TALLBOY BOMB

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 concrete structures against which earlier, smaller bombs had proved ineffective.

Contents

History

Design

Tallboy operations

See also

Notes

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 exploded deep underground beside a target would transmit shock into the foundations of the target, particularly since the shockwaves transmitted though the ground are less attenuated than through air. Barnes Wallis designed the "Victory Bomber" of 50 tons which would fly at 320 mph at 45,000 feet to carry the heavy bomb over 4,000 miles, 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 regularised 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 60 feet below the surface. Saumer Tunnel, 9th June 1944

Design

Most large Allied World War II aircraft bombs had very thin skins to maximise 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. When dropped from 20,000 ft (6,100 m) it made an 80 ft (24 m) deep crater 100 ft (30 m) across and could go through 16 ft (5 m) of concrete.Bombs Weapons Rockets Aircraft Ordnance
W. J. Lawrence wrote about the Tallboy bomb in his book, ''No 5 Bomber Group''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 3,700 feet 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, windspeed, etc. However it was only effective if the target could be identified and several missions were cancelled or unsuccessful because of difficulty in accurately identifying and marking the targets.
Each bomb was a precision-built instrument of war made from expensive materials and carefully finished. They 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.
The Tallboy was used to attack strategic targets that 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

★ 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.

★ E-boat pens at Le Havre and Boulogne — On 14 June 1944 as part of the first massive RAF daylight raid since the end of May 1943, 22 Lancasters of 617 Squadron attacked the concrete covered E-boat pens just before the first wave bombed. Several hits were scored on the pens and one bomb penetrated the roof. The E-boat pens at Boulogne were attacked the next day. The E-boats were targeted to prevent them attacking the Normandy invasion force.

'Operation Crossbow Tallboy Operations, June 19-July 27, 1944'
Operation & Target	Date	Result
Crossbow: Éperlecques	June 19 & July 27, 1944	The nearest Tallboy by No. 617 Squadron on June 19 landed 50 yards (46 m) from the target, while one Tallboy hit the target on July 27 (but did not penetrate the structure.) World War II German hardened A4/V2 rocket launch sites
Crossbow: La Coupole	June 24, 1944	No. 617 Squadron scored several hits with their Tallboy bombs and undermined the foundations but did not penetrate the concrete dome.
Crossbow: Siracourt	June 25, 1944	No. 617 Squadron Lancasters scored 3 direct hits on the concrete structure with Tallboy bombs without loss.
Crossbow: 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 1,000 lb bombs. The Mare's Nest, , David, Irving, William Kimber and Co, 1964, The Battle of the V-Weapons, 1944-1945, , Basil, Collier, The Emfield Press, 1976,
Crossbow: Mimoyecques	July 6, 1944	Target destroyed by Tallboys dropped by 617 Squadron.
Crossbow: Rilly La Montage railway tunnel	July 24, 1944	Both ends of the tunnel were collapsed by Tallboy bombs dropped by No. 617 Squadron.

★ U-boat pens at Brest etc. — on 5 August 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. Campaign Diary '1944': June, July, August, September, October, November, December '1945': January, February, March, April

★ Dortmund-Ems Canal near Ladbergen, north of Munster – 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.

★ The German battleship ''Tirpitz'' operations — The ''Tirpitz'' threatened the Arctic convoys to the USSR from her base in Northern Norway which was out of bombing range from British bases. No. 617 and No. 9 squadrons carried 24 Tallboys from Yagodnik near Arkhangelsk, formerly called Archangel in English, in Russia to attack the ''Tirpitz'' on the 15 September 1944. In the face of extensive flak and smoke cover they failed to sink the ship but damaged her so extensively that she was forced to head south to Tromsø fjord to be repaired. This fjord was in range of bombers operating from Scotland. She was unsuccessfully attacked in October from Lossiemouth base. Finally on 12 November 1944, the two squadrons attacked ''Tirpitz'' again and after three direct hits she capsized and sank. Tirpitz, November 12 1944

★ E-boat pens at IJmuiden — On 15 December, 1944 No 617 Squadron attacked the pens with Tallboys, but smoke obscured the results. Then on 3 February 1945, 36 Lancasters of No 5 Group attacked U-boat pens at Ijmuiden (No 9 Squadron) and Poortershaven (No 617 Squadron) with Tallboy bombs. It was believed that these pens, in that part of Holland still occupied by the Germans, were sheltering midget submarines. The weather was clear and hits were claimed at both targets without loss.

★ 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.^[1]

★ Politz — attacked by No. 617 21 December 1944 ^[2]

★ U-boat pens and shipping in Bergen — attacked by No. 617 and No. 9 squadrons with Tallboys on 12 January 1945. Three penetrated the 3½-metre-thick roof causing extensive damage at the cost of three Lancasters lost.

★ U-boat pens at Poortershaven — attacked by No. 617 Squadron with Tallboys on 3 February 1945 hits were claimed and no aircraft were lost.

★ Bielefeld and Arnsberg viaducts — 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.

★ Arnsberg viaduct — attacked again on 15 March 1945 by No. 9 Squadron it did not collapse.

★ Hamburg U-boat shelters — attacked on 9 April 1945 by No. 617 Squadron with Tallboys and Grand Slam bombs. Some of the bombs hit their target and no aircraft were lost.

★ Pocket battleship ''Lützow'' — 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.

★ Coastal battery positions at Heligoland — attacked on 19 April 1945 by No. 617 and No. 9 squadrons armed with Tallboys. All the positions were hit and no aircraft were lost.

★ Hitler's vacation home, Berghof, near Berchtesgaden — 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.

See also

★ Bunker buster

Notes

1. Urft Dam

★ 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 sources

★
★ Alan W. Cooper; ''From the Dams to the Tirpitz'', 1982 (Goodall).

★
★ Alan W. Cooper; ''The Men Who Breached the Dams'', 1982 (Kimber).
2. 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 'NOTE': The Campaign Diary does not indicate Tallboy bombs were used on this Politz mission.


★ Barnes Wallis Trust

★ English Bombs of WWII

★ A picture of a Lancaster carrying a Tallboy