Grand Slam bomb

Infobox Weapon
name = Grand Slam


caption = A Grand Slam bomb being handled
origin = United Kingdom
type = Conventional (gravity) bomb
is_ranged =
is_bladed =
is_explosive = Yes
is_artillery =
is_vehicle =
is_missile =
is_UK = Yes
service = 1945
used_by = UK Royal Air Force
wars = World War II
designer = Barnes Wallis
design_date = 1943
manufacturer = Vickers, Sheffield
unit_cost =
production_date = 1944-
number = 41 used [Referenced works indicate a Grand Slam tally different from 41::*Watten (testing): "three or four bombs":*Bielefeld: 1:*Arnsberg: 8:*Farge: 2+:*Hamburg: 2+:*RAF Scampton (display): 1]
variants = M110 (T-14) 22,000-lb GP Bomb (United States)
spec_label =
weight = 22,000 lb (9.98 t)
length = 26 ft 6 in( 7.70 m)
part_length = Tail 13 ft 6 in (4.11 m)
width =
height =
diameter = 3 ft 10 in (1.17 m)
crew =
filling = Torpex D1
filling_weight = 4,144 kg (9,135 lb)
detonation = penetration: 40 metres (earth)Fact|date=November 2007
2 metres (concrete)
yield = 6.5 tons TNT equivalent [cite web |url=http://www.atomicarchive.com/Docs/Hiroshima/PRHiroshima.shtml |date= |format=html |title=White House Press Release on Hiroshima |work= |accessdate=2008-02-25 |publisher=atomicarchive.com
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"]

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 that the bomb inventor Barnes Wallis had envisaged when he first developed his earthquake bomb idea.

Development

On July 18, 1943, work started on a larger version of the Tallboy bomb, which would become the Grand Slam. As with the original Tallboy, the Grand Slam's fins generated a stabilizing spincite web |url=http://www.constable.ca/bombs.htm |date= |format=html |title=English Bombs of WWII |work=Canadian Aces |accessdate=2008-02-25 |publisher=constable.ca] 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.Fact|date=November 2007 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.Fact|date=July 2008

After release from the Avro Lancaster B.Mk 1 (Special) bomber, the Grand Slam would reach supersonic speed and penetrate underground, with the earthquake explosion causing a camouflet [cite web|last=Kharin, Kuzmina, Danilova |first=|url=http://stinet.dtic.mil/oai/oai?verb=getRecord&metadataPrefix=html&identifier=AD0751247 |date=September 22, 1972|format=html|title=Ground Vibrations during Camouflet Blasts |work=|accessdate=2008-02-27|publisher=Foreign Technology Division] (cavern) and shift ground to undermine a target's foundation. After the Allied Operation Undergo [cite web |last=Hyrman |first=Jan |url=http://www.nasenoviny.com/indexEN.html |format=html |title=Operation Undergo - The Capture of Calais & Cap Gris Nez] 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.cite book |last=Heashall |first=Philip |title=Hitler’s Rocket Sites |year=1985 |publisher=St Martin's Press |location=New York |isbn= |pages=p61,64 |quote=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.]

Grand Slam bombing operations

Grand Slam bombs were successfully used against the 30 ft thick ceilings of the Huuge and Brest U-boat pens. By the end of the war, 41 Grand Slams had been dropped.cite web |last=Godwin |first=John |url=http://members.aol.com/nukeinfo2 |date= |format=html |title=The Man-Made Earthquake |work= |accessdate=2008-02-27 |publisher=]

;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. More than 100 yards of the Bielefeld viaduct collapsed through the earth quake bomb effect A camouflet from the Grand Slam caused the Bielefeld railway viaduct damage.] of the Grand Slam and Tallboy bombs of No. 617 Squadron. No aircraft were lost.cite web|last=|first=|url=http://www.raf.mod.uk/bombercommand/diary.html|title=Campaign Diary|work=Royal Air Force Bomber Command 60th Anniversary|accessdate=2007-05-24|publisher=UK Crown [http://www.raf.mod.uk/bombercommand/mar45.html March] , [http://www.raf.mod.uk/bombercommand/apr45.html April] ]

;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.

;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.

;Farge, March 27 1945:20 Lancasters of No. 617 Squadron RAF attacked the Valentin submarine pens, a huge, nearly-ready structure with a concrete roof 23 ft thick. Two Grand Slam bombs penetrated and detonated,cite web|last=mines|first=Christel|url=http://www.lostplaces.de/cms/content/view/41/33/ |date=February 28, 2006 |format=html (German language) |title=Submarine-Valentin, Bremen-Farge |work=Interessengemeinschaft für historische Militär-, Industrie- und Verkehrsbauten|accessdate=2008-02-25|publisher=lostplaces.de] [The Valentin submarine pens were also used as a post-war test bombing target in Operation Ruby.] which rendered the shelter unusable. No aircraft were lost.

;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.

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.Fact|date=November 2007

A "live" Grand Slam was (unknowingly) used as a static display at RAF Scampton until 1958.cite web|last=|first=|url=http://www.gunnies.pac.com.au/gallery/grand_slam.htm |date=|format=html|title=Australian Armourers Association |work=|accessdate=2008-02-25|publisher=]

References and notes

External links

* [http://www.computing.dundee.ac.uk/staff/irmurray/bigbounc.asp#grandslam Big & Bouncy - the special weapons of Sir Barnes Wallis] - University of Dundee
* [http://www.ww2aircraft.net/forum/album/showphoto.php?photo=5394&cat=550 A picture of a Lancaster carrying a Grand Slam]
* [http://youtube.com/watch?v=R-Mm-zFW_nA Movietone News "Ten Tonner" - video of a Grand Slam being dropped on the Bielefeld Viaduct on youtube.com ]