Tallboy bomb

Infobox Weapon
name=Tallboy bomb


caption=Modern replica of a Tallboy
origin=United Kingdom
type= Conventional
is_ranged=
is_bladed=
is_explosive=yes
is_artillery=
is_vehicle=
is_UK=yes
service=June 8 1944 - April 25 1945
used_by=No. 617 Squadron RAF
wars=World War II
designer=Barnes Wallis
design_date=
manufacturer=Vickers
production_date=
number= 854
variants=
weight=5,443 kg (12,000 lb)
length=6.35 m (21 ft)
part_length=
width=
height=
crew=
cartridge=
caliber=
action=
rate=
velocity=
range=
max_range=
feed=
sights=
breech=
recoil=
carriage=
elevation=
traverse=
blade_type=
hilt_type=
sheath_type=
head_type=
haft_type=
diameter= 950 mm (38 in)
filling= Torpex D1
filling_weight= 2,358 kg (5,200 lb)
detonation=No. 58 fuze - built from No. 30 Pistol (impact detonation) - or No. 47 time delay fuze. Fuzes were inserted into tetryl boosters.
yield=
armour=
primary_armament=
secondary_armament=
engine=
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suspension=
vehicle_range=
speed=

The Tallboy was an earth quake bomb developed by Barnes Wallis and brought into operation by the British in 1944. It weighed five tons and, carried by the Avro Lancaster bomber, was effective against hardened structures against which earlier, smaller bombs had proved ineffective.

History

The British aeronautical engineer Barnes Wallis presented his ideas for a 10 ton bomb in his 1941 paper "A Note on a Method of Attacking the Axis Powers", which showed that a very large bomb exploding deep underground next to a target would transmit the shock into the foundations of the target, particularly since shock waves transmitted through the ground are less attenuated than through air. Barnes Wallis designed the "Victory Bomber" of 50 tons which would fly at convert|320|mi/h|km/h|abbr=on at convert|45000|ft|m to carry the heavy bomb over convert|4000|mi|km, but the Air Ministry were against a single-bomb bomber and the idea was not pursued beyond 1942. Following Wallis's 1942 paper "Spherical Bomb — Surface Torpedo" and the design of the "bouncing bomb" for the Dam Busters of Operation Chastise, the actual design and production of Tallboy was done without a contract on the initiative of a single official within the Ministry. As such the RAF were using bombs they had not bought and which were actually still the property of the manufacturers; Vickers. This situation was regularized once their capabilities were recognised.

Amongst many spectacular accomplishments by the Tallboy, the June 24, 1944 Operation Crossbow attack on the La Coupole (along with Grand Slam bombing) undermined the foundations. A Tallboy of the June 8/9, 1944 Saumur tunnel attack passed straight through the hill and exploded right inside the tunnel convert|60|ft|m below the surface.cite web|last=|first=|publisher=Ministry of Defence/Deltaweb International |url=http://www.raf.mod.uk/bombercommand/saumur.html|title=Saumer Tunnel, 9th June 1944|work=Royal Air Force Bomber Command 60th Anniversary|accessdate=2007-05-24|publisher=] The last Kriegsmarine Bismarck class battleship, the Tirpitz, was sunk by an air attack using Tallboys.

Design

Most large Allied World War II aircraft bombs had very thin skins to maximize the weight of explosive which a bomber could carry—this was an improvement on the early part of the war when the actual HE content of British bomb designs was low. To be able to penetrate the earth (or hardened targets) without breaking apart, the casing of the Tallboy had to be strong. Each was cast in one piece of high tensile steel that would enable it to survive the impact before detonation. At the same time to achieve the penetration required, Wallis designed the Tallboy to be very aerodynamic so that when dropped from a great height it would reach a velocity higher than traditional bomb designs. In the final design the tail of the bomb was about half the overall length of the finished weapon—the bomb casing was some 10 feet (3 m) of the overall 21-foot (6 m) length. Initially the bomb had a tendency to tumble, so the tail was modified—the fins were given a slight twist so that the bomb spun as it fell. The gyroscopic effect thus generated stopped the pitching and yawing, improved the aerodynamics and improved accuracy. The improved design worked so well that it was found in development that it passed through the sound barrier as it fell.Fact|date=April 2008 When dropped from 20,000 ft (6,100 m) it made a crater 80 feet deep (24 m) and 100 feet (30 m) across and could go through 16 feet (5 m) of concrete. [http://www.ww2guide.com/bombs.shtml Bombs Weapons Rockets Aircraft Ordnance] ]

W. J. Lawrence wrote about the Tallboy bomb in his book, "No 5 Bomber Group": [http://www.spartacus.schoolnet.co.uk/2WWtallboy.htm Spartacus: Tallboy] ]

"It was an extraordinary weapon, an apparent contradiction in terms, since it had at one and the same time the explosive force of a large high-capacity blast bomb and the penetrating power of an armour-piercing bomb. On the ground it was capable of displacing a million cubic feet (29,000 m³) of earth and made a crater which it would have taken 5,000 tons of earth to fill. It was ballistically perfect and in consequence had a very high terminal velocity, variously estimated at 3,600 and convert|3700|ft|m per second (1,100–1,130 m/s or about 2,500 mph / 4,000 km/h), which was, of course, a good deal faster than sound so that, as with the V-2 rocket, the noise of its fall would be heard after that of the explosion."

The weight of the Tallboy (approximately 12,000 lb) and the high altitude required of the bombing aircraft meant that the Lancaster bombers used had to be specially adapted. Armour plating and even defensive armament were removed to reduce weight and the bomb-bay doors had to be adapted. Even then the Lancaster was not capable of reaching the bomb's intended dropping height of 40,000 ft (12,200 m) but only around 25,000 (7,700 m). At the same time No. 617 "Dambusters" Squadron trained in the use of a special bombsight the Stabilizing Automatic Bomb Sight (SABS). For accuracy multiple corrections had to be made for temperature, wind speed, etc. However it was only effective if the target could be identified and several missions were canceled or unsuccessful because of difficulty in accurately identifying and marking the targets.

For use on underground targets, the bomb was fitted with three separate inertia pistols. These triggered detonation after a pre-set delay, which give the bomb sufficient time to penetrate the target before exploding. Depending on mission requirements, the time delay could be set to 30 seconds or 30 minutes after impact. Three fuzes were used in order to guarantee detonation. Although the bomb was aimed at the target during an operation, and proved capable of penetrating amazing depths into hardened reinforced concrete when it did hit, this was not the primary intention of Barnes Wallis's design. The bomb was designed to impact close to the target, slide into the soil or rock on which the target was built, and then detonate, transferring all of its energy into the structure, or creating a camouflet into which it fell. This 'earthquake' effect caused more damage than even a direct hit which penetrated the armour of a target, since even a burst inside a bunker would only damage the immediate surroundings, with the the blast dissipating rapidly through the air. An earthquake impact, however, shook the whole target, and caused major structural damage to all parts of it, making repair uneconomic. The attack reports below should be considered with this in mind.

The construction of each Tallboy was labour intensive because each was largely hand-made, requiring much manual labour during each separate manufacturing stage. The materials used were costly, with very precise engineering requirements with regard to casting and machining. For example, in order to increase its penetrative power a large and specially hardened steel plug needed to be precisely machined and mated to a recess in the nose of the bomb. The ogive needed to be machined to a perfectly symmetrical shape in order to ensure optimum aerodynamic performance. This was no easy task when manipulating a bomb casing with the size and weight of Tallboy.

Similarly, the Torpex filling was poured into base of the the upturned casing by hand, after melting it in explosives "kettles". The final stage of explosive filling required a one inch layer of pure TNT to be poured over the Torpex filling, followed by sealing the base with a 4 inch layer of woodmeal-wax composite with 3 recesses into which the explosive boosters and fuzes were fitted.

Tallboys were not considered expendable and if not used on a raid were to be brought back to base rather than safely dropped in the sea. The value of the weapon offset the additional risk to the aircrew.

Given their high unit cost, Tallboys were used exclusively against high-value strategic targets which could not be destroyed by other means. When it was found that the Lancaster could be modified to carry a bomb larger than the Tallboy, Wallis produced the even larger Grand Slam bomb.

Tallboy operations

June - August 1944

* Saumur rail tunnel — The sole operational north-south route on the Loire. Nineteen Tallboy equipped, and six conventionally equipped Lancasters of No. 617 Squadron, attacked on the night of 8/9 June 1944. This was the first use of the Tallboy bomb and the line was destroyed — one Tallboy bored through the hillside and exploded in the tunnel about 60 ft (18 m) below, completely blocking it. No aircraft were lost during the raid.

Operation Crossbow sorties

Operation Crossbow was a set of offensive and defensive measures that were carried out to deal with the threat of German V-1 and V-2 rocket weaponry. As part of the operation, a number of bombing sorties that carried Tallboy bombs were deployed by the British to bomb and destroy a number of missile sites.

;Le_Blockhaus, June 19 1944:The nearest Tallboy by No. 617 Squadron landed 50 yards (46 m) from the targetcite 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 1944: [http://www.raf.mod.uk/bombercommand/jun44.html June] , [http://www.raf.mod.uk/bombercommand/jul44.html July] , [http://www.raf.mod.uk/bombercommand/aug44.html August] , [http://www.raf.mod.uk/bombercommand/sep44.html September] , [http://www.raf.mod.uk/bombercommand/oct44.html October] , [http://www.raf.mod.uk/bombercommand/nov44.html November] , [http://www.raf.mod.uk/bombercommand/dec44.html December] 1945: [http://www.raf.mod.uk/bombercommand/jan45.html January] , [http://www.raf.mod.uk/bombercommand/feb45.html February] , [http://www.raf.mod.uk/bombercommand/mar45.html March] , [http://www.raf.mod.uk/bombercommand/apr45.html April] ] The bunker was rendered useless.

;Wizernes, June 24 1944 :Several Tallboy hits undermined the foundations but did not penetrate the dome. The bunker was abandoned.

;Siracourt, June 25 1944: No. 617 Squadron Lancasters scored 3 direct Tallboy hits without loss.

;Saint-Leu-d'Esserent, July 4 1944:17 Lancasters, 1 Mosquito and 1 Mustang of No 617 Squadron used Tallboys in an attempt to collapse the limestone roof of the caves. No 5 Group follows with convert|1000|lb|abbr=on bombs.cite book |last=Irving|first=David|authorlink=David Irving|title=The Mare's Nest|year=1964|publisher=William Kimber and Co|location=London|pages=p245] cite book |last=Collier|first=Basil|title=The Battle of the V-Weapons, 1944-1945 |origyear=1964 |year=1976|month= |publisher=The Emfield Press|location=Yorkshire|isbn=0 7057 0070 4 |pages=p68,84]

;Mimoyecques July 6, 1944:Tallboys hit one of the V-3 cannon's shafts and block galleries with earth and debriscite book |last=Brickhill|first= Paul|coauthors=|title=The Dam-busters|series= Apogee Books Space Series 36|year=1951|month= |publisher=Thomas Y. Crowell|location=New York|isbn=0-330-37644-6|pages=] cite book |last=Irving|first=David|authorlink=David Irving
title=The Mare's Nest|year=1964|publisher=William Kimber and Co|location=London|pages=p220,245,246,247]

;Wizernes, July 17 1944:16 Lancasters, 1 Mosquito and a new P-51 Mustang bomb "Wizernes" -- 3 Lancasters managed to drop Tallboys (one caused the dome to shift out of alignment, two others blocked the entrance. [ [http://www.dambusters.org.uk/wizernes.htm Dambusters - The raid on Wizernes Rocket Base ] ]

;Rilly La Montage, July 24 1944:Both ends of the railway tunnel were collapsed by Tallboy bombs dropped by No. 617 Squadron. William Reid's Lancaster at convert|12000|ft|m|abbr=on was hit by a Tallboy dropped from convert|18000|ft|m|abbr=oncite web|last=|first=|url=http://www.telegraph.co.uk/news/main.jhtml;jsessionid=?xml=/news/2001/11/29/db2901.xml |title=Flight Lieutenant William Reid VC |work=News|date=November 29, 2001 |accessdate=2008-02-17|publisher=Telegraph Media Group Limited 2008]

;Le_Blockhaus, July 27, 1944:One Tallboy hit the target but did not penetrate the structure.cite web|url=http://www.leicapages.com/france.html|title=World War II German hardened A4/V2 rocket launch sites|work=|accessdate=2008-02-17|publisher=]

orties against German dockyards

Shipping in the English Channel and the Atlantic Ocean were threatened by U-boats and E-boats stationed in France. U-boat docks were protected against conventional aerial bombardment by thick concrete roofs.

;Le Havre, June 14, 1944:Part of the first massive RAF daylight raid since the end of May 1943, two waves attacked E-boat facilities at Le Havre: No 1 Group first, No 3 Group second. Just before the first wave, 22 Lancasters of 617 Squadron and 3 Mosquito marker aircraft attacked, with several hits on the pens and one bomb penetrated the roof.

;Boulogne harbour, June 15, 1944:297 aircraft - 155 Lancasters, 130 Halifaxes, 12 Mosquitos - of Nos 1, 4, 5, 6 and 8 Groups attacked Boulogne harbour. 1 Halifax was lost. A French report described the great destruction as the worst raid on Boulogne.Fact|date=March 2008 [The reference for Boulogne does not indicate Tallboy bombs were used.]

;Brest, August 5, 1944:15 Lancasters of No. 617 Squadron attacked the U-boat pens at Brest and scored 6 direct hits with Tallboys penetrating the concrete roofs. 1 Lancaster shot down by flak. Subsequent attempts to reinforce other sites with even thicker concrete diverted resources from other projects.

;Keroman, August 6, 1944 :Flight Lieutenant Thomas Clifford Iveson dropped one Tallboy.cite web|last=Keable|first=Jim|url=http://www.aeroventure.org.uk/eastkirkby.php|format=html |title=Flight Lieutenant Thomas Clifford Iveson|work=AeroVenture News|accessdate=2008-02-24|publisher=AeroVenture]

; Lorient, August 7 1944:The planned Tallboy mission against U-boat pens was scrubbed

;La pallice, August 8, 1944:Flight Lieutenant Thomas Clifford Iveson dropped one Tallboy.

;IJmuiden, August 28, 1944:Flight Lieutenant Thomas Clifford Iveson dropped one Tallboy.

eptember - November 1944

* Dortmund-Ems Canal near Ladbergen, north of Münsterndash No. 617 Squadron scored six direct hits with Tallboys on night September 23/24 1944.
* Kembs Dam north of Basle — The dam waters could have been kept in reserve to flood the area of a US advance. On 7 October 1944, the Dambusters destroyed the lock gates with Tallboys dropped at low level releasing the stored water.
* Sorpe Dam — This target of the original Dambusters raid survived a second attack by 9 Squadron on 15 October 1944 (617 Squadron did not participate in this raid). The Tallboy bombs were seen to hit the dam but did not breach it.

Bombing sorties against "Tirpitz"

The German battleship Tirpitz was a threat against convoys sailing to and from the Soviet Union.

;Operation Paravane, September 15 1944:One Tallboy hit near the bow of the "Tirpitz" and caused considerable damage. The bombing shock from the operation damaged the battleships engines, and the Germans converted the ship for use as a semi-static heavy artillery battery.

;Operation Obviate, October 29 1944 :No direct hits were scored during but one near miss bent a propeller shaft of "Tirpitz".

;Operation Catechism, November 12 1944:In the final operation the "Tirpitz" was sunk when at least two Tallboyscite web|last=|first=|url=http://www.raf.mod.uk/bombercommand/tirpitz.html|title=Tirpitz, November 12 1944|work=Royal Air Force Bomber Command 60th Anniversary|accessdate=2007-05-24|publisher=UK Crown] hit and capsized the battleship.

December 1944 - April 1945

;Bombing of U-boat pens, December 1944-April 1945
* IJmuiden, December 15 1944:Flight Lieutenant Thomas Clifford Iveson dropped one Tallboy.
* IJmuiden, January 12 1945 :No 617 Squadron attacked the U-boat pens with Tallboys, but smoke obscured the results.
* Bergen, January 12 1945:32 Lancasters and 1 Mosquito of Nos 9 and 617 Squadrons attacked U-boat pens and shipping in Bergen harbour. 3 Lancasters of No 617 Squadron and 1 from No 9 Squadron were lost; the Germans told the local people that 11 bombers had been shot down. A local report says that 3 Tallboys penetrated the 3½-metre-thick roof of the pens and caused severe damage to workshops, offices and stores inside.
* IJmuiden & Poortershaven February 3, 1945:36 Lancasters of No 5 Group attacked U-boat pens at IJmuiden (No 9 Squadron) and Poortershaven (No 617 Squadron) with Tallboy bombs. Hits were claimed at both targets without loss.
* Hamburg, April 9 1945:No. 617 Squadron attacked with Tallboys and Grand Slam bombs.Fact|date=February 2008 Some of the bombs hit their target and no aircraft were lost.
* Heligoland, April 19 1945:969 aircraft - 617 Avro Lancasters, 332 Handley Page Halifaxes, 20 de Havilland Mosquitos of all groups - successfully used Tallboys to bomb the Naval base, airfield, and town into crater-pitted moonscapes. Three Halifaxes were lost, and the islands were evacuated the following night.

The Urft Dam, (30 miles south west of Cologne) was attacked on 8 December and 11 December 1944 to prevent it being used to flood the area below as American troops advanced. The lip of the dam was damaged, but the Germans prevented further damage by lowering the water level. [ [http://www.dambusters.org.uk/docs/recordbook.pdf 617 Squadeon - The Operational Record Book 1943 - 1945] (pdf) with additional information by Tobin Jones; Binx Publishing, Pevensey House, Sheep Street, Bicester. OX26 6JF. Acknowledgement is given to HMSO as holders of the copyright on the Operational Record Book. Page 507] [Iain Murray " [Big & Bouncy: The Special Weapons of Barnes Wallis] ", 2005. Quotes Alan W. Cooper; "From the Dams to the Tirpitz", 1982 (Goodall), and Alan W. Cooper; "The Men Who Breached the Dams", 1982 (Kimber)]

Politz was attacked by No. 617 21 December, 1944Fact|date=March 2008 [ [http://www.aeroventure.org.uk/eastkirkby.php Memorabilia signing and veterans day at Lincolnshire Aviation Heritage Centre East Kirkby] South Yorkshire Aircraft Museum 29 August 2005] See Flight Lieutenant Thomas Clifford Iveson. The Campaign Diary does not indicate Tallboy bombs were used on this Politz mission.]

The Bielefeld and Arnsberg viaducts were attacked by No. 617 and No. 9 squadrons with Tallboys and the first Grand Slam bomb on 14 March 1945. The Arnsberg viaduct withstood the attack but 100 m of the Bielefeld viaduct collapsed through the 'earthquake effect' of the Grand Slam and Tallboys. The Arnsberg viaduct was attacked again on 15 March 1945 by No. 9 Squadron it did not collapse.

The Pocket battleship "Lützow" was attacked on 16 April 1945 by No. 617 Squadron. Despite intense flak, 15 aircraft managed to bomb the target with Tallboys or with 1,000-pounders. One near miss with a Tallboy tore a large hole in the bottom of the "Lützow" and she settled to the bottom in shallow water. One Lancaster was shot down, the Squadron's last loss in the war.

Hitler's vacation home, Berghof, near Berchtesgaden was attacked on 25 April 1945 with a mixed force which included 6 Lancasters of No. 617 Squadron dropping their last Tallboys. The bombing appeared to be accurate and effective.

ee also

* Bunker buster

Notes and references

External links

* [http://www.barneswallistrust.org/dambusters.htm Barnes Wallis Trust]
* [http://www.ww2aircraft.net/forum/album/showphoto.php?photo=5394&cat=550 A picture of a Lancaster carrying a Grand Slam]