Il-Widna

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The Maltese name Il-Widna (German: the ear) describes an acoustic air raid early warning system in Malta. It was built by the British Army in 1934/35 near the village of Għargħur in Malta .

background

In the 1920s and 1930s, the range of the then existing bombers had greatly improved. In 1918 the Handley Page HP15 reached a top speed of 159 km / h and a service ceiling of 3355 m, the Bristol Blenheim in 1935 flew over 400 km / h and over 8000 m high. At the same time, the views of Giulio Douhet and Billy Mitchell about the strategic role of air forces and the crucial importance of their deployment in the war were gaining increasing attention. Air defense and air defense also developed logically . In order to ensure the most efficient use of anti-aircraft artillery and fighter aircraft , the creation of an early warning system was essential. The provision of a comprehensive air defense in constant combat readiness was not possible for economic reasons, in addition, fighters need a certain time to climb to the altitude of the attacking bomber formations and must also be brought to them when visibility is poor. The aim was to enable air defense units and fighter pilots to be alerted by as long as possible in advance, while at the same time the population was given the opportunity to visit air raid protection facilities . Visual observation had generally proven its worth, but it was tied to good visibility conditions and in certain geographical conditions - such as in Malta - only allowed insufficient advance warning times. Acoustic reconnaissance with the unarmed ear was limited to distances of up to ten kilometers. Radar systems had been in development since the early 1930s, but were not yet ready for use by the middle of the decade. The only available technical reconnaissance method with a greater range was therefore only acoustic location. The fundamental suitability of acoustic reconnaissance was already proven in the First World War with the directional receiver.

The islands of the Maltese archipelago, which had belonged to the British Empire since 1804 , were of outstanding importance for it, as they were on the main route between the British Isles and the British colonies and dominions in Asia and Australia . Due to their location, they dominated the western Mediterranean . At the same time, the island's infrastructure - ports , docks , coal stations - was important for the operational readiness of the British war and merchant navy. The removal or destruction of the islands by a potential enemy would seriously disrupt communication between the motherland and the overseas possessions, impair supplies to the British Isles, weaken the operational readiness of the British fleet and sooner or later the position of the United Kingdom in the Asia-Pacific region Endanger space. Consequently, great importance was attached to the expansion of the island's defenses in the interwar period. Italy in particular was seen as a potential opponent . While the threat posed by the Regia Marina was relatively easy to take into account through the stationing of strong naval units, protection against threats from the air was more difficult. Due to the island location, there was no foreland that would have enabled a timely visual reconnaissance of approaching bomber groups. Therefore, after extensive tests, it was decided in 1933 to set up an acoustic early warning system in Malta.

Working principle

The structures dealt with here are concrete structures in the form of a parabolic mirror , which reflected the sound waves emitted by the aircraft and bundled them at the focal point of the mirror. In principle, the mode of operation is the same as that of a parabolic antenna . Due to the long wavelength, the dimensions were relatively large, so the construction was made of concrete. Since the systems could not be swiveled due to their size, the approach direction had to be determined by triangulating the measurement results of several mirrors. Mirror diameters of 20 or 30 feet were common . By increasing the diameter to around 200 feet and installing a series of microphones in front of the focal point of the mirror, a directional determination could be made with a single mirror. This construction is a truncated parabolic mirror, the elevation angle could not be determined due to the construction.

The first plants were built during the First World War on the north-east coast of England in Kilnsea , Boulby , Redcar , Hartlepool , Seaham and Sunderland . In the interwar period, further plants followed on the south coast ( Kent ) and on the north coast. In practice, wind noise, animal noise and reflections from surrounding buildings and rocks turned out to be problematic. The plants planned in Singapore and Gibraltar were not built because no suitable place could be found for the installation.

Planning, construction and testing

A total of five mirrors were planned to be built in Malta. The sites should be Għargħur , Zonqor , Ta Karach , Ta Zura and Tal Merhla . Because of the priority protection of Valletta and the Grand Harbor , the two flanking systems in Għargħur (northwest) and Zonqor (southeast) should be built first. The plan was to build 200-foot mirrors modeled on the Denge facility (near Dungeness in Kent). Construction of the mirror in Maghtab began in autumn 1934 and work was completed in summer 1935. The construction was similar to that of the mirror in Denge, only at the base of the mirror additional pillars were provided inside, which, however, impaired the performance of the system. The mirror was provided with a camouflage paint in order to fit it optically into the surrounding area and to make visual reconnaissance from the air more difficult. The electrical systems were installed in September 1935; the official commissioning took place on September 23, 1935. Training began on the following day. The total cost of construction was £ 4,500 . Tests of the system with a Supermarine Scapa showed a range of 21 to 37 miles , with an average of 25 miles, and an angular accuracy of 2.5 degrees. This enabled advance warning times of up to six minutes. However, not all tests were successful. During a test in the presence of Sir Cyril John Deverell , Chief of the Imperial General Staff , on February 5, 1936, the system failed. As a result of this event, no further mirrors were built in Malta and the system was decommissioned on May 5, 1937.

Current usage

There are several telecommunications systems in the Il-Widna area . The system itself is used as a ground station for the satellite communication system of the Maltese telecommunications company GO (formerly Maltacom).

See also

literature

  • Charles Stephenson: "The Fortifications of Malta 1530-1945", Osprey Publishing Limited, 2004, ISBN 1-84176-836-7

Web links

Coordinates: 35 ° 55 ′ 50.5 ″  N , 14 ° 26 ′ 37.4 ″  E