Rebound pump

The bouncing bombs (in English bouncing bombs) were a class of bombs designed during the Second World War by the English engineer Barnes Wallis to bounce on the surface of the water, thus allowing maritime targets protected by net defenses against torpedoes to be reached. A modified version was used in the aerial bombardment of industrial facilities in the Ruhr Valley in May 1943 to destroy the valley's dams, something impossible to achieve by conventional means due to the damping effect of water and the size of the structures.

In their final design, rebound bombs were cylindrical in shape; Before launching, a motor made them rotate on their longitudinal axis so that, when they hit the water, they would bounce, avoiding the anti-torpedo nets. Upon reaching the dam, they sank, and thanks to a system of hydrostatic fuses they exploded at the very base of the dam. In this way, the rebound of the water driven by the shock wave contributed to demolishing the dam.

British bouncing bombs

Barnes Wallis, in an article published in April 1942 titled "Spherical Bomb - Surface Torpedo" described a method of attack in which a bomb bounced off the water until it reached its target and then sank to explode underwater, like a depth charge. Bouncing it off the surface would allow it to be aimed directly at its target, while avoiding underwater defenses, as well as some on the surface, and taking advantage of the "bubble pulse" typical of underwater explosions, considerably increasing their effectiveness: Wallis's document identified suitable targets such as hydroelectric dams "and floating ships moored in calm waters such as Norwegian fjords".

Both types of objectives were already of great interest to the British military when Wallis wrote his article (which itself was not the first on the subject). German hydroelectric dams had been identified as important bombing targets before the outbreak of World War II, but existing bombs and bombing methods had little effect on these massive structures, as they were protected with nets from conventional torpedo attack and no practical means of destroying them had yet been created.

In 1942, the British were seeking a means to destroy the German battleship Tirpitz, which posed a threat to Allied supply shipping in the North Atlantic, and which had already survived several British attempts to destroy it. During this time, Tirpitz was kept safe from attack by being moored in Norwegian fjords, where she had the effect of a 'deterrent fleet'. Consequently, Wallis's proposed weapon attracted the attention of the command. and underwent active testing and development.

On July 24, 1942, a "spectacularly successful" of the weapon's potential when a redundant dam at Nant-y-Gro, near Rhayader in Wales, was destroyed by a mine containing 279 pounds (127 kg) of explosive, detonated against the side of the dam, underwater, in a test carried out by AR Collins, a scientific officer at the Road Research Laboratory, then based at Harmondsworth, Middlesex.

A.R. Collins was among a large number of people, in addition to Barnes Wallis, who made far-reaching contributions to the development of the ricochet bomb and its method of launching it at a target, to the extent that, in an article published in 1982, Collins himself stated that it was evident that Wallis "did not play a "very important" in the development of the project and, in particular, other people made very significant contributions, such as Sir William Glanville, Dr G. Charlesworth, Dr AR Collins and others from the Road Research Laboratory. However, the Modification of a Vickers Wellington bomber, to whose design Wallis himself had contributed, to work on the first tests of his proposed weapon, has been cited as an example of how Wallis "would have been the first to recognize" the contributions of others. Furthermore, in the words of Eric Allwright, who worked in the design office for Vickers-Armstrong at the time, "Wallis was trying to do his ordinary job [for Vickers Armstrongs], as well as perform numerous other functions: he was in the Ministry of Aircraft Production, at Fort Halstead and everywhere. Wallis's pressure and his documents, ideas and ongoing developments on the relevant authorities, helped ensure that development continued; He being the main 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 to RAF crews before executing the plan envisaged in Operation Chastise, to use one of his designs in combat.

A distinctive feature of the weapon, added in the course of development, was the rearward spin, which improved the height and stability of its flight and its ability to ricochet, and helped the weapon remain in contact with, or at the least very close to its target. Backspin is a normal feature in the flight of golf balls, due to the way they are hit by the club, and it is perhaps for this reason that all forms of the weapon that were developed They were known generically as 'Golf Mines', and some of the spherical prototypes featured dimples.

In November 1942 it was decided to devise a larger version of the Wallis gun for use against prey and a smaller one for use against ships. His codenames were 'Upkeep'. and "Highball" respectively. Although each version is derived from what was originally conceived as a spherical bomb, the first prototypes of "Upkeep" and "Highball" consisted of a cylindrical pump inside a spherical casing. The development, testing and use of "Upkeep" and "Highball" They had to be carried out simultaneously, as it was important to maintain the element of surprise: if one of them were used against a target independently, it was feared that German defenses for similar targets would be strengthened, rendering the other useless. However, the "Upkeep" was developed with a deadline, as its maximum effectiveness depended on the target dams being as full as possible thanks to seasonal rains, and the deadline for this was set for May 26, 1943. As it developed This date was approaching, "Highball" remained in development, while the development of "Upkeep" had been completed and the decision was made to use "Upkeep" independently.

January 1974 marked the 30th anniversary of numerous classified documents from the Second World War, and secret British government files related to both "Upkeep" as with 'Highball', although the technical details of the weapons had already been published in 1963.

Upkeep

The testing of the "Upkeep" prototypes with inert fill were carried out at Chesil Beach, Dorset, flying from the RAF base at Warmwell in December 1942, and at Reculver, Kent, flying from Manston base in April and May 1943. Initially it was used a Vickers Wellington bomber. However, the dimensions and weight of an "Upkeep" full size was such that it could only be carried by the largest British bomber available at the time, the Avro 683 Lancaster, which even had to undergo considerable modifications to be able to carry it. In testing, it was found that the spherical casing of "Upkeep" would break upon impact with the water, but the inner cylinder containing the bomb would continue to advance over the water surface as intended. As a result, the spherical casing of "Upkeep" was removed from the design. Development and testing concluded on May 13, 1943 with the dropping of an "Upkeep" cylindrical 5 miles (8 km) offshore at Broadstairs, Kent, at which time Wallis had specified that the bomb was to be dropped "precisely" 60 feet (18 m) above the water and at 232 miles per hour (373.4 km/h) ground speed, with a backspin of 500 rpm: the bomb "bounced seven times and covered about 800 yards, after which it sank and detonated.

On the night of May 16 to 17, 1943, during Operation Chastise, the dams of the Ruhr Region in Germany were attacked, using "Upkeep". Two dams burst, causing flooding and widespread damage and loss of life. Later, the importance of this attack on the progress of the war would be debated. British losses during the operation were heavy; eight of the 19 attacking aircraft did not return, along with 53 of the RAF's 113 aircrew. The "Upkeep" was not used operationally again. By the time the war ended, the remaining operational bombs had begun to deteriorate and were dumped into the North Sea without their detonation devices.

Highball

In April 1942, Wallis himself had described his idea as "a weapon essentially for the Naval Air Force." This naval aspect would be reinforced by a note issued by British Prime Minister Winston Churchill, in February 1943, asking 'Have all plans to do anything to the Tirpitz while she is in Trondheim been given up?... It is something terrible that this prize is waiting for us and no one is able to think of a way to win it. However, the "Highball" It was eventually developed as an RAF weapon for use against various targets, including the 'Tirpitz'.

Starting in November 1942, development and testing of the "Highball" They continued alongside those of the 'Upkeep', including the launch of prototypes at both Chesil Beach and Reculver. While the first prototypes launched at Chesil Beach in December 1942 were the precursors to both versions of the bomb, those launched at Chesil Beach in January and February 1943 and at Reculver in April 1943 included prototypes of the 'Highball' #34;. They were launched by the modified Wellington bomber and on Reculver by a modified de Havilland Mosquito B Mk IV, one of two assigned to Vickers Armstrong for this purpose. In early February 1943, Wallis imagined that the & #34;Highball" "contains a 500 lb (226.8 kg) charge in a cylinder surrounded by a 35 in (88.9 cm) sphere with (a total weight) of 950 lb (430.9 kg)", and a modified Mosquito could carry two of these weapons.

The "Highball" it was never used operationally: on 12 November 1944, in Operation Catechism, a Lancaster with a Tallboy bomb sank its main target, the "Tirpitz". Other potential targets had been considered during the development of the "Highball" and also later, such as Italian navy ships, canals, dry docks, submarine bases and railway tunnels (for which tests were carried out in 1943). But Italy surrendered in September 1943 and the other objectives were discarded as impracticable.

In January 1945, at the Vickers experimental facility at Foxwarren, near Cobham, Surrey, a USAAF Douglas A-26 Invader was adapted to carry two "Highball" almost completely enclosed in the bomb bay, using parts of a Mosquito adaptation. After a brief flight test in the United Kingdom, the kit was shipped to Wright-Patterson Air Force Base, Ohio, and installed on an A-26C Invader. Twenty-five "Highball" inert bombs, renamed 'Speedee' bombs, for use in USAAF tests conducted over Choctawhatchee Bay, near Eglin Field, Florida, but the program was abandoned after the bomb bounced and collided with A-26C-25-DT Invader 43-22644 at Water Range 60, causing the loss of the rear fuselage, producing a fatal accident on April 28, 1945.

Baseball

In addition to the two types listed above, the Admiralty proposed a smaller weapon for use on torpedo boats in December 1942. Known as the 'Baseball', it would be a tube-launched weapon. Weighing 300 pounds (136.1 kg), half of which would be explosive, its estimated range was 1,000 to 1,200 yards (914.4 to 1,097.3 m).

German rebound bomb

After Operation Chastise, German forces discovered an "Upkeep" intact in the wreckage of the Lancaster commanded by Lieutenant Barlow, which had struck a high tension cable at Haldern, near Rees, Germany, crashing. The bomb had not been dropped and the plane had crashed into the ground, without firing any of the detonation devices. The Germans later built a version of "Upkeep" weighing 385 kilograms (848.8 lb), known by the code name "Kurt" or "Emil". It was developed at the Luftwaffe's Erprobungsstelle, a "test site" located on the German Baltic coast, in Travemünde (one of a network of four such establishments in Nazi Germany). The importance of recoil was not understood and tests carried out with a Focke-Wulf Fw 190 proved to be dangerous to the aircraft, as the bomb maintained the speed at which it was dropped. Attempts to rectify this problem with rocket boosters failed, and the project was canceled in 1944.

Recreating a bounce bomb

In 2011, a project was started to recreate a "Dambusters" (prey hunters). Buffalo Airways was selected as the company chosen to fly the mission, with its own plane and pilots, for which it would have to drop an "Upkeep" recreated from a Douglas DC-4. The project was filmed for the television documentaries Dambusters Fly Again in Canada and Australia, Dambusters: Building the Bouncing Bomb in the United Kingdom and for the Nova episode titled Bombing Hitler's Dams in the United States. It involved dropping a replica of a dummy bomb, which worked as expected by hitting a dam that had been built especially for the test; and which would later be destroyed by a charge placed where the bomb had landed. The filming of the documentary was documented as part of Ice Pilots NWT, a reality television series that follows Buffalo Airways, in episode 2 of season 3 of "Dambusters".