CSIR continues to refine active aerostat


The Council for Scientific and Industrial Research (CSIR) has developed what is most likely a completely unique active aerostat which it hopes to offer for security and surveillance purposes.

An aerostat is a lighter than air balloon that gains its lift through the use of a buoyant gas. Although tethered, the CSIR’s active aerostat has control surfaces to allow it to better withstand the elements and provide better stability than traditional aerostats.

The helium-filled wing shaped balloon is fitted with rigid control surfaces, allowing it to be stabilised and trimmed to maintain its position in high wind conditions through the additional lift created by the shape of the envelope. This results in improved coverage from sensors fitted to the aerostat, as conventional aerostats would be pulled back and buffeted by the wind. The aerostat features an active control system, with an autopilot controlling pitch, roll and yaw.

The CSIR said the active aerostat can be rapidly deployed to its required heights for maximum surveillance. Line tension is maintained within pre-set limits by the active control system.

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 active aerostat first flew in April 2016 and in its second generation model was flying in mid-2018 after some modifications to the control surfaces – the fins were moved outwards and canted for better aerodynamic efficiency.

The aerostat was designed by the CSIR in collaboration with Dr Ralph Katzwinkel, a vet who wanted a persistent surveillance capability to help protect rhinos. The project was later joined by South African company Zeppelin Inflatables.

The CSIR is pursuing additional funding to continue with active aerostat development and to build a useable demonstrator – potential customers will be more receptive to a fully working model. Further developments will include a gas feed pipe integrated into the tether to maintain helium pressure, allowing the aerostat to stay up for weeks. The CSIR is seeking R1.5 million in investment for a trailer, weather system development and new envelope.

The active aerostat is also planned to be fitted with a stabilised sensor gimbal, camera system and datalink – so far it has only been flown with a GoPro camera for demonstration purposes.

CSIR engineer John Monk believes the active aerostat is quite unique and could be the first and only of its kind in the world.