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At a glance
GBU-28larger figure on 1 of 1
GBU-39 Small Diameter Bomb
Measured figures
bomb body
Single sourceoverall
Single sourceConfiguration
| Specification | GBU-28 | GBU-39 Small Diameter Bomb |
|---|---|---|
| Type | Laser-guided bunker busting bomb[source] | Glide bomb[source] |
| Place of origin | United States[source] | United States[source] |
| In service | 1991–present[source] | 2006–present[source] |
| Used by | United States Israel South Korea[source] |
Counts only measures both sources give with the same scope. A larger figure is not a better system.
19 ft 1.3 in (5.824 m) overall 13 ft 3 in (4.04 m) bomb body[source]
Length
Single source70.8 in (1.80 m)[source]
packed
Single sourcewings extended
Single source5 ft 3.3 in (1.61 m) (wings extended) 7.5 in (190 mm) packed[source]
main body
Single sourcewidest point
Single source15 in (382 mm) main body 16 in (407 mm) widest point[source]
Operational; All SDB I variants over when air-dropped
Single sourceOperational; when launched as a part of the GLSDB
Single sourceAll SDB I variants over 60 nmi (69 mi; 111 km) when air-dropped, 150 km (93 mi; 81 nmi) when launched as a part of the GLSDB ,[source]
Filling weight
Single source675 lb (306.2 kg)[source]
AFX 1209 MBX ("multiphase blast explosive"), composite case Laser SDB (GBU-39B/B)
Single sourceAFX 757 enhanced blast insensitive explosive, penetrating steel case
Single sourceAll SDB I variants total SDB I (GBU-39/B)
Single sourceExplosive fill AFX 757 Insensitive munition certified PBX Penetration: greater than 3 ft (0.91 m) of steel reinforced concrete SDB FLM (GBU-39A/B)
Single sourceAll SDB I variants 206 lb (93 kg) total SDB I (GBU-39/B) Explosive fill: 36 lb (16 kg) AFX 757 Insensitive munition certified PBX Penetration: greater than 3 ft (0.91 m) of steel reinforced concrete SDB FLM (GBU-39A/B) 137 lb (62 kg) AFX 1209 MBX ("multiphase blast explosive"), composite case Laser SDB (GBU-39B/B) 36 lb (16 kg) AFX 757 enhanced blast insensitive explosive, penetrating steel case[source]
Bars compare reported quantities only. A larger figure does not make a system better; configurations and test conditions differ.
United States Israel Italy Netherlands Ukraine Saudi Arabia Australia[source] |
| Wars | Gulf War Gaza war Israel–Hezbollah conflict (2023–2024) 2024 Hezbollah headquarters strike 2026 Iran war[source] | War in Afghanistan , Iraq War , Military intervention against ISIL , Syrian Civil War , Russian invasion of Ukraine , Gaza war[source] |
|---|
| Designer | Albert L. Weimorts[source] | — |
|---|
| Manufacturer | Raytheon General Dynamics Ordnance and Tactical Systems[source] | Boeing Integrated Defense Systems[source] |
|---|
| Filling | Tritonal , AFX‐757 IM[source] | — |
|---|
| Detonation mechanism | Impact, time delay[source] | — |
|---|
| References | Janes[source] | — |
|---|
| Role | 4,000–5,000-pound (1,800–2,300 kg) class laser-guided " bunker busting " bomb[source] | 250-pound (110 kg) precision-guided glide bomb[source] |
|---|
| Source measurement | The GBU-28 (Guided Bomb Unit‐28) is a 4,000–5,000-pound (1,800–2,300 kg) class laser-guided " bunker busting " bomb 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 . One GBU-28 was dropped during Operation Iraqi Freedom . It was designed by Albert L. Weimorts .[source]GBU-28 · Lead; only the objects and conditions stated in this passage The initial batch of GBU-28s was built from modified 8-inch (203 mm) artillery barrels (principally from deactivated M110 howitzers ), but later examples are purpose-built with the BLU-113 bomb body made by National Forge of Irvine, Pennsylvania. They weigh 5,000 pounds (2,268 kg) and contain 630 pounds (286 kg) of tritonal explosive.[source]GBU-28 · Design and development; only the objects and conditions stated in this passage The GBU-28 C/B version uses the 5,000-pound BLU-122 bomb body, which contains AFX-757 explosive in a 4,000-pound (1,800 kg) casing machined from a single piece of ES-1 Eglin steel alloy.[source]GBU-28 · Design and development; only the objects and conditions stated in this passage The bomb underwent testing at the Tonopah Test Range , Nevada , a test facility for United States Department of Energy funded weapon programs. An F-111F of the 431st Test and Evaluation Squadron based at McClellan AFB in California dropped the first GBU-28 at Tonopah on February 24, 1991. It proved capable of penetrating over 160 feet (50 m) of earth or 16 feet (5 m) of solid concrete; this was demonstrated when a test bomb, bolted to a missile sled, smashed through 22 feet (6.7 m) of reinforced concrete and still retained enough kinetic energy to travel a half-mile (800 m) downrange. The GBU-28 went from finalized design to first use in combat in only two weeks between 13 and 27 February 1991.[source]GBU-28 · Design and development; only the objects and conditions stated in this passage On the night of 27/28 February 1991, just hours before the ceasefire, two General Dynamics F-111Fs , loaded with one GBU-28 each, headed towards a target on the outskirts of Baghdad . The al-Taji Airbase, located 15 miles (24 km) northwest of the Iraqi capital, had been hit at least three times by GBU-27/Bs from F-117 Nighthawks , "digging up the rose garden". The first GBU-28 was dropped off-target due to target misidentification. The second GBU-28 was a direct hit and penetrated the thick reinforced concrete before detonating, killing everyone inside.[source]GBU-28 · Operational history; only the objects and conditions stated in this passage In October 2021, the USAF completed assessments of the GBU-72 Advanced 5K Penetrator (A5K), a 5,000 lb (2,300 kg) penetrator bomb consisting of a BLU-138 penetrator warhead combined with a JDAM GPS guidance kit. In development since 2017, the GBU-72 is expected to cause significantly more damage against hardened, buried targets and is fitted with a more durable and efficient smart electronic fuse that can activate at a preprogrammed location. The Air Force plans to begin buying the weapon in 2022 to replace the GBU-28. Israel is also reportedly interested.[source]GBU-28 · Operational history; only the objects and conditions stated in this passage | The GBU-39/B Small Diameter Bomb ( SDB ) is a 250-pound (110 kg) precision-guided glide bomb that is intended to allow aircraft to carry a greater number of smaller, 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-pound (910 kg) Mark 84 bomb . It first entered service in 2006. The Ground Launched Small Diameter Bomb (GLSDB) was later developed to enable the SDB to be launched from a variety of ground launchers and configurations.[source]GBU-39 Small Diameter Bomb · Lead; only the objects and conditions stated in this passage The small size of the bomb allows a strike aircraft to carry more of them than previously available bombs, and thus strike more targets. The SDB carries approximately 36 lb (16 kg) of AFX-757 high explosive . AFX-757 is an insensitive enhanced blast polymer-bonded explosive , containing 25% RDX high explosive, 30% ammonium perchlorate oxidizer, 33% aluminium powder , 4.44% HTPB binder and 6.56% dioctyl adipate plasticizer. AFX-757 has improved air blast equivalent, 1.39 times more than Composition B , but low brisance due to low RDX content. It 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 ft (1 m) of steel reinforced concrete under 3 ft (1 m) of earth and the fuze has electronic safe and fire (ESAF) cockpit selectable functions, including air burst and delayed options.[source]GBU-39 Small Diameter Bomb · Description; only the objects and conditions stated in this passage The SDB I has a circular error probable (CEP) precision of 3 ft (1 m). 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.[source]GBU-39 Small Diameter Bomb · Description; only the objects and conditions stated in this passage |
|---|
| Unit cost | — | US$40,000 (SDB I, FY 2021)[source] |
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| Produced | — | 2005–present[source] |
|---|
| No. built | — | 17,000+[source] |
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| Variants | — | GBU-39/B GBU-39A/B GBU-39B/B[source] |
|---|
| Warhead | — | SDB I (GBU-39/B) penetrating blast fragmentation, penetrating steel nosecone SDB FLM (GBU-39A/B) blast ultra-low fragmentation Laser SDB (GBU-39B/B) penetrating blast fragmentation, w/o steel nosecone[source] |
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| Guidance system | — | SDB I (GBU-39/B) SDB FLM (GBU-39A/B) GPS / INS Laser SDB (GBU-39B/B) GPS / INS with terminal semi-active laser guidance[source] |
|---|
| Accuracy | — | SDB I (GBU-39) 3 ft (1 m) CEP[source] |
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| Reported operators | — |
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In January 2016, the Air Force awarded a contract to Scientific Systems Co. Inc. to demonstrate the company's ImageNav technology, a vision-based navigation and precision targeting system that compares a terrain database with the host platform's sensor to make course corrections. ImageNav technology has demonstrated target geo-location and navigation precision within three meters.[source]GBU-39 Small Diameter Bomb · Description / Alternative guidance and warheads; only the objects and conditions stated in this passage
Under a contract awarded in September 2006, Boeing developed a version of the SDB I that replaces the steel casing with a lightweight composite casing and the warhead with a focused-blast explosive such as dense inert metal explosive (DIME). This should further reduce collateral damage when using the weapon for pinpoint strikes in urban areas. The USAF intends to use the same FLM casing on a weapon of 500 pounds (227 kg). Boeing celebrated the delivery of the first 50 FLM weapons on 28 February 2008 and delivered the last of the 500 FLMs under contract in December 2013.[source]GBU-39 Small Diameter Bomb · Variants / GBU-39A/B – SDB Focused Lethality Munition (FLM); only the objects and conditions stated in this passage
In 2011 Boeing began testing on a laser-guided version of the baseline SDB, integrating the same Semi Active Laser (SAL) from the GBU-54 Laser JDAM. Boeing claimed to have successfully hit targets moving at 30 mph (48.3 km/h) and 50 mph (80.5 km/h).[source]GBU-39 Small Diameter Bomb · Variants / GBU-39B/B – Laser SDB; only the objects and conditions stated in this passage
In August 2024, CNN reported that Israel used the GBU/39 again in the Al-Tabaeen school attack , killing over 90 people according to the Gaza Civil Defense. The IDF stated that it was a precision strike against a Hamas command and control center that killed at least 19 Hamas and PIJ militants.[source]GBU-39 Small Diameter Bomb · Operational history; only the objects and conditions stated in this passage