The Bouncing Bomb - "It will never work... "

The logic behind the bouncing bomb was dictated by Wallis's research. His initial investigations into destroying the Ruhr dams indicated he'd need a bomb of around 10,000kgs dropped from an altitude of 20,000 feet. The bomb was intended to hit the wall, penetrate then explode. Sounded easy in theory, however in 1940 he was confronted by many problems, including:

1.		There were no aircraft available capable of lifting such a heavy bomb over the distance required. Wallis investigated modifying existing designs, such as the Short Sterling and B-17 and while these were capable of lifting such weights, their range was limited to a few hundred miles at best at such high gross weights. Undettered, Wallis even investigated the possibility of in flight refueling to overcome the problem, but this was rejected by him at the time as being too experimental in nature. Ultimately he determined that if bombing the dams using a large penetrating bomb was accepted, he'd design a suitable aircraft to do the job. He proposed a six engined aircraft using goedesic construction based on his Wellington design.
2.		The bombing altitude of 20,000ft presented a big problem of accuracy. Again Wallis believed this could be overcome using a specially designed bombsight, or an adaptation of the American's Norden sight. There is some evidence to suggest that he made preliminary research into methods of guiding a large bomb to the target, possibly using an American system then under development that used a TV camera in the bomb's nose.
			Short Stirling. An early candidate to carry a large penetrator type bomb, it was quickly disqualified. Basically a good aircraft, the Stirling suffered from a 100ft wing span limitation placed on it by the original specification that required it to fit into a standard RAF hanger, which was at the time more suited to medium bombers than the new generation of heavies. The result was poor high altitude performance. Wallis considered lengthened span versions and even a six engine version. These were dropped by him in favor of a totally new design.

During his research he found that he could reduce the weight of explosives required by almost half if he could place the bomb up against the dam wall at a precise depth. Here he found that the shock waves from the explosion, would be reflected by the water and concentrated into the dam wall. After confirming this by experiments with scale model dams and explosives, he calculated that there was no need to design a special aircraft, as the Lancaster was then entering squadron service and was more than capable of carrying the required weight to the Ruhr and return. This added weight to his argument and eliminated many of the objections he was already facing from hostile Ministry of Aircraft Production bureaucrats. The next problem was placing the bomb in the right place.

There have been several explanations as to how Wallis arrived at his bouncing bomb concept including the one depicted in the classic 1954 movie, "The Dam Busters", which suggests he was inspired by Admiral Nelson's technique of aiming cannon to ricochet cannon balls of the water into enemy ships.

When Barnes Wallis first proposed a bouncing bomb it was greeted with skepticism by many of those involved. The movie gives an entertaining and reasonably accurate portrayal of the problems he encountered during his research, but tends to gloss over some of the main obstacles he confronted, namely hostility and obstruction from people in high places.

Years previously, Wallis had been critical of Air Ministry bureaucrats about their conduct of the R100 and R101 dirigible projects. Several of these had worked their way into senior positions and in typical Yes Minister fashion had begun a whispering campaign suggesting that Wallis had finally "lost his marbles" - a clever reference to his research where he shot marbles from a catapult across a pond in an initial attempt to determine the mathematical relationship between object mass, velocity, angle of incidence, and bounce distance.

A master of improvisation, Wallis often used simple techniques for his research, something that some in the scientific fraternity frowned on as it tended to undermine the established ethos of complexity surrounding other research. There was a culture then (and it still exists) that the bigger the budget, the better the research, so the sight of Wallis twanging marbles across a duckpond with a rubber catapult was an easy image to ridicule. The fact that Wallis later progressed to a more controlled experiment in his backyard (portrayed in the movie) then progressed to the controlled environment of a ship's testing tank at the National Physical Laboratory, Teddington, was purposely ignored.

However Wallis persisted and managed to progress to the stage where he was able to acquire a Wellington bomber for trials with a scale model of his bomb. Again the movie portrays this in a tongue in cheek fashion where a bureaucrat expresses doubt that a Wellington bomber could be made available for such a wild scheme:

Ministry official: "You say you need a Wellington Bomber for test drops. They're worth their weight in gold! Do you really think the authorities will lend you one? What possible argument could I put forward to get you a Wellington?"

Barnes Wallis: "Well, if you told them I designed it, do you think that might help?"

Wallis got his test budget and his Wellington.

The Dam Busters movie shows test bombs being dropped from a Wellington. These were actual films of tests made during late 1942, however for the movie the image of the test bomb was blacked out and replaced by a spherical object. The reason was that when the film was made in 1954, the weapon was still on Britain's secret list. The true shape of the weapon was cylindrical as show here.

Air Marshall Arthur Harris objects

Whether this anecdote is true isn't important, however it's an indication of the difficulties Wallis faced in proving his concept. The biggest obstacle was yet to be faced and it came in the form of the Chief of Bomber Command Air Marshall Arthur ("Bomber") Harris. Harris had recently taken charge of Bomber Command and was a man of short temper who didn't tolerate fools lightly.

Harris and Barnes Wallis had previously crossed swords over a number of issues and there was already friction between them. So when Wallis took his idea, supported by model drops conducted from a Wellington, unlike the scenes portrayed in the movie Harris was scathing in his criticism.

Referring to the details of Wallis's proposal and the possibility of having one less Lancaster squadron from his bombing campaign on Germany for 'two or three weeks', he wrote: 'This is tripe is of the wildest description. There are so many ifs ands and buts that there is not the smallest chance of its working.'

"Unless the bombs were perfectly balanced," he continued, "the vibration as it spun will either wreck the aircraft or tear the bomb loose. I don't believe a word of its supposed ballistics on the surface. The war will be over before it works – and it never will.'

He was utterly opposed to 'putting aside Lancasters and reducing our bombing effort on this wild goose chase'. Later in a personal note, Harris sought the support of the Chief of the Air Staff (CAS) against 'all sorts of enthusiasts and panacea mongers now careering round the Ministry of Aircraft Production suggesting the taking of about 30 Lancasters off the production line to rig them up for this weapon, when the weapon itself exists so far only within the imagination of those who conceived it'.

Harris thought Wallis's idea 'just about the maddest proposition as a weapon that we have yet come across – and that is saying something'.

'I am prepared,' Harris went on, 'to bet my shirt (a) that the weapon itself cannot be passed a prototype for trial inside six months; (b) that its ballistics will in no way resemble those claimed for it; (c) that it will be impossible to keep such a weapon in adequate balance either when rotating it prior to release or at all in storage; and (d) that it will not work, when we have got it.' He ended by reminding the CAS that attempts to use heavy bombers in low-level attacks had 'almost without exception been costly failures'.

Harris had a point. Wallis's weapon had not yet been finalised, and Harris retained a healthy suspicion of eccentric inventors from his First World War days in the Royal Flying Corps. Then he had reacted scathingly to a suggestion that he fire an explosive tipped harpoon at Zeppelins bombing London, pointing out that, as the gas-filled envelope exploded, his aircraft would have reached the vicinity of the exploding gas. "Damned if I'm going to commit suicide just to satisfy some crackpot that his invention works", he is reported to have said.

Crackpot schemes abounded during the present conflict – such as dropping rats with incendiaries tied to their tails, to set fire to the Black Forest in south-western Germany – and these scarcely improved his opinion. (even though many of these wild suggestions were inspired by a public appeal for inventors to come forth with ideas)

Skepticism

When Wallis travelled to High Wycombe in company with Captain 'Mutt' Summers, (who was also the test pilot of the Spitfire prototype) to show Harris films of the Wellington drop tests, he was greeted with an unwelcoming roar: 'What the hell do you damned inventors want? My boys' lives are too precious to be thrown away by you!'

Even after seeing the films, Harris remained hostile - and with good reason, as R A Cochrane – now AOC (Air Officer Commanding) No. 5 Bomber Group, who would eventually oversee the Dambusters raid – remarked. Wallis was proposing to project 'a five-ton lump of iron across a lake'. Harris's operational problems, given the continuing loss rate of his bombers, were acute and being bothered by such a diversion of resources at this stage was something he didn't need. The forecast production of new Lancasters for April 1943 was 123. Wallis wanted a quarter of this total for one operation.

Wallis Chastised

On 23 February, Wallis received a shock. Summoned to Vickers-Armstrongs' main office in London, he was instructed by the company's chairman, Sir Charles Craven, to 'stop this silly nonsense about the destruction of the dams'. He was making a thorough nuisance of himself at the Ministry of Air Production, upsetting members of the Air Staff and directly or indirectly damaging the firm's commercial interests.

Utterly shocked, Wallis offered to resign, to which Craven reacted violently, banging the desk and shouting, 'Mutiny!'

Wallis walked from the office, went home and confided in his wife that he'd had enough of beating his ead against a brick wall. (portrayed in the movie) Suspecting that Craven had been surreptitiously approached by colleagues from the Ministry, Wallis wrote in his diary: 'I wonder what happened on the golf links at Ulverston?'

Unknown to Wallis or Craven, events elsewhere were moving much more favourably, an indication of the bureaucratic maze at the centre of the decision making process. The proverbial right and left hands really did not know what each other was doing.

The CAS in 1943 was Air Chief Marshall Sir Charles Portal, who, while holding Harris's current post in 1940, had proposed sending a special squadron of Hampdens armed with torpedoes against the Möhne Dam. He therefore proved rather less critical than Harris had hoped.

Replying to Harris's personal plea, he refused to dismiss Wallis's plan out of hand and revealed that he had authorised the allocation of three Lancasters for trial purposes. He assured Harris that he would not allow more of his Lancasters to be diverted until the concept had been fully tested.

The implication from Harris's viewpoint was that, if these trials were successful, Portal would back the proposed operation. Shortly afterwards, he told Harris: 'If you want to win the war, bust the dams.'

What really tipped the balance in Walli's favor, however, was the intervention of the Prime Minister, Winston Churchill. Whether information regarding Wallis's concept was leaked to him by an Air Ministry official or via Wallis's 'old boy' network has never really been determined, however Churchill loved the idea and immediately ordered it given priority, despite Harris's objections.

Three days after his encounter with Craven, Wallis was called to a meeting at the Ministry of Aircraft Production on 26 February. There he not only learned that the operation was to go ahead, but that Portal wanted 'every endeavour' to carry it out that spring.

The Möhne reservoir would soon be full and the Germans would begin withdrawing water from it at a rate of 10 feet per month. Because Wallis's weapon would not be effective if exploded lower than 40 feet below the crest of the dam, (due to the increasing thickness of the dam wall) the operation had to be launched by 26 May at the latest.

Wallis had often forecast that only eight weeks would be needed to develop 'Upkeep', the codename allocated to his weapon. He later confessed that, as he left the meeting, he felt 'physically sick, because somebody had called my bluff' realising 'the terrible responsibility of making good all my claims'. For, in spite of Wallis's enthusiasm and optimism, on 26 February no full-size weapons had been tested and none were even on the drawing board.

The race to finalise the development of the bomb and train the aircrews was now on.

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