Flight Manual for Gas Balloons of Type NL-STU
Issue 2.0
May 02, 2016
Page 2-2
2.2.6 Flights at temperatures below freezing
When the envelope is stored in the packing sack, creases are formed. At temperatures above
0 C, these creases are smoothed by the tension of the envelope. At temperatures below 0 C,
the tension of the envelope may be insufficient to smooth the creases around the parachute
opening. Under certain circumstances, this could result in gas leaks, because the parachute will
not close properly.
Measures for reducing crease formation:
• Attach the edge protection of the parachute opening after landing
• Remove upper area of envelope from the packaging for approx. two hours before infla-
tion, lay it out in a circle and allow to warm up to around 20 C indoors. This enables the
folds to smooth out.
Measures for ensuring gas-tightness:
• Do not subject the parachute opening to loading in the kinked state in order to prevent
creasing when cold.
• Stop inflation when the inflation level corresponds to a full envelope at the expected
maximum flight altitude and listen out that there is no sound of gas escaping.
• If you intend to take off with the envelope not taut, perform the trial opening of the valve
by pulling the line after the desired inflation level has been reached.
• If you intend to take off with the envelope taut, continue to inflate until the maximum level
and leave the parachute opening subjected to the maximum possible envelope tension
for as long as possible before take-off. Perform the trial opening of the valve.
• In the case of inflation at night, it may be necessary to delay take-off until the edge of the
parachute opening has warmed up and turned smooth during the day. This can be
detected by means of a visual inspection or possibly seen as the envelope becomes taut
while the appendix is closed.
CAUTION:
If inflation and flight are to be carried out at temperatures consistently below 0°C,
the ballast quantity and the anticipated flight path must be planned to enable the
balloon to land with a slight gas leak.
2.3 Condition of the balloon
WARNING:
If damage impairing airworthiness is detected during the preflight checks, take-off
is not permissible!
NOTE:
All damage resulting in loss of airworthiness of the balloon must be repaired in
accordance with the maintenance manual.
