GBU-39 Small Diameter Bomb

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4 SDBs (training/ground handling variant) loaded on an F15

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.^[1]

1 Development
2 Specifications
3 Cost
4 Program status
5 Notes
6 See also
7 External links

[edit] Development

Two variants are being developed. One version of the SDB is equipped with an Inertial navigation system (INS)/ Global Positioning System (GPS) 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,[1] 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 a 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.

[edit] Specifications

Length: 70.8 in (1.8 m).^[2]
Width: 7.5 in (19 cm).
Weapon weight: 285 pounds (130 kg).
Warhead: 206 lb (93 kg) penetrating, blast frag.
- 50 lbs (23kg) of high explosive.^[3]
Warhead penetration:
- "six feet of reinforced concrete".
- "more than three feet (1 m) of steel-reinforced concrete".
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).

[edit] Cost

Although unit costs were somewhat uncertain as of 2006, the estimated value for the INS/GPS version was around $70,000. The cost of the second variant was more uncertain, but tentative estimates were $90,000 per unit or more.

[edit] Program status

October 2001 - Boeing is awarded the SDB contract.^[4]
September 2005 - Small Diameter Bomb certified for operational test, evaluation.^[5]
September 2006 - SDB team deliver the first SDBs to the USAF.^[6]
October 2006 - Initial Operational Capability declared for SDB on the F15E.^[7]
October 2006 - First use in combat.^[8]