GBU-39

GBU-39 (Small Diameter Bomb)
4 SDBs (training/ground handling variant) loaded on an F-15E Strike Eagle
Type	Bomb
Place of origin	United States
Service history
In service	2006–present
Used by	United States Israel Italy Saudi Arabia
Wars	War in Afghanistan, Iraq War, Gaza War, Military intervention against ISIL
Production history
Manufacturer	Boeing Integrated Defense Systems
Unit cost	US$40,000 (SDB) US$250,000FY2014 (SDB II)
Produced	2005–present
Number built	17,000+
Variants	GBU-39 / GBU-40
Specifications
Weight	285 lb (129 kg)
Length	70.8 in (1.80 m)
Width	7.5 in (190 mm)
Warhead	AFX-757 Dense Inert Metal Explosive SDB: penetrating blast fragmentation SDB FLM: blast ultra low fragmentation
Warhead weight	206 lb (93 kg)
Operational range	SDB I (GBU-39) more than 60 nmi (110 km) SDB II (GBU-53) 45 miles (72km) against moving targets
Guidance system	SDB I (GBU-39) GPS / INS SDB II (GBU-53) GPS/INS with coupled IMU/datalink, IIR and millimeter wave Active radar homing
Accuracy	SDB I (GBU-39) 5–8 m CEP SDB II (GBU-53) 1m CEP est.

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, adds a tri-mode seeker (radar, infrared homing, and semiactive laser guidance) to the INS and GPS guidance of the original SDB.

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 using 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.