Guided bomb

From Citizendium, the Citizens' Compendium

The first type of precision-guided munition used in warfare, a guided bomb is an air-dropped bomb that adjusts its path to a target using aerodynamic control surfaces. Such bombs may be under human control or have autonomous guidance.

Contents 1 History 2 Evolution 3 Current versions 3.1 Joint Direct Action Munition 3.2 Joint Standoff Weapon 4 Future developments 5 References

History

During the Vietnam War, the Paul Doumer Bridge was a critical and heavily-defended target, which had withstood hundreds of sorties with conventional bombs dropped by skilled crews, but had never out of service for more than two months.

Rockwell International developed the GBU-8 laser-guided bomb in 1967, but such weapons were not used against the Doumer Bridge until 1972. In comparison to the hundreds of aircraft sorties needed to deliver light damage, 16 F-4 Phantom II fighter-bombers struck the bridge in May 1972, using 2000 pound GBU-10 LGBs. This relatively small attack put the bridge, which carried four of the five railroad lines between North Vietnam and China, out of service for seven months.^[1]

Evolution

Upgraded versions of the GBU-10 Paveway bomb are still in service, although no longer the primary U.S. guided bomb. A laser-guided bomb can be extremely accurate, but requires good weather for visual observation, and a laser designator must be held on the target for the duration of the bomb's flight. While airborne designators have been developed that can continue to track the target, without human assistance, when dropped, the aircraft still has to remain in sight of the target and any of its air defenses. Laser designators and laser rangefinders, which use an invisible infrared beam, have been developed and are used by soldiers on the ground to control air support.

Current versions

GBU-24 Paveway III LGBs remain in service, but other all-weather weapons, although without a capability to hit moving targets, are the primary guided bombs in service with the U.S. and many other nations who have bought the weapons.

Joint Direct Action Munition

In U.S. inventory, the primary guided bomb is the Joint Direct Action Munition (JDAM), whose basic Go-onto-location-in-space guidance is inertial, with the drop and target coordinates set by the aircraft just before drop. Newer versions use supplemental GPS guidance.

While troops on the ground cannot directly control a JDAM, they can use a GPS-equipped laser rangefinder to take a precise sighting on the target and radio the data to the bomber. Still, the JDAM can be used only against fixed target; LGBs are still useful against moving targets when powered guided missiles are not appropriate.

The higher and faster that a basic guided bomb can be dropped, the farther the dropping aircraft can be from the target -- and safer from its defenses. This is one of the reasons that the attack version of the F-22 Raptor can drop from at least 50,000 feet and at supersonic speed, which gives it a much greater JDAM range than a current fighter-bomber or heavy bomber.

Joint Standoff Weapon

Even more range comes with the AGM-154 Joint Standoff Weapon (JSOW), known informally as the "flying pig". Where a JDAM is actually a guidance kit that bolts control fins to the tail of a conventional bomb, a JSOW deploys wings when launched, and can glide much farther than a JDAM.

The JSOW is used by the Air Force and Navy, but is a Navy program. ^[2]

Future developments

Go-Onto-Target guidance modes are in development to give guided bombs a capability against moving targets.

References