain.”

And it can do this at a distance of more than 20 miles from its target--well out of sight and range of all but the most far-reaching Iraqi artillery. From the enemy perspective, “all of a sudden, the whole world explodes,” Hallenbeck said. “It’s incredibly lethal . . . horrendous firepower.”

Nonetheless, the 1st Infantry Division’s ear-splitting rocket attack on artillery batteries and communications centers in southern Iraq was slowed last week when one of about 30 MLRS launchers caught fire seconds after the assault began. A rocket had ignited fiberglass packing inside the launcher, melting some cables and burning the coating off the outside of the launcher before soldiers extinguished the flames.

A switch jammed on a second MLRS, delaying reloading for about an hour; and as the barrage ended, one of the last rockets went off course and appeared to fly straight up. For a few seconds, the soldiers of Bravo Company braced themselves, nervously waiting the second burst that would shower hundreds of bomblets on them. Suddenly, however, the rocket corrected its path and roared down range.

Another launch early Wednesday was delayed in part by human error--a sergeant in charge of the unit’s communications lost his way in the dark and did not return to his assigned post, which meant the unit commander could not communicate with a launcher.

“You get into an extended war and people are tired,” said the artillery officer, Col. Freddy McFarren, 47, of Cleburne, Tex. “That worries me a lot.”

At the same time, U.S. troops are likely to discover that many of the weapons they will use to thwart Iraq’s tank force have major shortcomings.

Critics say the Maverick and Hellfire missiles, tank-killers launched at their targets from aircraft and helicopters, respectively, have problems that could cause them either to miss their targets or hit “friendly” vehicles, as they did Jan. 30 in Saudi Arabia.

Both missiles are guided from distances of four to six miles, well beyond the distance at which pilots can see their targets. Because the Hellfire relies on lasers to reach its targets, there is widespread concern that its accuracy may be degraded by dust, smoke and fog--expected to be ever-present on the Persian Gulf battlefield.

The Maverick relies on heat-seeking sensors to find its target, and pilots traveling at speeds of 500 m.p.h. may have trouble using the missile’s infrared image to identify targets and distinguish them from decoys or from friendly forces.

The missiles’ performance in skirmishes Jan. 30 between Iraqi and allied ground troops dramatized the longstanding concern that these missiles could claim friendly casualties. With combat in Kuwait expected to involve enemy tanks in close combat with allied vehicles, the task of distinguishing friend from foe will become extremely difficult, said Greg Williams, an analyst at the Project on Military Procurement, a Washington watchdog group.

That problem may be complicated further by the cost of the missiles. At $74,317 apiece, the Maverick is so expensive that the A-10 pilots who will be shooting them in close-combat situations fired only one per year during training, according to one published report.

Among the Army’s most serious deficiencies are problems with the infantry’s short-range and medium-range antitank weapons. The short-range missile, called the Viper, was canceled in the early 1980s, and the Army decided not to replace it with any new weapon. The Dragon medium-range antitank weapon is widely regarded, even in the Army, as a weapon that will not destroy the Iraqis’ best tanks and will probably get its gunner killed.

“It’s very hard to fire. I can’t imagine why the Army bought it. It has grave shortcomings,” said one Army officer familiar with the system.

Carl Bernard, a consultant to the Pentagon and several weapons contractors, called the Dragon “a disgrace.” A former infantry officer, Bernard said that to guide the Dragon warhead to its target, a gunner must sit behind it in an exposed position for the duration of the weapon’s 15-second flight. During that period, the gunner becomes vulnerable to fire from tanks and antitank missiles called Saggers. Indeed, infantrymen speak with black humor of having to do the “Sagger dance.”

As gunners come under fire, the missiles they must guide to their targets also go off course.

What experts call an “ergonomic problem” forces the Dragon off course in as many as two of every five firings. The weapon is so heavy that, as the warhead leaves the launch tube, even the husky gunners that the Army trains to use them commonly “buck” the launch tube off their shoulders, sending the warhead into the ground short of its target.

The Army has a replacement for the Dragon, called Advanced Antitank Weapon System-Medium, or “Awesome,” under development. But the program has been plagued by problems, and the weapon is not expected to be in the infantry’s hands for several years.

Tumulty reported from Washington and Drogin from Saudi Arabia. Staff writer Melissa Healy, in Washington, contributed to this story.