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Over the past two decades, aerostats have already been used effectively by the US military in Iraq and Afghanistan, amongst other places. They are also being deployed by an increasing number of countries in border safeguarding roles. In addition, aerostats are perfect platforms on which to mount wideband communications repeaters providing coverage over a wide area. The South African Council for Scientific and Industrial Research (CSIR) has developed a novel active aerostat, which although tethered, has control surfaces to allow it to better withstand the elements and provide better stability than traditional aerostats.
According to defenceweb.co.za, the helium-filled wing shaped balloon is fitted with rigid control surfaces, allowing it to better maintain its position in high wind conditions through the additional lift created by the envelope. This results in better coverage from sensors fitted to the aerostat, as conventional aerostats will be pulled back and buffeted by the wind. The aerostat features an active control system.
The CSIR said the active aerostat can be rapidly deployed to its required heights for maximum surveillance.
The system has application in all areas where persistent aerial surveillance is needed and isn’t required to meet the strict civil aviation requirements governing the use of unmanned aircraft systems. Applications could include military and security, farming, wildlife monitoring, crowd control, border surveillance, mining surveillance, shark monitoring, advertising and communications relay.
The CSIR’s Francois Anderson believes that with an appropriate mix of mountain-based and aerostat-based radars it should be possible to cost-effectively cover all of South Africa’s land and coastal border zones.
The problem with land-based radar systems, even when radar stations are set up high on mountain tops, is their coverage against surface-based and low-flying targets is limited by the horizon as well as by the terrain casting radar shadows, for instance behind topographical features, such as lower hills or neighbouring mountain ranges, that obscure the line of sight.
When fitted with a special lightweight radar system, relatively affordable aerostats flying at heights up to 1 500 meters above the surface of the Earth are capable of providing low-level coverage up to ranges of 150 km for periods of up to a month at a time.