Earth quake bomb
Encyclopedia
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.
An explosion in air does not transfer much energy into a solid, due to acoustic impedance
. Due to a 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 the target was 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 a bomb could be designed to explode in water, soil, or other less compressible materials, the explosive force would be transmitted more efficiently to the target object.
Wallis' idea was to drop a large, heavy bomb with a hard armoured tip at supersonic speed so that it penetrated the ground — an effect comparable to 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 would produce the equivalent of a miniature earthquake, destroying any nearby structures such as dams, railways, viaducts, etc. Any concrete reinforcement of the target would likely 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 thus produce an underground cavern (a camouflet
) which would remove the structure's underground support, thus causing it to collapse. The process 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, however, and Barnes Wallis' ideas were then shown to be superbly successful, considering the standards at the time.
Wallis' first concept was for a ten-ton bomb that would explode some 130 ft (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 the "Victory Bomber
", but he was not taken seriously by the military hierarchy of the day.
Wallis took a different line with attacks on Germany's industrial structure developing a means to destroy the supply of hydroelectric power. After he had developed the bouncing bomb
and shown its possibilities, however, RAF Bomber Command
were prepared to listen to his other ideas, even though they often thought them strange. The officer classes of 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 (8 km). Even from this low height, the earthquake bomb had the ability to disrupt German industry while causing minimum civilian casualties. It was used to disable the V2
factory, bury the V3 guns
, sink the Tirpitz
and damage the U-boat
s' protective pens at St. Nazaire, as well as to attack many other targets which had been impossible to damage before. One of the most spectacular attacks was shortly after D-Day
, when a Tallboy was used to prevent German tank reinforcements from moving by train. Rather than blow up the tracks — which would be repaired in a day or so — the bomb was targeted on a tunnel near Saumur which carried the line under a mountain. It was dropped on the mountain, drilled straight through the rock, and exploded in the tunnel below. As a result, the entire rail line remained unusable until the end of the war.
After World War II, the United States developed the 43,600 lb (19,800 kg) T12 demolition bomb that was designed to create an earthquake effect. Given the availability of nuclear weapons, however, there was little or no development of conventional deep penetrating bombs until the first 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 the 5,000 lb (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 begun development of the 30000 pounds (13,607.8 kg) Massive Ordnance Penetrator
, designed to attack very deeply buried targets without the use of nuclear weapons and their attendant risk of retaliation in kind.
Barnes Wallis
Sir Barnes Neville Wallis, CBE FRS, RDI, FRAeS , was an English scientist, engineer and inventor. He is best known for inventing the bouncing bomb used by the RAF in Operation Chastise to attack the dams of the Ruhr Valley during World War II...
early in World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
and subsequently developed and used during the war against strategic targets in Europe.
Development
Acoustic impedance
The acoustic impedance at a particular frequency indicates how much sound pressure is generated by a given air vibration at that frequency. The acoustic impedance Z is frequency dependent and is very useful, for example, for describing the behaviour of musical wind instruments...
. Due to a lack of accuracy of bombing in the face of anti-aircraft defences, air forces used area bombardment
Area bombardment
In military aviation, area bombardment is aerial bombardment targeted indiscriminately at a large area, such as a city block or an entire city.Area bombing is a form of strategic bombing...
, dropping large numbers of bombs so that it would be likely that the target was 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 a bomb could be designed to explode in water, soil, or other less compressible materials, the explosive force would be transmitted more efficiently to the target object.
Wallis' idea was to drop a large, heavy bomb with a hard armoured tip at supersonic speed so that it penetrated the ground — an effect comparable to 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 would produce the equivalent of a miniature earthquake, destroying any nearby structures such as dams, railways, viaducts, etc. Any concrete reinforcement of the target would likely 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 thus produce an underground cavern (a camouflet
Camouflet
A camouflet, in military science, is an artificial cavern created by an explosion. If the explosion reaches the surface then it is called a crater....
) which would remove the structure's underground support, thus causing it to collapse. The process was graphically described as a "trapdoor effect" or "hangman's drop".
Wallis foresaw that disrupting German
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
industry would remove its ability to fight, and also understood that precision bombing
Precision bombing
Precision bombing is bombing of a small target with extreme accuracy, to limit side-effect damage. An example would be destroying a single building in a built up area causing minimal damage to the surroundings...
was virtually impossible in the late 1930s. The technology for precision aiming was developed during World War II, however, and Barnes Wallis' ideas were then shown to be superbly successful, considering the standards at the time.
Wallis' first concept was for a ten-ton bomb that would explode some 130 ft (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 the "Victory Bomber
Victory Bomber
The British "Victory Bomber" was a Second World War design by Barnes Wallis at Vickers-Armstrongs at Brooklands for a bomber to carry his projected "earthquake bomb" to strategic targets in Germany.-Background:...
", but he was not taken seriously by the military hierarchy of the day.
Wallis took a different line with attacks on Germany's industrial structure developing a means to destroy the supply of hydroelectric power. After he had developed the bouncing bomb
Bouncing bomb
A bouncing bomb is a bomb designed specifically to bounce to a target across water in a calculated manner, in order to avoid obstacles such as torpedo nets, and to allow both the bomb's speed on arrival at the target and the timing of its detonation to be pre-determined...
and shown its possibilities, however, RAF Bomber Command
RAF Bomber Command
RAF Bomber Command controlled the RAF's bomber forces from 1936 to 1968. During World War II the command destroyed a significant proportion of Nazi Germany's industries and many German cities, and in the 1960s stood at the peak of its postwar military power with the V bombers and a supplemental...
were prepared to listen to his other ideas, even though they often thought them strange. The officer classes of 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 (8 km). Even from this low height, the earthquake bomb had the ability to disrupt German industry while causing minimum civilian casualties. It was used to disable the V2
V-2 rocket
The V-2 rocket , technical name Aggregat-4 , was a ballistic missile that was developed at the beginning of the Second World War in Germany, specifically targeted at London and later Antwerp. The liquid-propellant rocket was the world's first long-range combat-ballistic missile and first known...
factory, bury the V3 guns
V-3 cannon
The V-3 was a German World War II supergun working on the multi-charge principle whereby secondary propellant charges are fired to add velocity to a projectile....
, sink the Tirpitz
German battleship Tirpitz
Tirpitz was the second of two s built for the German Kriegsmarine during World War II. Named after Grand Admiral Alfred von Tirpitz, the architect of the Imperial Navy, the ship was laid down at the Kriegsmarinewerft in Wilhelmshaven in November 1936 and launched two and a half years later in April...
and damage the U-boat
U-boat
U-boat is the anglicized version of the German word U-Boot , itself an abbreviation of Unterseeboot , and refers to military submarines operated by Germany, particularly in World War I and World War II...
s' protective pens at St. Nazaire, as well as to attack many other targets which had been impossible to damage before. One of the most spectacular attacks was shortly after D-Day
D-Day
D-Day is a term often used in military parlance to denote the day on which a combat attack or operation is to be initiated. "D-Day" often represents a variable, designating the day upon which some significant event will occur or has occurred; see Military designation of days and hours for similar...
, when a Tallboy was used to prevent German tank reinforcements from moving by train. Rather than blow up the tracks — which would be repaired in a day or so — the bomb was targeted on a tunnel near Saumur which carried the line under a mountain. It was dropped on the mountain, drilled straight through the rock, and exploded in the tunnel below. As a result, the entire rail line remained unusable until the end of the war.
After World War II, the United States developed the 43,600 lb (19,800 kg) T12 demolition bomb that was designed to create an earthquake effect. Given the availability of nuclear weapons, however, there was little or no development of conventional deep penetrating bombs until the first Gulf War
Gulf War
The Persian Gulf War , commonly referred to as simply the Gulf War, was a war waged by a U.N.-authorized coalition force from 34 nations led by the United States, against Iraq in response to Iraq's invasion and annexation of Kuwait.The war is also known under other names, such as the First Gulf...
. 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
Eglin Air Force Base
Eglin Air Force Base is a United States Air Force base located approximately 3 miles southwest of Valparaiso, Florida in Okaloosa County....
in Florida
Florida
Florida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...
developed the 5,000 lb (2,300 kg) GBU-28
GBU-28
The Guided Bomb Unit 28 is a 5,000 pound laser-guided "bunker busting" bomb nicknamed "Deep Throat" 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...
that was used successfully by F-111Fs against a deep underground complex not far from Baghdad
Baghdad
Baghdad is the capital of Iraq, as well as the coterminous Baghdad Governorate. The population of Baghdad in 2011 is approximately 7,216,040...
just before the end of the war.
The United States has begun development of the 30000 pounds (13,607.8 kg) Massive Ordnance Penetrator
Massive Ordnance Penetrator
The Massive Ordnance Penetrator GBU-57A/B is a project by the U.S. Air Force to develop a massive, precision-guided, "bunker buster" bomb...
, designed to attack very deeply buried targets without the use of nuclear weapons and their attendant risk of retaliation in kind.