The Aeroclipper Device
The Aeroclipper device is a balloon vertically stabilized near the ocean surface by a guide-rope and providing in situ measurements in the atmospheric surface layer. The guide-rope keeps the balloon close to the surface and prevents the instrumented gondola from dropping into the ocean in case of rain or condensation loading on the balloon.
The Aeroclipper can measure low-level wind and thermodynamic parameters for several days or weeks in remote regions of tropical oceans. The Aeroclipper follows a quasi-Lagrangian trajectory following the surface wind.
A new development started in 2018 in order to validate the instrumental concept for cyclone monitoring. Given the potential use of the Aeroclipper for operational purposes, we also want to develop a system that is easy to deploy at an affordable cost. A new balloon – the Helikite – will be first tested during the La Réunion campaign in January-February 2021.
The light gondola of the new Aeroclipper aims to measure pressure, wind, air temperature and humidity, and sea surface temperature (IR radiometer) every minute. The data will be transmitted to the processing center every 1 to 5 minutes via the Iridium satellite system. In normal flight conditions, the height of the gondola is 30 m over the sea surface. The gondola can also receive remote commands, in particular for the destruction of the balloon if the Aeroclipper approaches an inhabited coast. Once the balloon destroyed, the system is designed to sink after a while.
Aeroclipper Helikite characteristics
The balloon is a 16 m3 Helikite Skyhook ( http://www.allsopp.co.uk/ ) inflated with helium. The dimensions of the Helikite are : (L) 396 cm x (l) 305 cm x (h) 300 cm. The balloon mass is around 8 kg and the mass of the payload, including the batteries is lower than 3 kg (around 1.5 kg of battery located immediately under the balloon and 1.5 kg for the instrumented payload located under the keel). A rope connects the balloon to a guide-rope of 40m. The balloon destruction is done by a hot wire cutting device that creates a large hole in the balloon material which quickly release the helium gas and causes the Helikite to descend. This hot wire is activated by a remote command transmitted by Iridium, or by a software is the Iridium communication system is cut off.
A 16 m3 “Skyhook” Helikite.