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40-483: The GBU-72 is described as a 5,000 lb (2,300 kg) class precision-guided bunker busting bomb which uses a JDAM guidance kit. The GBU-72 is said to resemble an enlarged GBU-31/B JDAM fitted with a bunker busting BLU-109 or BLU-137/B warhead. It is fitted with the GBU-31/B JDAM’s GPS and INS tail-mounted guidance kit and two long fins fitted to either side of the bomb's underside. No official data

80-457: A 3.6 magnitude earthquake, destroying any nearby structures such as dams, railways, viaducts, etc. Any concrete reinforcement of the target would probably serve to enclose the force better. Wallis also argued that, if the bomb penetrated deep enough, the explosion would not breach the surface of the ground and would thus produce a cavern (a camouflet ) which would remove the structure's underground support, thus causing it to collapse. The process

120-438: A conventional bomb, as well as damage or destroy difficult targets such as bridges and viaducts . Earthquake bombs were used towards the end of World War II on massively reinforced installations, such as submarine pens with concrete walls several meters thick, caverns, tunnels, and bridges. During development Barnes Wallis theorised that a highly aerodynamic, very heavy bomb with a delayed detonation would cause damage to

160-404: A deeply buried bunker. 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

200-621: 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. Earth quake bomb 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

240-589: A modified 2,000-pound joint-direct-attack-munition tail kit’s ability to control and navigate a 5,000-pound weapon." In May 2024 it was reported that as part of joint American-British strikes during the Red Sea crisis , the US Air Force used a GBU-72 to destroy an underground Houthi facility in Yemen . On 23 July 2021, the test series consisting of three flights started, planned by the 780th Test Squadron and carried out by

280-557: A reported strike accuracy of 7 m (23 ft) CEP . 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: 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

320-423: 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

360-407: A target through shock waves travelling through the ground, hence the nickname earthquake bombs. The airmen who dropped the bombs reported that the target structures stood undamaged by the detonation; "But then the crater collapsed, the ground shifted and the target collapsed". Later computer simulations reached the same conclusions; the significant part of the damage was done by generating a cavity in

400-454: 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

440-730: Is available for how deep the GBU-72 can penetrate before exploding, although the weapon's program manager has been quoted as saying "lethality [of the GBU-72] is expected to be substantially higher compared to similar legacy weapons like the GBU-28 ". The capabilities of the later versions of the GBU-28 remain classified, but the earliest versions could reportedly penetrate 150 ft (46 m) of earth and over 15 ft (4.6 m) of reinforced concrete. The US Air Force's B-1Bs and F-15Es are capable of deploying

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480-401: 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

520-412: 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

560-752: The 40th Flight Test Squadron ; it aimed to "validate a modified 2,000 pounds (910 kg) Joint Direct Attack Munition tail kit’s ability to control and navigate a 5,000 pounds (2,300 kg) weapon." In September 2024 it was reported that the Israeli Air Force deployed up to ten GBU-72s on 27 September 2024 to kill Hezbollah 's Secretary-General, Hassan Nasrallah , in his underground headquarters complex in Beirut. Subsequent reporting stated 2,000 lb (910 kg) class JDAM-equipped BLU-109 bunker busting bombs were likely used. On 7 October 2021, an 96th Test Wing McDonnell Douglas F-15E Strike Eagle released

600-582: The Valentin U-Boat pens at Farge , two Grand Slams went through the 15 ft (4.5 m) reinforced concrete hardening —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

640-420: 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. 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

680-628: The strikes that killed Hezbollah leader Hassan Nasrallah in Beirut on 27 September 2024. 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

720-448: The " Victory Bomber ", but there was no support for an aircraft with only a single purpose. Wallis then took a different line in developing a means to destroy Germany's industrial structure with attacks on its supply of hydroelectric power. After he had developed the bouncing bomb and shown its possibilities, RAF Bomber Command were prepared to listen to his other ideas, even though they often thought them strange. The officer classes of

760-500: The 5,000-pound (2,300 kg) GBU-28 that was used successfully by F-111Fs against a deep underground complex not far from Baghdad just before the end of the war. The United States has developed a 30,000-pound (14,000 kg) Massive Ordnance Penetrator , designed to attack very deeply buried targets without the use of nuclear weapons with the inherent huge levels of radioactive pollution and their attendant risk of retaliation in kind. Anglo-American bomb tests (Project Ruby) on

800-513: The Admiralty's Directorate of Miscellaneous Weapons Development , 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)). They would free-fall for around 30 seconds until, at 5,000 ft (1,500 m),

840-617: The GBU-72 (known as the GBU-72 Advanced 5K Penetrator), over the Eglin Air Force Base range, which ended the initial testing phase. It is to moves on to additional JDAM integration test flights and developmental and operational testing in 2022. Bunker buster 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

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880-479: The GBU-72, along with the Israeli Air Force's F-15Is . The GBU-72 underwent a series of tests at Eglin Air Force Base . These included a number of ground based tests which included detonating the bomb’s warhead within an array of barriers to measure its blast and other effects, and airborne tests between July and October 2021 which included confirming "the weapon could safely release from the aircraft and validate

920-592: 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 . 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

960-510: The RAF at that time were often trained not in science or engineering, but in the classics , Roman and Greek history and language. They provided enough support to let him continue his research. Later in the war, Barnes Wallis made bombs based on the "earthquake bomb concept", such as the 6-ton Tallboy and then the 10-ton Grand Slam , although these were never dropped from more than about 25,000 feet (7.6 km). Even from this relatively low altitude,

1000-556: 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

1040-481: The anti-shipping role, however, great damage could be done to the critical equipment on board a battleship by the shock wave alone. An explosion in air does not transfer much energy into a solid, as their differing acoustic impedances makes an impedance mismatch that reflects most of the energy. Due to the lack of accuracy of bombing in the face of anti-aircraft defences, air forces used area bombardment , dropping large numbers of bombs so that it would be likely that

1080-403: 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

1120-591: The earthquake bomb had the ability to disrupt German industry while causing minimum civilian casualties. It was used to disable the V2 launch sites at La Coupole and Blockhaus d'Éperlecques , put out of action the V-3 cannon sites at Fortress of Mimoyecques , sink the battleship Tirpitz and damage the U-boats ' protective pens at St. Nazaire , as well as to attack many other targets which had been impossible to damage before. One of

1160-409: The ground. That cavity collapsing caused the ground to shift, hence the target's foundation to shift or break causing catastrophic structural damage to the target. The shifting ground caused any larger structure to become severely damaged, even if the bomb missed the target but created a crater near it. They were not true seismic weapons, but effective cratering weapons when used on ground targets. In

1200-409: The most spectacular attacks was shortly after D-Day , when the Tallboy was used to prevent German tank reinforcements from moving by train. Rather than blow up the tracks – which would have been repaired in a day or so – the bombs were targeted on a tunnel near Saumur which carried the line under a mountain. Twenty-five Lancasters dropped the first Tallboys on the mountain, penetrating straight through

1240-564: 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

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1280-609: 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

1320-489: The rock, and one of them exploded in the tunnel below. As a result, the entire rail line remained unusable until the end of the war. The Bielefeld viaduct was only closed for brief periods by 54 raids dropping 3,500 tons; but in its first use on 14 March 1945 the "Grand Slam" destroyed whole sections of the viaduct. After World War II, the United States developed the 43,000-pound (20,000 kg) T12 demolition bomb, which

1360-515: The rockets were ignited, causing the tail section to be expelled. The rocket burn lasted for three seconds 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), approximately Mach 1.29. Post-war tests demonstrated that the bombs were able to penetrate a 14-foot-8-inch (4.47 m) thick concrete roof, with the predicted (but untested) ability to penetrate 16 feet 8 inches (5.08 m) of concrete. Post war,

1400-399: The standards at the time. Wallis' first concept was for a ten-ton bomb that would explode some 130 feet (40 m) underground. To achieve this, the bomb would have had to be dropped from 40,000 feet (12 km). The RAF had no aircraft at the time capable of carrying a ten-ton bomb load aloft, let alone lifting it to such a height. Wallis designed a six-engine aeroplane for the task, called

1440-415: The target would be hit. Although a direct hit from a light bomb would destroy an unprotected target, it was comparatively easy to armour ground targets with many yards of concrete, and thus render critical installations such as bunkers essentially bombproof. If the bomb could be designed to explode in water, soil, or other less compressible materials, the explosive force would be transmitted more efficiently to

1480-420: The target. Barnes Wallis' idea was to drop a large, heavy bomb with a hard armoured tip at supersonic speed (as fast as an artillery shell) so that it penetrated the ground like a ten-ton bullet being fired straight down. It was then set to explode underground, ideally to the side of, or underneath, a hardened target. The resulting shock wave from the explosion would then produce force equivalent to that of

1520-609: Was designed to create an earthquake effect. Given the availability of nuclear weapons with surface detonating laydown delivery , there was little or no development of conventional deep penetrating bombs until the 1991 Gulf War . During the Gulf War, the need for a conventional deep penetrator became clear. In three weeks, a cooperative effort directed by the Armament Systems Division at Eglin Air Force Base in Florida developed

1560-491: Was graphically described as a "trapdoor effect" or "hangman's drop". Wallis foresaw that disrupting German industry would remove its ability to fight, and also understood that precision bombing was virtually impossible in the late 1930s. The technology for precision aiming was developed during World War II, and Barnes Wallis' ideas were then shown to be successful (see for example the Bielefeld raid on 14 March 1945), considering

1600-557: Was proven effective for the intended role. 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

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