Shaped charge

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Hollow charge - cutaway model. Yellow ... explosives.

The shaped charge is a special arrangement of explosive explosives around a conical or hemispherical metal insert , which is particularly suitable for penetrating armor . The explosives used are mostly based on Nitropenta , Hexogen or Octogen .

Shaped charges are used in the military as armor-piercing ammunition in tank ammunition and anti-tank weapons . In the civil sector, variants with the same operating principle are used as cutting charges , which are used, for example, for the demolition of structures made of reinforced and reinforced concrete .

history

Conventional shaped charges

Drawing of a shaped charge
Size 38HL, basic type, types A, B, C (from left to right)

It has been known since the end of the 18th century that the geometric shape of an explosive charge plays a decisive role in its explosive effect, or that a hollow explosive device has a particularly high penetrating power . In 1792 Franz von Baader was the first to describe this effect. Scientific descriptions followed from 1883 by Max von Förster , 1885 by Gustav Bloem and 1888 by Charles Edward Munroe . Munroe was the namesake for the Munroe effect , on which the shaped charge is based. In 1910, the German scientist Egon Neuman rediscovered the effect and the German explosives company WASAG was the first to patent it . Although the knowledge and technology were available, the shaped charge was not used during the First World War (1914–1918). One possible explanation is that the military insisted on head detonators , but the shaped charge could only develop its effect with a bottom detonator . Further scientific publications followed, for example by Alfred Stettbacher , Ernst Richard Escales and Robert Williams Wood .

In the interwar period , the technical advantage shifted towards tanks and the infantry were desperately looking for suitable defense weapons. In 1932 Franz Rudolf Thomanek designed a 70 mm tank rifle with shaped charge ammunition, albeit without taking into account the as yet unknown effect of the lining of the shaped charge. The TG 70 / M34 tank rifle was the first weapon to exploit the effect of the shaped charge. The presentation of the tank rifle was not successful; but the value of the concept was recognized.

In the period 1935–1938, the lining effect was discovered, which led to an increase in penetration performance. The Swiss Heinrich Mohaupt claims to have discovered this in late 1935. Thomanek made this discovery on February 4, 1938 at the Aviation Research Institute in Braunschweig . The discoveries happened randomly and probably independently of one another; a detailed investigation of this phenomenon was not possible at first. Mohaupt received a patent on November 9, 1939 in France, Thomanek on December 9, 1939 in Germany. However, the date of Mohaupt's discovery is controversial. While Thomanek's events can be well substantiated by documents, Mohaupt's only depend on his retrospective reports, which he wrote in 1966.

The shaped charge was first used on May 10, 1940 when German paratroopers stormed the Belgian fort Eben-Emael . Shaped charges weighing up to 50 kg were used to destroy the armored domes. These shaped charges did not correspond to the German state of knowledge, because they were used with no distance to the target and without taking the lining effect into account.

Shortly after his discovery, Thomanek moved to Hubert Schardin at the Air Force Technical Academy in Berlin-Gatow . Shortly after Thomanek had given shaped charge research a new direction, Siemens scientist Max Steenbeck proposed an X-ray photometric study of the gas discharge in shaped charges. In the period that followed, the Ballistic Institute and the Siemens research laboratory developed X-ray flash tubes with which more than 45,000 images per second were recorded. This made it possible for the first time to observe and analyze the jet formation with a shaped charge and the effect on an armor plate. As a result, extensive optimizations were carried out by Schardin in the Heereswaffenamt (HWA) and at the Air Force Academy, which were used directly in the development of weapons, of which the bazooka in particular became known. After Erich Schumann had taken over the management of army research at the Heereswaffenamt , Walter Trinks rose to head of the Wa FI b 'Explosive Physics and Shaped Charges Division in 1940. By the end of the war, Trinks' group of scientists had developed at least forty secret patents on the subject of hollow charges.

Heinrich Mohaupt brought shaped charge technology to the USA in 1940 , which led to shaped charge rifle grenades and later to the development of the bazooka .

Atomic shaped charges

The theoretical work of the flow researchers Adolf Busemann and Gottfried Guderley in 1942 gave the impetus for a completely new working direction in nuclear physics. Both worked at the Aviation Research Institute in Braunschweig and focused on the focus of shock waves . They showed how high-energy, shock-like waves could be used to achieve pressure and temperature jumps in a small area around the center of convergence. Their research gave the impetus for experiments to initiate fusion reactions using extremely high pressures and temperatures .

At the suggestion of Carl Ramsauer , the head of the research department at AEG , experiments with deuterium-filled hollow bodies began in autumn at the HWA (Walter Trinks, Kurt Diebner ) and the Navy Weapons Office (MWA, Otto Haxel ). In October 1943, Trinks began a series of experiments at the Kummersdorf-Gut Army Research Institute, releasing atomic energy through reactions between light elements . According to his own statement, the attempts failed, but were apparently continued in secret.

Erich Schumann , Trinks and Diebner explained in patents and publications after the war the scientific and technical way of producing hollow atomic charges. However, only Diebner responded to the need to add fissile materials ( 235 U , 233 U , plutonium ). The author HJ Hajek published in 1956 under a pseudonym in the magazine "Explosivstoffe" (issue 5/6 1955, p. 65 ff) an article about atomic shaped charges. In it he also referred to a work by the French Ministry of Atomic Energy on atomic charges, which is still blocked today.

functionality

A cone-shaped metal insert with an opening pointing forward is surrounded by explosives that are as explosive as possible. The detonator sits on the back of the cargo. When the charge is ignited, a spike of cold-formed metal forms - starting from the tip of the metal cone - which penetrates the target at very high speed, followed by a slower “pestle”, which forms the main mass.

Contrary to popular belief, the material does not reach the melting point. It is pure cold forming at very high pressure. Nevertheless, when using shaped charges, fires and fires often occur, which can be attributed to the pressure-liquefied target material, which is pyrophorically distributed in the air and burns.

Formation of the cumulative metal beam when a shaped charge detonates (drawing B)

The insert or lining ( English liner ) is made of a well malleable metal with the highest possible density to increase the penetration power . For this reason, copper is often used. Uranium , as in the Russian 3BK-21B, and tantalum , for example in the TOW2B , are also used and, thanks to their pyrophoric, fire-generating properties, intensify the damage after the armor penetrates.

The generation of this metal beam is made possible by a geometrical-dynamic peculiarity during detonations of shaped charges, according to which the detonation front propagates as a shock wave at supersonic speed and the metal insert is bundled in a line along the axis to interact (see drawing B). Individual particles called “spindles” are detached from the resulting sting, which then act on the target in a highly energetic manner. If the arrangement is sufficiently precise, a channel with small cavities is created . On the other hand, the explosion gases flowing in at subsonic speed are irrelevant for the effect.

Animation of the detonation of a shaped charge

The speed of the spike depends on the one hand on the explosive nature of the explosive and on the other hand on the taper angle of the metal insert. The more acute the cone angle, the higher the speed of the sting. At the same time, however, with a more acute cone angle, the mass of the spike decreases compared to the mass of the plunger. Therefore, to optimize the cone angle, a compromise is required between a high pin speed and a favorable ratio between the pin mass and the ram mass. Under laboratory conditions, speeds of around 100 km / s were achieved, but this is of no importance for commercial and military purposes because of the effort involved - including the expansion in vacuum chambers.

Since the detonation front alone would not have a great penetration force , the surface of the shaped charge is provided with a metal layer, as described above. During the detonation , the metal is cold-deformed by the pressure and thrown towards the longitudinal axis of the cone. There the metal meets and forms a cumulative metal beam .

The tip of this beam is moving at a very high speed. In military systems, this speed is in the range of about 7 km / s to 10 km / s. If this jet hits an obstacle, it creates extremely high pressure. At a jet speed of 10 km / s, the pressure is in the order of 200  GPa . At this pressure, solids behave like liquids, so that the metal jet penetrates the obstacle like a liquid according to the laws of fluid dynamics .

If such a shaped charge penetrates the armor of a vehicle, the explosive penetrating metal beam and splinters of the armor can ignite the fuel or the ammunition and kill the crew. The opening that such a jet leaves is much smaller than the caliber of the original bullet.

Since the cumulative beam needs some space to develop, shaped charges often have an elongated ballistic hood through which the charge can be ignited at a sufficient distance on impact. Because of the high velocity of the cumulative jet, the flight speed of the projectile loaded with the shaped charge is of secondary importance. Therefore, relatively slow, partly recoil-free projectiles are often provided with shaped charges, which means that the weight of the launcher can be kept low ( e.g. bazooka or bazooka ).

Reactive armor is used in tanks to defend against shaped charge projectiles . It consists of many attached explosive segments that detonate on impact and thereby swirl the jet. As a countermeasure, the tandem hollow charge was developed, whereby the front smaller hollow charge triggers the reactive armor and the rear main charge, which is ignited immediately afterwards, can then break through the now “unprotected” armor. Double shaped charges are mainly used in anti-tank guided weapons . The aircraft carriers of the Gerald R. Ford class use armor in which two plates are provided with sufficient electrical charge by means of capacitors so that the beam is evaporated as soon as it makes contact between the plates.

If the bullet is stabilized by means of a twist , the penetration performance is greatly reduced. The reason is that the centrifugal force expands the jet. For this reason, most shaped charge projectiles are wing stabilized.

See also

literature

  • Ian V. Hogg : Infantry Support Weapons. Motorbuch-Verlag, Stuttgart 1997, ISBN 3-613-01843-8 , ( weapons and device 4).
  • Rainer Karlsch : Hitler's bomb. The secret history of the German nuclear weapon tests. Deutsche Verlags-Anstalt, Munich 2005, ISBN 3-421-05809-1 .
  • Rainer Karlsch, Heiko Petermann (eds.): Pros and cons of “Hitler's bomb”. Studies on atomic research in Germany. Waxmann Verlag, Münster et al. 2007, ISBN 978-3-8309-1893-6 ( Cottbus studies on the history of technology, work and the environment 29).
  • Günter Nagel: Nuclear tests in Germany. Secret uranium works in Gottow, Oranienburg and Stadtilm. Heinrich-Jung-Verlagsgesellschaft, Zella-Mehlis et al. 2002, ISBN 3-930588-59-5 .
  • Donald R. Kennedy: History of the Shaped Charge Effect: The First 100 Years. Defense Technical Information Center, 1990 [3]

Web links

  • Helmut W. Malnig: Professor Thomanek and the development of the precision hollow charge. In: Troop service (magazine) . Episode 289, Issue 1/2006, [4]
  • James R. Chiles: From Bazookas To RPGs. In: Invention & Technology. Spring 2009, Volume 24 [5]

Individual evidence

  1. ^ Kennedy: History of the Shaped Charge Effect. 1990, pp. 6-9.
  2. ↑ Franz von Baader: Attempt a theory of explosive work. In: Bergmännisches Journal. [5], 1. 1792, St. 1–6 (Jan. - June) [1]
  3. ↑ Cf. Heinz Freiwald: On the history of the cavity effect in explosive charges. In: Writings of the German Academy of Aviation Research. Berlin 1941; Hubert Schardin : About the development of the shaped charge. Wehrtechnische Hefte 1954, Heft 4, S. 97ff.
  4. ↑ Helmut W. Malnig: Professor Thomanek and the development of the precision hollow charge. In: Troop service , episode 289, issue 1/2006 [2]
  5. ^ Kennedy: History of the Shaped Charge Effect. 1990, pp. 9-11.
  6. ^ Kennedy: History of the Shaped Charge Effect. 1990, p. 20.
  7. ^ Kennedy: History of the Shaped Charge Effect. 1990, p. 12.
  8. ^ Kennedy: History of the Shaped Charge Effect. 1990, p. 60.
  9. ↑ Cf. Max Steenbeck: Scientific publications of the Siemens factories. Vol. XVIII, 1938, p. 363.
  10. ↑ See Rudi Schall: X-ray strobes in operation and application. May 1953.
  11. ↑ Cf. Hubert Schardin: About the development of the hollow charge. In: Wehrtechnische Hefte 1954. Heft 4, p. 119.
  12. ↑ Interview with Professor Hauke ​​Trinks on April 29, 2004, recorded by Heiko Petermann. The group around Trinks included the PhD physicists Rudi Schall, Gerd Hinrichs, Werner Holtz, Ortwin Schulze, Werner Schwietzke and Günter Sachsse
  13. ↑ See e.g. B. Erich Schumann, Gerd Hinrichs: Preliminary communication to report 43/2 on increasing the effectiveness of hollow explosive devices through ignition guidance (lenses). and Erich Schumann: About explosive weapons. Explosives Physics Report 44/9, November 16, 1944, Erich Schumann estate.
  14. ^ Kennedy: History of the Shaped Charge Effect. 1990, p. 11.
  15. ↑ Cf. Gottfried Guderley: Strong spherical and cylindrical compression shocks near the center of the sphere or the cylinder axis. In: Zeitschrift für Luftfahrtforschung. 1942, Vol. 19, Vol. 9, pp. 302-312; Adolf Busemann: The axially symmetrical spherical supersonic flow . In: ibid., Vol. 19, Lfg. 4, pp. 137-145.
  16. ↑ a b c 1948/49 - Erich Schumann: The truth about the German work and suggestions on the atomic nuclear energy problem (1939-45). Chapter II of the manuscript contains information and construction suggestions for the ignition of fusion reactions. Federal Archives , Federal Archives-Military Archives
  17. ↑ Cf. Walter Trinks: About the nature of detonation and the mode of action of hollow explosive charges. In: Soldier und Technik. 1958/11 and Rudi Schall : Advances in military explosives research. In: Defense technical monthly books. 54th year 1957, pp. 386-394.
  18. ↑ See Walter Herrmann, Georg Hartwig, Heinz Rackwitz, Walter Trinks, H. Schaub: Experiments on the initiation of nuclear reactions through the action of exploding substances. G-303, German Museum Munich.
  19. ↑ Reports from contemporary witnesses about ball experiments (cooled shell arrangements and strong explosions in the Friedland area ( Mecklenburg ), mentioned in Rainer Karlsch: Hitler's bomb.
  20. ^ Written communication from Walter Gerlach to Hermann Göring about fusion experiments
  21. ↑ See patent device to bring material for the initiation of mechanical, thermal or nuclear processes to extremely high pressures and temperatures. No. 977.825, Inventor Schumann, Trinks; Applicant: Federal Ministry of Defense August 13, 1952, publication April 8, 1971, cf. also Patent No. 977863; Process for the ignition of thermonuclear reactions by means of convergent detonation compression collisions. Patent No. D 23685, applicant Kurt Diebner, Friedwardt Winterberg , filing date August 28, 1956; "Method for the electromagnetic ignition of thermonuclear fuel"; Patent No. D 24361, applicant Kurt Diebner, Friedwardt Winterberg, filing date November 30, 1956.
  22. ↑ a b Cf. Kurt Diebner: Fusion processes with the help of convergent shock waves - some older and newer experiments and considerations. In: Kerntechnik, March 1962, p. 90.
  23. ↑ Cf. Walter Trinks: About a process for generating the highest pressures and temperatures. (Unpublished manuscript 1943), quoted from: H. von Falser: About the explosive-driven implosion of gas-filled metallic hollow bodies. August 1972 (unpublished manuscript).
  24. ↑ Cf. 1960 was followed by a detailed article "The possibility of nuclear reactions using shaped charges" published in Wehrtechnische Monatshefte 1960, p. 8 ff. Hajek explained in detail the mode of operation of the atomic shaped charge with reference to successful experiments with oppositely directed shaped charge cascade ignition.
  25. ^ G. I. Pokrowski: Explosion and demolition. BSB BG Teubner publishing company