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A bunker buster is a type of munition that is designed to penetrate hardened targets or targets buried deep underground, such as military bunkers.
Röchling shells were bunker-busting artillery shells, developed by the German engineer August Coenders, based on the theory of increasing sectional density to improve penetration. They were tested in 1942 and 1943 against the Belgian Fort d'Aubin-Neufchâteau. [1]
In World War II the Luftwaffe developed a series of unguided rocket-propelled armor-piercing bombs for use against shipping and fortifications.
In World War II, the British designer Barnes Wallis, already famous for inventing the bouncing bomb, designed two bombs that would become the conceptual predecessors of modern bunker busters: the five tonne Tallboy and the ten tonne Grand Slam. These were "Earthquake" bombs—a concept he had first proposed in 1939. [3] The designs were very aerodynamic, allowing them to exceed the speed of sound as they fell from 22,000 ft (6,700 m). The tails were designed with offset fins causing the bombs to spin as they fell. Using the same principle as a spinning top, this enabled them to resist being deflected, thereby improving accuracy. They had casings of high grade steel, much stronger than the typical World War II bomb so that they would survive hitting a hardened surface, or penetrate deep into the ground.
Though these bombs might be thought of as "bunker busters" today, in fact the original "earthquake" theory was more complex and subtle than simply penetrating a hardened surface. The earthquake bombs were designed not to strike a target directly, but to impact beside it, penetrate under it, and create a 'camouflet', or large buried cavern, at the same time as delivering a shock wave through the target's foundations. The target then collapses into the hole, no matter how hardened it may be. The bombs had strong casings because they needed to travel through rock rather than reinforced concrete, though they could perform equally well against hardened surfaces. In an attack on the Valentin U-Boat pens at Farge, two Grand Slams went through the 15 ft (4.5 m) reinforced concrete hardening [4] —equalling or exceeding the best current penetration specifications.
The British Disney bomb (officially "4500 lb [2,000 kg] Concrete piercing/Rocket Assisted Bomb", also known as the "Crab") was a World War II device designed to be used against U-boat pens and other super-hardened targets. Devised by Captain Edward Terrell RNVR of the Admiralty's Directorate of Miscellaneous Weapons Development, [5] it had a streamlined hardened case and weighed about 4,500 lb (2,000 kg) including the rocket assembly. The actual explosive content was about 500 lb (230 kg).
For accuracy, the bombs had to be dropped precisely from a pre-determined height (usually 20,000 ft (6,100 m)). [6] They would free-fall for around 30 seconds until, at 5,000 ft (1,500 m), the rockets were ignited, causing the tail section to be expelled. [6] The rocket burn lasted for three seconds [7] and added 300 ft/s (91 m/s) to the bomb's speed, giving a final impact speed of 1,450 ft/s (440 m/s; 990 mph), [7] approximately Mach 1.29. [lower-alpha 1] Post-war tests demonstrated that the bombs were able to penetrate a 14-foot-8-inch (4.47 m) thick concrete roof, [8] with the predicted (but untested) ability to penetrate 16 feet 8 inches (5.08 m) of concrete. [8]
Post war, the US added a form of remote guidance to the Tallboy to create the Tarzon , a 12,000 lb (5,400 kg) bomb deployed in the Korean War against an underground command center near Kanggye.
The BLU-109 bomb is intended to penetrate concrete shelters and other hardened structures before exploding. It entered service in 1985. Israeli F-15I fighter jets are believed to have used BLU-109s in the strikes that killed Hezbollah leader Hassan Nasrallah in Beirut on 27 September 2024. [9] [10]
During Operation Desert Storm (1991), there was a need for a deep penetration bomb similar to the British weapons of World War II, but none of the NATO air forces had such a weapon. As a stop-gap, some were developed over a period of 28 days, using old 8 inch (203 mm) artillery barrels as casings. These bombs weighed over two tons but carried only 647 lb (293 kg) of high explosive. They were laser-guided and were designated "Guided Bomb Unit-28 (GBU-28)". It was proven effective for the intended role. [11]
An example of a Russian bunker buster is the KAB-1500L-Pr. It is delivered with the Su-24M and the Su-34 aircraft. It is stated to be able to penetrate 10–20 m of earth or 2 m of reinforced concrete. The bomb weighs 1,500 kg (3,300 lb), with 1,100 kg (2,400 lb) being the high explosive penetrating warhead. It is laser guided and has a reported strike accuracy of 7 m (23 ft) CEP. [12]
The US has a series of custom made bombs such as the Paveway series of laser-guided bombs to penetrate hardened or deeply buried structures:
| Depth of Penetration reinforced concrete | Weapon Systems | |
|---|---|---|
| 1.8 m (6 ft) | BLU-109 Penetrator | GBU-10, GBU-15, GBU-24, GBU-27, AGM-130, GBU-31(V)3/B & GBU-31(V)4/B |
| 3.4 m (11 ft) | BLU-116 Advanced Unitary Penetrator (AUP) | GBU-15, GBU-24, GBU-27, AGM-130 |
| BLU-118/B Thermobaric Warhead | GBU-15, GBU-24, AGM-130 | |
| more than 6 m (20 ft) | BLU-113 Super Penetrator | GBU-28, GBU-37 |
More recently, the US has developed the 30,000 lb (14,000 kg) GBU-57.
Turkey is another country known to be developing bunker busters, such as the SARB-83 and NEB-84.
The traditional fuze is the same as a classic armor-piercing bomb: a combination of timer and a sturdy dynamic propeller on the rear of the bomb. The fuze is armed when the bomb is released, and detonates when the propeller stops turning and the timer has expired.
Modern bunker busters may use a traditional fuze, but some also include a microphone and microcontroller. The microphone listens, and the microcontroller counts the number of floors until the bomb breaks through the desired numbers of floors. Northrop Grumman is working on the Hard Target Void Sensing Fuze (HTVSF), an electronic, cockpit programmable, fuze capable of destroying deeply buried and targets. It provides multiple delay arming and detonation times, as well as a void-sensing capability, which allows for precision activation of the fuze for 2,000-and-5,000-pound (910 and 2,270 kg) weapons to explode when they reach an open space in a deeply buried bunker. [13] [14]
The extra speed provided by a rocket motor enables greater penetration of a missile-mounted bunker buster warhead. To reach maximum penetration (impact depth), the warhead may consist of a high-density projectile only. Such a warhead carries more energy than a warhead with chemical explosives (kinetic energy of a projectile at hypervelocity).
The nuclear bunker buster is the nuclear weapon version of the bunker buster. The non-nuclear component of the weapon is designed to greatly enhance the penetration into soil, rock, or concrete to deliver a nuclear warhead to a target. These weapons would be used to destroy hardened, underground military bunkers deeply buried. In theory, the amount of radioactive nuclear fallout would be reduced from that of a standard, air-burst nuclear detonation because they would have relatively low explosive yield. However, because such weapons necessarily come into contact with large amounts of earth-based debris, they may, under certain circumstances, still generate significant fallout. Warhead yield and weapon design have changed periodically throughout the history of the design of such weapons. An underground explosion releases a larger fraction of its energy into the ground, compared to an explosion at or above the surface which releases most of its energy into the atmosphere.
A nuclear bunker buster, also known as an earth-penetrating weapon (EPW), is the nuclear equivalent of the conventional bunker buster. The non-nuclear component of the weapon is designed to penetrate soil, rock, or concrete to deliver a nuclear warhead to an underground target. These weapons would be used to destroy hardened, underground military bunkers or other below-ground facilities. An underground explosion releases a larger fraction of its energy into the ground, compared to a surface burst or air burst explosion at or above the surface, and so can destroy an underground target using a lower explosive yield. This in turn could lead to a reduced amount of radioactive fallout. However, it is unlikely that the explosion would be completely contained underground. As a result, significant amounts of rock and soil would be rendered radioactive and lofted as dust or vapor into the atmosphere, generating significant fallout.
The GBU-43/B Massive Ordnance Air Blast is a large-yield bomb, developed for the United States military by Albert L. Weimorts, Jr. of the Air Force Research Laboratory. It was first tested in 2003. At the time of development, it was said to be the most powerful non-nuclear weapon in the American arsenal. The bomb is designed to be delivered by a C-130 Hercules, primarily the MC-130E Combat Talon I or MC-130H Combat Talon II variants. The bomb's name and nickname were inspired by Iraqi president Saddam Hussein's invocation of the "mother of all battles" during the 1991 Gulf War.
The GBU-28 is a 4,000-pound (1,800 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.
The Mark 84 or BLU-117 is a 2,000-pound (900 kg) American general purpose aircraft bomb. It is the largest of the Mark 80 series of weapons. Entering service during the Vietnam War, it became a commonly used US heavy unguided bomb. At the time, it was the third largest bomb by weight in the US inventory behind the 15,000-pound (6,800 kg) BLU-82 "Daisy Cutter" and the 3,000-pound (1,400 kg) M118 "demolition" bomb. It is currently sixth in size due to the addition of the 5,000 lb (2,300 kg) GBU-28 in 1991, the 22,600 lb (10,300 kg) GBU-43/B Massive Ordnance Air Blast bomb (MOAB) in 2003, and the 30,000 lb (14,000 kg) Massive Ordnance Penetrator.
Paveway is a series of laser-guided bombs (LGBs).
Tallboy or Bomb, Medium Capacity, 12,000 lb was an earthquake bomb developed by the British aeronautical engineer Barnes Wallis and used by the Royal Air Force (RAF) during the Second World War.
A general-purpose bomb is an air-dropped bomb intended as a compromise between blast damage, penetration, and fragmentation in explosive effect. They are designed to be effective against enemy troops, vehicles, and buildings.
The Mk/B53 was a high-yield bunker buster thermonuclear weapon developed by the United States during the Cold War. Deployed on Strategic Air Command bombers, the B53, with a yield of 9 megatons, was the most powerful weapon in the U.S. nuclear arsenal after the last B41 nuclear bombs were retired in 1976.
The BLU-109/B is a hardened bunker buster penetration bomb used by the United States Air Force. As with other "bunker busters", it is intended to penetrate concrete shelters and other hardened structures before exploding. In addition to the US, it is part of the armament of the air forces of Australia, Belgium, Canada, Denmark, France, Germany, Greece, Italy, Israel, Netherlands, Norway, Pakistan, Saudi Arabia, United Kingdom, and United Arab Emirates.
Laydown delivery is a mode of delivery found in some nuclear gravity bombs: the bomb's descent to the target is slowed by parachute so that it lands on the ground without detonating. The bomb then detonates by timer some time later. Laydown delivery requires the weapon to be reinforced so that it can survive the force of impact.
The Panzerfaust 3 is a modern semi-disposable recoilless anti-tank weapon, which was developed between 1978 and 1985 and first entered service with the Bundeswehr in 1987. It was first ordered in 1973 to provide West German infantry with an effective weapon against contemporary Soviet armor, thereby replacing West Germany's aging PzF 44 Light Lanze launchers and the heavy Carl Gustaf 84 mm anti-tank recoilless rifle manufactured in Sweden.
The RP-3 was a British air-to-ground rocket projectile introduced during the Second World War. The "3 inch" designation referred to the nominal diameter of the rocket motor tube. The use of a 60 lb (27 kg) warhead gave rise to the alternative name of the "60-pound rocket". Though an air-to-ground weapon, it saw limited use in other roles. They were generally used by British fighter-bomber aircraft against targets such as tanks, trains, motor transport and buildings, as well as by Coastal Command and Royal Navy aircraft against U-boats and ships.
The GBU-57A/BMassive Ordnance Penetrator (MOP) is a precision-guided, 30,000-pound (14,000 kg) "bunker buster" bomb used by the United States Air Force. The GBU-57 is substantially larger than the deepest-penetrating bunker busters previously available, the 5,000-pound (2,300 kg) GBU-28 and GBU-37. Due to its size it can only be carried by large bombers—for instance, the B-2 Spirit.
The W86 was an American earth-penetrating nuclear warhead, intended for use on the Pershing II intermediate-range ballistic missile (IRBM). The W86 design was canceled in September 1980 when the Pershing II missile mission shifted from destroying hardened targets to targeting soft targets at greater range. The W85 warhead, which had been developed in parallel with the W86, was used for all production Pershing II missiles.
The earthquake bomb, or seismic bomb, was a concept that was invented by the British aeronautical engineer Barnes Wallis early in World War II and subsequently developed and used during the war against strategic targets in Europe. A seismic bomb differs somewhat in concept from a traditional bomb, which usually explodes at or near the surface and destroys its target directly by explosive force; in contrast, a seismic bomb is dropped from high altitude to attain very high speed as it falls and upon impact, penetrates and explodes deep underground, causing massive caverns or craters known as camouflets, as well as intense shockwaves. In this way, the seismic bomb can affect targets that are too massive to be affected by a conventional bomb, as well as damage or destroy difficult targets such as bridges and viaducts.
The HOPE and HOSBO are a family of precision-guided munitions, currently under development by Diehl Defence for the German Luftwaffe. Diehl BGT was expected to reach production readiness in 2010, although neither the weapon nor the integration has been ordered so far. German officials have announced that HOPE has greater penetration capability than a USAF GBU-28 munition.
The BLU-116 is a United States Air Force bomb, designed as an enhanced bunker buster penetration weapon, designed to penetrate deep into rock or concrete and destroy hard targets.
The Disney bomb, also known as the Disney Swish, officially the 4500 lb Concrete Piercing/Rocket Assisted bomb was a rocket-assisted bunker buster bomb developed during the Second World War by the British Royal Navy to penetrate hardened concrete targets, such as submarine pens, which could resist conventional free-fall bombs.
A precision-guided munition (PGM), also called a smart weapon, smart munition, or smart bomb, is a guided munition intended to hit a specific target, to minimize collateral damage and increase lethality against intended targets. During the Persian Gulf War guided munitions accounted for only 9% of weapons fired, but accounted for 75% of all successful hits. Despite guided weapons generally being used on more difficult targets, they were still 35 times more likely to destroy their targets per weapon dropped.
The Guided Bomb Unit‐72 (GBU‐72), also known as the Advanced 5K (A5K) Penetrator, is a bunker busting bomb developed in the United States.
This is a standalone report documenting the latest version of the Young/Sandia penetration equations and related analytical techniques to predict penetration into natural earth materials and concrete.