Operation Outward

Operation Outward was the name given to the British World War II program to attack Germany by means of free-flying balloons. It made use of cheap, simple gas balloons filled with hydrogen. They carried one of two types of payload: a trailing steel wire intended to damage high voltage power lines by producing a short circuit, or three incendiary devices - 6-pound (2.7 kg) flexible socks filled with flammable material - that were intended to start fires in forests and heathland.

A total of 99,142 Outward balloons were launched: 53,343 carried incendiaries and 45,599 carried steel wires.^[1] Compared to Japan's better known fire balloons, Outward balloons were crude. They had to travel a much shorter distance so they flew at a lower altitude - 16,000 feet (4,900 m), compared with 38,000 feet (12,000 m) - and had only a simple mechanism to regulate altitude by means of dropping ballast or venting lifting gas. This meant the balloons were simple to mass produce and only cost 35 shillings each (£71 when adjusted for inflation).

History and development

In 1937, the British carried out a study on the damage that may be caused by a balloon-carried wire hitting power lines, as there was concern over what could happen if a barrage balloon accidentally got loose. The idea of using balloons to carry bombs was proposed in the winter of 1939-1940. The balloons, launched from France, would carry transmitters and their position would be tracked by radio triangulation. The bomb would be released by radio control when the balloon drifted over a worthwhile target.^[2] The idea became redundant after defeat in the Battle of France put possible launch sites out of British control.

On the night of 17-18 September, 1940, a gale broke loose a number of British barrage balloons and carried them across the North Sea. In Sweden and Denmark, they damaged power lines, disrupted railways and the antenna for the Swedish International radio station was knocked down, bearing out the findings of the 1937 report. Five balloons were reported to have reached Finland^[3]. A report on the damage and confusion reached the British War Cabinet on 23 September, 1940. Winston Churchill then directed that the use of free-flying balloons as weapons against Germany should be investigated.^[3]

The Air Ministry initially produced a negative report, possibly because the Ministry of Aircraft Production felt balloons would be ineffective weapons and would use up too many resources. However, the Admiralty took up the idea with more enthusiasm. They concluded balloons had the advantages of being low cost and not placing British personnel at risk. The design of the German power grid made it vulnerable to damage by short-circuit. Large areas of pine forest and heathland in Germany made the countryside vulnerable to random incendiary attack and the Germans would be forced to assign large numbers of people to the task of fire watching, possibly diverting them from more productive war-work. Furthermore, winds above 16,000 feet tended to blow from west to east, making it harder for the Germans to retaliate with similar balloons.^[4]

Design

The balloons had no guidance control and operated only on a timing fuse. Each balloon was about 2.4 metres in diameter and carried a simple timing and regulating mechanism. A double-walled can contained mineral oil in an inner chamber and a roll of hemp cord and piano wire in an outer chamber. At deployment, a slow-burning fuse was lit, calibrated to the estimated time to arrive over German-controlled territory. At launch the balloon rose and expanded in size until an internal cord tightened, releasing some gas and preventing further increase in altitude beyond 25,000 feet (7620 m); the balloon would begin a slow descent. After several hours, the fuse would burn through the cord holding the trailing wire. The payload consisted of about 200 metres of light hemp cord secured to the balloon at one end and tied to about 90 metres of steel wire at the other. This would unroll as the balloon sank to working altitude of about 300 metres. A stopper on the canister of mineral oil was also released, so that it would slowly drip out and lighten the load on the balloon, to assist in maintaining altitude.^[5]

The plan was that the wire tail would be dragged for many miles (kilometres) across the countryside, eventually encountering a high-voltage transmission line. A phase-to-phase short circuit would be initiated; during trials, arcs 4 metres long were initiated by the piano wire. The arc would burn for some time before the transmission line protection operated; there was a good chance the circuit breaker itself would be damaged, and the line conductors might burn through due to arcing, causing a line to collapse and require repairs. German efforts to protect transmission lines from attack were unsuccessful; neither a new type of line conductor clamp, nor different overcurrent protection settings had any useful effect.

Just less than half of the Operation Outward balloons carried wire; the rest carried an incendiary bomb intended to set fires in forests.

Deployment

After a lengthy bureaucratic struggle between the opponents in the Air Ministry and proponents in the Admiralty, the British Chiefs of Staff gave the go-ahead in September 1941 and a launch site was set up at Landguard Fort near Felixstowe in Suffolk.^[6] The first launches took place on 20 March 1942. Within days, the British were receiving reports of forest fires near Berlin and Tilsit in East Prussia.^[6]

Intercepts of Luftwaffe communications soon showed German fighters were trying to shoot down balloons. This encouraged the British as it was felt that the harassment value on German air defences alone justified Operation Outward. It cost the Germans more, in terms of fuel and wear and tear on aircraft, to destroy each balloon than it cost the British to make them.

In July, a second launch site was set up at Oldstairs Bay near Dover^[6] On 12 July, 1942, a wire-carrying balloon struck a 110,000-volt power line near Leipzig. A failure in the circuit breaker at the Böhlen power station caused a fire that destroyed the station^[1]; this was Outward's greatest success. ^[5] In August 1942 launches reached 1000 per day. Most of the personnel employed were from the WRNS, with up to 140 women being employed in balloon operations against Germany.

Balloon launches continued, though they were frequently suspended when there were large air-raids on Germany as it was feared the balloons might damage Allied bombers. Also, they continued to cause damage in neutral countries - on the night of January 19-20, 1944, two trains collided at Laholm in Sweden after an Outward balloon knocked out electrical lighting on the railway.^[1]

In the lead-up to D-day invasion, balloon launches became more sporadic. The last balloons were launched on 4 September 1944.^[1]

See also

• Fire balloon

Notes

1. ^ ^{a b c d} Peebles, p56.
2. ^ Peebles, p52.
3. ^ ^{a b} Peebles, p53.
4. ^ Peebles, p54.
5. ^ ^{a b} Raoul F. Drapeau, Operation Outward Britains World War II offensive ballons, IEEE Power&Energy Magazine", September/October 2001 pp. 94-105
6. ^ ^{a b c} Peebles, p55.

References

• Peebles, Curtis (1991). The Moby Dick Project. Smithsonian Books. ISBN 1-56098-025-7. 

External links

• Balloons In Peace & War 1900:1945