Police protected Sonde Hunt

#7 De Bilt – Herscheid
Vaisala RS41-SGP + Ozone / N4540309 / 06.12.2018 1200Z
🔗 sondehub.org in storage
🔗 radiosondy.info individual transport

Inspired even more by the failure in Wuppertal, I finally wanted to catch an ozone sonde. On 06.12. I observed N4540309 from De Bilt, which should go too south for me and land behind Siegen. However, the balloon already burst over Hagen and the probe was falling from the sky like a stone. I spoke with Kai briefly, and we decided to retrieve the probe, which had landed southeast of Lüdenscheid in a residential area in the meantime. I had reception at the entrance of the village, and the sonde was lying in a front garden, directly at the church. We parked at the village pub and set off by foot. The village was located on a slope, and so we only saw the police vehicle with blue lights in front of the house shortly before reaching the sonde. We went into the front garden, and already on entering I shouted: “This is just a harmless weather balloon”. Three officers, together with the occupants, stood around the sonde and looked at us. I purposefully went to the probe to convince them that it was harmless and to stop the humming.
Apparently, the residents had dialed 911 out of fear, and then none of the five people around had the idea of reading the accompanying letter. In defence, it may be said that the probe was crashed in the garden at over ten metres per second.

After that the obligatory questions (“Did you start it?”, “How do you know about it?”, “And if it falls on someones head?”) were answered, the officers left, and the inhabitants didn’t want anything more to do with the sonde and left it to us.

Instead of a water activated battery, De Bilt uses two 9V lithium blocks in series, soldered to the old wires of a water activated battery. The reamining cavity in the battery compartment is filled with polyurethane foam. The starting configuration is probe – 10 m cord – parachute – 5 m cord – parachute – 5 m cord – balloon, which was a single pile in our case. They use thick cotton cord and the same big red parachutes as the Bundeswehr.

A video shows another launch from De Bilt, but still with RS92.