Dereelers

On line dereeler (launching with only one operator)

These auto-stable dereelers, developped by Flowtronic S.A. (the unwinding resistance varies as the square of the descent speed), use an original cord unwinding/braking system without any moving rigid part and give a constant unwinding speed for a known hanged mass. This allows two advantages :

  • Frictions are very reduced and the range of usable masses (radiosondes) is very large. They cannot block and give a warranty on the good positioning of the radiosonde in relation with the balloon.
  • They are « on line » : it means that they may be inserted into the chain with the usual soft threads without being integral with the balloon or the sonde.


Following the recommended procedure the dereeler is fixed to the neck of the already inflated balloon by means of the included fixing device. The parachute, if so, being inserted between both. The fixing device may be used to attach the balloon to the ground before launching. The end of the thin dereeler’s cord is then attached as near as possible to the radiosonde.

The operator may then went to the launching field holding in one hand the balloon (and the parachute, if so) through the dereeler and in the other hand the radiosonde, and may proceed to the launching.

Technical characteristics :

  • Dereeler’s weight : 31 g
  • Cylinder with a 26 mm diameter and a length of 100 mm
  • Standard dereeling length : 32m (other length on request)
  • Descent speed : adapted to user’s requests and located between 0.5 et 1.5m/s for the radiosondes actually on the market (mass between 200 et 600g)

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