Bunker buster
A bunker buster is a bomb designed to penetrate hardened targets or targets buried deep underground.
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[edit] Artillery delivered bombs
[edit] Germany
Röchling shells were bunker-busting artillery shells, developed by German engineer August Cönders, 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]
[edit] Aircraft delivered bombs
[edit] World War II
[edit] United Kingdom
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 "Earthquake" bombs. The designs were very aerodynamic with a tail which caused them to spin. This allowed them to exceed the speed of sound as they fell from 22,000 ft (6,700 m). They had casings of high grade steel, much stronger than the typical WWII 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 U-boat pens at Farge two Grand Slams went through the 15 ft (4.5 m) reinforced concrete hardening[2] — equalling or exceeding the best current penetration specifications.
The Disney Rocket-Assisted Bomb was another WWII device 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[3] it had a streamlined hardened case and weighed some 4,500 lb (2 tonnes) including the rocket assembly. Actual exposive content was about 500 lb (230 kg). The bomb was dropped from 20,000 ft (6,100 m). At 5,000 ft (~1,500 m) a barometric fuze fired the rockets in the tail to give it a velocity at impact of up to 2,400 ft/second (730 m/s). It was first used by the USAAF's 92nd Bomb Group on 10 February 1945 on S-boat pens at IJmuiden, Netherlands, one bomb under each wing of nine B-17 Flying Fortresses. On that occasion a single direct hit was scored. A total of 158 "Disney Bombs" were used operationally by the end of hostilities in Europe.
[edit] United States
Post war the US added a form of remote guidance to the Tallboy to create the Tarzon, a 12,000-pound bomb deployed in the Korean War against an underground command center near Kanggye.
[edit] Modern
During Operation Desert Storm (1991) there was a need for a deep penetration bomb similar to the British weapons of WWII, 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)", and were effective.
An example of a Russian bunker buster is the KAB-1500L-Pr. It is delivered with the Su-24M and the Su-27IB 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.
The US has a series of custom made bombs to penetrate hardened or deeply buried structures:
| Depth of Penetration | Weapon Systems | |
|---|---|---|
| Penetration of reinforced concrete: 1.8 m (6 ft) | BLU-109 Penetrator | GBU-10, GBU-15, GBU-24, GBU-27, AGM-130 |
| Penetration of reinforced concrete: 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 | |
| Penetration of reinforced concrete: more than 6 m (20 ft) | BLU-113 Super Penetrator | GBU-28, GBU-37 |
More recently, the US has developed the 30,000-pound GBU-57.
[edit] Fusing
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 the traditional fuze, but some also include a microphone and microcontroller. The microphone listens, and the micro controller counts floors until the bomb breaks through the desired numbers of floors.
ATK is working on a Hard Target Void Sensing Fuze (HTVSF) for 2000 and 5000 pound weapons to explode when they reach an open space in a deeply buried bunker.[4]
[edit] Missiles
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).
[edit] Nuclear
[edit] See also
[edit] Further reading
- Guided Bomb Unit-28 (GBU-28) BLU-113 Penetrator
- BBC: 'Bunker buster' missiles aim at Moon
- Annotated bibliography for nuclear bunker buster bombs from the Alsos Digital Library for Nuclear Issues
- Read Congressional Research Service (CRS) Reports regarding Bunker Busters
- Video against usage (produced by Union of Concerned Scientists)
[edit] References
[edit] Notes
- ^ http://derelicta.pagesperso-orange.fr/aubin3.htm
- ^ "Grand Slam Raids" Royal Air Force Bomber Command 60th Anniversary raf.mod.uk
- ^ Terrell, 1958. pp. 197-212
- ^ "ATK Awarded Contract for Hard Target Void Sensing Fuze (HTVSF) Engineering & Manufacturing Development (EMD) Phase." ATK, 5 April 2011.
[edit] Bibliography
- Terrell, Edward (1958). Admiralty Brief: the story of inventions that contributed to victory in the Battle of the Atlantic. Harrap.
- Young, C.W. (1997). Penetration equations (Report). SAND94-2726. Albuquerque NM: Sandia National Laboratories. http://www.fas.org/sgp/othergov/doe/lanl/lib-www/sand/972426.pdf. "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."
- Young, C.W. (1967). The Development Of Empirical Equations For Predicting Depth Of An Earth Penetrating Projectile (Report). SC-DR-67-60. Albuquerque NM: Sandia National Laboratories.
- Alekseevskii, V. P. (1966). "Penetration of a rod into a target at high velocity". Combustion, Explosion, and Shock Waves (Fizika Goreniya i Vzryva) 2 (2): 99–106. doi:10.1007/BF00749237. ISSN 0010-5082.
- Tate, A. (1 November 1967). "A theory for the deceleration of long rods after impact". Journal of the Mechanics and Physics of Solids 15 (6): 387–399. doi:10.1016/0022-5096(67)90010-5. http://hep.ph.liv.ac.uk/~ibailey/target/shielding/tate_1967.pdf. Retrieved 23 June 2011.
- Bernard, Robert S. (1978). Depth and Motion Prediction for Earth Penetrators (Report). ADA056701. Army Engineer Waterways Experiment Station Vicksburg. http://www.dtic.mil/cgi-bin/GetTRDoc?Location=U2&doc=GetTRDoc.pdf&AD=ADA056701.
- Walters, William P.; Segletes, Steven B. (1991). "An exact solution of the long rod penetration equations". International Journal of Impact Engineering 11 (2): 225–231. doi:10.1016/0734-743X(91)90008-4.
- Segletes, Steven B.; Walters, William P. (2002). Efficient Solution of the Long-Rod Penetration Equations of Alekseevskii-Tate (Report). ARL-TR-2855. Army Research Lab Aberdeen Proving Ground MD. http://www.arl.army.mil/arlreports/2002/ARL-TR-2855.pdf.
- Segletes, Steven B.; Walters, William P. (2003). "Extensions to the exact solution of the long-rod penetration/erosion equations". International Journal of Impact Engineering 28 (4): 363–376. doi:10.1016/S0734-743X(02)00071-4. http://aux.ciar.org/ttk/mbt/papers/ijie00/ijie_28_363.pdf. Retrieved 23 June 2011.
- Parsch, Andreas (2006). "Textron (Avco) BLU-106/B BKEP (Boosted Kinetic Energy Penetrator)". Directory of U.S. Military Rockets and Missiles (Appendix 4). http://www.designation-systems.net/dusrm/app4/blu-106.html. Retrieved 27 June 2011. US rocket-boosted submunition against runways and hardened aircraft shelters.
