Flight Manual for Gas Balloons of Type NL-STU
Issue 2.0
May 02, 2016
Page 5-1
Chapter 5 – Size and weights
5.1 Introduction
This section describes the size and lifting capacity of the certified balloon envelopes and their
classification in various sport categories.
5.2 Sizes
In accordance with the regulations of the FAI, free balloons are divided into different classes
and sub-classes, depending on their type and volume.
The following sizes of gas balloon are listed in FAI class AA:
Balloon volume
Class
250 m³ or less
AA-1
250 m³ to 400 m³
AA-2
400 m³ to 600 m³
AA-3
600 m³ to 900 m³
AA-4
900 m³ to 1200 m³
AA-5
1200 m³ to 1600 m³
AA-6
1600 m³ to 2200 m³
AA-7
The permissible volume tolerance is +5%, i.e. a balloon with a volume of 630 m³ can still be
flown as class AA-3. The sizes are based on balloons filled with coal gas. To determine the
class of a balloon filled with hydrogen, the volume must be multiplied by a factor of 1.63. For
balloons filled with helium, the factor is 1.509.