A British 22,000 lb (10,000 kg) Grand Slam bomb

The Grand Slam (Earth Quake bomb), was a very large bomb developed by the British aeronautical engineer Barnes Wallis in late 1944. The Grand Slam bomb was twice the weight of his previous large bomb, the Tallboy; both weapons were intended for use against large and protected buildings, and structures against which smaller bombs would be ineffective. The Grand Slam weighed nearly ten tonnes. Image File history File links Please see the file description page for further information. ... Image File history File links Please see the file description page for further information. ... The earth quake bomb concept was invented by Barnes Wallis before the second world war. ... Aerospace engineering is the branch of engineering that concerns aircraft, spacecraft and related topics. ... Sir Barnes Neville Wallis Sir Barnes Neville Wallis, CBE, FRS, RDI, commonly known as Barnes Wallis, (September 26, 1887 – October 30, 1979) was an English scientist, engineer and inventor. ... 1944 (MCMXLIV) was a leap year starting on Saturday (the link is to a full 1944 calendar). ... Tallboy bomb The Tallboy was an Earth Quake bomb developed by Barnes Wallis and brought into operation by the British in 1944. ...

Development history

The idea of the earthquake bomb was explored by Barnes Wallis at the very start of the war (see Tallboy bomb for the principle of his 'earthquake' bombs and their intended purpose in strategic warfare) but at the time there were no aircraft capable of carrying the 10 ton weapon he envisaged (notwithstanding Wallis's suggestions to build one, a six engine high-altitude bomber called "Victory"). Wallis returned to his designs in the latter part of the war and the first earthquake bomb he developed was the 5-ton Tallboy. It proved effective in demolishing large structures, including heavily-protected bunkers (an early "bunker buster"). Image File history File links Grand_slam_bomb. ... Image File history File links Grand_slam_bomb. ... Tallboy bomb The Tallboy was an Earth Quake bomb developed by Barnes Wallis and brought into operation by the British in 1944. ... The Victory Bomber was a design by Barnes Wallis for a bomber that could carry a single large earthquake bomb. ... A bunker buster bomb is designed to penetrate hardened targets or targets buried deep underground. ...

The reasoning behind the earth penetration bomb is that the explosive waves transmit power more efficiently in a non-compressible medium. Barnes Wallis used the non-compressible nature of water as a factor in the bouncing bombs. The earthquake bomb was designed to penetrate the earth and explode some 30 m down. An explosion carried through the medium of the earth would thus cause damage for a much greater distance than if the bomb were to explode in open air. Wallis also understood that bomb aiming was very poor at the time. The major advantage of the earthquake bomb, therefore, was that it could miss by hundreds of yards and still achieve the desired result. The intention before the war started was to destroy dams, railway bridges and general infrastructure. Thus it is possible that German industry and infrastructure could have been seriously damaged with minimal loss of civilian lives, compared to Area bombing. His ideas were not fully understood, appreciated, or even realisable at the time. The bouncing bomb was a variety of depth charge style of bomb designed by Barnes Wallis of Vickers-Armstrong at Brooklands, Surrey. ... Area bombardment is the policy of indiscriminate bombing of an enemys cities, for the purpose of destroying civilian morale. ...

When it was calculated that the Avro Lancaster B1 Special bombers used for Tallboy could carry an even larger bomb, work started on the Grand Slam, which was effectively a scaled-up Tallboy. The new design was highly aerodynamic, with a long tail incorporating offset fins, causing it to spin as it fell and stabilizing it, much as the spin imparted by the rifling of a gun barrel increases the accuracy of a bullet. The spin also allowed the bomb to reach supersonic speeds, as the increased stability enabled it to pass through the sound barrier without wobbling or being thrown off-course. The Avro Lancaster was a four-engine World War II bomber aircraft made initially by Avro for the Royal Air Force (RAF). ... Rifling of a Canon de 75 modèle 1897 A 35 caliber Remington, with a microgrove rifled barrel with a right hand twist. ... U.S. Navy F/A-18 at transonic speed. ...

The Grand Slam had a much thicker case than typical World War II bombs, so it would survive the impact of hitting a hardened surface. The hardened steel bomb casing was cast in one piece in a sand mould using a concrete core. Torpex was then poured in, bucket by bucket. When filled, the hot molten explosive took a month to cool down and set, greatly limiting production. Like the Tallboy, the rate of production and material and manpower investment in each bomb meant that aircrews were told to land with their unused bombs onboard, rather than jettison them into the sea if a sortie was aborted. Torpex is a secondary explosive 50% more powerful than TNT by weight. ...

When dropped from high altitude onto compacted earth, the Grand Slam would penetrate over 40 metres into the ground. The explosion would leave a camouflet (cavern) which would undermine foundations of structures above, causing collapse. This is what happened to the Bielefeld railway viaduct, the first enemy target destroyed by a Grand Slam. A Camouflet is military science term to describe an artificial cavern created by an explosion to undermine a structure. ... Bielefeld is a city in North Rhine-Westphalia, Germany. ... Torontos Bloor Street Viaduct bridges the Don valley; road traffic uses the upper deck, rail traffic uses the lower deck. ...

Operational use

The Farge U-boat pen after being hit by a Grand Slam - note the figure standing on the pile of rubble.

The 'B1 (Special)' Lancaster bomber could only carry one at a time and it had to be dropped from 22,000 feet (6700 m) which limited its accuracy. The Grand Slam was first used on March 14, 1945 when the Royal Air Force No. 617 "Dambusters" Squadron, lead by Squadron Leader C.C. Calder, attacked the Bielefeld railway viaduct destroying two spans of the viaduct.^[1] Image File history File links Download high resolution version (800x1142, 549 KB) Please see the file description page for further information. ... Image File history File links Download high resolution version (800x1142, 549 KB) Please see the file description page for further information. ... U-boat pens were large concrete bunkers erected along Frances Bay of Biscay by the German Third Reich during World War II. The pens were designed to protect German submarines (U-boats) from Allied bombs, and were generally effective until the introduction of the Tallboy bomb which was able... March 14 is the 73rd day of the year in the Gregorian Calendar (74th in leap years) with 292 days remaining in the year. ... Year 1945 (MCMXLV) was a common year starting on Monday (the link is to a full 1945 calendar). ... The Royal Air Force (RAF) is the air force branch of the British Armed Forces. ... No. ... A Squadron Leaders sleeve/shoulder insignia Squadron Leader is a commissioned rank in some air forces. ... Bielefeld is a city in North Rhine-Westphalia, Germany. ... Torontos Bloor Street Viaduct bridges the Don valley; road traffic uses the upper deck, rail traffic uses the lower deck. ...

The viaduct at Arnsberg was bombed on 15 March 1945 with 2 Grand Slam and 14 Tallboy bombs but they failed to bring the viaduct down. Four days later on 19 March 1945 another attack by No 617 Squadron using 6 Grand Slams, was successful and a 12 m (40 ft) gap was blown in the viaduct.^[1] Map of Germany showing Arnsberg Arnsberg is a town in North Rhine-Westphalia, Germany. ... March 15 is the 74th day of the year in the Gregorian Calendar (75th in Leap years). ... Year 1945 (MCMXLV) was a common year starting on Monday (the link is to a full 1945 calendar). ... March 19 is the 78th day of the year in the Gregorian calendar (79th in leap years). ... Year 1945 (MCMXLV) was a common year starting on Monday (the link is to a full 1945 calendar). ...

Farge is a small port on the Weser River north of Bremen, and was the site of an oil-storage depot and the Valentin submarine pens that were attacked by the RAF on 27 March 1945. The pens had a ferrous concrete roof up to 7 metres (23 feet) thick. Two Grand Slam bombs penetrated a section with a 4.5 m roof.^[2] Farge is a small port on the Weser River north of Bremen. ... Weser watershed Orthographic projection centred over Bremen The Weser is a river of north-western Germany. ... The river Weser flows through Bremen to the estuary at Bremerhaven. ... March 27 is the 86th day of the year in the Gregorian Calendar (87th in leap years). ... Year 1945 (MCMXLV) was a common year starting on Monday (the link is to a full 1945 calendar). ... Reinforced concrete at Sainte Jeanne dArc Church (Nice, France): architect Jacques Dror, 1926–1933 Reinforced concrete, also called ferroconcrete in some countries, is concrete in which reinforcement bars (rebars) or fibers have been incorporated to strengthen the material that would otherwise be brittle. ... metre or meter, see meter (disambiguation) The metre is the basic unit of length in the International System of Units. ...

Grand Slams were also successfully used against the Huuge and Brest submarine pens. By the end of the war 41 Grand Slam bombs had been dropped, mainly against bridges and viaducts. Torontos Bloor Street Viaduct bridges the Don valley; road traffic uses the upper deck, rail traffic uses the lower deck. ...

Marshal of the Royal Air Force Sir Arthur Harris GCB OBE AFC RAF, of RAF Bomber Command wrote in 1947 that: Marshal of the Royal Air Force Sir Arthur Travers Harris, 1st Baronet GCB OBE AFC RAF (April 13, 1892 - April 5, 1984), commonly known as Bomber Harris by the press, and often within the RAF as Butcher Harris[1], was commander of RAF Bomber Command and later a Marshal of... Bomber Command badge RAF Bomber Command was the organisation that controlled the RAFs bomber forces. ...

We already had Wallis's 12,000 lb. [Tallboy] medium capacity bomb, which was capable of breaking through the roof of a railway tunnel or a very thick concrete roof, and when the success of this bomb was proved Wallis designed a yet more powerful weapon, the 22,000 lb. bomb, the most destructive missile in the history of warfare until the invention of the atom bomb. This 22,000 lb. Bomb did not reach us before the spring of 1945, when we used it with great effect against viaducts or railways leading to the Ruhr and also against several U-boat shelters.

Post-war the Handley Page Victor was designed with the provision to carry either a single Grand Slam, or two of the smaller Tallboys, internally. The Handley Page Victor was a British jet bomber aircraft, one of the V bombers intended to carry Britains nuclear arsenal. ...

The US developed a larger bomb using the same principles as the Grand Slam, the T-12 Cloudmaker, which weighed 44,000 pounds (20,000 kg), but it was not employed during the war. T-12 shell at the U.S. Army Ordnance Museum, Aberdeen Proving Ground, Aberdeen, Maryland. ...

Characteristics

• Length: 7.70 m (26 ft 6 in)
• Tail: 4.11 m (13 ft, 6 in)
• Diameter: 1.17 m (3 ft, 10 in)
• Weight: 9.98 t (22,000 lb)
• Warhead: 4,144 kg (9,135 lb) "Torpex D1" (Torpedo explosive)
• Number used:41

A tonne or metric ton (symbol t), sometimes referred to as a metric tonne, is a measurement of mass equal to 1,000 kilograms. ... Torpex is a secondary explosive 50% more powerful than TNT by weight. ...

See also

• Nuclear bunker buster
• GBU-43 Massive Ordnance Air Blast bomb
• GBU-28
• BLU-82

• T12

Subsidence craters left over after underground nuclear (test) explosions Bunker-busting nuclear weapons, also known as earth-penetrating weapons (EPW), are a type of nuclear weapon designed to penetrate into soil, rock, or concrete to deliver a nuclear warhead to a target. ... The Massive Ordnance Air Blast (MOAB) (also known as the Mother Of All Bombs) is a large-yield conventional bomb developed by the United States military by Albert L. Weimorts Jr. ... Categories: Air-dropped bombs ... The factual accuracy of this article is disputed. ... T-12 shell at the U.S. Army Ordnance Museum, Aberdeen Proving Ground, Aberdeen, Maryland. ...

Further reading

• 612 attacked the Bielefeld railway viaduct
• Grand Slam bomb from WW2 (J Mullen)
• A live Grand Slam that survived in plain sight until 1958
• English Bombs of WWII
• Code Named "Aphrodite"
• Bombs Weapons Rockets Aircraft Ordnance
• Guinness world records
• camouflet
• Picture of the destroyed Arnsberg viaduct (German language site)
• A picture of a Grand Slam being released

Footnotes

1. ^ ^{a b} http://www.raf.mod.uk/bombercommand/mar45.html RAF: Bomber Command Campaign diary: March 1945]
2. ^ RAF: Bomber Command: Grand Slams