Bouncing bomb

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Vickers Type 464
code name: Upkeep store

Upkeep bouncing bomb at the Imperial War Museum Duxford
Type Conventional (depth charge)
Place of origin Flag of the United Kingdom United Kingdom
Service history
In service May 16/17 May 1943
(Operation Chastise)[1]
Used by No. 617 Squadron RAF
Wars World War II
Production history
Designer Barnes Wallis
Designed April 1942
Manufacturer Vickers-Armstrongs[2]
Produced February 1943
Number built 19
Variants Highball spherical bouncing bomb, concrete training bombs
Specifications
Weight 4195 kg (9,250 pounds)[3]
Length 60 inches (152 cm)
Width 56 inches (142 cm )

Rate of fire 500 rpm backward spin[4][5]
Muzzle velocity 240-250 mph (386-402 km/h)
Effective range 400-500 yards (365-457 m)
Filling Torpex
Filling weight 6,600 pounds (2,990 kg)[3]
Detonation
mechanism
hydrostatic fuze (depth of 30 ft),[5] with backup chemical time fuze.

A bouncing bomb is a bomb designed specifically to bounce to a target such as across water to avoid torpedo nets. Unlike skip bombing,[6] which uses conventional bombs as during the March 1943 Battle of the Bismarck Sea, the British, Germans, and Soviets developed World War II bombs specifically for bouncing to targets and then exploding. The inventor of this technique was the brilliant British engineer Barnes Wallis. His Upkeep bouncing bomb was used in the May 1943 British Operation Chastise to bounce into dams and explode underwater with similar effect to the underground detonation of the earth quake bomb (e.g., Grand Slam bomb and Tallboy bomb), which he also invented.

Contents

[edit] British bouncing bomb

Highball bouncing bomb dropped from de Havilland Mosquito at the Fleet Lagoon behind Chesil Beach, Dorset.
Highball bouncing bomb dropped from de Havilland Mosquito at the Fleet Lagoon behind Chesil Beach, Dorset.

Barnes Wallis' April 1942 paper Spherical Bomb — Surface Torpedo described the attack on a battleship by bouncing a weapon on the surface of the water, striking the ship, and then dropping to explode at a depth where the hull is less protected. The initial spherical design with dimples codenamed Highball was developed to be dropped from a modified de Havilland Mosquito that could carry two of the bombs. The mechanical differential analyzer analogue computer used during design is preserved in New Zealand at MOTAT.[citation needed] In September 1942, full-scale test drops of the spherical design began at Chesil Beach using a modified Vickers Wellington.[7] At the start of 1943, Wallis' paper Air Attack on Dams reporting the results of scale model experiments and aircraft drops.[8]

[edit] Upkeep bouncing bomb

The operational British bouncing bomb was officially code named Upkeep store[citation needed] and was known by the manufacturers as Vickers Type 464. The cylindrical bomb used Torpex ("torpedo explosive") to provide a longer explosive pulse for greater effect against underwater targets. Testing of the bouncing bomb was done at Reculver, Kent. During this time, Barnes Wallis lived at the Mill House, Chislet.[9] In May 1943, Operation Chastise attacked dams in Germany's Ruhr Valley -- two were breached "with limited effect".[10] The British losses during the operation prompted the project to be discontinued[citation needed] and, in January 1974 under Britain's "thirty year rule", the files for both Upkeep and Highball (along with Ultra files) were released.

Animation of a bouncing bomb path over torpedo nets into a dam
Animation of a bouncing bomb path over torpedo nets into a dam

[edit] Surviving bombs

All combat Upkeep bombs were disposed of at the end of hostilities.[citation needed] However, concrete-filled bombs used in test and training drops at Reculver, Kent have been recovered and are displayed at various sites:

[edit] German bouncing bomb

The Germans recovered an unexploded Operation Chastise bomb in some woods and a recovered 385 kg (850 pound) version of the bouncing bomb was tested by the Luftwaffe. Designed for use against British shipping, the German bouncing bomb was code named Kurt and built at the Luftwaffe Experimental Centre in Travemünde. However without backspin, the dropped bomb matched the speed of the Focke-Wulf Fw 190 during trials. Booster rockets failed to rectify the problem and the project was discontinued in 1944.[11]

[edit] Soviet bouncing bomb

The Soviets are reputed to have used two bouncing bombs during the attack that sunk the World War II German anti-aircraft cruiser Niobe in Kotka, Finland on 16 July 1944.[citation needed]. No development details are known for this device, and it may have been a skip bombing incident.

[edit] External links

[edit] References and Notes

  1. ^ Campaign Diary (html). Royal Air Force Bomber Command 60th Anniversary. UK Crown. Retrieved on 2007-05-24.
  2. ^ Field, Brian. Dambuster Bomb Development (html). WW2 People's War. bbc.co.uk. Retrieved on 2008-02-21.
  3. ^ a b Upkeep: The Bouncing Bomb (html). The Dambusters (617 Squadron). thedambusters.org.uk. Retrieved on 2008-02-21.
  4. ^ NOTE: In addition to slowing the bomb on each successive bounce so it would trail behind the aircraft (for safety), the backward spin increased the relative speed of the surface of the bomb against the surface of the water, allowing the bomb to skip at lower airspeeds. The prolate spinning also helped to keep the bomb horizontal during the skip trajectory (in a different manner than the flat oblate spin of a skipped rock.)
  5. ^ a b Moorcraft, Lucy. The Bouncing Bomb (html). The Dambusters. University of Bristol. Retrieved on 2008-02-21.
  6. ^ In the 1600s, Vauban had finalized the use of bouncing artillery shells for attacking forts.[citation needed] In the nineteenth century, the Royal Navy had observed that cannonballs had increased range when they bounced on water.
  7. ^ Murray, Iain. Big & Bouncy - the special weapons of Sir Barnes Wallis. University of Dundee. Retrieved on 2008-02-21.
  8. ^ The Second World War Experience Centre - The Dams Raid May 1943. Retrieved on 2008-02-21.
  9. ^ The Times, 20 October 2005
  10. ^ Secondary Campaigns (html). United States Strategic Bombing Survey, Summary Report (European War) (1945-09-30). Retrieved on 2008-02-21. “ The breaking of the Mohne and the Eder dams, though the cost was small, also had limited effect.”
  11. ^ Sweetman, John. The Dambusters Raid. London: Cassell, 1999. ISBN 0-304-35173-3