Bouncing bomb
Overview
 
A bouncing bomb is a bomb designed specifically to bounce to a target across water in a calculated manner, in order to avoid obstacles such as torpedo nets, and to allow both the bomb's speed on arrival at the target and the timing of its detonation to be pre-determined. The inventor of the first such bomb was the British engineer Barnes Wallis
Barnes Wallis
Sir Barnes Neville Wallis, CBE FRS, RDI, FRAeS , was an English scientist, engineer and inventor. He is best known for inventing the bouncing bomb used by the RAF in Operation Chastise to attack the dams of the Ruhr Valley during World War II...

, whose "Upkeep" bouncing bomb was used in the RAF
Royal Air Force
The Royal Air Force is the aerial warfare service branch of the British Armed Forces. Formed on 1 April 1918, it is the oldest independent air force in the world...

's Operation Chastise
Operation Chastise
Operation Chastise was an attack on German dams carried out on 16–17 May 1943 by Royal Air Force No. 617 Squadron, subsequently known as the "Dambusters", using a specially developed "bouncing bomb" invented and developed by Barnes Wallis...

 of May 1943 to bounce into German dams and explode underwater, with similar effect to the underground detonation of the earthquake bombs Grand Slam
Grand Slam bomb
The Grand Slam was a 22,000 lb earthquake bomb used by RAF Bomber Command against strategic targets during the Second World War.Known officially as the Bomb, Medium Capacity, 22,000 lb, it was a scaled up version of the Tallboy bomb and closer to the original size that the bombs' inventor,...

 and Tallboy
Tallboy bomb
The Tallboy or Bomb, Medium Capacity, 12,000 lb, was an earthquake bomb developed by the British aeronautical engineer Barnes Wallis and deployed by the RAF in 1944...

, both of which he also invented.
Barnes Wallis
Barnes Wallis
Sir Barnes Neville Wallis, CBE FRS, RDI, FRAeS , was an English scientist, engineer and inventor. He is best known for inventing the bouncing bomb used by the RAF in Operation Chastise to attack the dams of the Ruhr Valley during World War II...

's April 1942 paper "Spherical Bomb — Surface Torpedo" described a method of attack in which a weapon would be bounced across water until it struck its target, then sinking to explode underwater, much like a depth charge
Depth charge
A depth charge is an anti-submarine warfare weapon intended to destroy or cripple a target submarine by the shock of exploding near it. Most use explosives and a fuze set to go off at a preselected depth in the ocean. Depth charges can be dropped by either surface ships, patrol aircraft, or from...

.
Encyclopedia
A bouncing bomb is a bomb designed specifically to bounce to a target across water in a calculated manner, in order to avoid obstacles such as torpedo nets, and to allow both the bomb's speed on arrival at the target and the timing of its detonation to be pre-determined. The inventor of the first such bomb was the British engineer Barnes Wallis
Barnes Wallis
Sir Barnes Neville Wallis, CBE FRS, RDI, FRAeS , was an English scientist, engineer and inventor. He is best known for inventing the bouncing bomb used by the RAF in Operation Chastise to attack the dams of the Ruhr Valley during World War II...

, whose "Upkeep" bouncing bomb was used in the RAF
Royal Air Force
The Royal Air Force is the aerial warfare service branch of the British Armed Forces. Formed on 1 April 1918, it is the oldest independent air force in the world...

's Operation Chastise
Operation Chastise
Operation Chastise was an attack on German dams carried out on 16–17 May 1943 by Royal Air Force No. 617 Squadron, subsequently known as the "Dambusters", using a specially developed "bouncing bomb" invented and developed by Barnes Wallis...

 of May 1943 to bounce into German dams and explode underwater, with similar effect to the underground detonation of the earthquake bombs Grand Slam
Grand Slam bomb
The Grand Slam was a 22,000 lb earthquake bomb used by RAF Bomber Command against strategic targets during the Second World War.Known officially as the Bomb, Medium Capacity, 22,000 lb, it was a scaled up version of the Tallboy bomb and closer to the original size that the bombs' inventor,...

 and Tallboy
Tallboy bomb
The Tallboy or Bomb, Medium Capacity, 12,000 lb, was an earthquake bomb developed by the British aeronautical engineer Barnes Wallis and deployed by the RAF in 1944...

, both of which he also invented.

British bouncing bombs

Barnes Wallis
Barnes Wallis
Sir Barnes Neville Wallis, CBE FRS, RDI, FRAeS , was an English scientist, engineer and inventor. He is best known for inventing the bouncing bomb used by the RAF in Operation Chastise to attack the dams of the Ruhr Valley during World War II...

's April 1942 paper "Spherical Bomb — Surface Torpedo" described a method of attack in which a weapon would be bounced across water until it struck its target, then sinking to explode underwater, much like a depth charge
Depth charge
A depth charge is an anti-submarine warfare weapon intended to destroy or cripple a target submarine by the shock of exploding near it. Most use explosives and a fuze set to go off at a preselected depth in the ocean. Depth charges can be dropped by either surface ships, patrol aircraft, or from...

. Bouncing it across the surface would allow it to be aimed directly at its target, while avoiding underwater defences, as well as some above the surface, and such a weapon would take advantage of the "bubble pulse" effect typical of underwater explosion
Underwater explosion
An underwater explosion, also known as an UNDEX, is an explosion beneath the surface of water. The type of explosion may be chemical or nuclear...

s, greatly increasing its effectiveness: Wallis's paper identified suitable targets as hydro-electric dams
Hydroelectricity
Hydroelectricity is the term referring to electricity generated by hydropower; the production of electrical power through the use of the gravitational force of falling or flowing water. It is the most widely used form of renewable energy...

 "and floating vessels moored in calm waters such as the Norwegian fjord
Fjord
Geologically, a fjord is a long, narrow inlet with steep sides or cliffs, created in a valley carved by glacial activity.-Formation:A fjord is formed when a glacier cuts a U-shaped valley by abrasion of the surrounding bedrock. Glacial melting is accompanied by rebound of Earth's crust as the ice...

s".

Both types of target were already of great interest to the British military when Wallis wrote his paper, which itself was not his first on the subject: German hydro-electric dams had been identified as important bombing targets before the outbreak of World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

, but existing bombs and bombing methods had little effect on them, torpedo nets protected them from attack by conventional torpedo
Torpedo
The modern torpedo is a self-propelled missile weapon with an explosive warhead, launched above or below the water surface, propelled underwater towards a target, and designed to detonate either on contact with it or in proximity to it.The term torpedo was originally employed for...

es, and a practical means of destroying them had yet to be devised; and, in 1942, the British were seeking a means of destroying the German battleship
Battleship
A battleship is a large armored warship with a main battery consisting of heavy caliber guns. Battleships were larger, better armed and armored than cruisers and destroyers. As the largest armed ships in a fleet, battleships were used to attain command of the sea and represented the apex of a...

 Tirpitz
German battleship Tirpitz
Tirpitz was the second of two s built for the German Kriegsmarine during World War II. Named after Grand Admiral Alfred von Tirpitz, the architect of the Imperial Navy, the ship was laid down at the Kriegsmarinewerft in Wilhelmshaven in November 1936 and launched two and a half years later in April...

, which posed a threat to Allied
Allies of World War II
The Allies of World War II were the countries that opposed the Axis powers during the Second World War . Former Axis states contributing to the Allied victory are not considered Allied states...

 shipping in the North Atlantic, had already survived a number of British attempts to destroy it, and for much of the time was being kept safe from attack by being moored in Norwegian fjords, where nonetheless it had the effect of a "fleet in being
Fleet in being
In naval warfare, a fleet in being is a naval force that extends a controlling influence without ever leaving port. Were the fleet to leave port and face the enemy, it might lose in battle and no longer influence the enemy's actions, but while it remains safely in port the enemy is forced to...

". Consequently Wallis's proposed weapon attracted attention, and underwent active testing and development.

On 24 July 1942, a "spectacularly successful" demonstration of such a weapon's potential occurred when a redundant dam at Nant-y-Gro
Elan Valley Reservoirs
The Elan Valley Reservoirs are a chain of man-made lakes and reservoirs in the Elan Valley in Powys, Mid Wales , using the rivers Elan and Claerwen...

, near Rhayader
Rhayader
Rhayader is a market town and community in Powys, Mid Wales. It has a population of 2,075, and is the first town on the banks of the River Wye, from its source on the Plynlimon range of the Cambrian Mountains....

, in Wales, was destroyed by a mine
Naval mine
A naval mine is a self-contained explosive device placed in water to destroy surface ships or submarines. Unlike depth charges, mines are deposited and left to wait until they are triggered by the approach of, or contact with, an enemy vessel...

 containing 279 pounds (127 kg) of explosive: this was detonated against the dam's side, underwater, in a test undertaken by A.R. Collins, a scientific officer from the Road Research Laboratory
Transport Research Laboratory
TRL is a British transport consultancy and research organisation based at Wokingham Berkshire with approximately 500 staff. TRL is owned by the Transport Research Foundation , which is overseen by 80 sector members from the transport industry. TRL also own small UK regional offices situated in...

, that was then based at Harmondsworth
Harmondsworth
Harmondsworth is a village in the London Borough of Hillingdon, close to London Heathrow Airport. The village is situated south of West Drayton.The nearest places are: Hayes, Harlington, Heathrow Airport, Longford, London, Sipson, West Drayton and Yiewsley....

, Middlesex.

A.R. Collins was among a large number of other people besides Barnes Wallis who made wide-ranging contributions to the development of a bouncing bomb and its method of delivery to a target, to the extent that, in a paper published in 1982, Collins himself made it evident that Wallis "did not play an all-important role in the development of this project and in particular, that very significant contributions were made by, for example, Sir William Glanville
William Glanville
Sir William Henry Glanville CB CBE was a British civil engineer. During WWII he and the Road Research Laboratory were involved in important war work, developing temporary runways, beach analysis, and tank and aircraft design...

, Dr. G. Charlesworth, Dr. A.R. Collins and others of the Road Research Laboratory." However, the modification of a Vickers Wellington
Vickers Wellington
The Vickers Wellington was a British twin-engine, long range medium bomber designed in the mid-1930s at Brooklands in Weybridge, Surrey, by Vickers-Armstrongs' Chief Designer, R. K. Pierson. It was widely used as a night bomber in the early years of the Second World War, before being displaced as a...

 bomber, the design of which Wallis himself had contributed to, for work in early testing of his proposed weapon, has been cited as an example of how Wallis "would have been the first to acknowledge" the contributions of others. Also, in the words of Eric Allwright, who worked in the Drawing Office for Vickers Armstrongs at the time, "Wallis was trying to do his ordinary job [for Vickers Armstrongs] as well as all this – he was out at the Ministry
Minister of Aircraft Production
The Minister of Aircraft Production was the British government position in charge of the Ministry of Aircraft Production, one of the specialised supply ministries set up by the British Government during World War II...

 and down to Fort Halstead
Fort Halstead
Fort Halstead is a research site of Dstl, an Executive Agency of the UK Ministry of Defence. It is situated on the crest of the Kentish North Downs, overlooking the town of Sevenoaks...

 and everywhere"; Wallis's pressing of his papers, ideas and ongoing developments on relevant authorities helped ensure that development continued; Wallis was principal designer of the models, prototypes and "live" versions of the weapon; and, perhaps most significantly, it was Wallis who explained the weapon in the final briefing for RAF
Royal Air Force
The Royal Air Force is the aerial warfare service branch of the British Armed Forces. Formed on 1 April 1918, it is the oldest independent air force in the world...

 crews before they set off on Operation Chastise
Operation Chastise
Operation Chastise was an attack on German dams carried out on 16–17 May 1943 by Royal Air Force No. 617 Squadron, subsequently known as the "Dambusters", using a specially developed "bouncing bomb" invented and developed by Barnes Wallis...

, to use one of his designs in action.

A distinctive feature of the weapon, added in the course of development, was back-spin, which improved the height and stability of its flight and its ability to bounce, and helped the weapon to remain in contact with, or at least close proximity to, its target on arrival. Back-spin is a normal feature in the flight of golf ball
Golf ball
A golf ball is a ball designed to be used in the game of golf.Under the Rules of Golf, a golf ball weighs no more than 1.620 oz , has a diameter not less than 1.680 in , and performs within specified velocity, distance, and symmetry limits...

s, owing to the manner in which they are struck by the club, and it is perhaps for this reason that all forms of the weapon which were developed were known generically as "Golf mines", and some of the spherical prototypes featured dimples.

It was decided in November 1942 to devise a larger version of Wallis's weapon for use against dams, and a smaller one for use against ships: these were code-named
Code name
A code name or cryptonym is a word or name used clandestinely to refer to another name or word. Code names are often used for military purposes, or in espionage...

 "Upkeep" and "Highball" respectively. Though each version derived from what was originally envisaged as a spherical bomb, early prototypes for both Upkeep and Highball consisted of a cylindrical bomb within a spherical casing. Development, testing and use of Upkeep and Highball were to be undertaken simultaneously, since it was important to retain the element of surprise: if one were to be used against a target independently, it was feared that German defences for similar targets would be strengthened, rendering the other useless. However, Upkeep was developed against a deadline, since its maximum effectiveness depended on target dams being as full as possible from seasonal rainfall, and the latest date for this was set at 26 May 1943. In the event, as this date approached, Highball remained in development, whereas development of Upkeep had completed, and the decision was taken to deploy Upkeep independently.

In January 1974, under Britain's "thirty year rule
Thirty year rule
The "thirty year rule" is the popular name given to a law in the United Kingdom, the Republic of Ireland, and Australia that provides that the yearly cabinet papers of a government will be released publicly thirty years after they were created....

", secret government files for both Upkeep and Highball were released, although technical details of the weapons had been released in 1963.

Upkeep


Testing of Upkeep prototypes with inert filling was carried out at Chesil Beach
Chesil Beach
Chesil Beach, sometimes called Chesil Bank, in Dorset, southern England is one of three major shingle structures in Britain. Its toponym is derived from the Old English ceosel or cisel, meaning "gravel" or "shingle"....

, Dorset, flying from RAF Warmwell
RAF Warmwell
RAF Warmwell was a Royal Air Force station near Warmwell in Dorset, England from 1937 to 1946, located about 5 miles east-southeast of Dorchester; 100 miles southwest of London....

 in December 1942, and at Reculver
Reculver
Reculver is a hamlet and coastal resort situated about east of Herne Bay in southeast England. It is a ward of the City of Canterbury district in the county of Kent. Reculver once occupied a strategic location at the western end of the Wantsum Channel, between the Isle of Thanet and the Kent...

, Kent, flying from RAF Manston
RAF Manston
RAF Manston was an RAF station in the north-east of Kent, at on the Isle of Thanet from 1916 until 1996. The site is now split between a commercial airport Kent International Airport and a continuing military use by the Defence Fire Training and Development Centre , following on from a long...

 in April and May 1943, at first using a Vickers Wellington
Vickers Wellington
The Vickers Wellington was a British twin-engine, long range medium bomber designed in the mid-1930s at Brooklands in Weybridge, Surrey, by Vickers-Armstrongs' Chief Designer, R. K. Pierson. It was widely used as a night bomber in the early years of the Second World War, before being displaced as a...

 bomber. However, the dimensions and weight of the full-size Upkeep were such that it could only be carried by the Avro Lancaster
Avro Lancaster
The Avro Lancaster is a British four-engined Second World War heavy bomber made initially by Avro for the Royal Air Force . It first saw active service in 1942, and together with the Handley Page Halifax it was one of the main heavy bombers of the RAF, the RCAF, and squadrons from other...

, which was the largest British bomber available at the time, and nonetheless had to undergo considerable modification in order to carry it. In testing, it was found that Upkeep's spherical casing would shatter on impact with water, but that the inner cylinder containing the bomb would continue across the surface of the water much as intended. As a result, Upkeep's spherical casing was eliminated from the design. Development and testing concluded on 13 May 1943 with the dropping of a live, cylindrical Upkeep bomb 5 miles (8 km) out to sea from Broadstairs
Broadstairs
Broadstairs is a coastal town on the Isle of Thanet in the Thanet district of east Kent, England, about south-east of London. It is part of the civil parish of Broadstairs and St Peter's, which includes St. Peter's and had a population in 2001 of about 24,000. Situated between Margate and...

, Kent, by which time Wallis had specified that the bomb must be dropped at "precisely" 60 feet (18 m) above the water and 232 miles per hour (103.7 m/s) groundspeed, with back-spin at 500 rpm
Revolutions per minute
Revolutions per minute is a measure of the frequency of a rotation. It annotates the number of full rotations completed in one minute around a fixed axis...

: the bomb "bounced seven times over some 800 yards (731.5 m), sank and detonated".

In the operational version of Upkeep, known by its manufacturer as "Vickers Type 464", the explosive charge was Torpex
Torpex
Torpex is a secondary explosive 50% more powerful than TNT by mass. Torpex is composed of 42% RDX, 40% TNT and 18% powdered aluminium. It was used in the Second World War from late 1942. The name is short for Torpedo Explosive', having been originally developed for use in torpedoes...

, originally designed for use as a torpedo explosive, to provide a longer explosive pulse for greater effect against underwater targets; the principal means of detonation was by three hydrostatic pistols, as used in depth charge
Depth charge
A depth charge is an anti-submarine warfare weapon intended to destroy or cripple a target submarine by the shock of exploding near it. Most use explosives and a fuze set to go off at a preselected depth in the ocean. Depth charges can be dropped by either surface ships, patrol aircraft, or from...

s, set to fire at a depth of 30 feet (9 m); and its overall weight was 9250 pounds (4,196 kg), of which 6600 pounds (2,994 kg) was Torpex. Provision was also made for "self-destruct" detonation by a fuze
Fuze
Fuze Beverage, commercially referred to as just Fuze , is a manufacturer of teas and non-carbonated fruit drinks enriched with vitamins. Currently the brand consists of five vitamin-infused lines: Slenderize, Refresh, Tea, Defensify, and Vitalize...

, armed automatically as the bomb was dropped from the aircraft, and timed to fire after 90 seconds. The bomb was held in place in the aircraft by a pair of calipers, or triangulated carrying arms, which swung away from either end of the bomb to release it. Back-spin was to be initiated 10 minutes prior to arrival at a target, and was imparted via a belt driven by a Vickers Jassey hydraulic motor mounted forward of the bomb's starboard side, the motor itself being powered by the hydraulic system normally intended for the upper gun turret, which had been removed as part of the aircraft's modification. Aiming was by a pair of intersecting spotlight beams, which, when converged on a surface of water, indicated correct height for the aircraft, and by a simple, hand-held, triangular device: with one corner held up to the eye, projections on the other two corners would line up with pre-determined points on the target when it was at the correct distance for bomb release. In practice, this could prove awkward to handle, and some aircrews replaced it with their own arrangements, fixed within the aircraft itself, and involving chinagraph
Grease pencil
The grease pencil, a wax writing tool also known as a wax pencil, china marker, , is made of hardened colored wax and is useful for marking on hard, glossy non-porous surfaces such as porcelain, glass, polished stone, plastic, ceramics and other glazed, lacquered or polished surfaces, as well as...

 and string.

On the night of 16/17 May 1943, Operation Chastise
Operation Chastise
Operation Chastise was an attack on German dams carried out on 16–17 May 1943 by Royal Air Force No. 617 Squadron, subsequently known as the "Dambusters", using a specially developed "bouncing bomb" invented and developed by Barnes Wallis...

 attacked dams in Germany's Ruhr Valley, using Upkeep: two dams were successfully breached, causing widespread flooding and damage, and significant loss of life, though the significance of this attack for the progress of the war is debated. British losses during the operation were heavy, with 8 of the 19 attacking aircraft failing to return, along with 53 of 113 RAF aircrew. Upkeep was not used again operationally, and all remaining operational Upkeep bombs were dumped into the North Sea
North Sea
In the southwest, beyond the Straits of Dover, the North Sea becomes the English Channel connecting to the Atlantic Ocean. In the east, it connects to the Baltic Sea via the Skagerrak and Kattegat, narrow straits that separate Denmark from Norway and Sweden respectively...

, without their detonation devices, prior to the end of hostilities, as their condition had started to deteriorate.

Highball

In April 1942, Wallis himself had described his proposed weapon as "essentially a weapon for the Fleet Air Arm
Fleet Air Arm
The Fleet Air Arm is the branch of the British Royal Navy responsible for the operation of naval aircraft. The Fleet Air Arm currently operates the AgustaWestland Merlin, Westland Sea King and Westland Lynx helicopters...

", and this naval aspect was later to be pressed by a minute
Minutes
Minutes, also known as protocols, are the instant written record of a meeting or hearing. They typically describe the events of the meeting, starting with a list of attendees, a statement of the issues considered by the participants, and related responses or decisions for the issues.Minutes may be...

 issued to relevant authorities by British prime minister Winston Churchill
Winston Churchill
Sir Winston Leonard Spencer-Churchill, was a predominantly Conservative British politician and statesman known for his leadership of the United Kingdom during the Second World War. He is widely regarded as one of the greatest wartime leaders of the century and served as Prime Minister twice...

, in February 1943, in which he asked, "Have you given up all plans for doing anything to Tirpitz
German battleship Tirpitz
Tirpitz was the second of two s built for the German Kriegsmarine during World War II. Named after Grand Admiral Alfred von Tirpitz, the architect of the Imperial Navy, the ship was laid down at the Kriegsmarinewerft in Wilhelmshaven in November 1936 and launched two and a half years later in April...

 while she is in Trondheim
Trondheimsfjord
The Trondheimsfjord , an inlet of the Norwegian Sea, is Norway's third longest fjord at long. It is located in the west central part of the country, and it stretches from Ørland in west to Steinkjer in north, passing the city of Trondheim on its way...

?... It is a terrible thing that this prize should be waiting and no one be able to think of a way of winning it". However, Highball was ultimately developed as an RAF weapon for use against various targets, including Tirpitz.

From November 1942, development and testing for Highball continued alongside that of Upkeep, including the dropping of prototypes at both Chesil Beach and Reculver. While early prototypes dropped at Chesil Beach in December 1942 were forerunners for both versions of the bomb, those dropped at Chesil Beach in January and February 1943 and at Reculver in April 1943 included prototypes specifically for Highball. They were dropped by both the modified Wellington bomber and, at Reculver, by a modified de Havilland Mosquito B Mk IV
De Havilland Mosquito
The de Havilland DH.98 Mosquito was a British multi-role combat aircraft that served during the Second World War and the postwar era. It was known affectionately as the "Mossie" to its crews and was also nicknamed "The Wooden Wonder"...

, one of two assigned to Vickers Armstrongs for the purpose. By early February 1943, Wallis had come to envisage Highball as "comprising a 500 lb [227 kg] charge in a cylinder contained in a 35-in [89 cm] sphere with (an overall weight) of 950 lb [431 kg]", and, with modification, the Mosquito could carry two such weapons.

In tests at Reculver in the middle of April 1943, it was found that Highball's spherical casing suffered similar damage to that of Upkeep. However, one prototype with an altered design of casing strengthened by steel plate, but empty of either inert filling or explosive, was dropped on 30 April, and emerged "quite undamaged". Further testing of two examples of this prototype on 2 May, now with inert filling, was successful with regard to their ability to bounce across the surface of the water as intended, though, on inspection, both were found to be dented.

Further testing was carried out by three modified Mosquitoes flying from RAF Turnberry, north of Girvan
Girvan
Girvan is a burgh in Carrick, South Ayrshire, Scotland, with a population of about 8000 people. Originally a fishing port, it is now also a seaside resort with beaches and cliffs. Girvan dates back to 1668 when is became a municipal burgh incorporated by by charter...

, on the west coast of Scotland, against a target ship, the former French battleship Courbet
French battleship Courbet (1911)
Courbet was the lead ship of her class, the first dreadnoughts built for the French Navy. She was completed before World War I and named in honour of Admiral Amédée Courbet. She spent the war in the Mediterranean, helping to sink the Austro-Hungarian protected cruiser in August 1914...

, which had been moored for the purpose in Loch Striven
Loch Striven
Loch Striven is a sea loch adjoining the west side of the Firth of Clyde just north of the Isle of Bute, where it forms a narrow inlet about 8 miles long extending north into the Cowal peninsula. During times of recession in shipping the loch has been used as a sheltered anchorage for laid...

. This series of tests, on 9 and 10 May, was hampered by a number of errors: buoy
Buoy
A buoy is a floating device that can have many different purposes. It can be anchored or allowed to drift. The word, of Old French or Middle Dutch origin, is now most commonly in UK English, although some orthoepists have traditionally prescribed the pronunciation...

s intended to mark a point 1200 yards (1,097 m) from the Courbet, where the prototypes were to be dropped, were found to be too close to the ship by 400 yards (366 m), and, according to Wallis, other errors were due to "Variations in dimensions of [prototypes] after filling and [dimensionally incorrect] jigs for setting up the [caliper] arms". Effects were that the prototypes hit their target too fast, and too hard, and that two aircraft failed to release their prototypes, one of which then fell while the aircraft concerned was turning for a second attempt.

It was under such circumstances that Upkeep came to be deployed independently of Highball. In addition to continuing problems in testing Highball, it had been observed at the end of March 1943 that "At best [aircrews] would need two months’ special training". With this in mind, 618 Squadron
No. 618 Squadron RAF
No. 618 Squadron RAF was a squadron of the Royal Air Force during the Second World War, intended to carry of a variation of the Barnes Wallis designed Bouncing bomb code-named "Highball"...

 had been formed on 1 April 1943 at RAF Skitten, near Wick
Wick, Highland
Wick is an estuary town and a royal burgh in the north of the Highland council area of Scotland. Historically, it is one of two burghs within the county of Caithness, of which Wick was the county town. The town straddles the River Wick and extends along both sides of Wick Bay...

, in north-eastern Scotland, to undertake what was intended to be "Operation Servant", in which Tirpitz would be attacked with Highball bouncing bombs. On 18 April it was recommended that Operation Servant should be undertaken before the end of June, since 618 Squadron could not be held back for this purpose indefinitely: nonetheless, it was not until early September 1943 that, in view of continuing problems with both Highball and its release mechanism, most of 618 Squadron was "released for other duties", which in practice meant the abandonment of Operation Servant. Core personnel of 618 Squadron were retained, however, and these continued to be involved in the development of Highball.

Demonstrations of progress with Highball occurred in testing between 15 and 17 May 1944. By this time Courbet had been used as part of a Gooseberry breakwater for the D-Day landings, and HMS Malaya, a veteran of World War I, was used as its replacement, also moored in Loch Striven. With crew on board HMS Malaya, inert Highball prototypes fitted with hydrostatic pistols were aimed at the ship and released, successfully striking the ship, and one punched a hole in the ship's side. On 17 May, for the first time, prototypes were released in pairs, only one second apart.

By the end of May 1944, problems with releasing Highball had been resolved, as had problems with aiming, which required a different method to that for Upkeep, and were resolved by Wallis's design of a ring aperture sight fixed to a flying helmet
Leather helmet
A leather helmet is a form of protective headgear fashioned primarily out of leather .People have manufactured leather clothing, including headgear, for millennia....

. Highball itself was now a sphere with flattened poles, and the explosive charge was Torpex, enclosed in a cylinder, as in Upkeep; detonation was by a single hydrostatic pistol, set to fire at a depth of 27 feet (8 m); and its overall weight was 1280 pounds (581 kg), of which 600 pounds (272 kg) was Torpex.

However, Highball was never used in action. On 12 November 1944, its primary target, Tirpitz, was capsized by Lancasters from 9 Squadron and 617 Squadron
No. 617 Squadron RAF
No. 617 Squadron is a Royal Air Force aircraft squadron based at RAF Lossiemouth in Scotland. It currently operates the Tornado GR4 in the ground attack and reconnaissance role...

 in Operation Catechism
Operation Catechism
Operation Catechism was the last of nine attempts to sink or sabotage the Kriegsmarine battleship Tirpitz during World War II. On November 12, 1944, the RAF Bomber Command dispatched 30 Avro Lancaster heavy bombers from No. 9 Squadron RAF and No. 617 Squadron RAF Operation Catechism was the last of...

, using Tallboy bomb
Tallboy bomb
The Tallboy or Bomb, Medium Capacity, 12,000 lb, was an earthquake bomb developed by the British aeronautical engineer Barnes Wallis and deployed by the RAF in 1944...

s: these were also developed by Wallis, independently of his work on bouncing bombs. Other potential targets were considered, both during Highball's development and later, including ships of the Italian navy
Regia Marina
The Regia Marina dates from the proclamation of the Kingdom of Italy in 1861 after Italian unification...

, canals, dry docks, submarine pen
Submarine pen
A submarine pen is a bunker which is designed to protect submarines from air attack.The term is generally applied to submarine bases constructed during World War II, particularly in Germany and the occupied countries which were also known as U-boat pens .-Background:Amongst the first...

s, and railway tunnels – for which testing took place, in 1943 – but, while the Italian navy ceased to be an enemy from 3 September 1943, the remainder were dismissed, in effect, as impracticable.

In January 1945, a Douglas A-26 Invader
A-26 Invader
The Douglas A-26 Invader was a United States twin-engined light attack bomber built by the Douglas Aircraft Co. during World War II that also saw service during several of the Cold War's major conflicts...

 of the USAAF
United States Army Air Forces
The United States Army Air Forces was the military aviation arm of the United States of America during and immediately after World War II, and the direct predecessor of the United States Air Force....

 was adapted at the Vickers' experimental facility at Foxwarren, near Cobham, Surrey
Cobham, Surrey
Cobham is a town in the Borough of Elmbridge in Surrey, England, about south-west of central London and north of Leatherhead. Elmbridge has been acclaimed by the Daily Mail as the best place to live in the UK, and Cobham is a prosperous part of the London commuter belt...

, to carry two Highballs almost completely enclosed in the bomb bay, using parts from a Mosquito conversion. After brief flight testing in the UK, the kit was sent to Wright Field
Wright Field
Wright Field was an airfield of the United States Army Air Corps and Air Forces near Riverside, Ohio. From 1927 to 1947 it was the research and development center for the Air Corps, and during World War II a flight test center....

, Ohio, and installed in an A-26C Invader. Twenty-five inert Highballs, renamed "Speedee" bombs, were also sent for use in the USAAF trials. Drop tests were carried out over Choctawhatchee Bay
Choctawhatchee Bay
Choctawhatchee Bay is a bay in the Emerald Coast region of the Florida Panhandle. The bay, located within Okaloosa and Walton counties, has a surface area of 129 mi2...

 near Eglin Field
Eglin Air Force Base
Eglin Air Force Base is a United States Air Force base located approximately 3 miles southwest of Valparaiso, Florida in Okaloosa County....

, Florida, but the programme was abandoned after the bomb bounced back at A-26C-25-DT Invader 43-22644 on Water Range 60, causing loss of the rear fuselage and a fatal crash on 28 April 1945.

Baseball

As well as the two types listed above, a smaller weapon for use by MTB
Motor Torpedo Boat
Motor Torpedo Boat was the name given to fast torpedo boats by the Royal Navy, and the Royal Canadian Navy.The capitalised term is generally used for the Royal Navy boats and abbreviated to "MTB"...

's was proposed by the Admiralty in December 1942. Known as Baseball, this would be a tube-launched weapon weighing 300 pounds (136.1 kg), of which half would be explosive, and with an anticipated range of 1000 to 1200 yd (914.4 to 1,097.3 ).

Surviving examples

Inert prototypes of both Upkeep and Highball that were dropped at Reculver have been recovered and these, along with a number of other examples, are displayed at various sites:
  • Abbotsbury Swannery
    Abbotsbury Swannery
    Abbotsbury Swannery is the only managed colony of nesting mute swans in the world. It is situated near the village of Abbotsbury in Dorset, England, west of Weymouth on a site around the Fleet lagoon protected from the weather of Lyme Bay by Chesil Beach. The colony can number over 600 swans with...

    , near the test site at Chesil Beach
    Chesil Beach
    Chesil Beach, sometimes called Chesil Bank, in Dorset, southern England is one of three major shingle structures in Britain. Its toponym is derived from the Old English ceosel or cisel, meaning "gravel" or "shingle"....

  • Brenzett Aeronautical Museum, Brenzett
    Brenzett
    Brenzett is a village and civil parish in the Shepway District of Kent, England. The village lies on the Romney Marsh, three miles west of New Romney....

    , on Romney Marsh
    Romney Marsh
    Romney Marsh is a sparsely populated wetland area in the counties of Kent and East Sussex in the south-east of England. It covers about 100 mi ² .-Quotations:*“As Egypt was the gift of the Nile, this level tract .....

    .
  • Brooklands Museum
    Brooklands Museum
    Brooklands Museum is an independent charitable trust, established in 1987, whose aim is to conserve, protect and interpret the unique heritage of the Brooklands site. It is located south of Weybridge, Surrey and was first opened regularly in 1991 on of the original 1907 motor-racing circuit...

    , Weybridge
  • Dover Castle
    Dover Castle
    Dover Castle is a medieval castle in the town of the same name in the English county of Kent. It was founded in the 12th century and has been described as the "Key to England" due to its defensive significance throughout history...

    .
  • Haverfordwest Aerodrome
    Haverfordwest Aerodrome
    Haverfordwest Aerodrome is a minor airport located north of Haverfordwest, Pembrokeshire.Haverfordwest Aerodrome has a CAA Ordinary Licence that allows flights for the public transport of passengers or for flying instruction as authorised by the licensee .Haverfordwest Airport accepts genuine...

     (Highball)
  • Herne Bay Museum and Gallery
    Herne Bay, Kent
    Herne Bay is a seaside town in Kent, South East England, with a population of 35,188. On the south coast of the Thames Estuary, it is north of Canterbury and east of Whitstable. It neighbours the ancient villages of Herne and Reculver and is part of the City of Canterbury local government district...

    , west of the test site at Reculver
    Reculver
    Reculver is a hamlet and coastal resort situated about east of Herne Bay in southeast England. It is a ward of the City of Canterbury district in the county of Kent. Reculver once occupied a strategic location at the western end of the Wantsum Channel, between the Isle of Thanet and the Kent...

     (Highball)
  • Imperial War Museum Duxford
    Imperial War Museum Duxford
    Imperial War Museum Duxford is a branch of the Imperial War Museum near the village of Duxford in Cambridgeshire, England. Britain's largest aviation museum, Duxford houses the museum's large exhibits, including nearly 200 aircraft, military vehicles, artillery and minor naval vessels in seven...

  • Lincolnshire Aviation Heritage Centre
    Lincolnshire Aviation Heritage Centre
    Lincolnshire Aviation Heritage Centre, East Kirkby, Lincolnshire, England, was founded in 1988 by Lincolnshire farmers Fred and Harold Panton, as a memorial to their brother Pilot Officer Christopher Panton, who along with 55,000 other aircrew of RAF Bomber Command lost his life during World War II...

    , East Kirkby
    East Kirkby
    East Kirkby is a village and civil parish in the East Lindsey district of Lincolnshire, England. It lies on the A155 south-east of Horncastle....

    .
  • Newark Air Museum
    Newark Air Museum
    right|thumb|200px|[[Handley Page Hastings]] T5 TG517 at the Newark Air Museum.Newark Air Museum is an air museum located on a former Royal Air Force station at Winthorpe, near Newark on Trent in Nottinghamshire, England. The museum contains a variety of aircraft...

     (Upkeep)
  • Petwood Hotel, Woodhall Spa
    Woodhall Spa
    Woodhall Spa is a civil parish and village in the East Lindsey district of Lincolnshire, England within a wooded area on the Southern edge of the Lincolnshire Wolds, about south-west of Horncastle and about east-south-east of Lincoln...

    , Lincolnshire (Upkeep)
  • RAF Lossiemouth
    RAF Lossiemouth
    RAF Lossiemouth is a Royal Air Force station to the west of the town of Lossiemouth in Moray, Scotland. It is one of the RAF's biggest bases and is currently Britain's main base for Tornado GR4s. From 2013 the Northern QRA force of Typhoon F2 will relocate to Lossiemouth following the closure of...

    , Moray – only accessible to the public with prior permission.
  • Spitfire & Hurricane Memorial Museum at RAF Manston
    RAF Manston
    RAF Manston was an RAF station in the north-east of Kent, at on the Isle of Thanet from 1916 until 1996. The site is now split between a commercial airport Kent International Airport and a continuing military use by the Defence Fire Training and Development Centre , following on from a long...

    , Kent.


In 2010, a diving project in Loch Striven successfully located "at least eight" Highball prototypes, under more than 114 feet (35 m) of water. There are plans to recover some of these prototypes, for conservation and restoration at Brooklands Museum.

German bouncing bomb

After Operation Chastise, German forces discovered an Upkeep bomb intact. This was in the wreckage of the Lancaster commanded by Flt Lt
Flight Lieutenant
Flight lieutenant is a junior commissioned rank in the Royal Air Force and the air forces of many Commonwealth countries. It ranks above flying officer and immediately below squadron leader. The name of the rank is the complete phrase; it is never shortened to "lieutenant"...

 Barlow, which had struck high tension cable
Electric power transmission
Electric-power transmission is the bulk transfer of electrical energy, from generating power plants to Electrical substations located near demand centers...

s at Haldern, near Rees, Germany
Rees, Germany
Rees is a town in the district of Cleves in the state of North Rhine-Westphalia, Germany. It is located on the right bank of the Rhine, approx. 20 km east of Cleves...

, and crashed: since the bomb had not been released, and the aircraft had crashed on land, none of the detonation devices had fired. Subsequently, a 385 kg (850 pound) version of Upkeep, code-named 'Kurt' or 'Emil', was built at the Luftwaffe
Luftwaffe
Luftwaffe is a generic German term for an air force. It is also the official name for two of the four historic German air forces, the Wehrmacht air arm founded in 1935 and disbanded in 1946; and the current Bundeswehr air arm founded in 1956....

 Experimental Centre in Travemünde
Travemünde
Travemünde is a borough of Lübeck, Germany, located at the mouth of the river Trave in Lübeck Bay. It began life as a fortress built by Henry the Lion, Duke of Saxony, in the 12th century to guard the mouth of the Trave, and the Danes subsequently strengthened it. It became a town in 1317 and in...

. However, the importance of back-spin was not understood, and, dropped in trials by a Focke-Wulf Fw 190
Focke-Wulf Fw 190
The Focke-Wulf Fw 190 Würger was a German Second World War single-seat, single-engine fighter aircraft designed by Kurt Tank in the late 1930s. Powered by a radial engine, the 190 had ample power and was able to lift larger loads than its well-known counterpart, the Messerschmitt Bf 109...

, 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.

Re-creating the bouncing bomb

In 2011, a project was initiated to re-create a Dambusters
Operation Chastise
Operation Chastise was an attack on German dams carried out on 16–17 May 1943 by Royal Air Force No. 617 Squadron, subsequently known as the "Dambusters", using a specially developed "bouncing bomb" invented and developed by Barnes Wallis...

 raid. Buffalo Airways
Buffalo Airways
Buffalo Airways is a family-run airline based in Hay River, Northwest Territories, Canada established in 1970 by Joe McBryan, also known as "Buffalo Joe". It operates scheduled passenger, scheduled cargo, charter passenger, charter cargo, firefighting and fuel services...

 was selected as the company to fly the mission, with their own plane and pilots. Buffalo would drop a re-created 'Upkeep' bouncing bomb from their DC-4. The project was documented in the documentary television show Dambusters Fly Again in Canada, and Dambusters: Building the Bouncing Bomb in the UK. It involved dropping a replica dummy bomb, and blowing up a replica dam. The filming of the documentary was itself documented as part of the Ice Pilots NWT
Ice Pilots NWT
Ice Pilots NWT is a reality television documentary series broadcast on History Television that portrays Buffalo Airways, an airline based in Yellowknife, Northwest Territories, Canada. Buffalo flies WWII-era propeller planes year-round in the Canadian North. It premiered on November 18, 2009...

 reality series, that follows Buffalo Airways, in season 3 episode 2 "Dambusters".

External links

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