Grand Slam bomb: Wikis

  
  
  

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Grand Slam
British Grand Slam bomb.jpg
A Grand Slam bomb being handled
Type Gravity bomb
Place of origin United Kingdom
Service history
In service 1945
Used by Royal Air Force
Wars World War II
Production history
Designer Barnes Wallis
Designed 1943
Manufacturer Vickers, Sheffield
Produced 1944-
Number built 42 used[1]
Variants M110 (T-14) 22,000-lb GP Bomb (United States[2]
Specifications
Weight 22,000 lb (10 t)
Length 26 ft 6 in( 7.70 m)
 length Tail 13 ft 6 in (4.11 m)
Diameter 3 ft 10 in (1.17 m)

Filling Torpex D1
Filling weight 4,144 kg (9,135 lb)
Detonation
mechanism
penetration: 40 metres (earth)[citation needed]
2 metres (concrete)[3]
Blast yield 6.5 tons TNT equivalent[4]

The Grand Slam was a 22,000 lb (10,000 kg) earthquake bomb used by RAF Bomber Command against strategic targets during the Second World War.

Known officially as the Bomb, Medium Capacity, 22,000lb, it was a scaled up version of the Tallboy bomb and closer to the original size that the bomb inventor Barnes Wallis had envisioned when he first developed his earthquake bomb idea.

Contents

Development

When the success of [the Tallboy bomb] was proved Wallis designed a yet more powerful weapon… 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.

Marshal of the Royal Air Force Sir Arthur Travers Harris 1947

On 18 July 1943, work started on a larger version of the Tallboy bomb, which would become the Grand Slam.[2] As with the original Tallboy, the Grand Slam's fins generated a stabilizing spin[5] and the bomb had a thicker case than a conventional bomb, which allowed deeper penetration. After the hot molten Torpex 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.[6]

After release from the Avro Lancaster B.Mk 1 (Special) bomber,[2] the Grand Slam would reach near sonic speed, approaching 320 m/s, and penetrate deep underground, with the explosion causing a camouflet[7] (cavern) and shifting the ground to undermine a target's foundation. After the Allied Operation Undergo[8] captured the Watten V-2 rocket facility in October 1944, a single Avro Lancaster attempted to bomb the bunker's dome from 10 November-20 November with a Grand Slam at precisely midday.[9]

Like Tallboy, Grand Slam had not been designed to directly penetrate concrete roofs and tended to detonate prematurely or break up,[10] but nonetheless they were still far more effective than any existing bomb.

Grand Slam bombing operations

A 'Grand Slam' bomb

By the end of the war, 42 Grand Slams had been dropped on active service.[11]

Bielefeld, 14 March 1945
The No. 617 Squadron RAF Avro Lancaster of Squadron Leader CC Calder dropped the first Grand Slam bomb from 11,965 ft (3,647 m) on the Bielefeld viaduct[12] More than 100 yards of the Bielefeld viaduct collapsed through the earthquake bomb effect[13] of the Grand Slam and Tallboy bombs of No. 617 Squadron. No aircraft were lost.[14]
Arnsberg, 15 March 1945
Two aircraft of No. 617 Squadron RAF each carried a Grand Slam and 14 aircraft of No. 9 Squadron RAF carried Tallboy bombs to attack the railway viaduct. One Grand Slam and 10 Tallboys were dropped. The viaduct was not cut and no aircraft were lost.[14][15]
Arnsberg, 19 March 1945
19 Lancasters of No. 617 Squadron, 6 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.[14][16]
Arbergen, 21 March 1945
20 Lancasters of No. 617 Squadron, 2 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 sufficiently damaged to the approaches to the bridge to put it out of use. One 617 Lancaster was lost.[17]
Nienburg, 22 March 1945
20 Lancasters of No. 617 Squadron, 6 carrying Grand Slams the remainder Tallboys, attacked the railway bridge at Nienburg. 5 Grand Slams made direct hits and the bridge was destroyed.[18]
Bremen, 23 March 1945
20 Lancasters of No. 617 Squadron, 6 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.[19]
Farge, 27 March 1945
20 Lancasters of No. 617 Squadron attacked the Valentin submarine pens,[3] 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,[20][3][21] which rendered the shelter unusable. No aircraft were lost.[14][22]
Hamburg, 9 April 1945
17 aircraft of No. 617 Squadron, 2 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.[14][23]
Heligoland, 19 April 1945
20 aircraft of No. 617 Squadron, 6 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.[14][24]

See also

References and notes

A Grand Slam bomb at the RAF Museum, London
  1. ^ Flower "Bombs", appendix 4
  2. ^ a b c Godwin, John. "The Man-Made Earthquake" (html). http://members.aol.com/nukeinfo2. Retrieved 2008-02-27. 
  3. ^ a b c mines, Christel (28 February 2006). "Submarine-Valentin, Bremen-Farge" (html (German language)). Interessengemeinschaft für historische Militär-, Industrie- und Verkehrsbauten. lostplaces.de. http://www.lostplaces.de/cms/content/view/41/33/. Retrieved 2008-02-25. 
  4. ^ "White House Press Release on Hiroshima" (html). atomicarchive.com. http://www.atomicarchive.com/Docs/Hiroshima/PRHiroshima.shtml. Retrieved 2008-02-25. 
    Torpex is 50% more powerful than TNT.
    Truman described the Little boy bomb (yield > 13 kilotons) against Hiroshima in terms of the Grand Slam: ...more than two thousand times the blast power of the British Grand Slam
  5. ^ "English Bombs of WWII" (html). Canadian Aces. constable.ca. http://www.constable.ca/bombs.htm. Retrieved 2008-02-25. 
  6. ^ Flower "Bombs", p.335
  7. ^ Kharin, Kuzmina, Danilova (22 September 1972). "Ground Vibrations during Camouflet Blasts" (html). Foreign Technology Division. http://stinet.dtic.mil/oai/oai?verb=getRecord&metadataPrefix=html&identifier=AD0751247. Retrieved 2008-02-27. 
  8. ^ Hyrman, Jan. "Operation Undergo - The Capture of Calais & Cap Gris Nez" (html). http://www.nasenoviny.com/indexEN.html. 
  9. ^ Heashall, Philip (1985). Hitler’s Rocket Sites. New York: St Martin's Press. pp. 61,64. "Why these raids were carried out when the site was in Allied hands and no longer a threat is something of a mystery, unless it was to test the bomb's effectiveness against a reinforced concrete target. In the event apparently visibility was suitable only for the release of three or four bombs, resulting in two, possibly three, hits." 
  10. ^ Flower "Bombs", p.375.
  11. ^ Flower "Bombs", Appendix 4.
  12. ^ Flower "Bombs", p.331
  13. ^ A camouflet from the Grand Slam caused the Bielefeld railway viaduct damage.
  14. ^ a b c d e f "Campaign Diary". Royal Air Force Bomber Command 60th Anniversary. UK Crown. http://www.raf.mod.uk/bombercommand/diary.html. Retrieved 2007-05-24.  March, April
  15. ^ Flower "Bombs", p.332-334
  16. ^ Flower "Bombs", p.334-40
  17. ^ Flower "Bombs", p.340-42
  18. ^ Flower "Bombs", p.342-43
  19. ^ Flower "Bombs", p.344-47
  20. ^ RAF: Bomber Command: Grand Slams
  21. ^ The Valentin submarine pens were also used as a post-war test bombing target in Operation Ruby.
  22. ^ Flower "Bombs", p.348-52
  23. ^ Flower "Bombs", p.355-58
  24. ^ Flower "Bombs", p.362-64
  • Flower, Stephen. "Barnes Wallis’ Bombs." Published 2004; Tempus Publishing Ltd, Strood. ISBN 0752429876. Researched from the original records and interviews with those involved with the development and use of the bombs.

External links








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