The San Diego Union-Tribune March 21, 2003
Precision JDAMs can pack big punch; On-board systems guide air-to-surface weapons
By Mark Sauer
Among the differences between this military action against Iraq and the one 12 years ago is that U.S. bombs have gotten a lot smarter.
Despite Pentagon claims at the time and footage showing precise hits on buildings and bridges, only 7 percent of the bombs used in Desert Storm were considered "precision-guided munitions," the Air Force recently reported.
But "precision is certainly the name of the game now," said Rob Hewson, London-based editor of the publication Jane's Air-Launched Weapons. "Nobody goes dumb-bombing anymore."
What the military has done with air-to-surface weapons is to teach old bombs new tricks.
The bulk of what U.S. planes will drop on Iraq are Vietnam War-vintage, free-fall bombs fitted with a guidance system and tail kit called JDAM, for Joint Direct Attack Munition.
"The JDAM family of bombs -- from 500 to 2,000 pounds, which the Air Force and Navy will rely on for the lion's share of the work -- are all guided now by global-positioning satellites," said Hewson.
"They can be launched from bombers and fighters 15 miles from the target in any kind of weather and are accurate to within a few meters."
Tens of thousands of bombs have been fitted with JDAM kits, which cost about $21,000 apiece.
That's cheap compared with the $600,000, Tomahawk missile, used in the Wednesday night attack, or a $317,000 HARM (high-speed, anti-radiation) missile, though both weapons can travel much farther than JDAMs.
Designed to strike relatively small targets, JDAM bombs are still capable of enormous destruction to "fixed targets" and humans alike.
The government concedes that civilian casualties are inevitable, despite the precision of new weapon systems.
A software program, called "Bug Splat," was developed in an attempt to quantify what happens. Pentagon officials decline to discuss what it has learned about the specific impact of its common bombs.
But in interviews with Newhouse News Service, engineers and weapons designers recently described what happens when the 2,000-pound Mark-84 JDAM, for example, strikes.
Dropped from a plane and hurtling toward its target at 300 mph, the 14-foot steel bomb uses small gears in its fins to pinpoint its path based on satellite data received by a small antenna and fed into a computer.
Just before impact, a fusing device triggers a chemical reaction causing the 14-inch-wide weapon to swell to twice its size. The steel casing shatters, shooting forth 1,000 pounds of white-hot fragments traveling at speeds of 6,000 feet per second.
The explosion creates a shock wave exerting thousands of pounds of pressure per square inch. By comparison, a shock wave of 12 psi will knock a person down; and the injury threshold is 15 pounds psi.
The pressure from the explosion of a device such as the Mark-84 JDAM can rupture lungs, burst sinus cavities and tear off limbs hundreds of feet from the blast site, according to trauma physicians.
When it hits, the JDAM generates an 8,500-degree fireball, gouges a 20-foot crater as it displaces 10,000 pounds of dirt and rock and generates enough wind to knock down walls blocks away and hurl metal fragments a mile or more.
"There is a very great concussive effect. Damage to any human beings in the vicinity would be pretty nasty," said Rob Hewson of Jane's. "A 2,000-pound bomb has an effective damage radius of at least 800 meters (about 2,600 feet)."
Because of guidance systems that are far more sophisticated than in the 1991 Persian Gulf War, Hewson said, far fewer bombs will be dropped and far more targets hit this time around.
"The whole 'shock and awe' tactic depends on hitting multiple targets swiftly and with great precision," he said.
GRAPHIC: 2 PICS | 1 GRAPHIC; 2. Vincent Laforet / The New York Times 3. SOURCES: U.S. Marine Corps; U.S. Army; GlobalSecurity.org; Program Executive Office Strike Weapons and Unmanned Aviation; Jane's Information Group; Union-Tribune wire services | DAVID HARDMAN / Union-Tribune; 1. SPECIAL DELIVERY -- The Navy's F/A-18 Super Hornet, flown by Navy and Marine Corps aviators, is an attack aircraft as well as a fighter. It oerates from aircraft carriers and can put missiles and smart bombs on target in any weather. 2. A member of the ordnance team aboard the aircraft carrier Abraham Lincoln loaded an MK-84 JDAM bomb onto the wing of an F-14 Tomcat yesterday as deck crews prepared attack jets for Operation Iraqi Freedom. 3. 'Smarter' weapons -- The Joint Direct Attack Munition (JDAM) is a guidance kit that converts gerneral purpose, free-fall bombs into guided "smart" weapons capable of accurate strikes in bad weather. The bombs are guided by movable tail fins controlled by an inertial navigation system (INS) aided by a global positioning system (GPS).
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