GBU-39 Small Diameter Bomb

The GBU-39 Small-Diameter Bomb (SDB) is a 250 pound (110 kg) guided bomb that is intended to provide aircraft with the ability to carry a higher number of bombs. Most US Air Force aircraft will be able to carry a pack of four of these bombs in place of a single 2,000 lb bomb using the BRU-61/A rack.
Development
Two variants are being developed. One version of the SDB is equipped with a GPS-aided inertial navigation system which makes it ideal for fixed/stationary targets such as fuel depots, bunkers etc. The second variant (GBU-40) includes a thermal seeker with automatic target recognition features which makes it ideal for striking mobile targets such as tanks, vehicles, and mobile command posts.
The GBU-39 has a circular error probable (CEP) of only 5-8 meters,[2] which means it has a 50% probability of hitting within 5-8 meters its intended target, which should minimize collateral damage. CEP is reduced by updating differential GPS offsets prior to weapon release. These offsets are calculated using an SDB Accuracy Support Infrastructure, consisting of three or more GPS receivers at fixed locations transmitting calculated location to a correlation station at the theatre Air Operations Center. The corrections are then transmitted by Link 16 to SDB-equipped aircraft.
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. It is currently integrated on the F-15E Strike Eagle; future integration is planned for the F-16 Fighting Falcon, F-22 Raptor, F-35 Lightning II, A-10 Thunderbolt II, F-117 Nighthawk, B-1 Lancer, B-2 Spirit, and the B-52 Stratofortress. Other aircraft, including UCAVs, may also receive the necessary upgrades.
The SDB carries approximately 50 lb (23 kg) of high explosive, yet because of its design it has the same penetration capabilities as the 2000 lb BLU-109. During demonstrations, the SDB has successfully penetrated more than 6 ft (1.8 m) thick reinforced concrete. It also has integrated "DiamondBack" type wings which deploy after release, increasing the glide time and therefore the maximum range.
GBU-39 began separation tests on the F-22 in early September 2007 after more than a year of sometimes difficult work to integrate the weapon in the weapons bay and carry out airborne captive carry tests. Flight tests so far have produced a few in-flight problems, including one incident in which an F-22 suffered a brief, dual-engine flameout while performing a negative-g, 360 degree roll with eight SDBs loaded in the weapons bay. The flameout occurred because the aircraft entered the maneuver with an incorrect trim setting. However, the engines were restarted almost immediately. The pilot remained in control of the aircraft and landed at Edwards AFB, California, without incident.[3]
Specifications
Length: 70.8 in (1.8 m).[4]
Width: 7.5 in (19 cm).
Weapon weight: 285 pounds (130 kg).
Warhead: 206 lb (93 kg) penetrating, blast fragmentation.
50 lbs (23kg) of high explosive.[5]
Warhead penetration:
"six feet of reinforced concrete"[attribution needed].
"more than three feet (1 m) of steel-reinforced concrete"[attribution needed].
Fuse: Electronic safe and fire (ESAF) cockpit selectable functions, including air burst and delayed options.
Guidance: SDB I - GPS/INS.
Accuracy: 5-8 m circular error probable.
Standoff maximum range: more than 60 nautical miles (110 km).