Flight Manual for Gas Balloons of Type NL-STU
Issue 2.0
May 02, 2016
Page 6-1
Chapter 6 – Components of the gas balloon
6.1 Introduction
A gas balloon consists of a gas-tight envelope with a basket suspended beneath it. The basket
is attached to the envelope by means of ropes. The following chapter describes all functions of
the individual components of the gas balloon.
6.2 Envelope
6.2.1 Material
The envelope material consists of a layer of polyamide fabric with rip-stop threads. It is coated
on the inside and outside with artificial rubber or polyurethane. The inside coating is electrostat-
ically conductive in order to distribute electrostatic charges uniformly over the entire envelope
and to ensure equipotential bonding with the ground on landing. The maximum surface re-
sistance on the inside is 10
9
Ohms. Coatings of different colors are used for the outside.
6.2.2 Openings in the envelope
The envelope of the netless gas balloon has two or three openings.
6.2.2.1 Deflation opening
The deflation opening is also used as a parachute opening. It combines the maneuvering valve
and quick deflation functions. In traditional netted balloons, these tasks were shared between
the flap valve and the rip panel. The deflation opening is located at the north pole of the enve-
lope, where it is sealed with a parachute. The edge of the opening is protected against tearing
by means of a bolt rope made of steel or Kevlar and is reinforced with several layers of fabric.
The parachute is held in its correct position by means of centering belts. To deflate the balloon,
the parachute is pulled down by the pull-down belts. The parachute is also used as a flight
valve.
6.2.2.2 Emergency opening
The emergency opening is an option for this type of balloon. The emergency opening serves as
a substitute for the appendix. If the balloon is equipped with an emergency opening, this open-
ing is located above the appendix. The emergency opening is a triangular section of the enve-
lope, the area of which roughly corresponds to the cross section of the appendix. If, for whatev-
er reason, it should not be possible to open the appendix during flight, the emergency opening
is opened by means of the emergency opening line and the expanding gas can escape during
flight.