Grand Slam bomb
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| Grand Slam | |
|---|---|
 A Grand Slam bomb being handled |
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| Type | Conventional (gravity) bomb |
| Place of origin | United Kingdom |
| Service history | |
| In service | 1945 |
| Used by |  United Kingdom Royal Air Force |
| Wars | World War II |
| Production history | |
| Designer | Barnes Wallis |
| Designed | 1943 |
| Manufacturer | Vickers, Sheffield |
| Produced | 1944- |
| Number built | 41 used[1] |
| Variants | M110 (T-14) 22,000-lb GP Bomb (United States)[2] |
| Specifications | |
| Weight | 22,000 lb (9.98 t)[3] |
| 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) |
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| Filling | Torpex D1 |
| Filling weight | 4,144 kg (9,135 lb)[3] |
| Detonation mechanism |
penetration: 40 metres (earth)[citation needed] 2 metres (concrete)[4] |
| Blast yield | 6.5 tons TNT equivalent[5] |
The Grand Slam was a 22,000 lb earth quake bomb used by RAF Bomber Command against strategic targets during the Second World War.
It was a scaled up version of the Tallboy bomb and closer to the original size of the bomb inventor Barnes Wallis had envisaged when he first developed his earthquake bomb idea.[verification needed]
The name of the bomb comes from the term 'Grand Slam' in the card game of bridge.[verification needed]
Contents |
[edit] Development
- See also: Tallboy_bomb#Design
| “ | 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. | ” |
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—Marshal of the Royal Air Force Sir Arthur Travers Harris 1947 |
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On July 18, 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[6] and 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.[citation needed] 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.[verification needed]
After release from the Avro Lancaster B.Mk 1 (Special) bomber,[2] the Grand Slam would reach supersonic speed and penetrate underground, with the earthquake explosion causing a camouflet[7] (cavern) and shift ground to undermine a target's foundation.[citation needed] 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 November 10-November 20 with a Grand Slam at precisely midday.[9]
[edit] Grand Slam bombing operations
Grand Slam bombs were successfully used against the 30 ft thick ceilings of the Huuge and Brest U-boat pens.[6] By the end of the war, 41 Grand Slams had been dropped.[2]
- Bielefeld, March 14, 1945
- The No. 617 Squadron RAF Avro Lancaster of Squadron Leader CC Calder dropped the first Grand Slam bomb from 16,000 ft on the Bielefeld viaduct.[2] More than 100 yards of the Bielefeld viaduct collapsed through the earth quake bomb effect[10] of the Grand Slam and Tallboy bombs of No. 617 Squadron. No aircraft were lost.[11]
- Arnsberg, March 15, 1945
- Two aircraft of No. 617 Squadron each carried a Grand Slam and 14 aircraft of No. 9 Squadron RAF carried Tallboy bombs to attack the railway viaduct. The viaduct was not cut and no aircraft were lost.[11]
- Arnsberg, March 19, 1945
- 37 Lancasters of No. 5 Group RAF attacked the railway viaduct at Arnsberg and the bridge at Vlotho, near Minden. The attack at Arnsberg by No. 617 Squadron RAF using 6 Grand Slams blew a 40-foot gap in the viaduct. No. 9 Squadron RAF's attack at Vlotho was not successful.[11]
- Farge, March 27, 1945
- 20 Lancasters of No. 617 Squadron RAF attacked the Valentin submarine pens,[4] a huge, nearly-ready structure with a concrete roof 23 ft thick. Two Grand Slam bombs penetrated two metres and detonated[4] [12], which rendered the shelter unusable. No aircraft were lost.[11]
- Hamburg, April 9, 1945
- 17 aircraft of No. 617 Squadron with Grand Slams and Tallboy bombs successfully attacked the U-boat shelters. No aircraft were lost.[11]
[edit] Post-war
The post-war Handley Page Victor strategic jet bomber was designed to carry either a single Grand Slam or two Tallboy bombs internally.[citation needed]
A "live" Grand Slam was (unknowingly) used as a static display at RAF Scampton until 1958.[3]
[edit] References and notes
- ^ Referenced works indicate a Grand Slam tally different from 41:
- ^ a b c d e Godwin, John. The Man-Made Earthquake (html). Retrieved on 2008-02-27.
- ^ a b c Australian Armourers Association (html). Retrieved on 2008-02-25.
- ^ a b c mines, Christel (February 28, 2006). [www.lostplaces.de/cms/content/view/41/33/ Submarine-Valentin, Bremen-Farge] (html (German language)). Interessengemeinschaft für historische Militär-, Industrie- und Verkehrsbauten. lostplaces.de. Retrieved on 2008-02-25.
- ^ White House Press Release on Hiroshima (html). atomicarchive.com. Retrieved on 2008-02-25.
Torpex is 50% more powerful than TNT.
Truman described the Little boy bomb (yield > 13 kiloton) against Hiroshima in terms of the Grand Slam: ...more than two thousand times the blast power of the British Grand Slam - ^ a b English Bombs of WWII (html). Canadian Aces. constable.ca. Retrieved on 2008-02-25.
- ^ Kharin, Kuzmina, Danilova (September 22, 1972). Ground Vibrations during Camouflet Blasts (html). Foreign Technology Division. Retrieved on 2008-02-27.
- ^ Hyrman, Jan. Operation Undergo - The Capture of Calais & Cap Gris Nez (html).
- ^ Heashall, Philip (1985). Hitler’s Rocket Sites. New York: St Martin's Press, p61,64. “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.”
- ^ A camouflet from the Grand Slam caused the Bielefeld railway viaduct damage.
- ^ a b c d e Campaign Diary. Royal Air Force Bomber Command 60th Anniversary. UK Crown. Retrieved on 2007-05-24. March, April
- ^ The Valentin submarine pens were also used as a post-war test bombing target in Operation Ruby.
[edit] External links
- Big & Bouncy - the special weapons of Sir Barnes Wallis - University of Dundee
- A picture of a Lancaster carrying a Grand Slam
- Movietone News "Ten Tonner" - video of a Grand Slam being dropped on the Bielefeld Viaduct on youtube.com
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