This was a British undertaking to create a free-floating barrage of explosive-armed balloons to intercept German bombers (1940/42).
During the early part of the war there was the Royal Navy Directorate of Miscellaneous Weapon Development, a deliberately vague designation for an organisation which possessed no connection with the Royal Air Force or the Royal Auxiliary Air Force. Early in 1940 the First Lord of the Admiralty (soon Prime Minister) Winston Churchill convened a meeting to discuss the possibility of lofting into the air a lethal curtain of wires on parachutes that would tangle around propellers to bring down German aircraft, telling the meeting that he wanted a 'square of wire in the sky as big as Horse Guards Parade with parachutes to hold it in place'.
On the night of 17/18 September 1940, a number of British barrage balloons broke loose in a gale and were carried across the North Sea to arrive in Sweden and Denmark, where they damaged power lines, disrupted railways and knocked down the antenna for a Swedish international radio station. Five balloons were reported to have reached Finland. A report on the damage and confusion reached the war Cabinet on 23 September, and Churchill then directed that the use of free-flying balloons as weapons against Germany was to be developed as a matter of priority.
At first the Air Ministry disparaged the concept, largely on the grounds that the Ministry of Aircraft Production delivered itself of the opinion that balloons would be ineffective as weapons and would also require much manpower and gas to deploy. However, the Air Ministry’s counterparts in the Admiralty took up the idea with greater enthusiasm, deciding that balloons were inexpensive and likely to succeed without risking the lives of servicemen. The rivalry between the two services about free balloons continued throughout the war.
A certain Commander Fraser, an officer working in the Admiralty Boom Defence department supplying all grades of wire rope for naval use, developed the idea of lifting a cloud of wire into the sky by attaching it to free-floating balloons. He knew of the Long Aerial Mine concept, which used parachute-retarded mines on long wires, released from bombers flying above and ahead of a German bomber stream, and suggested his concept as a half-brother to this. Fraser’s idea was assessed by Dr F. D. Richardson, who became Director of the Nuffield Research Group after the war, and after some weeks Richardson found quarters at the lighter-than-air base at Cardington in Bedfordshire. Fraser gradually began to make and modify the first Free Balloon Barrage.
The concept was to produce hundreds of hydrogen-filled rubber balloons, to each of which was attached a small yellow-coloured round box and a wooden spool with 2,000 ft (610 m) of wire to which a parachute was attached. Richardson envisaged that the balloon would be released with its 22-lb (10-kg) payload. On the top of the bomb was a circular slow-burning fuse which was ignited at launch, and as it burned this caused one of seven bags of sand to fall away, giving the balloon more lift and therefore greater altitude. When the balloon had reached a specific altitude, a atmospheric pressure switch was activated, firstly to free the spool of wire to unravel with the parachute at its lower end, and secondly to arm the bomb on a board beneath the balloon.
When an aeroplane struck the cable the resulting shock wave initiated a shock wave which caused two other events: firstly, the parachute opened and was dragged under the impacting aeroplane’s wing, and secondly, the bomb began to descend until it touched the wing, a small spring on the rim of the bomb then being deflected to explode the bomb.
As with most novel concepts and ideas, the practical testing of this idea revealed a mass of problems. The behaviour of the balloons was quite unpredictable. A certain time after the balloon’s release, an inbuilt fail-safe mechanism, a timer, was designed to cause the bomb to explode, and additionally after one hour the fuse reached the bomb detonator and initiated it, thus destroying it and making it safe to fall back to the ground.
Theory and practice were not always as might have been expected, however. The balloon might climb to operating altitude, become armed and then descend in a dangerous state because the fail-safe timer had failed or the fuse, which was particularly sensitive to rain and moisture, had gone out. On contact with the ground it might or might not explode depending on what and how it struck the ground. The balloon might leak hydrogen, the fail-safe timer fail and the device descend to the ground as a dangerous unexploded device. One of the early problems was that the height-adjusting mechanism of seven small sand-filled bags failed to work.
On 24 March 1941, at a meeting of the Night Air Defence Committee, Churchill insisted that trials of the free balloon barrage should continue.
A secret memorandum of 1 June 1941 reveals the dismissive attitude to the free balloon barrage of J. Whitworth Jones, the Director of Flying Operations: 'When the Free Balloon Barrage was first inflicted by an enthusiastic Admiralty on a reluctant Air Ministry with the connivance of a cigar smoking Prime Minister, the latter said that great care was to be taken that this brilliant weapon did not fall into the hands of the enemy.' Jones then went on to complain about the consistent failures of the balloons but that 'a suspicious Air Ministry felt that the spirit of the Prime Minister’s original instructions must be observed'. He then pointed out that after a small-scale trial of 220 balloons near Liverpool, with fuses set to self-destroy after one hour, 'The Germans were kind enough to inform us in their communiqué that some of these units had been picked up in Sweden.'
It was clear that the Air Ministry and the Admiralty would never agree over the free balloon barrage, and while several prominent RAF officers wished to see its abandonment they seemed to feel that the Admiralty was demanding continued development in a desire to appease Churchill.
The piano wire was as much of a problem as the bomb, for it could trail over electric railway lines and overhead power cables, short-circuiting the area for miles around. Moreover, if the wire draped itself over 30,000-volt overhead lines, any touch on the trailing edge could electrocute the toucher.
In Wales , trials at the experimental establishment at Aberporth resulted in tragedy: on 30 September 1941, the 13 year old John Butler was fatally electrocuted when he took hold of a piece of free-barrage balloon wire which had become draped over the high-tension wires, and a passing soldier who tried to help was burnt and had to be hospitalised. In another incident, a children’s nurse rushed to help the child in her charge when he picked up a balloon wire which was connected to the mains: the cild could not let go, and when she seized the child then she too could not let go. Luckily for both, the child’s father managed to knock the cable from their hands, saving both their lives.
It was decided in January 1942 to put up notices within a 25-mile (40-km) radius of the Aberporth establishment to warn people of the dangers of touching anything that came down from the air.
The codename 'Albino' resulted from the use of a large white rabbit which was pinned to the notice board at the Directorate of Miscellaneous Weapon Development offices by a civil servant.
The man who supervised the free balloon trials was a South African officer of the Royal Naval Volunteer Reserve, Lieutenant T. F. W. Harris. On nights when free barrage balloon trials were being undertaken, arris recruited volunteers from the Directorate of Miscellaneous Weapon Development to help at the launch sites.
The whole project was classically secret, and consequently the public and as well as large numbers of military personnel were denied all knowledge of the project. It was decided to give air raid precaution wardens a limited degree if information, and they were accordingly warned that a new form of night defence might be used and advised not to touch them if they came down in the hours of darkness.
The mechanical failures of these new balloon weapons were numerous, and the course that the balloons took on release was unpredictable despite best efforts of the meteorologists to provide accurate forecasts about wind speeds and directions.
The object was for the balloons to rise and saturate a limited volume of the air. Once launched, however, the balloons were wholly at the mercy of the elements: the wind could change, and balloons launched in the London area could arrive Devon or anywhere in the same approximate radius. It was therefore decided to establish a team of retrievers to travel far and wide to retrieve these devices wherever they came down. On one occasion members of the team travelled to Piddletrenthide in Dorset, where a police officer showed them two free balloons lying side-by-side in his garden. Attached to each was only 2 ft (0.6 m) of wire, and the policeman told the retrievers that he had found the balloons in a field and, ignorant of their nature, had cut the wire and tied the two armed bombs to his bicycle;s handlebars and cycled home.
In the last days of December 1940 Churchill ordered a full-scale test against the Germans. On 31 December the Germans launched a major incendiary raid on London, and the RAF was instructed to assemble a force of several hundred men and 800 lorries, trailers and other equipment across a 2-mile (3.2-km) arc in the Hatfield in Hertfordshire. At each site tents 12 ft (3.67 m) high were erected, and in these the 10-ft (3.05-m) balloons were inflated with hydrogen. Some 2,000 free balloons were launched at the height of the German raid, and the resulting statistics did not make for happy reading. Over three zones in which the balloons were released, some 30% failed near the launch as a result of problems with the wire spool; about 15% landed in London, one of them in the grounds of Buckingham Palace; in the last zone another 30% failed to perform as planned; and some were found on the south coast of England, while several passed across the English Channel to come down in France.
At dawn on the following day, a massive retrieval operation began. Anyone who could walk and look for the bright yellow bombs was commandeered: this included boy scouts, firemen, policemen and any service personnel the military could spare.
The bombs were clearly marked in large lettering with the legend DANGER – DO NOT TOUCH, but almost inevitably this seemed to have exactly the opposite result. One shop keeper was found cycling up the road with four of the armed bombs tied by their wire to his handlebars. A number of bombs were hung up in trees and some had hit houses. One farmer had 14 land on his farm, and he dragged all of them to a corner of one field, where he had then laboriously covered the units in cow dung because he thought that this would prevent them from detonating.
Despite the fact the results had not been good, it was nonetheless decided to carry out a small-scale test of 200 balloons in Bedfordshire. Some 50 sailors were allocated to help with recovery, but it was very difficult for a man on foot to see the devices, and in desperation the recovery team hired 14 horses and this allowed the search to be effected more rapidly and successfully. This small-scale trail showed that the two main problems with the device were firstly that the wire on the spool failed to unreel smoothly when the unit reached its operating altitude as the hole in the bomb board was not sufficiently smooth and made the springy wire kink, and secondly that the safety valve which prevented the balloon raising above the operating height of 14,000 to 18,000 ft (4265 to 5485 m) was jamming, which allowed the balloon to rise to an altitude at which the balloon burst and allowed its lethal payload to plummet down to earth.