The idea sounded impressive: Instead of sending your own bombers and, above all, their crews into enemy airspace and thereby exposing yourself to deadly danger, could you also use free-flying balloons? A simple radio beep would allow the (approximate) position to be determined by triangulation, and when the balloon was over a worthwhile target the payload, a high-explosive bomb, could also be radio-dropped.
In the winter of 1939/40, after the first costly attacks by the Royal Air Force, especially on German naval bases on the North Sea, the Air Ministry in London calculated this proposal. But because after the Wehrmacht's attack on France in May 1940, the planned take-off sites in Alsace and Lorraine were no longer available, the proposal was shelved.
It probably would not have had any real chances of being implemented either, because the area of suitable targets for high-explosive bombs was tiny compared to the area of fields, forests and the like, where high-explosive bombs would have little or no effect.
However, as early as 1937 there had been a proposal to use balloons as weapons against overland power lines. The idea became topical in September 1940 due to the effects that loose barrage balloons had had against air raids over southern England: They had flown (actually: “driven”) across the German Bight to occupied Denmark and neutral Sweden and were now free to go there with theirs the air swinging suspension ropes caused serious short circuits and thus large-scale power failures; even the mast of the Swedish international radio station was damaged.
What happened accidentally with your own balloons, could it also be used as a weapon against the enemy? But the Air Ministry was disinterested because the consumption of resources was too high and the chances of success too low. The Royal Navy, however, took up the idea.
Captain Gerald C. Banister became the driving force. He had suitable balloons and two payloads developed: one was a cable reel that, controlled by a simple clockwork, rolled out after an adjustable flight time. The technical structure of the power grid in Germany was ideal for damaging it in this way through short circuits - and many industrial companies were dependent on electricity.
On the other hand, small incendiary bombs were designed, which should also be dropped by a kind of alarm clock. Large areas of the Third Reich consisted of forest and arable land, making them vulnerable to fire attack, and the Germans would need to deploy large numbers of people to fire watch, potentially diverting them from more productive war work.
Each of the incendiary devices weighed about three kilos. They were filled with an incendiary gel made from petrol, a carrier and some white phosphorus. The impact on the ground triggered spontaneous combustion. A light fabric casing called a "sock" containing fuel was attached to the grenade so that the incendiary device had enough fuel to ignite (in the case of the RAF's thermite incendiary bombs, the aluminum casing of the mostly hexagonal rods took over this task).
Banister calculated that the balloons would climb to an altitude of about 5,000 meters (16,000 feet) after launch. There stable air currents blew from west to east. This is exactly what protected Britain from the Germany copying the idea: because of the Earth's rotation, there were no stable reverse winds, and at lower altitudes (where reverse winds did exist), balloons would not have the range to take it all the way to England create. The payloads were just under two pounds each, so it was a cheap weapon.
During World War II, Japan used over 9,000 balloon bombs. These unmanned aerial vehicles were carried towards the USA by the so-called jet stream. There their explosive charges were automatically dropped.
Source: WELT/Sebastian Struwe
In September 1941 the British Chiefs of Staff Committee settled the disagreement between the Admiralty and the RAF and ordered the use of balloon bombs. The company was given the code name "Operation Outward". We used weather balloons that were in stock and were no longer needed due to technical advances in aircraft and their mass deployment; around 100,000 pieces were available. They had a diameter of 2.4 meters. Because of their construction, these balloons, once filled with hydrogen, quickly climbed to an altitude of about 7500 meters and then descended to the ideal altitude for their onward flight ("ride") eastward.
The wire-tipped balloons descended to a height of about 300 meters over the assumed target area, dragging an equally long "tail" made of hemp and a 1.8 millimeter thin steel wire behind them. Under normal weather conditions, you should hover about 30 miles (almost 50 kilometers) above Germany.
The first balloons were launched on March 21, 1942 at Felixstowe in Suffolk. A little later, untypical for this time of year, there were forest fires near Berlin and in East Prussia. The German Luftwaffe issued an order to shoot down free-flying balloons over Germany. The British Admiralty was pleased with this information. An area near Dover was equipped as a second launch site.
On July 12, 1942, the wire from a balloon hit a 110-kilovolt line near Leipzig. Because the fuse in the Böhlen industrial power plant was defective, a fire broke out that severely damaged the power plant. This was considered the greatest success of "Operation Outward".
The launches continued, but were suspended when major air raids took place - the balloons could have damaged Allied bombers. Because the RAF and especially its Bomber Command continued to rely on conventional attacks, mostly nocturnal mass attacks, especially since the new boss Arthur Harris took office in early 1942.
However, the “Outward” balloons also repeatedly caused damage in neutral countries. For example, on the night of January 19/20, 1944, two trains collided near Laholm in Sweden after a cable balloon had switched off the electric lights.
The last balloons were launched on September 4, 1944. A total of 99,142 "Outward" balloons were launched: 53,343 carried incendiary devices and 45,599 steel cables. The actual effect is difficult to determine, but given that the total cost was less than half a million pounds (not counting the balloons themselves, which were stockpiled), the equivalent of just ten Avro Lancaster bombers, it was a cheap weapon and a good addition to the British arsenal.
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