Vaisala RS92-D - Manual (Page 20)

User's Guide ______________________________________________________________________
18 __________________________________________________________________ M210987EN-C
Optional Sounding Accessories
The RS92 unwinder RSU911 is designed to be attached directly to the
folded balloon neck. However, you can use the same unwinder if you
use optional sounding accessories, such as a parachute or a radar
reflector.
Always attach the unwinder to a relatively firm support, such as the
balloon or the parachute spreader. 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.
The unwinder must also be able to swing slightly during the sounding.
Attach all optional sounding accessories next to the balloon, or
otherwise they disturb the measuring environment of the radiosonde
and no proper temperature and humidity measurements can be made.
Totex Parachute 5710-5
The recommended parachute is the Totex type 5710-5 (Vaisala code
15046). In the Totex parachute, an elastic ribbon loop hangs the
unwinder securely under the spreader.
Attach the parachute directly to the balloon with the parachute string.
NOTE When using a balloon with an integrated parachute, make sure that a
sufficiently long piece of the parachute string is poking out of the
balloon neck in order to fasten the string to the radiosonde unwinder.
CAUTION The strength of all the strings used during soundings must exceed 25
kp (250 N). Knots in the strings weaken the strength to the minimum
of 40 % of the original string strength. This results in a string strength
of 10 kp (100 N), which is sufficient for RS92 soundings.
Table 3 Ordering Codes for Optional Sounding Accessories
Item Code Note
Totex parachute 15046
Rubber plate RS46158 Used with a radar reflector
Hanger board RS46157 Used with a non-Totex parachute