Small Diameter Bomb

The GBU-39 Small Diameter Bomb (SDB) is a 250 lb (110 kg) precision-guided glide bomb that is intended to provide aircraft with the ability to carry a higher number of more accurate bombs. Most US Air Force aircraft will be able to carry (using the BRU-61/A rack) a pack of four SDBs in place of a single 2,000 lb (907 kg) bomb.

The Small Diameter Bomb II (SDB-II) / GBU-53/B, scheduled to enter production in January 2014, will add a tri-mode seeker (radar, infrared homing, and semiactive laser guidance) to the INS and GPS guidance of the original SDB.

Description

The original SDB is equipped with a GPS-aided inertial navigation system to attack fixed/stationary targets such as fuel depots, bunkers etc. The second variant (Raytheon's GBU-53 SDB II) will include a thermal seeker and radar with automatic target recognition features for striking mobile targets such as tanks, vehicles, and mobile command posts.

The small size of the bomb allows a single strike aircraft to carry more of the munitions than is possible utilizing currently available bomb units. The SDB carries approximately 38 lb (17 kg) of AFX-757 high explosive. It also has integrated "DiamondBack" type wings which deploy after release, increasing the glide time and therefore the maximum range. Its size and accuracy allow for an effective munition with less collateral damage. Warhead penetration is 3 feet (0.91 m) of steel reinforced concrete and the fuze has Electronic safe and fire (ESAF) cockpit selectable functions, including air burst and delayed options.

GBU

GBU may refer to:

GBU-28

The Guided Bomb Unit 28 (GBU-28) is a 5,000-pound (2,268 kg) laser-guided "bunker busting" bomb nicknamed "Deep Throat" (and unofficially nicknamed "The Saddamizer" by a design team worker, alluding to its initial purpose of bombing a bunker believed to be then-occupied by Saddam Hussein during Operation Desert Storm) produced originally by the Watervliet Arsenal, Watervliet, New York. It was designed, manufactured, and deployed in less than three weeks due to an urgent need during Operation Desert Storm to penetrate hardened Iraqi command centers located deep underground. Only two of the weapons were dropped in Desert Storm, both by F-111Fs.

The Enhanced GBU-28 augments the laser-guidance with Inertial navigation and GPS guidance systems.

Design and development

In August 1990, the U.S. military began planning an air offensive campaign against Iraq. Planners noticed that a few command and control bunkers in Baghdad were located deep underground to withstand heavy fire. Doubts were raised about the ability of the BLU-109/B to penetrate such fortified structures, so the USAF Air Armament Division at Eglin AFB, Florida was asked to create a weapon that could, and engineer Al Weimorts sketched improved BLU-109 variants. By January 1991, as the Persian Gulf War was well underway, it was determined that the BLU-109/B-equipped laser-guided bombs (LGB) would be unable to penetrate fortified bunkers deep underground.

Joint Direct Attack Munition

The Joint Direct Attack Munition (JDAM) is a guidance kit that converts unguided bombs, or "dumb bombs" into all-weather "smart" munitions. JDAM-equipped bombs are guided by an integrated inertial guidance system coupled to a Global Positioning System (GPS) receiver, giving them a published range of up to 15 nautical miles (28 km). JDAM-equipped bombs range from 500 pounds (227 kg) to 2,000 pounds (907 kg). When installed on a bomb, the JDAM kit is given a GBU (Guided Bomb Unit) nomenclature, superseding the Mark 80 or BLU (Bomb, Live Unit) nomenclature of the bomb to which it is attached.

The JDAM is not a stand-alone weapon; rather it is a "bolt-on" guidance package that converts unguided gravity bombs into Precision-Guided Munitions, or PGMs. The key components of the system consist of a tail section with aerodynamic control surfaces, a (body) strake kit, and a combined inertial guidance system and GPS guidance control unit.

The JDAM was meant to improve upon laser-guided bomb and imaging infrared technology, which can be hindered by bad ground and weather conditions. Laser seekers are now being fitted to some JDAMs.