Bouncing bomb
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| Vickers Type 464 code name: Upkeep store |
|
|---|---|
 Upkeep bouncing bomb at the Imperial War Museum Duxford |
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| Type | Conventional (depth charge) |
| Place of origin |  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 ) |
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|
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| Muzzle velocity | 240-250 mph (386-402 km/h) 500 rpm backward spin[4][5] |
| 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 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.
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[edit] British bouncing bombs
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. Exploding these weapons underneath a target's hull also took advantage of the bubble pulse phenomenon typical of underwater explosions, greatly increasing their effectiveness.
[edit] 'Highball' bomb
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 diameter was 35 inches (890 mm), designed with a charge weight of 600 lb (272 kg) of Torpex and an all-up weight of 950 lb (431 kg). 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]
A variant of the Highball design was developed without dimples for the USAF, that named it the 'Speedee' bomb. The spherical shape was modified with flat sides about 30 inches (760 mm) across to enable carriage in the bomb bay of a Douglas A-26C Invader light bomber, that had been adapted at Brooklands. Trials were carried out over the sea near Eglin AFB, Florida, but were abandoned after the bomb bounced back at the A-26 causing loss of the rear fuselage and fatal crash on 28 April 1945.[9]
[edit] 'Upkeep' 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.[10] In May 1943, Operation Chastise attacked dams in Germany's Ruhr Valley -- two were breached "with limited effect".[11] 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.
[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:
- Dover Castle.
- Imperial War Museum Duxford
- Brookland's Museum in Weybridge
- Herne Bay Museum and Gallery.
- Brenzett Aeronautical Museum on Romney Marsh.
- Spitfire & Hurricane Museum at RAF Manston, Kent.
- Lincolnshire Aviation Heritage Centre, East Kirkby.
- Haverfordwest Aerodrome displays a section of a Highball bomb
- Abbotsbury Swannery displays a section of a Highball bomb
- RAF Lossiemouth - only accessible to the public with prior permission.
- The Petwood Hotel museum, Woodhall Spa, Lincolnshire, displays a damaged Upkeep bomb.
- Eden Camp Museum North Yorkshire
- Newark Air Museum displays an Upkeep test piece bomb[12]
[edit] German bouncing bomb
After Operation Chastise, the Germans discovered an Upkeep bomb that had failed to explode lying in some woods and subsequently a 385 kg (850 pound) version of the bouncing bomb was also found and tested by the Luftwaffe.[citation needed] Designed for use against British shipping, it was given the codename Kurt, and was built at the Luftwaffe Experimental Centre in Travemünde. However, they failed to understand the importance of backspin, and in trials, dropped by an Fw 190, it proved to be dangerous to the delivering planes as the bomb matched the speed at which it was dropped. Attempts to rectify this with booster rockets were ultimately a failure, and the project was discontinued in 1944.[13]
[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
- Test film of both Upkeep and Highball bouncing bombs including US A-26 Invader test drops
- The bouncing bombs - History, pictures and videos.
- Barnes Wallis Memorial Trust http://www.barneswallistrust.org/
[edit] References and Notes
- ^ "Campaign Diary" (html). Royal Air Force Bomber Command 60th Anniversary. UK Crown. http://www.raf.mod.uk/bombercommand/may43.html. Retrieved on 2007-05-24.
- ^ Field, Brian. "Dambuster Bomb Development" (html). WW2 People's War. bbc.co.uk. http://www.bbc.co.uk/ww2peopleswar/stories/27/a2163827.shtml. Retrieved on 2008-02-21.
- ^ a b "Upkeep: The Bouncing Bomb" (html). The Dambusters (617 Squadron). thedambusters.org.uk. http://www.thedambusters.org.uk/upkeep.html. Retrieved on 2008-02-21.
- ^ 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.)
- ^ a b Moorcraft, Lucy. "The Bouncing Bomb" (html). The Dambusters. University of Bristol. http://www.chm.bris.ac.uk/webprojects2001/moorcraft/The%20Bouncing%20Bomb.htm. Retrieved on 2008-02-21.
- ^ 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.
- ^ Murray, Iain. "Big & Bouncy - the special weapons of Sir Barnes Wallis". University of Dundee. http://www.computing.dundee.ac.uk/staff/irmurray/bigbounc.asp. Retrieved on 2008-02-21.
- ^ "The Second World War Experience Centre - The Dams Raid May 1943". http://www.war-experience.org/history/keyaspects/damsraid0543/default.asp. Retrieved on 2008-02-21.
- ^ Johnsen, Frederick A. (1999). Douglas A-26 Invader (Warbird Tech Series Vol.22). Minnesota: Specialty Press Publishers. pp. 85-90. ISBN 1580070167.
- ^ The Times, 20 October 2005
- ^ "Secondary Campaigns" (html). United States Strategic Bombing Survey, Summary Report (European War). 1945-09-30. http://www.usaaf.net/surveys/eto/ebs14.htm. Retrieved on 2008-02-21. " The breaking of the Mohne and the Eder dams, though the cost was small, also had limited effect."
- ^ http://www.thisisnottingham.co.uk/bygones/Bouncing-Bomb-goes-display-Notts/article-1119511-detail/article.html
- ^ Sweetman, John. The Dambusters Raid. London: Cassell, 1999. ISBN 0-304-35173-3
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