Grand Slam bomb
Overview
 
The Grand Slam was a 22,000 lb
Pound (mass)
The pound or pound-mass is a unit of mass used in the Imperial, United States customary and other systems of measurement...

 (10,000 kg) earthquake bomb used by 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...

 against strategic targets during the Second World War
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...

.

Known officially as the Bomb, Medium Capacity, 22,000 lb, it was a scaled up version of the Tallboy bomb
Tallboy bomb
The Tallboy or Bomb, Medium Capacity, 12,000 lb, was an earthquake bomb developed by the British aeronautical engineer Barnes Wallis and deployed by the RAF in 1944...

 and closer to the original size that the bombs' inventor, Barnes Wallis
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...

, had envisaged when he first developed his earthquake bomb idea.
On 18 July 1943, work started on a larger version of the Tallboy bomb, which became the Grand Slam.
Encyclopedia
The Grand Slam was a 22,000 lb
Pound (mass)
The pound or pound-mass is a unit of mass used in the Imperial, United States customary and other systems of measurement...

 (10,000 kg) earthquake bomb used by 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...

 against strategic targets during the Second World War
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...

.

Known officially as the Bomb, Medium Capacity, 22,000 lb, it was a scaled up version of the Tallboy bomb
Tallboy bomb
The Tallboy or Bomb, Medium Capacity, 12,000 lb, was an earthquake bomb developed by the British aeronautical engineer Barnes Wallis and deployed by the RAF in 1944...

 and closer to the original size that the bombs' inventor, Barnes Wallis
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...

, had envisaged when he first developed his earthquake bomb idea.

Development

On 18 July 1943, work started on a larger version of the Tallboy bomb, which became the Grand Slam. As with the original Tallboy, the Grand Slam's fins generated a stabilizing spin
Gyroscope
A gyroscope is a device for measuring or maintaining orientation, based on the principles of angular momentum. In essence, a mechanical gyroscope is a spinning wheel or disk whose axle is free to take any orientation...

 and the bomb had a thicker case than a conventional bomb, which allowed deeper penetration. After the hot molten Torpex
Torpex
Torpex is a secondary explosive 50% more powerful than TNT by mass. Torpex is composed of 42% RDX, 40% TNT and 18% powdered aluminium. It was used in the Second World War from late 1942. The name is short for Torpedo Explosive', having been originally developed for use in torpedoes...

 was poured into the casing, the explosive took a month to cool and set. Like the Tallboy, because of the low rate of production and consequent high value of each bomb, aircrews were told to land with their unused bombs on board rather than jettison them into the sea if a sortie was aborted.

After release from the Avro Lancaster
Avro Lancaster
The Avro Lancaster is a British four-engined Second World War heavy bomber made initially by Avro for the Royal Air Force . It first saw active service in 1942, and together with the Handley Page Halifax it was one of the main heavy bombers of the RAF, the RCAF, and squadrons from other...

 B.Mk 1 (Special) bomber, the Grand Slam would reach near-supersonic speed, approaching 320 m/s, and penetrate deep underground, with the explosion
Earth quake bomb
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.-Development:...

 causing 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....

 (cavern) and shifting the ground to undermine a target's foundation.

Like Tallboy, Grand Slam had not been designed to directly penetrate concrete roofs and tended to detonate prematurely or break up, but nonetheless they were still far more effective than any existing bomb.

Grand Slam combat operations

By the end of the war, 42 Grand Slams had been dropped on active service.

Bielefeld
Bielefeld
Bielefeld is an independent city in the Ostwestfalen-Lippe Region in the north-east of North Rhine-Westphalia, Germany. With a population of 323,000, it is also the most populous city in the Regierungsbezirk Detmold...

, 14 March 1945
The No. 617 Squadron RAF
No. 617 Squadron RAF
No. 617 Squadron is a Royal Air Force aircraft squadron based at RAF Lossiemouth in Scotland. It currently operates the Tornado GR4 in the ground attack and reconnaissance role...

 Avro Lancaster
Avro Lancaster
The Avro Lancaster is a British four-engined Second World War heavy bomber made initially by Avro for the Royal Air Force . It first saw active service in 1942, and together with the Handley Page Halifax it was one of the main heavy bombers of the RAF, the RCAF, and squadrons from other...

 of Squadron Leader CC Calder dropped the first Grand Slam bomb from 11,965 ft (3,647 m) on the Schildesche viaduct. More than 100 yards of the Bielefeld viaduct collapsed through the earthquake bomb effect of the Grand Slam and Tallboy bomb
Tallboy bomb
The Tallboy or Bomb, Medium Capacity, 12,000 lb, was an earthquake bomb developed by the British aeronautical engineer Barnes Wallis and deployed by the RAF in 1944...

s of No. 617 Squadron. No aircraft were lost. 50 Civilians died.


Arnsberg
Arnsberg
Arnsberg is a town in the Hochsauerland district, in North Rhine-Westphalia, Germany. It is the location of the Regierungsbezirk Arnsberg's administration and one of the three local administration offices of the Hochsauerlandkreis.-Geography:...

, 15 March 1945
Two aircraft of No. 617 Squadron RAF
No. 617 Squadron RAF
No. 617 Squadron is a Royal Air Force aircraft squadron based at RAF Lossiemouth in Scotland. It currently operates the Tornado GR4 in the ground attack and reconnaissance role...

 each carried a Grand Slam and 14 aircraft of No. 9 Squadron RAF carried Tallboy bomb
Tallboy bomb
The Tallboy or Bomb, Medium Capacity, 12,000 lb, was an earthquake bomb developed by the British aeronautical engineer Barnes Wallis and deployed by the RAF in 1944...

s to attack the railway viaduct in poor weather. One Grand Slam and 10 Tallboys were dropped, while one of the Lancasters was forced to bring its bomb back. The viaduct was not cut and no aircraft were lost.


Arnsberg, 19 March 1945
19 Lancasters of No. 617 Squadron, six carrying Grand Slams, the remainder Tallboys, attacked the railway viaduct at Arnsberg. All Grand Slams were dropped and blew a 40-foot (12 m) gap in the viaduct. The standing structure was severely damaged.


Arbergen, 21 March 1945
20 Lancasters of No. 617 Squadron, two carrying Grand Slams, the remainder Tallboys, attacked the railway bridge at Arbergen. The Grand Slams landed off target due to heavy flak and aiming problems; 2 Tallboy hits caused sufficient damage to the approaches to the bridge to put it out of use. One 617 Lancaster was lost.


Nienburg
Nienburg, Lower Saxony
Nienburg is a town and capital of the district Nienburg, in Lower Saxony, Germany.-Geography:Situated on the scenic German Framework Road, Nienburg lies on the river Weser, approximately southeast of Bremen, and northwest of Hanover...

, 22 March 1945: 20 Lancasters of No. 617 Squadron, six carrying Grand Slams, the remainder Tallboys, attacked the railway bridge at Nienburg, between Bremen
Bremen
The City Municipality of Bremen is a Hanseatic city in northwestern Germany. A commercial and industrial city with a major port on the river Weser, Bremen is part of the Bremen-Oldenburg metropolitan area . Bremen is the second most populous city in North Germany and tenth in Germany.Bremen is...

 and Hannover. 5 Grand Slams made direct hits and the bridge was completely destroyed. Another 5 bombs were brought home by the squadron.

Bremen
Bremen
The City Municipality of Bremen is a Hanseatic city in northwestern Germany. A commercial and industrial city with a major port on the river Weser, Bremen is part of the Bremen-Oldenburg metropolitan area . Bremen is the second most populous city in North Germany and tenth in Germany.Bremen is...

, 23 March 1945
20 Lancasters of No. 617 Squadron, six carrying Grand Slams, the remainder Tallboys, attacked a railway bridge near Bremen The Grand Slams appear to have landed too far from the target, which was brought down by a Tallboy. Author Jon Lake claims instead that two Grand Slams struck the bridge.


Farge
Farge
Farge is a small port on the Weser River in the City of Bremen. The bombing of Bremen in World War II attacked Farge targets, including the oil storage and the Valentin submarine pens.-Bremen-Farge concentration camp:...

, 27 March 1945
20 Lancasters of No. 617 Squadron attacked the Valentin submarine pens
Valentin submarine pens
The Valentin submarine pens are a protective shelter built to construct German U-boats during World War II at Farge, a small port on the Weser River in Bremen. The pens were under construction from 1943 to March 1945 using forced labour, but were damaged by air-raids and unfinished by the end of...

, a huge, nearly-ready structure with a concrete roof up to 23 ft (7.2 m) thick. Two Grand Slam bombs penetrated in parts of the pen with a 14 ft 5 inches (4.5 m) thick roof, which rendered the shelter unusable. No aircraft were lost.


Hamburg
Hamburg
-History:The first historic name for the city was, according to Claudius Ptolemy's reports, Treva.But the city takes its modern name, Hamburg, from the first permanent building on the site, a castle whose construction was ordered by the Emperor Charlemagne in AD 808...

, 9 April 1945
17 aircraft of No. 617 Squadron, two with Grand Slams and the remainder with Tallboy bombs successfully attacked the U-boat shelters. The Grand Slams appear to have missed, but six Tallboy hits caused considerable damage. No aircraft were lost.


Heligoland
Heligoland
Heligoland is a small German archipelago in the North Sea.Formerly Danish and British possessions, the islands are located in the Heligoland Bight in the south-eastern corner of the North Sea...

, 19 April 1945
20 aircraft of No. 617 Squadron, six with Grand Slams and the remainder with Tallboy bombs, along with 16 aircraft from No. 9 Squadron, attacked coastal gun-batteries. No aircraft were lost.

Post–war operations

Beginning in March 1946, Project Ruby was a joint, Anglo–American project to investigate the use of penetration bombs against heavily–protected, concrete targets. The target selected was the Valentin submarine pens, that had been rendered unusable and abandoned since 617 Squadron's attack on 27 March 1945. Grand Slams were carried by Lancasters from No. 15 Squadron RAF and US Boeing B-29 Superfortress. Around 140 sorties were flown, testing a range of different bombs.

Survivors

Grand Slam bombs are preserved and displayed in the United Kingdom at the RAF Museum, London, the Brooklands Museum
Brooklands Museum
Brooklands Museum is an independent charitable trust, established in 1987, whose aim is to conserve, protect and interpret the unique heritage of the Brooklands site. It is located south of Weybridge, Surrey and was first opened regularly in 1991 on of the original 1907 motor-racing circuit...

, RAF Lossiemouth
RAF Lossiemouth
RAF Lossiemouth is a Royal Air Force station to the west of the town of Lossiemouth in Moray, Scotland. It is one of the RAF's biggest bases and is currently Britain's main base for Tornado GR4s. From 2013 the Northern QRA force of Typhoon F2 will relocate to Lossiemouth following the closure of...

 and the Battle of Britain Memorial Flight Visitors' Centre at RAF Coningsby
RAF Coningsby
RAF Coningsby , is a Royal Air Force station in Lincolnshire, England. It has been commanded by Group Captain Martin Sampson since 10 December 2010.-Operational units:...

. The main portion of a bomb, without the lightweight tail, is at the Kelham Island Museum
Kelham Island Museum
The Kelham Island Museum is an industrial museum on Alma Street, alongside the River Don, in the centre of Sheffield, England. It was opened in 1982.-The site:...

 in Sheffield.

A T-14 bomb (an American-made variant of the Grand Slam) is displayed at the Air Force Armament Museum
Air Force Armament Museum
The Air Force Armament Museum, adjacent to Eglin Air Force Base, Florida, is the only facility in the U.S. dedicated to the display of Air Force armament...

in the United States.

External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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