By Marshall Brain
On March 11, 2003, the USAF tested one of the largest conventional bombs ever built. It is called the MOAB -- Massive Ordnance Air Burst. It is a bomb designed to destroy heavily reinforced targets or to smash ground forces and armor across a large area.
The MOAB is currently the largest conventional (as opposed to nuclear) bomb in the U.S. arsenal. It weighs 21,000 pounds, is 30 feet long and 40.5 inches in diameter. The MOAB is a satellite-guided, very large "smart bomb," that explodes about 6 feet above the ground.
The idea behind an "air burst" weapon, as opposed to one that explodes on contact with the ground, is to increase its destructive range. A bomb that penetrates the earth, then bursts, tends to send all of its force either down into the ground or straight up into the air; air burst weapons propel a great deal of energy sideways.
The MOAB replaces the BLU-82 (aka the "Daisy Cutter"), a 15,000-pound air-burst bomb developed during the Vietnam conflict. The Air Force could clear out trees in a 500-foot-diameter circle by dropping a Daisy Cutter -- creating an instant helicopter landing site.
Rather than launching from a bomber through bomb bay doors, the MOAB is pushed out of the back of a cargo plane like a C-130. It rides on a pallet that is pulled out of the plane by parachute; after launch, the pallet separates from the MOAB so that the bomb can fall. It uses a GPS-based guidance system to direct the payload to its target.
The MOAB contains approximately 18,000 pounds of tritonal - a mixture of 80%TNT and 20% aluminum powder. The aluminum improves the brisance - the speed at which the explosive develops maximum pressure -- of the TNT. The addition of aluminum makes tritonal about 18% more powerful than TNT alone.
