How loud was the heavy Gustav weapon

Syria: tank destroyers in slippers

The civil war in Syria shows again how rebels with small pipes on their shoulders destroy powerful battle tanks. But how does it work? About the function and history of the bazooka and Austria's contribution to it.

The "Kalashnikov" is already a household name to the last pacifist and Tanti Anni: the automatic rifle developed by Mikhail Kalashnikov in Russia at the end of the 1940s with the characteristic curved magazine, of which more than 80 to 100 million units have so far been built and which are not part of the basic equipment belongs only to many armies, but to every rebel force between Nigeria and the Philippines.

Less conspicuous for laypeople are images from the Syrian civil war, showing rebels in tracksuits or caftans and sneakers or slippers, carrying small pipes on their shoulders and thus firing a strangely conical projectile about the size of two eggplants amid a lot of smoke.

Then you can see smoke and fire rising from tanks, sometimes the turrets are blown away and lie like nutshells on the ground, while the men with the pipes cheer all around.

Apparently the eggplant-sized projectiles destroyed the steel colossi. But how can a small object that is fired from the shoulder by a man with no apparent effort knock out a heavily armored vehicle? For example, a Russian-type T-72 main battle tank, of which Syria had at least 1700 pieces on paper two years ago, which weighs around 42 tons and whose steel armor on the most common models is more than eleven centimeters thick at the thickest points?

Part one of the answer is "RPG" - that's the name of these pipes, which in Russian stands for "Rutschnoi Protiwotankowy Granatomjot" ("manually operated anti-tank grenade launcher").

In English this is interpreted as "Rocket Propelled Grenade". Since the Second World War, the casual term "Panzerfaust" has been used for such weapons. The RPG was developed in the USSR at the end of the 1940s to give the infantry a portable anti-tank weapon below the threshold of the anti-tank guns customary at the time, those bulky, hundreds of kilograms and more heavy guns that half a dozen men needed to operate and pulled by trucks were.

Basically, RPGs are metal tubes with a diameter of 40 millimeters from which rocket propelled grenades are launched.

Because of the heat development, the pipes are clad with wood on the outside and have a visor. Because the exhaust gases escape to the rear at the start, this compensates for the recoil, the shooter is not knocked over and feels almost nothing.

The first RPG model ejected the projectile not with a rocket, but with a gunpowder launch charge, it flew only 150 meters. Stronger variants emerged later; the most widespread and most visible in trouble spots such as Syria or Somalia has been the legendary RPG-7 since 1961: the projectile has rocket propulsion and flies about 1000 meters. More than nine million pieces of it alone were built, also under license in other countries. It is one of the most widespread weapons and is in the arsenal in over 80 countries, from Angola to Poland to Vietnam.

Grenade accelerates to just 300 meters per second

The launch tube weighs around seven kilograms and is easy to operate: the shooter or a helper takes one of the projectiles with a tubular rocket on the back, screws a launch propellant to the latter and sticks the whole elongated thing, which weighs a few kilograms, in the front into the starting pipe. The shooter aims and pulls the trigger. The starting set drives the projectile out of the barrel, after ten meters the rocket ignites and accelerates the grenade to a good 300 meters per second.

The accuracy drops quickly: at 50 meters you can hardly miss, but at 200 meters the chance of hit is only about 50 percent, at 500 meters five percent. In addition, due to their elongated shape, the projectiles are susceptible to side winds, wind can act on them like a lever and disrupt their path.

But when it hits the target, the RPG-7 shells have a terrifying effect: two armor-piercing models (caliber 85 and 93 millimeters with a total weight of 2.5 kg including rocket) penetrate 26 and 50 centimeters, respectively, of typical armor steel. There is a "tandem bullet", in which two charges mounted one behind the other act on the target and pierce 75 cm of steel. There are fragmentation grenades against unarmored targets. The RPG-29 "Vampire" (since 1989) can use a tandem warhead to reach 75 cm of steel or 1 , Shoot through 5 meters of concrete or four meters of earth.

How does the grenade crack the tank?

But how does the little grenade crack the tank? One would think that a bullet would have to be very fast and / or heavy and hard for this. Indeed, anti-tank guns accelerate their grenades from 600 to 1,300 meters per second, whereas RPG grenades are snails. The anti-tank bullets were often not much heavier than those of the RPGs, but made of hard steel. The bullets of the RPGs, however, are mostly made of plastic, some explosives - and mostly hollow.
But therein lies the solution to the riddle and part two of the answer, and this is: Panzerfausts use a shaped charge.

In principle, explosives emit their explosive energy uniformly in all directions. If you simply place it on an armored plate, at least half of the energy in the air evaporates and the plate is often only dented. But you can bundle parts of the explosion in one direction by giving explosives certain shapes: Then the explosion pierces the steel.
And that's what happens with a shaped charge grenade like that of the RPG-7.

Inside it is a metal cone shell (you can also call it a funnel), which is clad with explosives on the outside of the sloping sides (you can also imagine it as a cylinder made of explosives, into which you drive a cone-shaped indentation and coat it with metal). The funnel opening points to the target, it is covered by an aerodynamic, mostly conical plastic cover with an ignition sensor at the tip.
Upon impact, the sensor electrically activates the detonator on the back of the explosive, which burns forward in fractions of a second - and generates the "shaped charge effect": The fronts of the detonation waves are bundled in the conical cavity as if by a focal lens and become an energy beam, a converging shock wave , condensed.

At the same time, the pressure liquefies the metal insert and ejects it forward along the shock wave beam in the form of a "spike" that penetrates the target.

The forces and speeds that occur are enormous: the spike made of liquid metal reaches seven to 14 kilometers per second after 40 millionths of a second at pressures of 600,000 to two million bar. Such pressures prevail near the Earth's core, where carbon turns into diamond. And: Metals behave like a liquid - if the sting hits the armor, it too becomes liquid there and the sting "drives" through it like a submarine through the water.

Contrary to popular assumption, the metals do not reach the melting point: The sting is "only" about 600 degrees hot; it is only the pressure that causes the "cold" liquefaction.

In the tank, the splashing metal causes damage, can kill or injure the crew, and ignite ammunition and fuel. In addition, there is the "pyrophoric" (fire-carrying) effect: metal dusts finely distributed in the air tend (especially under heat and pressure) to react strongly with oxygen. In other words, they form clouds of fire.

-> YouTube video: Effect of a shaped charge

But because the high-pressure sting has little mass, it evaporates quickly: In the open air, it dissolves after two to three meters with normal shaped charges. But at short distances it looks enormous; Roughly speaking, a modern military shaped charge has a penetration depth into steel of more than seven times its caliber, which is sufficient for most tanks.

The history of the hollow charge is quite old: In 1792 the Bavarian philosopher and mining engineer (what a strange combination) Franz Xaver von Baader described in the "Bergmännischen Journal" that a conical indentation in a gunpowder charge increases the explosive effect. Max von Förster, director of the gun cotton factory "Wolff & Co." in Walsrode (Lower Saxony) studied the consequences of a cavity in the explosive device in 1883.

Accidental discovery by a US chemist

The accidental discovery of the US chemist Charles Munroe (1849-1938) became famous: he worked at a research center for torpedoes for the US Navy in Newport, Rhode Island, and carried out explosive tests with balls of gun cotton, among other things; the name of the manufacturer or the letters "USN" (United States Navy) were stamped on the bales. In 1888 he noticed that if a bale exploded on or next to a metal plate, the lettering was then cut into the metal.

Later he built a crude shaped charge grenade by bundling dynamite sticks around a tin can and placing the can opening down on a massive safe: the explosion punched a hole in it.
For a long time Munroe and other shaped charge experimenters were not fully aware of the importance of the can: The funnel-shaped metal layer in the shaped charge that forms the sting multiplies the penetration power of the indented explosive. This is called the "lining effect", and this was discovered by the Viennese engineer and physicist Franz Thomanek (1913-90).

Surprisingly, the military was not interested in shaped charges for a long time, although such explosive devices (without a metal insert) were already used in mining and demolition work in the 19th century. Thomanek, who studied in Vienna and Berlin and tinkered with rockets, was one of the first to deal with a warlike benefit. In 1932 he designed an anti-tank rifle with a shaped charge projectile. The armed forces were not interested, Thomanek went to Germany and built the weapon by 1935. It was not a success, the Army Weapons Office refused. Nevertheless, the German military recorded the possibilities of shaped charges and carried out further research on many lines. And so Thomanek came across the lining effect in February 1938 while working at the Research Institute for Aviation in Braunschweig.

Due to the speed of events, it has been a long time not known what was happening in a shaped charge and its destination. This could only be observed when Siemens built special cameras at the end of the 1930s that worked with X-ray flashes and took over 45,000 images per second.

Almost all metals and other substances have been tested as lining, such as titanium, lead, uranium, gold. Most commonly, copper, tantalum in modern weapons, is an expensive transition metal. Sometimes you add a second lining made of a highly pyrophoric material such as magnesium and aluminum to create more fire in the target.

Thomanek's work led to explosives with which the Belgian fortress Eben-Emael on the Dutch border near Maastricht, which was considered to be impregnable, was cracked at the beginning of the western campaign on May 10, 1940 - by around 80 parachute pioneer soldiers who landed on its roof with gliders and with shaped charges destroyed the more than 50 centimeter thick armored domes of the gun turrets and the meter thick casemates; the more than 700 defenders gave up the next day.

-> YouTube video: Storming Fort Eben Emael

After 1945, Thomanek continued to work on missiles and anti-tank warheads in Germany, especially at Messerschmitt-Bölkow-Blohm in Schrobenhausen near Augsburg (now MBDA Missile Systems). Its charges were used, for example, in the Franco-German "Milan" and "HOT" anti-tank missiles.
Nevertheless, when it came to shaped charge weapons, the Americans were slightly ahead of the curve (in English it is called "Shaped Charge"): First of all, in November 1918, the Army rocket researcher Robert Goddard (1882-1945), who later became famous, had the draft of one Introduced an explosive head missile that a soldier could launch from a pipe. The First World War was over days later and the project died.

US military developed the "Bazooka"

In the 1930s, the Swiss Henry Mohaupt studied shaped charges and came across the lining effect around the same time as Thomanek - possibly even earlier, we don't know for sure, because the work was done secretly, but Mohaupt didn't patent his discovery until 1939. He passed on his knowledge to the French and British and was invited by the USA in 1940 because they were keen on his technology. Some bright minds in the US military combined Mohaupt's grenades with Goddard's rocket launchers. Result: the "Bazooka" (the idea for the name came from a radio comedian), a tube from which an electrically ignited rocket with a slim 60-millimeter shaped charge head flew around 360 meters Projectile pierced eight to ten centimeters of steel.