The unwinder is designed to be attached directly to the folded balloon neck, but in case you cannot attach the unwinder to the balloon, the unwinder can also be used with optional sounding accessories which provide the necessary support during the sounding. The sounding accessories are needed to restrict the movement of the unwinder. Optional sounding accessories here refer to a hanger board or a parachute.
The unwinder must always be attached to a relatively firm support. The support must not let the unwinder twist freely, or otherwise the suspension string might unwind at too high a speed and the radiosonde hit the ground during the launch. However, the unwinder must be able to swing slightly during the sounding.
Similar to the balloon, the unwinder and the optional sounding accessories must be prepared before launching the radiosonde. The following figure shows the different options.
| CAUTION The strength of all the strings used during soundings must not exceed 23 kp (230 N). Knots in the strings weaken the strength to the minimum of 45 % of the original string strength. This results in a string strength of 10 kp (100 N) which is sufficient for soundings with Radiosonde RS41. |
Attach all optional sounding accessories next to the balloon, otherwise they disturb the measuring environment of the radiosonde and no proper temperature and humidity measurements can be made.
| Visit www.vaisala.com/RS41 to watch short videos on how to make a hanger board and how to attach the unwinder to the hanger board, and how to attach the unwinder to the parachute. |